(BQ) Part 2 book “Lippincott’s illustrated review of neuroscience” has contents: Hearing and balance, brainstem systems and review, the thalamus, the cerebral cortex, the visual system, the basal ganglia, the integration of motor control, the integration of motor control,… and other contents.
Hearing and Balance 11 I OVERVIEW Both hearing and balance are sensations carried by special somatic afferent fibers that form the vestibulocochlear nerve (cranial nerve [CN] VIII) The sensory organs and the peripheral ganglia associated with CN VIII are located in the petrous part of the temporal bone in the base of the skull (Figure 11.1) The labyrinth is specialized to translate motion of the head into information about balance, and the afferents from the labyrinth that carry balance information are bundled together as the vestibular division The afferents from the cochlea, which carry sound information, are bundled together as the cochlear division Both divisions come together as the vestibulocochlear nerve, which travels from the receptor organs in the temporal bone through the auditory canal into the cranial cavity through the internal auditory meatus Afferents then enter the brainstem at the pontomedullary junction (Figure 11.2) Hearing and balance are two very different types of senses Both the cochlear (hearing) and vestibular (balance) divisions of CN VIII receive stimuli from specialized end organs that contain mechanoreceptors called Cochlea Semicircular canals Anterior Lateral Posterior Petrous part of temporal bone Internal acoustic meatus Vestibule Figure 11.1 Position of the inner ear in the temporal bone of the skull 199 Krebs_Chap11.indd 199 5/9/2011 7:10:10 PM 200 11 Hearing and Balance “hair cells” because of their appearance Although similar in appearance, hair cells respond to different stimuli They respond to sound in the cochlear division, and position and head movement in relation to gravity in the vestibular division II HEARING Vestibulocochlear nerve (CN VIII) Pontomedullary junction For hearing, sound waves are interpreted in terms of their pitch, loudness, and their location of origin The human ear has the remarkable capability to distinguish a large range of sounds that can be either very close together in pitch (maybe just a quarter note apart) or far apart in pitch (ranging from the low rumblings of a pipe organ to the highest notes of a piccolo flute) Hearing is an integral component of communication The sounds of speech are perceived and then relayed to higher centers where they are reassembled to make sense as words and phrases Figure 11.2 The vestibulocochlear nerve at the pontomedullary junction of the brainstem CN = cranial nerve A Structures involved in hearing The structures involved in hearing are specialized to bundle, amplify, and fine-tune the sounds that surround us so that we can make sense of them The outer ear is shaped to collect sound waves and focus them onto the tympanic membrane, which separates the outer ear from the middle ear The middle ear is an air-filled space, which contains three small bones that amplify the sound energy from the tympanic membrane to the fluid-filled inner ear The inner ear contains the cochlea, which contains the sensory organ of hearing, the organ of Corti Outer ear: The outer ear is the visible part of the ear on the side of the head It is composed of the auricle and the external auditory meatus, or outer ear canal These structures gather sound energy and focus this energy on the tympanic membrane, also referred to as the eardrum, at the medial end of the outer ear canal (Figure 11.3) Interestingly, the external ear also reflects sound, causing it to reach the tympanic membrane in a time-delayed manner This plays a role in sound localization, as is discussed below The external auditory meatus also plays a role in how sound waves are transmitted to the middle ear Sound pressure at frequencies around kHz (the frequency to which the human ear is most sensitive) is boosted in the external auditory meatus through passive resonance effects (echo) Middle ear: The middle ear is located between the tympanic membrane and the inner ear It is an air-filled chamber that contains three small bones, or ossicles, that transfer the sound energy from the tympanic membrane to the inner ear The middle ear is continuous with the nasopharynx through the pharyngotympanic (Eustachian) tube (see Figure 11.3) This connection is important to ensure that air pressure in the middle ear corresponds to the air pressure around us The pharyngotympanic tube opens to let air into the middle ear and equilibrate the pressure (for example, during a plane landing when the ears “pop”) Krebs_Chap11.indd 200 5/9/2011 7:10:11 PM II Hearing 201 Outer ear Middle ear Inner ear Semicircular canals Cochlea Incus Malleus Cochlear nerve Concha Auricle Tympanic membrane (eardrum) Stapes footplate covering oval window External auditory meatus Stapes Tympanic Round cavity window Pharyngotympanic (Eustachian) tube Figure 11.3 Overview of structures of the outer, middle, and inner ear a Bones in the middle ear: The ossicles in the middle ear are the malleus, the incus, and the stapes The malleus is directly attached to the tympanic membrane The malleus articulates with the incus, which is connected to the stapes The stapes is connected to the oval window of the inner ear (see Figure 11.3) The function of these articulating ossicles is to boost the sound energy from the tympanic membrane into the inner ear This boost is necessary so that the sound waves traveling through the air can be transferred efficiently to the fluid-filled space of the inner ear Without a boost, the sound energy would be lost through reflection once the sound waves hit fluid The boost is achieved through the lever action of the ossicles as well as through compression of sound waves from the large-diameter tympanic membrane to the small-diameter oval window b Muscles in the middle ear: The middle ear also contains two muscles: the tensor tympani, which attaches to the malleus and is innervated by CN V, and the stapedius muscle, which attaches to the stapes and is innervated by CN VII Contraction of the stapedius muscle can reduce the transmission of vibration into the inner ear, especially for low-frequency sounds, possibly to selectively filter out low-frequency background noises These two muscles also dampen movements of the ossicles in response to loud sounds, which serves as a protective mechanism for the auditory nerve Inner ear: The inner ear contains the cochlea, the sensory organ that mediates the transformation of the pressure waves of sound into the electrical energy of a nerve impulse (Figure 11.4) a Cochlea: The cochlea sits in the petrous portion of the temporal bone, with its base facing medially and posteriorly It is Krebs_Chap11.indd 201 5/9/2011 7:10:11 PM 202 11 Hearing and Balance COCHLEA CROSS SECTION Vestibular nerve Auditory nerve Scala vestibuli Scala media = cochlear duct Tectorial membrane Oval window Spiral ganglion Round window Scala tympani Cochlea Inner hair cells Basilar membrane Outer hair cells COCHLEA UNCOILED Incus Oval window Scala vestibuli Scala media = cochlear duct Helicotrema Stapes Round window Scala tympani Endolymph Perilymph Figure 11.4 Structures of the inner ear: the cochlea a bony tube that coils through two and three-quarter turns in the shape of a snail’s shell (cochlea is Latin for “snail”), from a relatively broad base to a narrow apex b Three chambers: A membranous tube or membranous labyrinth, also called the cochlear duct, is suspended within the bony labyrinth Viewed in cross section, the bony labyrinth and cochlear duct together form three chambers (or scalae) along most of their length (see Figure 11.4) The cochlear duct, anchored to the bony labyrinth, has a triangular shape in cross section It forms the middle chamber, or scala media (cochlear duct) The chamber above the cochlear duct is the scala vestibuli and is continuous with the vestibule (see below) The chamber below the cochlear duct is called the scala tympani because it ends at the round window or secondary tympanic membrane Both the bony labyrinth and the membranous labyrinth are filled with fluid The fluid in the bony labyrinth (scalae vestibuli and tympani) is called perilymph, which is similar in composition to cerebrospinal fluid (and also to extracellular fluid) Perilymph is low in K+ and high in Krebs_Chap11.indd 202 5/9/2011 7:10:13 PM II Hearing 203 Na+ The cochlear duct (or scala media) is filled with endolymph, which is similar in composition to intracellular fluid, and is high in K+ and low in Na+ Endolymph is produced by the stria vascularis, a layer of cells on the lateral surface of the scala media (Figure 11.5) The high concentration of K+ in the endolymph plays a critical role in signal transduction, as discussed below The scalae tympani and vestibuli are joined at the apex of the cochlea by a small opening called the helicotrema (see Figure 11.4), where perilymph can pass from one chamber to the other The scala media is separated from the scala vestibuli Scala vestibuli is a perilymph-filled space continuous with scala tympani at the apex of the vestibule Scala media (cochlear duct) is an endolymph-filled tube, continuous with membranous labyrinth Spiral ganglion contains cell bodies of cochlear afferents Scala tympani perilymph-filled space, continuous with scala vestibuli CN VIII—cochlear division gives afferents from the inner hair cells and efferents to the outer hair cells Reissner membrane separates the scala media from the scala vestibuli Stria vascularis produces the K+-rich endolymph Tectorial membrane is where the stereocilia of the outer hair cells are embedded CN VIII—cochlear division gives afferents from the inner hair cells and efferents to the outer hair cells Outer hair cells amplify and fine-tune the sound information Inner hair cells transmit sound information to cochlear nerve fibers Basilar membrane is displaced in a frequencydependent manner by sound waves Figure 11.5 Histology of the cochlea CN = cranial nerve Krebs_Chap11.indd 203 5/9/2011 7:10:15 PM 204 11 Hearing and Balance Sound energy is amplified through the articulation of the ossicles in the middle ear Incus Malleus Stapes transmits the sound energy to the oval window, into the fluid-filled scala vestibuli Oval Stapes window The tympanic membrane deflects Tympanic membrane “ear drum” Cochlear nerve Spiral ganglion Scala vestibuli Scala media contains organ of Corti External auditory meatus Middle Ear air-filled Pharyngotympanic tube Sound waves travel through the external auditory meatus to the tympanic membrane Round window The round window bulges out as the sound wave travels through the scala tympani Scala tympani The sound wave causes frequency-specific displacement of the basilar membrane, which causes activation of the hair cells in the organ of Corti Figure 11.6 Sound transduction in the ear by the Reissner (or vestibular) membrane and from the scala tympani by the flexible basilar membrane Sound energy is transmitted onto the oval window, which displaces the fluid in the scala vestibuli Vibrations are then transmitted along the cochlea to the end, where it joins the scala tympani and ultimately causes the round window at the end of the scala tympani to bulge The sound energy or vibrations also cause the basilar membrane, which separates the scala tympani from the scala media, to vibrate (Figure 11.6) Scala vestibuli Tectorial membrane Supporting cell Inner hair cell Outer hair cells Basilar membrane Spiral ganglion Scala tympani Figure 11.7 Organ of Corti Krebs_Chap11.indd 204 Scala media (cochlear duct) filled with endolymph c Organ of Corti: The auditory sensory organ, or the organ of Corti, is located within the scala media and sits on the flexible basilar membrane One row of inner hair cells and three rows of outer hair cells, along with supporting cells, comprise the organ of Corti The hair cells are the signal-transducing cells Their name comes from the hair-like microvilli, known as stereocilia, that are arranged symmetrically and in graded height (with the tallest toward one side of the hair cell) in a V shape on the apex of the cells The tectorial membrane, a gelatinous extracellular structure, extends over the hair cells Both the inner and the outer hair cells are anchored to the basilar membrane Importantly, the outer hair cells are also directly embedded in or coupled to the tectorial membrane via their stereocilia The inner hair cells not have direct contact with the tectorial membrane but respond to fluid movement in the scala media (Figure 11.7) 5/9/2011 7:10:19 PM II Hearing Frequency (Hz) = number of repeats of the wave within a set interval Amplitude (dB) = height of the sound wave The spiral ganglion, which contains the nerve cell bodies of the primary auditory afferents, sits within the turns of the cochlea, close to the organ of Corti (see Figure 11.5) Peripheral processes travel to the scala media where they receive input from the receptor cells 205 B Physiology of sound perception in the inner ear Sound is a pressure wave that travels through the air It is then amplified in the outer and middle ear before it reaches the fluid-filled inner ear, where the sensory organ of Corti sits The organ of Corti transduces this pressure to a neuronal signal Sound waves have different shapes and sizes The amplitude of a sound wave determines its loudness and is measured in decibels (dB) The frequency of a sound wave determines the pitch and is measured in Hertz (Hz) (Figure 11.8) The human ear can hear frequencies between 20 and 20,000 Hz The lowest note on a large pipe organ is at 20 Hz, and the highest note on a piano is at 4,200 Hz (Figure 11.9) The human voice ranges between 300 and 3,000 Hz Basilar membrane: When a sound wave reaches the inner ear, it sets off a wave in the basilar membrane at the same frequency as the sound This wave propagates from the base to the apex until it reaches a point of maximal displacement of the basilar membrane This point is reached because of the geometry and flexibility of the basilar membrane The base of the basilar membrane is narrow and stiff and is where the propagation of each sound wave begins High-frequency sounds produce their maximal displacement at the base The apex of the basilar membrane, on the other hand, is wider and more flexible and is where low-frequency sounds are perceived (Figure 11.10) These mechanical properties result in the tonotopy of the inner ear, with distinct locations interpreting discrete frequencies Tonotopy is then carried forward throughout the auditory pathway Figure 11.8 The physics of frequency and amplitude Lowest note on large pipe organ: 20 Hz Most of the sounds we hear are a combination of different frequencies As the sound waves travel into our inner ear, they are broken up into their component parts Each component will individually reach its point of maximal displacement on the basilar membrane Inner and outer hair cells: Basilar membrane vibrations create a shearing force against the stationary tectorial membrane, causing the stereocilia of the outer hair cells to be displaced in that plane (Figure 11.11) The inner hair cells are not in direct contact with the tectorial membrane and are activated through fluid movement in the scala media Stereocilia are arranged symmetrically by height Displacement toward the tallest stereocilium causes depolarization of the cell, whereas displacement toward the shortest stereocilium causes hyperpolarization of the cell (Figure 11.12) Depolarization of the cell occurs when cation channels open at the apex of the stereocilia Stereocilia are connected to each other via tip links that transmit force to an elastic gating spring, which, in turn, opens the cation channel (see Figure 11.12) These cation channels are examples of mechanotransduction channels, which have the advantage of conferring immediate effects In fact, hair cells can respond to a stimulus within 50 μs Such a rapid response Krebs_Chap11.indd 205 Human voice: 300–3000 Hz Highest note on a piano: 4200 Hz Figure 11.9 Examples of different frequencies 5/9/2011 7:10:21 PM 206 11 Hearing and Balance Basilar membrane Stapes The basal end of the basilar membrane is narrow and stiff It is “tuned” for high frequencies Cochlear base Scala vestibuli The apical end of the basilar membrane is wide and flexible It is “tuned” for low frequencies “Uncoiled” cochlea Helicotrema Helicotrema 10,000 Hz 4000 Hz Stapes on oval window Round window Traveling wave A specific frequency reaches its point of maximal displacement at a specific point along the basilar membrane Scala tympani Basilar membrane (in scala media) Cochlear apex 200 Hz Different frequencies reach their point of maximal displacement along the basilar membrane Figure 11.10 Basilar membrane tuning A would not be possible with a slow chemical signal transduction process Another advantage of mechanotransduction channels is that they not require receptor potentials, thereby increasing the sensitivity of the response (see Chapter 1, “Introduction to the Nervous System and Basic Neurophysiology”) The sensitivity of the ion channel opening is remarkable: even small vibrations of 0.3 nm (the size of an atom) will cause channel opening Resting position Tectorial membrane Inner hair cell B Outer hair cells Basilar membrane Sound-induced vibration Shear force Upward phase Shear force Downward phase Figure 11.11 Because the stereocilia are bathed in the K+-rich endolymph of the scala media, the opening of the cation channels will cause a rapid influx of K+ to the cell (the driving force for K+ uptake is about 150 mV) The hair cells then depolarize, which causes Ca2+ channels at the base of the cells to open Calcium influx causes neurotransmitter-filled vesicles to fuse with the basal membrane and release the neurotransmitter glutamate into the synaptic cleft The afferent cochlear neurons are stimulated and transmit this signal to the central nervous system (CNS) The inner hair cells are responsible for hearing About 90% of cochlear nerve fibers come from the inner hair cells The outer hair cells amplify the signals that are then processed by the inner hair cells Frequency selectivity: The frequency selectivity, or tuning, of the basilar membrane is due to and limited by its mechanical properties The sound wave traveling along the basilar membrane and its associated point of maximal displacement cannot be as selective in frequency tuning as our hearing is, which suggests The organ of Corti during displacement by sound waves Krebs_Chap11.indd 206 5/9/2011 7:10:23 PM II Hearing 207 A Hyperpolarization B Depolarization Hyperpolarization Depolarization Tip links Movement away from the kinocilium, or toward the shortest steriocilium, prevents opening of the mechanicallygated K+ channels Tip links K+ K+ K+ Kinocilium Movement toward the kinocilium, or toward the longest stereocilium, causes the opening of the mechanically gated K+ channels K+ from the K+-rich endolymph enters the cell K+ Kinocilium The increase in K+ leads to depolarization of the cell Depolarization Ca2+ Ca2+ channel Vesicles Ca2+ Transmitter Afferent nerve To brain Vesicles Transmitter Afferent nerve The depolarization of the cell leads to opening of voltage-gated Ca2+ channels To brain The increase in intracellular Ca2+ causes neurotransmitter-filled vesicles to fuse with the membrane in the synaptic cleft, leading to excitation of the afferents to the CNS Figure 11.12 Hyperpolarization and depolarization of hair cells in the inner ear CNS = central nervous system involvement of an additional mechanism of sound amplification and tuning This additional mechanism is from movement of the outer hair cells in response to specific frequencies When the outer hair cells are depolarized, their cell bodies actively contract When they are hyperpolarized, their cell bodies actively lengthen High frequencies cause contraction of the outer hair cells at the base, and low frequencies cause contraction at the apex This mechanism influences the movement of the basilar membrane in that particular segment, increasing the fluid displacement around the inner hair cells This amplifies the magnitude of the K+ influx into the inner hair cells, increasing the signal to the cochlear nerve Because of this fine-tuning and amplification of the sound wave through the outer hair cells, we can both discriminate tones of neighboring frequencies with astounding accuracy and detect low-level sounds In addition, the outer hair cells are innervated by efferents originating from the auditory pathway (Figure 11.13) These inputs hyperpolarize, or inhibit, the outer hair cells, reducing their response to displacement of the basilar membrane through sound and allowing the central auditory pathway to influence sound amplification in the inner ear A possible function of this mechanism is to help focus the inner ear on relevant sounds while filtering out background noises Otoacoustic emissions: Because the motility of the outer hair cells can cause the basilar membrane to move, it is conceivable Krebs_Chap11.indd 207 5/9/2011 7:10:26 PM 208 11 Hearing and Balance that this movement could be retrograde, or backward, toward the oval window and through the middle ear via the ossicles to cause displacement of the tympanic membrane This process would result in the ear itself producing a sound and is, indeed, what actually happens These sounds can be measured in the external auditory meatus as otoacoustic emissions Such measurements are routinely done in infants to assess the function of the inner and middle ears CLINICAL APPLICATION 11.1 Cochlear Implants Hearing loss can have several underlying causes and is divided into two main categories: conductive hearing loss and sensorineural hearing loss Conductive hearing loss is from obstruction in the conduction of sound energy from the outer ear to the inner ear The causes can be either in the outer ear (such as earwax or rupture of the tympanic membrane) or in the middle ear (for example, fluid or arthritis of the ossicles) A hearing aid, which amplifies sound energy, can significantly ameliorate conductive hearing loss Sensorineural hearing loss is from a problem in the inner ear, either with hair cells or with the cochlear nerve itself Hair cells are very susceptible to damage and not regenerate in humans Common causes for Receiver under the skin receives signal and transmits it to the electrode array in the cochlea Microphone and speech processor convert sounds into a digital signal Electrode array in the cochlea stimulates the cochlear nerve tonotopically along the basilar membrane Sound information is relayed via the cochlear nerve to the brainstem The cochlear implant Krebs_Chap11.indd 208 5/9/2011 7:10:28 PM VII Chronic Pain 421 Musculoskeletal system: Pain often results in, or is caused by, changes in the function of the musculoskeletal system Pain will lead to postural changes and underuse of muscles This can lead to muscle pain, spasms, and a shortening of muscles • Botulinum toxin (BoTox) blocks the release of acetylcholine at the neuromuscular junction, which blocks neuromuscular transmission It has been shown to be effective in decreasing muscle tone, thereby decreasing pain and muscle spasms • Therapeutic exercise is an important part of pain therapy Exercise will help to return muscles to their normal length and correct postural changes that can lead to secondary problems Exercise also causes the release of endorphins, which can act to relieve pain as well Descending Pain Modulation Ascending Pain Modulation Projections from cortex and limbic system Cortex Antidepressants Cognitive-behavioral therapy Mind-body therapy Relaxation and coping strategies Psychological processing of pain Projections from hypothalamus Periaqueductal gray Locus coeruleus (noradrenergic) Raphe nuclei (serotinergic) Brainstem Spinomesencephalic tract Antidepressants: increase of serotonin and norepinephrine at the synapse, increasing descending pain inhibition Opioids: block the facilitation of pain transmission Spinoreticular tract Various reticular formation nuclei Peripheral nociceptors NSAIDs: reduce inflammation Lidocain: blocks Na+ channels Capsaicin: depletes substance P Musculoskeletal system BoTox: decreases muscle tone and muscle spasms Therapeutic exercise: returns muscles to normal length and corrects postural changes Posterior horn of spinal cord Spinal ganglion Pain and temperature Convergence of pain afferents and descending modulation in the posterior horn Opioids: block presynaptic Ca2+ channels and open postsynaptic K+ channels Gabapentin: blocks presynaptic Ca2+ channels Methadone: blocks NMDA receptors Ketamine: blocks NMDA receptors Anterolateral system NSAIDs = nonsteroidal anti-inflammatory drugs; NMDA = N-methyl-D-aspartic acid Krebs_Chap22.indd 421 5/9/2011 7:52:22 PM 422 22 Pain Chapter Summary • Pain is detected by the free nerve endings of myelinated Aδ and unmyelinated C fibers These fibers respond to noxious thermal, mechanical, and chemical stimuli Aδ fibers mediate the “first pain,” a sharp, well-localized pain C fibers mediate the “second pain,” a dull, poorly localized throbbing sensation Both Aδ and C fibers project to the posterior horn of the spinal cord, cross the midline, and ascend in the anterolateral system • The ascending nociceptive pathways can be divided into two components The lateral sensory-discriminative component comprises the neospinothalamic tract, which projects to the ventral posterolateral nucleus and ventral posteromedial nucleus of the thalamus and, from there, to the primary and secondary somatosensory cortices It allows for the localization of pain The medial affective motivational component comprises all other tracts of the anterolateral system It projects to brainstem structures, where it influences the descending modulation of pain, and to the limbic system, hypothalamus, and association areas of cortex, where it mediates the affective-motivational and emotional response to pain • A pain matrix, which includes the lateral somatosensory cortices and medial limbic structures, is activated in response to the perception of pain • Sensitization of pain occurs both peripherally and centrally Peripheral sensitization is due to neurotransmitters released by stimulated nociceptors and to substances released during tissue injury and inflammation These substances exacerbate the stimulation of nociceptors and can recruit so-called “silent nociceptors,” which expand the receptive field Central sensitization occurs in the spinal cord due to the continued activation of the posterior horn neurons One of the main components of this process, called “wind-up,” is the activation of N-methyl-D-aspartic acid receptors This has a number of downstream effects that lower the activation threshold of the postsynaptic neuron • Modulation of pain occurs both at the level of the spinal cord and through descending fibers from the brainstem reticular formation and the periaqueductal gray • The modulation can be explained through the gate control theory, which describes a shift in the balance of input through nociceptive fibers and touch fibers resulting in either more or less pain transmission The descending fibers from the brainstem can either inhibit the nociceptive signal or facilitate the signaling to the cortex, depending on the behavioral needs of the situation Another pain modulating system is the endogenous opioid system • The nociceptive system can be amplified through peripheral and central sensitization, which increases the salience of the signal and gives it priority for a behavioral response When sensitization is maladaptive, either centrally or peripherally, neuropathic pain (continued pain after nerve injury) can result Sprouting of Aβ fibers onto nociceptive-specific neurons in the posterior horn results in innocuous stimuli being interpreted as painful Many of these changes can result in permanent rewiring of the nociceptive pathways Study Questions Choose the ONE best answer 22.1 A patient was admitted to the emergency room with severe burns to his hand The pathway by which the nociceptive stimulus reached a level of awareness in his cortex is through the: A B C D E Spinohypothalamic pathway Spinomesencephalic tract Spinoreticular tract Spinothalamic tract Spinocerebellar tract Krebs_Chap22.indd 422 The correct answer is D The spinothalamic tract is part of the anterolateral system and is responsible for sensory discrimination and affective appreciation of pain It reaches consciousness through the thalamus to the cortex The spinohypothalamic pathway is a projection to the hypothalamus and can be involved in the neuroendocrine–visceral response to pain The spinomesencephalic tract projects to the PAG and the superior colliculus The spinoreticular tract is a projection to the reticular formation and mediates activation of the reticular formation The spinocerebellar tract is a tract carrying nonconscious proprioception to the cerebellum 5/9/2011 7:52:23 PM Study Questions 423 The next three questions are based on this scenario: An elderly lady noticed that the right side of her face had become extremely painful with a burning sensation like a bad sunburn The hypersensitive area then developed a rash with blister-like nodules Her doctor told her that she had developed herpes zoster, more commonly known as shingles, which is caused by the same virus that causes chickenpox Unfortunately, after treatment for the disease and the disappearance of the rash, her painful burning sensation continued When pain persists after the shingles outbreak has disappeared, it is called postherpetic pain for which there is no known cure The herpes virus attacks the nerve cell bodies in the ganglia of sensory neurons and is carried to the areas of skin supplied by the peripheral processes of those neurons 22.2 The nerve cell bodies of which ganglion are involved in this patient’s case? A B C D E Spinal ganglion T12 Glossopharyngeal Inferior vagal Geniculate Trigeminal 22.3 After treatment for the disease and the disappearance of the rash, her painful burning sensation continued This phenomenon is referred to as: A B C D E Hyperalgesia Allodynia Paresthesia Dysesthesia Summation 22.4 A likely mechanism underlying the persistence of pain in this patient is A A downregulation of peripheral N-methyl-D-aspartic acid receptors B A loss of Na+ channels in the postsynaptic membrane of the second-order neuron C Altered synaptic circuitry in the posterior horn of the spinal cord resulting in central sensitization D An upregulation of opioid receptors on peripheral nerves in the face E A change in the balance of inputs to the face favoring Aβ fibers over Aδ and C fibers Krebs_Chap22.indd 423 The correct answer is E The trigeminal ganglion contains the nerve cell bodies of the sensory nerves of the face The spinal ganglion is associated with spinal nerves The glossopharyngeal ganglion is the sensory ganglion of cranial nerve (CN) IX that is sensory to the pharynx The inferior vagal ganglion is concerned with sensory input from the pharynx and larynx The geniculate ganglion is the sensory ganglion of CN VII associated with taste from the anterior two thirds of the tongue The correct answer is D Dysesthesia is burning, electrical sensations, or shooting pain in the absence of an external stimulus Hyperalgesia is heightened reaction to low-intensity noxious stimuli Allodynia is painful reaction to nonnoxious stimuli Paresthesia is spontaneous tingling sensations Summation is when repeated application of a low-intensity noxious stimulus leads to a worsening pain experience The correct answer is C Postherpetic pain is an example of chronic neuropathic pain It is most likely due to central sensitization or wind-up, which includes a lowered pain threshold, disinhibition, and spontaneous activity of nociceptive neurons N-methyl-D-aspartic acid (NMDA) receptor activation plays a role in wind-up and a downregulation of NMDA receptors would result in less excitability During sensitization, more Na+ channels are inserted into the membrane of the postsynaptic neuron, which leads to heightened excitability Downregulation rather than upregulation of opioid receptors could play a role in increasing pain However, the pain being experienced by this patient is likely due to changes in central mechanisms Increased pain is likely to involve a shift in the balance of inputs favoring Aδ and C fibers 5/9/2011 7:52:23 PM 424 22 Pain 22.5 In the processing of pain, which statement is true? A Synaptic targets of Aδ and C fibers include both nociceptive-specific and wide dynamic range neurons B Descending inputs to posterior horn cells from brainstem areas are exclusively inhibitory C Afferent nociceptive fibers release primarily norepinephrine D Hot thermal stimulation activates primarily TRPM8 receptors E The lateral sensory-discriminative pathway mediates the emotional response to pain Krebs_Chap22.indd 424 The correct answer is A Aδ and C fibers target both nociceptive-specific and wide dynamic range neurons Descending input to the posterior horn cells can be either inhibitory or facilitatory Afferent nociceptive fibers release glutamate, calcitonin gene–related peptide, and substance P but not norepinephrine Cold sensitivity is mediated through TRPM8 receptors, whereas hot thermal stimulation activates TRPV1 receptors The medial affective-motivational pathway mediates the emotional response to pain The lateral pathway is important in perception and localization of pain 5/9/2011 7:52:23 PM Index Note: Page numbers in italics denote figures; those followed by a t denote tables A Abdominal viscera, 59, 63 Abducens (CN VI) nerve, 98, 106, 108 eye movements control, 152, 153, 156 Abducens nucleus, 158, 163 Abduction, 151, 166, 169 ACA (see Anterior cerebral artery (ACA) ) Accessory cuneate nucleus, 130 Accessory (CN XI) nerve, 96, 111, 195t overview of, 194 somatic motor (GSE) nerve, 194 Accommodation cornea, 290 disconjugate gaze, 167, 167–168 optic reflexes, 306, 307–308 Acetylcholine (ACh), 19, 55 Acetylcholinesterase, 19 Acoustic verbal agnosia, 252 Action potential (AP), 2, 5, 57 generation of, 10–11, 11 Na+ (sodium) channels, 21 propagation of continuous conduction, 11, 12 Ohm law, 11, 11 passive current and active current, 11, 11 saltatory conduction, 11, 12 velocity of active current, 13 capacitance, 12 passive current, 13 resistance, 12 visual pathway, 296 Active current, 11, 11 Aδ fibers, 407 Aδ mechanosensitive fibers and receptors, 123–124 Aδthermoreceptors, 124 Addiction dopamine and saliency, 390–391, 391, 394 dopamine and stress, 391 reward circuitry, 390Adenohypophysis, 364 ADH (see Antidiuretic hormone (ADH) ) ADHD (see Attention deficit hyperactivity disorder (ADHD) ) Ageusia, 395 Agnosia, 257 Agranular cortex, 242 Akinesia, 320b, 328 Alar plate, 101, 102, 103 Allodynia, 410, 418, 419 α motor neurons, 88, 351 Alveus, 378 Alzheimer disease, 230, 386b, 394 Amacrine cells, retinal layers, 291, 292 Aminergic systems neurotransmitter systems, 225–227, 226–227 noradrenergic neurons, 227–230, 228 serotonergic neurons, 230–231, 230–231 Ammon horn, 377 Amygdala, 32, 60, 282 anatomy, 379–381, 380, 381 clinical damage, 392 functions, 387 emotional learning and memory, 386–387 fear and fear conditioning, 387–388 reward, 388–389 β Amyloid, 386b Amyotrophic lateral sclerosis, 146 Anastomosis, 263, 263 Anhidrosis, 235b Anosmia, 395, 399b Anterior cerebral artery (ACA) basal ganglia, blood supply, 325, 326, 326t blood supply, cerebral cortex, 263, 263, 264t Anterior horn, 36, 82, 140 spinocerebellar tract, 130 Anterior inferior cerebellar arteries (AICAs), 114 blood supply, cerebellum, 343, 344, 344t Anterior lobe syndrome, 339b Anterior spinal artery, 148 Anterior white commissure, 75, 125 Anterograde transport, Anterolateral system, 413 visceral afferents, 59 Antidiuretic hormone (ADH), 364 Antisaccade, 161, 161 AP (see Action potential (AP) ) Aphasia, 258 Apraxia, 249 Arachnoid granulations, 39 Arachnoid mater, 39, 40, 77, 78 Archicerebellum, 336 Archicortex, 241 Arcuate fasciculus, 243, 244 classical concepts, language processing, 258 modern concepts, language processing, 261 Area postrema, 233, 233 Arterial aneurysm, 41 Artery of Adamkiewicz, 88 Ascending sensory tracts anterolateral system anatomy, 124–125, 126 lesions, 125, 127 pain and temperature sensations, loss of, 135 posterior column–medial lemniscus pathway anatomy, 120–122, 121, 122 lesions, 122–123, 123 spinocerebellar tracts, 127–133 lesions of, 133 Association areas, cerebral cortex frontal lobes, 253–255, 254–255 parietal lobe, 255–256, 255–256 temporal lobe, 257, 257 Association fibers, 33 cerebral cortex, 243–244, 244 Association nuclei, thalamus dorsomedial nucleus, 282, 282 pulvinar, 281–282, 282 Associative circuit, basal ganglia, 324, 324 Astereognosis, 251 Astrocytes, 6, 22, 419 Ataxias, 133, 236b, 283b Attention deficit hyperactivity disorder (ADHD), 229 Auditory area, cerebral cortex, 252 Auditory association cortex, 282, 282 Axon, Axonal diameter, 48 B Babinski sign, 350b Balance central vestibular pathways cortical projections, 220 vestibulocervical reflex, 220, 221 vestibulospinal reflex, 220, 221 physiology of linear acceleration, 218, 218, 220 rotational acceleration, 216–218, 217, 218 structures involved in membranous labyrinth and hair cells location, in inner ear, 215 semicircular canals, 215–216, 216 vestibule, 216, 216 vestibular for, 108 Ballism, 321b Baroreceptors, 59, 65, 188 reflex, 65 Basal ganglia, 31–32, 277–278 anatomy, 312–315, 312–315 blood supply, 325, 325–326, 326t, 328 functional relationships, 323 associative circuit, 324, 324 limbic circuit, 324, 325 motor circuit, 323–324, 323–324 tracts direct pathway, 317, 317–318, 318 indirect pathway, 317, 318–319, 319 internal circuits, 316, 316–318 Basal plate, 101, 102, 103 Basal pons, 34, 140 Basilar artery, 41, 114 Basilar membrane, 204, 205, 206 Basis pedunculi (crus cerebri), 99 Basket cells, cerebellar cortex, 342, 342 Basolateral amygdala (BLA), 379–380, 381 Bell palsy, 184–185b Benedikt syndrome, 236b–237b Benign paroxysmal position vertigo (BPPV), 219b Biogenic amines, 19–20 Bipolar cells retinal layers, 291, 292 visual pathway, 296–298, 297 Bistratified ganglion cells, 299, 299 Bitter taste, 402, 406 Bladder, 59 control after spinal cord injury, 69 function, control of, 65–69, 66, 68, 72 Blind spot, 291 Blink reflex, 184 Blood pressure control, 65, 65 Blood supply, 41–42 to brain, 41 to brainstem, 111–112, 112, 113, 114 vertebral–basilar system, 112, 113, 114 to dura mater, 40 to spinal cord, 87 anterior spinal artery, 88 artery of Adamkiewicz, 88 posterior spinal arteries, 88 to thalamus, 284, 285 Blood–brain barrier, 6, 7, 8, 22 Blue-yellow cells, 305 Body movement, 142 orientation of, 144 Bony labyrinth, 215 Botulinum toxin, 421 Bowman glands, 396 Bradykinin, 409 Brain brainstem, 33–34, 34 cerebellum, 35, 35 development, 26 cerebral hemispheres, 25 flexures in, 25 primary and secondary vesicles, 25 forebrain cerebral hemispheres, 27–31, 31 components of, 30 deep structures, 31–33, 32, 33 diencephalon, 33, 33 425 Krebs_Index.indd 425 5/9/2011 9:23:09 PM 426 Brain (Continued ) orientation in anterior and posterior surface of, 27 caudal, 27 gray matter and white matter, 27, 29 inferior and dorsal surface of, 27 planes of, 27, 28 rostral, 27 ventral surface of, 26 Brainstem, 33–34, 34, 138 ascending and descending pathways, 93 blood supply to arterial systems, 112, 112 vertebral–basilar system, 112, 113, 114 breathing center central pattern generator, 232–233, 233 nonrespiratory functions, 233–234, 234 clinically oriented review central midbrain syndrome, 236b–237b lateral medullary syndrome, 235b medial pontine syndrome, 236b corticospinal fibers, 238 cranial nerves (see Cranial nerves) drug-seeking behavior, 238 intrinsic systems, 223–224 medulla oblongata, 94, 95–97, 96–97 midbrain, 99, 99–100 motor nuclei, 142 motor program, 224 pons, 98, 98–99 posterior cranial fossa, 93 reticular formation, 59, 223 cholinergic neurons, 231, 231–232 histaminergic neurons, 232 interneurons, 224 lateral zone, 225, 225 locus coeruleus, 238 medial zone, 225, 225 neurotransmitter systems, 225–227, 226–227 noradrenergic systems, 227–230, 228 serotonergic systems, 230–231, 230–231 surface anatomy and relationship to components of, 94 vertebral artery, 239 Branchial efferent (BE), 101, 108 (see also Special visceral efferent (SVE) ) Breathing control, 144 Bridging veins, 40 Broca aphasia, 258, 259 Broca area, 258 Brown-Séquard syndrome, 80b, 127, 127b Bruch membrane, 291–292 Burst firing, thalamic neurons, 273, 275 C C fibers, 407 anterolateral system, 124, 125 Calcarine cortex, 289 Calcarine fissure, 30 Calcarine sulcus, 251, 251, 303 Caloric testing nystagmus cold water, 165, 165–166, 165t warm water, 166 vestibular function, 171 Capacitance, 12 Capsaicin, 320b, 408–409 Capsule, cerebral cortex, 246, 246, 247t Carotid arteries, internal, 41 Carotid body, 187 and sinus, 190 Catecholamines, 19, 228 Cauda equina, 35, 75 Caudal midbrain, inferior colliculus, 117 Caudate nucleus, 312, 312 Cell membrane, as capacitor, 22 Central auditory pathways convergence of, 213–214, 214 pitch and volume, 209–210, 210 Krebs_Index.indd 426 Index sound localization horizontal spatial mapping, 210 intensity difference detection, at high frequencies, 211, 213 time difference detection, at low frequencies, 211, 212 vertical and horizontal plane, 210 vertical sound mapping, 210, 222 Central canal, of spinal cord, 37 Central midbrain syndrome, 236b–237b Central nervous system (CNS) arterial systems, 112, 112 blood supply, 41, 41–42 brain brainstem, 33–34, 34 cerebellum, 35, 35 forebrain, 27–33, 30–33 orientation in, 26–27, 27–29 meningeal coverings arachnoid mater, 40 dura mater, 39–40, 40 pia mater, 40 neurotransmitters in, 18t spinal cord gray and white matter, 36 length, 35 organization, 35, 36 ventricular system, 37 CSF, 35–39, 38, 38t Central pattern generators (CPGs), 232, 232–233 Central sulcus, 28 Central tegmental tract, 189 Centromedian (CM) nuclei, 272 Cerebellar afferents, 342 Cerebellar arteries blood supply, superior, 343, 344, 344t superior, 114 Cerebellar cortex, 35 Cytoarchitecture, 341–343, 341, 342 histology, 341 Cerebellar glomerulus, 343, 343 Cerebellar information, 162 Cerebellar peduncles, 35 inferior, 34 middle, 34 superior, 34, 99 Cerebellar tonsils, 330 Cerebellum, 35, 35, 93 afferent tracts, 332–334, 333 anatomy, 329, 330 cerebellar deep nuclei, 331, 331 cerebellar peduncles, 331, 331, 331t, 345 cerebral cortex, 332, 332 lobes, 330, 330 blood supply anterior inferior cerebellar artery, 343, 344, 344t posterior inferior cerebellar artery, 343, 344, 344t superior cerebellar artery, 343, 344, 344t cerebellar cortex, 332, 332 wiring, 343, 343 efferent tracts, 334, 335 flocculonodular lobe lesion, 356 functional relationships cerebrocerebellar connections, 338–340, 340, 346 feedback mechanism, 336 feed-forward mechanism, 336 spinocerebellar connections, 337–338, 338, 345 vestibulocerebellar connections, 336, 336–337 functions, 329 motor control system, 352, 352–353 nonconscious sensory input and tracts to, 134 posterior lobe lesion, 356 prediction and coordination, 329 Cerebral aqueduct, 33, 36 Cerebral arteries anterior, 42 middle, 41 posterior, 42, 114, 284, 285 Cerebral cortex anatomy, cerebral hemispheres, 240–241, 241 histological organization, 241–243, 242–243 subcortical fiber bundles, 243–247, 244–246, 247t association areas frontal lobes, 253–255, 254–255 parietal lobe, 255–256, 255–256 temporal lobe, 257, 257 blood supply anterior cerebral artery, 263, 263, 264t anterior choroidal artery, 263, 264t, 267, 267 middle cerebral artery, 264t, 265–266, 265–267 posterior cerebral artery, 263, 264t–265t, 266, 267, 267 frontal lobe of, 67 gender differences, 262 language processing classical concepts, 258–259, 258–259 modern concepts, 259–261, 260 mirror neuron system, 261, 261–262 primary cortical areas, 247 auditory, 251, 252 insula, 252–253 motor, 248–250, 249 olfactory system, 253 sensory, 250, 250–251 visual, 251, 251–252 Cerebral hemispheres anatomy, 240–241, 241 histological organization, 241–243, 242–243 subcortical fiber bundles, 243–247, 244–246, 247t development, 25 frontal lobe, 28–29 limbic lobe, 30–31 occipital lobe, 30 parietal lobe, 29–30 temporal lobe, 30 Cerebral peduncles, 33, 99, 140 Cerebrocerebellum, 338 Cerebrospinal fluid (CSF), 91 circulation of, 37–39, 38 production of, 36–37, 38 reabsorption of, 38, 39 Cervical enlargement, 35 Cervical ganglion, superior, 63 Cervical spinal cord, 144 Chemical synapses, 14, 14 Chemonociceptors, 124 Chemoreceptors, 50, 59, 188 Cholinergic neurons, 231, 231–232 Choroid, 290 plexus, 7, 36 Choroidal artery, anterior basal ganglia, blood supply, 325, 326, 326t blood supply, cerebral cortex, 263, 267, 267 Chronic pain (see Pain) Ciliary body, 290 Ciliary ganglion, 153 Ciliary muscles, 152, 168, 290, 308 Cingulate cortex, 279, 280 Cingulate gyrus, 29, 30, 181, 281, 377 Cingulum, 244, 244, 377 Circadian rhythms, 371, 371 Circle of Willis, 41, 263, 263 basal ganglia, blood supply, 325, 325–326, 326t Circuit neurons, 140 Circumvallate papillae, 401 Cisterna magna, 38 Cisterns, 40 Clarke nucleus, 84, 85, 128 Clonus, 350b Cochlea, 201–202 duct (see Membranous labyrinth) implants, 208–209b 5/9/2011 9:23:09 PM Index nerve, 208 nuclei, 209, 211 Cold water caloric testing, 165, 165–166, 165t Colliculus, 33 inferior, 209, 213 superior, 142, 144, 160, 166, 308 Color vision color information processing, 304, 304–305 influences behavior, 305 Comatose patient, 145 Commissural fibers, 33 cerebral cortex, 244–246, 245 Communicating artery, 267 anterior, 42 posterior, 42 Conditioned reflexes, 385 Conductance, 11 Conduction aphasia, 259, 259 Conduction block, 17 Conduction velocity, 48 Cones, retinal layers, 291, 292, 294 Conjugate gaze, 156 Consciousness, 224 reticular nucleus, thalamus, 284 Consensual response, optic reflexes, 306–307 Constrictor pupillae, 152, 306 Contralateral neglect syndrome, 255 Contrecoup brain injury, 399b Conus medullaris, 35, 75 Convergence, disconjugate gaze, 166 Cornea, 290, 290, 309 blink reflex, optic reflexes, 308, 308 Corona radiata, 33, 122, 125, 140, 142, 246, 246 Corpus callosum, 33, 244–245, 245 Cortex, 138 Cortical motor system, 348–349, 349 Cortical pain matrix lateral pain system, 414–415, 415 medial pain system, 415, 415 saliency, 415–416 Cortical processing, vision dorsal pathway, 303–304 primary visual cortex, 303 ventral pathway, 303 Cortical projections, 220 Corticobulbar fibers, 195, 269 Corticobulbar tracts, 96, 138, 140, 149, 190 Corticocortical connections, 281, 281 Corticohypothalamic fibers, 361 Corticospinal fibers, 34 Corticospinal tracts, 33, 96, 138, 248 anterior, 77, 85, 138, 140–142 lateral, 77, 85, 138, 140 Corticostriatal pathway, 317 Co-transmitter, 20 Coughing, 234 CPGs (see Central pattern generators (CPGs) ) Cranial nerves (CNs), 33, 59 in brainstem CN I (olfactory), 104 CN II (optic), 104 CN III (oculomotor), 99, 104–105, 106 CN IV (trochlear), 100, 106, 106 CN IX (glossopharyngeal), 96, 109–110, 110 CN V (trigeminal), 106, 108 CN VI (abducens), 98, 106, 108 CN VII (facial), 98, 106, 108, 109 CN VIII (vestibulocochlear), 98, 108–109 CN X (vagus), 96, 110, 111 CN XI (accessory), 96, 111 CN XII (hypoglossus), 96, 111 columnar organization, 101, 103, 103, 104 functional components, 101 location of, 105 nuclei and functions, 107t nuclei, development of, 101, 102, 103, 103 Craniosacral outflow, 61 Crocodile tear syndrome, 185 Cuneocerebellar tract, ipsilateral, 130 Cupula, 216 Krebs_Index.indd 427 427 Current, 11 Cutaneous receptors (exteroceptors), 128 Cytoarchitecturem, cerebral cortex, 242, 242–243 D Dark current, 296 Deafness, 252 Decerebrate/extensor posturing, 145 Decibels (dB), 205 Declarative memory, 384 Decorticate posturing, 145 Decussation, 141 of pyramids, 96 Déjèrine-Roussy syndrome, 287 Demyelination, 17 Dendrites, Dendritic axon, 120 Dentate gyrus, 377, 379, 379 Dentate nucleus, 331 Dentatorubrothalamic tract, 334, 339 Dentatothalamic tract, 339 Denticulate ligaments, 78 Depolarization, 205 Depression, 229b Dermatome, 74, 79, 81 Descending cortical fibers, 142 Descending corticospinal fibers, 148 Descending facilitation, pain, 416 Descending fibers, hypothalamus, 362–363 Descending inhibition, pain, 416 Descending medial longitudinal fasciculus, 142 Descending motor tracts, 349 brainstem reticulospinal tract, 143–144, 144 rubrospinal tract, 144, 145 tectospinal tract, 144, 146 vestibulospinal tracts, 142–143, 144 cortex, pathways from, 141 anterior corticospinal tract, 141–142, 142 corticobulbar tract, 142, 143 lateral corticospinal tract, 140 motor tracts and functions, 139t overview, 138, 138–139 Detrusor muscle, innervation, 67 Detrusor-sphincter-dyssynergia, 69 Diaphragma sellae, 40 Diencephalon, 25, 27, 33 Diffusion, Dilator muscle, 307, 307 Direct response, optic reflexes, 306 Disconjugate gaze, 166, 166–167 accommodation, 167, 167–168 Distal muscle groups, 140 Divergence, disconjugate gaze, 166 DM (see Dorsomedial nucleus (DM) ) Dopamine as biogenic amines, 19 reward circuitry saliency, 390–391, 390–391 stress, 391 Dopaminergic neurons, brainstem, 225, 226–227 Dorsal motor nucleus of vagus, 193 Dorsomedial nucleus (DM), thalamus, 272 association nuclei, 282, 282 limbic relay nucleus, 280, 281 Drug-seeking behavior, VTA, 227 Dura mater, 39–40, 40, 77, 78 Dural reflections, 39 Dysarthrias, 146, 235b, 258 Dysdiadochokinesia, 283b, 341b Dysesthesias, 418, 423 Dysmetria, 283b, 341b Dysphagia, 235b E Edinger-Westphal nucleus, 105, 306, 306 Ejaculation, 71 Electrical gradient, Electrical potential (see Membrane potential) Electrical synapses, 13–14, 14 Electrochemical equilibrium (see Equilibrium potential) Emesis, 233, 233 Emotional memory, 385 learning and, 386–387 Emotional motor system, 144 Endocrine function regulation anterior lobe, 365, 365–367, 366 posterior lobe, 364, 364–365 Endogenous opioid system, pain modulation, 417–418, 418 Endolymph, 165, 203 Endoneurium, 48 Endplate potential (see Excitatory postsynaptic potential) Enkephalin receptors, 418 Enteric nervous system, 58, 60, 63, 63–64 Enteroceptors, 54, 118 Entorhinal cortex, 253, 377, 393, 398 Ependymal cells, Epidural anesthesia, 79b Epidural/extradural space, 41, 78 Epilepsy, temporal lobe, 392b Epinephrine, 19 Epineurium, 48 Episodic memory, 384, 385b Epley maneuver, 219b Equilibrium potential, 8–9 Excitatory postsynaptic potential (EPSP), 14, 15, 55 Explicit/declarative memory, 384 Expressive/productive aphasia, 258, 259 Extended Papez circuit, 382, 383 Exteroceptive information, 129 Exteroceptors, 50, 118 Extrafusal fibers, 52 Extraocular muscles elevation/depression, 151 eyeball and orbit, axis of, 151, 151 horizontal and vertical axis, 151 intorsion/extorsion, 151 oblique muscles, 151, 152, 153 rectus muscles, 151, 151, 152 Extrapyramidal system, motor control system, 353–354, 354t Eye, 289 (see also Visual system) cornea, 290, 290 disconjugate gaze, 166, 166–168, 167 horizontal gaze nystagmus, 164, 164–166, 165, 165t saccades, 159–161, 159–162 smooth pursuit, 162, 162–163 vestibuloocular reflex, 163, 163 wiring of, 158, 158–159 H-test, 168b internuclear ophthalmoplegia, 169–170b overview, 150 pupil, 290 structures involved in cranial nerves, 152–153, 153–156 extraocular muscles, 151, 151, 152 eyeball, 150 medial longitudinal fasciculus, 153–156, 157 vertical gaze, 166, 166 Eyeball, movements, 150 F Facial (CN VII) nerve, 98, 106, 108, 109, 183t motor component of general visceral efferents, 181–182 special visceral efferents, 181, 184 sensory component of general sensory afferents, 182 special visceral afferents, 182 Facial nucleus, 181 Facial pain, 185 Falx cerebelli, 40 5/9/2011 9:23:09 PM 428 Falx cerebri, 39 Fasciculus cuneatus, 34, 76, 87, 96, 121, 130 Fasciculus gracilis, 34, 76, 87, 96, 121 Fear conditioning, 387–388 Feedback mechanism, cerebellum, 336 Feed-forward mechanism, cerebellum, 336 Feeding center, hypothalamus, 370 Fibers association, 33 commissural, 33 projection, 33 Fight-or-flight system, 62 Filum terminale, 35, 44, 75, 78 Fissures, 75 calcarine, 30 lateral/sylvian, 28 longitudinal, 28 parietooccipital, 28, 29 Flexor reflex, 132 (see alsoWithdrawal reflex) Flocculonodular lobe, 330, 330 syndrome, 337b Folia, 329 Foliate papillae, 401 Food intake regulation, hypothalamus, 369–371, 370, 375 Foramina of Luschka, 45 Forceps, cerebral cortex, 245, 245 Forebrain, 27–33, 30–33 (see also Cerebral cortex) medial bundle, 360 Fornix columns, 359, 375 limbic system, 379 Fourth ventricle, 34, 36, 97, 99 Fovea, 156, 167, 291, 309 Frequency, 205, 209 selectivity, inner ear, 206–207, 209 Friedreich ataxia, 339b Frontal eye fields (FEFs), 159, 161, 166 Frontal gyrus, inferior, 258 Frontal lobe cerebral cortex function, 254, 254 innervation, 254–255 lesions, 255 magnetic resonance image, 270 prefrontal cortex, 253 size, 253–254 dysfunction, 283b Fungiform papillae, 400 Funiculi, 75 Fusiform gyrus, 257 G γ motor neurons, 89, 351 G protein, 396 transducin, 294, 296 Gabapentin, 320b Gag reflex, 59, 188, 189 γ aminobutyric acid (GABA), 19 Ganglion, 27 Ganglion cell layer, retina, 292, 293 visual pathway, 298–299, 299 Gap junctions, 13 Gate control theory, pain modulation, 416, 416–417 Gaze conjugate, 156 disconjugate gaze, 166, 166–167 accommodation, 167, 167–168 horizontal gaze, 157 nystagmus, 164, 164–166, 165, 165t saccades, 159–161, 159–162 smooth pursuit, 162, 162–163 vestibuloocular reflex, 163, 163 wiring of, 158, 158–159 synergistic movement of, 156 vertical gaze, 166, 166 Krebs_Index.indd 428 Index Gender differences, 262 Generator potentials, 49 Geniculate ganglion, 182 Geniculate nuclei, lateral, 299, 300–301 Genioglossus muscle, 195 Glia, astroglia, ependymal cells, microglia, oligodendroglia, polydendrocytes, Schwann cells, 6–7 types of, Globus pallidus, 312, 313 Glossopharyngeal ganglion, inferior, 187, 188 Glossopharyngeal (CN IX) nerve, 59, 96, 109–110, 110, 186t motor component of general visceral efferents, 190 special visceral efferents, 190 sensory component of gag reflex, 189, 189 general sensory afferents, 186–187 general visceral afferents, 187, 187–188, 198 special visceral afferents, 188–189 Glucocorticoid hormones, 228 Goldmann equation, 9, 9–10 Golgi tendon organs, 52, 53, 53–54, 128 Granular cortex, 242 Granular neurons, 242 Granule cells, 397 Gray horn lesion, spinal cord, 356 Gray matter anterior horn, 82–84 Clarke nucleus, 84, 85 lateral horn, 82, 84, 84 posterior horn, 82 discriminative touch and proprioception, 84 pain and temperature, 84 preganglionic visceral motor cell bodies, 82 subdivisions of, 82–83, 82t, 83 and white matter, 27, 29, 36 Gray rami communicantes, 63 Guillain–Barré syndrome, 22, 53b Gustatory system neuronal pathways, 403–404, 404 signal transduction, taste, 401 bitter, 402, 406 receptor cells, 401 salty, 401 sour, 401 sweet, 401 umami, 403 taste buds, 400 circumvallate papillae, 401 foliate papillae, 401 fungiform papillae, 400 H Hair cells, 200, 208 inner, 204 outer, 204 Hair follicle receptors, 51 HD (see Huntington disease (HD) ) Head and neck, sensory and motor innervation (see also specific nerves) accessory nerve, 194–195 facial nerve, 181–185 glossopharyngeal nerve, 186–190 hypoglossal nerve, 195–196 trigeminal nerve, 175–180 vagus nerve, 190–193 Hearing central auditory pathways pitch and volume, 209–210, 210 sound localization, 210, 210–211, 212–214, 213–214 loss, 208 conductive, 208 sensorineural, 208 overview, 199–200 sound perception physiology, in inner ear basilar membrane, 205, 206 frequencies, 205 frequency selectivity, 206–207, 209 hair cells, 205–206, 206, 207 otoacoustic emissions, 207–208 physics of frequency and amplitude, 205 structures involved in inner ear, 201–205, 202–204 middle ear, 200–201, 201 outer ear, 200, 201 Helicotrema, 203 Hemiparesis, 236b Hertz (Hz), 205 Heschel gyri, 252 Hiccuping, 234 Hindbrain, 34 Hippocampus, 32, 266, 358 anatomy, 377–379, 379 clinical damage, 392 formation, 377 functions long-term memory, 384, 384–385 short-term memory, 383–384, 384 Histamine, 19 Histaminergic neurons, 232 Horizontal cells, retinal layers, 291, 292 Horizontal gaze, 157 nystagmus, 164, 164–166, 165, 165t saccades, 159–161, 159–162 smooth pursuit, 162, 162–163 vestibuloocular reflex, 163, 163 wiring of, 158, 158–159 H-test, eye movements, 168b Hunger, hypothalamus, 370 Huntington disease (HD), 321b–322b Hydrocephalus, 42b Hyperacusis, 185 Hyperalgesia, 410, 418, 419 Hyperpolarization, 205, 296 Hyperreflexia, 146 Hyperthermia, 368, 369 Hypoglossal (CN XII) nerve, 96, 111, 196t anterolateral sulcus, 195 central and peripheral lesions of, 196 overview of, 195 Hypoglossal nucleus, 195 Hypokinesia, basal ganglia, 320b, 328 Hypothalamic-hypophyseal portal system, 365–366, 366 Hypothalamomedullary tracts, 64 Hypothalamospinal fibers, 64 Hypothalamospinal tracts, 64 Hypothalamus, 33, 59, 64, 377, 378 afferent connections, 361–362, 362 anatomy anterior, and posterior area, 359, 360t, 361 hypothalamic sulcus, 358, 358 lamina terminalis, 358, 358 lateral and medial zone, 359, 360t mammillary bodies, 358, 359 tuber cinereum, 358, 358 tuberal area, 359 blood supply, 373, 373 deficits, 372b efferent connections, 362–363, 363 function, 357, 357–358 circadian rhythms, 371, 371 endocrine function regulation, 364–366, 364–367 food intake regulation, 369–371, 370, 375 sleep-wake cycle, 371–372 temperature regulation, 368–369, 369 visceral function regulation, 367, 368 water balance regulation, 371 hormone regulation, 367 melatonin, 373b 5/9/2011 9:23:09 PM Index nuclei, 361 pituitary gland, 358 posterior, 307 posterior hypothalamus lesion, 374, 375 sulcus, 358, 358 I Immune cells, Implicit nondeclarative memory, 384–385, 394 Inferior brachium, 209 Inferior cerebellar peduncle (ICP) afferent tracts, 333, 334 efferent tracts, 333, 334, 335 spinocerebellar connections, 337 Inferior horn, 36 Inflammation, severe, 17 Infratentorial compartment, dura mater, 40 Infundibulum, 358, 358 Inhibiting hormones, 365 Inhibitory interneurons, 88, 341 Inhibitory postsynaptic potential (IPSP), 14, 15 Inner ear, 143, 202 chambers, 202–204, 203, 204 cochlea, 201–202 organ of Corti, 204, 204–205 oval window, 204 position of, 199 round window, 204 sound perception physiology in basilar membrane, 205, 206 frequencies, 205 frequency selectivity, 206–207, 209 hair cells, 205–206, 206, 207 otoacoustic emissions, 207–208 physics of frequency and amplitude, 205 Innervation, dura mater, 40 Insula, 252–253, 314, 315–316 Interhemispheric fissure, 263 Internal capsule, 33 cerebral cortex, 246, 246, 247t genu of, 142 Interneurons, 140, 291 Internode distance, 13 Internuclear ophthalmoplegia, 169–170b Interthalamic adhesion, 271, 272 Interventricular foramen, of Monro, 36 Intervertebral foramen, 78 Intrafusal fibers, 52 Intralaminar nuclei, 272, 282–283, 283 Involuntary movement, 138 Iodopsin, 294 Ion channels, movements equilibrium potential, Nernst equation, 8, 8–9, intracellular and extracellular ion concentrations, 8t resting membrane potential, Goldmann equation, 9, 9–10, 10 pumps, Ionotropic receptors, 16 glutamte, 297 Iris, 290 Itch, 124 J Jaw-jerk reflex, 180, 181 Joint receptors, 54, 128 Jugular foramen, 190, 194, 197 Jugular vein, internal, 40 K Ketamine, 320b Kinocilium, 216 Koniocellular layers, 299, 300 Koniocellular pathay, 299, 299 K+-rich endolymph, 215 Krebs_Index.indd 429 429 L Labyrinth, 199 Lacrimal gland, 184 Lamina terminalis, 358, 358 Language processing, cerebral cortex classical concepts, 258–259, 258–259 modern concepts, 259–261, 260 Lateral foramina of Luschka, 37 Lateral geniculate nucleus (LGN), 272, 276, 277 Lateral horn, 63, 64, 65 Lateral medullary syndrome, 235b Lateral pain system, 414–415, 415 Lateral rectus, 151, 152, 158 Lateral superior olivary nucleus (LSO), 211 Lateral vestibular nucleus, 143 Leak current, 13 Left-sided neglect syndromes, 269 Lemniscus, lateral, 209 Lenticulostriate arteries, 266 Lentiform nucleus, 313 Lesions anterolateral system, 125, 127 facial nerve, 181 posterior column-medial lemniscus pathway, 122–123, 123 spinocerebellar tracts, 133 Levator palpebrae superioris, 152 LGN (see Lateral geniculate nucleus (LGN) ) Lidocaine, 320b Ligand-gated ion channels, Limb anterior, 246 movement, cerebellum, 337–338, 338 posterior, 246 Limbic afferents, hypothalamus, 361 Limbic circuit, basal ganglia, 324, 325 Limbic lobe, 243, 244, 376, 377 Limbic relay nuclei, thalamus, 279–281, 280 Limbic structures, 32 Limbic system, 144 anatomy amygdala, 379–381, 380, 381 hippocampus, 377–379, 379 hypothalamus, 377, 378 limbic lobe, 376, 377 Papez circuit, 382, 383 septal nuclei, 378, 381–382 clinical deficits, 392 cortical areas, 376, 376 functions amygdala, 386–389, 387 hippocampus, 382–385, 384 reward circuitry addiction, 389–390 dopamine and saliency, 390–391, 390–391 dopamine and stress, 391 Limen insulae, 398 Limiting membrane, 292, 293 Linear acceleration, balance, 216, 218, 218, 220 Lissauer tract, 124 LMN (see Lower motor neurons (LMNs) ) Local circuit neurons, 351 Long-term memory, 384 explicitdeclarative memory, 384 implicitnondeclarative memory, 384–385 Lower limb position and movement, spinocerebellar tract, 128 Lower motor neurons (LMNs), 73, 82, 138, s351 lesions, 351b L-type cones, 294, 304 Lumbar cistern, 78 Lumbar puncture, 91 Lumbar segments, 130 Lumbosacral enlargement, 35 M Macula, 216 Magnocellular layers, 299, 300 Magnocellular pathway, 298, 299 Malleus, 201 Mammillary bodies, 279, 358, 359 Mammillothalamic tract, 279, 363 MCA (see Middle cerebral artery (MCA) ) Mechanical stimuli, 119 Mechanically gated ion channels, 10 Mechanoreceptors, 50, 58, 59 Mechanotransduction, 205 Medial foramen of Magendie, 37 Medial geniculate nucleus (MGN), 209, 272, 275, 277 Medial lemniscus, 120–123 Medial longitudinal fasciculus (MLF), 120, 153–156, 157, 169, 171 ascending component, 154 descending component, 154 Medial medullary syndrome, 238 Medial pontine syndrome, 236b Medial rectus, 158 Medial superior olivary nucleus (MSO), 211 Medial vestibular nucleus, 142 Medulla, 34, 93, 195 anterior surface of, 140 CN X, 190 Medulla oblongata anterior surface, motor information, 96, 96 posterior surface, sensory information, 97 central canal of, 96 closed/caudal, 96 cuneate tubercle and gracile tubercle, 97 open/rostral, 97 posterior columns, 96 relationship of external to internal structures in, 95 Medullary lamina, internal, 272 Medullary velum inferior, 97 superior, 99 Meissner corpuscles, 52 Melatonin, 371, 373b Membrane depolarization, 408 Membrane potential, Membranous labyrinth, 202, 215 Memory Alzheimer disease, 386b long-term memory, 384, 384–385 saccades, 161, 161 short-term memory, 383–384, 384 Meningeal arteries, 41 Meningeal coverings arachnoid mater, 40 dura mater, 39–40, 40 pia mater, 40 Merkel cell, 51 Mesencephalic nucleus, 106, 176, 177 of CN V, 116, 179–180, 180, 181 Mesencephalon, 25 Mesocorticolimbic dopamine system, brainstem, 226 Metabotropic glutamate receptors (mGluRs), 19, 298 Metabotropic receptors, 16 Metencephalon, 25 Methadone, 320b Meyer loop, 302 MGN (see Medial geniculate nucleus (MGN) ) Microglia, 6, 7, 419 Alzheimer disease, 230 Microtubules, Micturition automatic, 69 central control of, 67–68 Midbrain, 33, 34, 93 anterior surface, 99, 99 inferior and superior colliculi, 100 posterior surface, 99, 100 Middle cerebellar peduncle (MCP) afferent tracts, 333, 334 Middle cerebral artery (MCA) basal ganglia, blood supply, 325, 326, 326t blood supply, cerebral cortex, 264t, 265–266, 265–267 infarction, 269 5/9/2011 9:23:09 PM 430 Middle ear bones in, 201 infection, 222 muscles in, 201 Midget ganglion cells, 298, 299 Midpons, trigeminal nerve, 175, 180 Miosis, 235b Mirror neuron system, 261, 261–262 Mitral cells, 397 Mixed pain syndromes, 418 Modulatory system, thalamus, 276 Monoamine hypothesis, 229b Monoaminergic neurotransmitters, 144 Monoaminergic systems, 255 Monro, interventricular foramen of, 36 Morality, prefrontal cortex, 254 Mossy fibers, 342, 342 Motor area, 248–250, 249 Motor circuit, basal ganglia, 323–324, 323–324 Motor control system, 347 basal ganglia lesions, 354–355 extrapyramidal system, 353–354, 354t lower motor neuron system, 351 modulatory influences basal ganglia, 351–352, 352 cerebellum, 352, 352–353 pyramidal system, 353–354, 354t substantia nigra, 355 upper motor neuron lesions, 350b, 354, 354t upper motor neuron system cortical motor system, 348–349, 349 red nucleus, 349, 349 reticular formation, 349, 349 vestibular nuclei, 349, 349 Motor cortex, primary, 269 Motor endplate (see Neuromuscular junction (NMJ) ) Motor homunculus, 140 Motor learning, mirror neuron system, 261–262 Motor neurons, 83, 161 Motor relay nuclei, thalamus, 277–279, 278 Motor unit, 54, 54–55 M-type cones, 294, 304 Müller cells, 292 Multiple sclerosis (MS), 17–18b, 170 Muscarinic ACh receptors, 19 Muscle fibers, intrafusal and extrafusal, 52–53 Muscle length, 52 Muscle spindles, 52, 57, 128 density, 53 Muscle tone, 144 Muscles of facial expression, 184 Myelencephalon, 25 Myelin, Myelinating cells, Myenteric plexus (of Auerbach), 63 Myotomes, 74, 81, 81 N Na+ channel blocker, 320b Na+/K+ ATPase, Narcolepsy, 372 Nasal septum, 395, 396 Near triad, 167 Neck, sensory and motor innervation (see Head and neck, sensory and motor innervation) Neocerebellum, 338 Neocortex, 241 Neospinothalamic tract, 413 Nernst equation, 8–9 Nerve fiber layer, retina, 292, 293 Nervous system cellular components of, blood–brain barrier, 7, circuits/networks, glia, 5–7, neurons, 2–5, 4–6 development brain, 25, 26 Krebs_Index.indd 430 Index neural crest cells, 44 neural tube, 24, 24–25 Nervus intermedius, 108 Neural crest cells, 25 Neural tube, 101 development, 24, 24–25 Neurodegeneration, 17 Neuroendocrine, 69, 414 Neurogenesis, 379 Neurohypophysis, 364 Neuromodulators, 20 Neuromuscular junction (NMJ), 7, 54, 55 signal transduction, 55 Neurons functional organization of, 2–4 histology of, synapses, types of, 5, types of, bipolar, multipolar, pseudounipolar, Neuropathic pain, chronic, 418–419 Neuropeptides, 20 Neurophysiology action potential, 10–13, 11–13 ion movements, 8–10, 8–10, 8t neurotransmitters, 16, 18t, 19–20 synaptic transmission, 13–14, 14–17, 16 Neuropil, Neurotransmitters, 410–411 acetylcholine, 19 activation, of visceral motor system, 60, 61 ATP, 20 biogenic amines, 19–20 in CNS, 18t GABA and glycine, 19 glutamate, 16, 19 neuropeptides, 20 reticular formation dopaminergic neurons, 225, 226–227 emotional learning and memory, 227 ventral tegmental area, 226, 226–227 Neurotrophic factor, serotonergic neuron, 230 Nicotinic ACh receptors, 19 Nigrostriatal pathway, 317 Nigrostriatal system, brainstem, 225 Nissl substance, Nociceptive pathways lateral sensory-discriminative pathway, 413, 413 medial affective-motivational pathways, 413, 413–414 Nociceptive-specific (NS) cells, 410 Nociceptors, 50, 52, 58 activation, 408, 408–409 fibers, 407–408 peripheral, pain treatment, 320b peripheral receptors, sensitization, 409, 409–410 Nodes of Ranvier, 6, 13 Nonconscious proprioception, 179 Nondeclarative memory, 384–385, 394 Nondominant hemisphere, 255 Nonsteroidal anti-inflammatory drugs, 320b Noradrenaline, 227 Noradrenergic systems, reticular formation Alzheimer disease, 230 attention disorders, 229 wakefulness, 228 Norepinephrine (NE), 19, 227 Nose, olfactory system, 395 Notochord, 24 Nuclear bag fiber, 53 Nuclear chain fiber, 53 Nuclear layer, retina, 292, 293 Nucleus, 27, 47 accumbens, 312, 313, 389, 390 ambiguus, 110, 189, 190, 193 cuneatus, 97 gracilis, 97 solitarius, 65, 108, 110, 182, 188, 189, 192, 403 thalamus, 273 lateral and posterior nuclei, 272 medial and lateral nuclei, 272 surrounding nuclei, 273 Nystagmus cold water caloric testing, 165, 165–166, 165t horizontal, 164 left-beating, 164 optokinetic, 165 vestibular, 164 warm water caloric testing, 166 O Obex, 97 Oblique eye movements, 166 Oblique muscles inferior, 151, 152 superior, 151–153 Occipital lobes, 167, 251, 251 Occipitofrontal fasciculus, 243, 244 Oculomotor circuit, basal ganglia, 324, 328 Oculomotor (CN III) nerve, 99, 104–105, 106, 116, 306, 310 eye movements, 152–153, 153, 154 Oculomotor nuclear complex, 152, 308 Ohm law, 11, 11 Olfactory (CN I) nerve, 104 Olfactory system, 253 bipolar cells, 396 bulb, 397–398, 398 central projections, pathway, 398–399, 399 cortex, 399 epithelium, 396, 396–397, 405 knob, 396 neurons, 396 olfactory bulb, 397–398, 398 olfactory epithelium, 396 basal cells, 396, 405 processing and coding, 396–397, 397 secretory cells, 396 supporting cells, 396 stria, 398 whiplash injury, 405 Olfactory tract, 104 Oligodendrocytes, 18 Olivary nuclear complex, inferior, 96, 342 Olives, 34, 117 Onuf nucleus, 67 Ophthalmic artery, 41 Ophthalmic division, trigeminal nerve, 308 Opioid receptors, 417–418 Opioids, 320b Opponency neurons, 304, 304–305 Optic chiasm, 358 and tract, 299–300, 300 Optic disc, 291 Optic (CN II) nerve, 104, 291 Optic radiations clinical visual deficit, 302b visual cortex, 251 visual field, 301, 301–302 visual pathway, 301, 301–302 Optic reflexes accommodation, 306, 307–308 corneal blink reflex, 308, 308 pupillary light reflex, 306, 306–307 pupillodilator reflex, 307, 307 Optokinetic nystagmus, 165, 165 Orbicularis oculi, 308 Orbitofrontal cortex, 387 Orbitofrontal cortices, 280, 281 Orgasm, 71 Osmoreceptors, 371 Ossicles, 200 Otic ganglion, 190 Otoacoustic emissions, 207–208 Otoconia/otoliths, 216 Otolithic membrane, 216 Otolithic organs, 216, 218, 222 5/9/2011 9:23:09 PM Index Outer ear, 200, 201 Oval window of inner ear, 201, 204 Oxytocin fear conditioning, 388 regulation, 364, 365 P Pacinian corpuscles, 52, 56 Pain chronic pain chronic neuropathic pain, 418–419 chronic nociceptive pain, 418 glial signaling, 419 maladaptive central sensitization, 419 maladaptive peripheral sensitization, 419 cortical pain matrix lateral pain system, 414–415, 415 medial pain system, 415, 415 saliency, 415–416 definition, 407 inhibition, 416 modulation descending influences, brainstem, 417, 417 endogenous opioid system, 417–418, 418 gate control theory, 416, 416–417 nociceptive pathways lateral sensory-discriminative pathway, 413, 413 medial affective-motivational pathways, 413, 413–414 nociceptors activation, 408, 408–409 fibers, 407–408 peripheral receptors, sensitization, 409, 409–410 processing, in spinal cord increased excitation, 412 sensitization, 412 substance P, 412 synaptic targets, 410–411, 411 wind-up, 411, 412 secondary pain, 124 sensory afferents, 59 system lateral, 414–415, 415 medial, 415, 415 and temperature, 66–67, 85, 119 and temperature fibers, 178, 179 treatment, 420b–421b Paleocerebellum, 337 Paleocortex, 241 Paleospinothalamic tract, 414 Papez circuit, 382, 383 Papilla, 291, 400 Parafascicular (PF) nuclei, thalamus, 272 Parahippocampal gyri, 30, 243, 244, 377 Paralysis, 351b Paramedian pontine reticular formation (PPRF), 157, 159–161 Parasol ganglion cells, 298, 299 Parasympathetic Edinger-Westphal nuclei, 168 Parasympathetic efferents, 65 Parasympathetic fibers, 71 GVE, 108, 110, 152, 190, 193 Parasympathetic ganglia in heart, 65 Parasympathetic nervous system, 58, 60, 61, 62 preganglionic PNS, 72 Parasympathetic tone, 70 Parasympathetic visceromotor neurons, 67 Paraventricular nucleus, 64 Paresthesias, 18, 418 Parietal association, 282, 282 Parietal cortices, 280 Parietal lobe cerebral cortex function, 255, 255 lesions, 255–256, 256 dorsal stream, 303 Parietooccipital fissure, 29 Krebs_Index.indd 431 431 Parkinson disease, 320b, 328 Parvocellular layers, 299, 300 Parvocellular pathway, 298, 299 Passive current, 11, 11 PCA (see Posterior cerebral artery (PCA) ) Peduncles, 93 Pelvic floor, contraction of, 71 Pelvic nerves, 59 Pelvic viscera, 63 Periaqueductal gray (PAG), 64, 67, 153, 362 Periglomerular cells, 397 Perikaryon (see Soma) Perilymph, 202 Perineal pouch, deep, 67 Perineurium, 48 Periosteal layer, 39 Peripheral facial nerve, 184 Peripheral nervous system (PNS), effector endings motor unit, 54, 54–55 neuromuscular junction, 55, 55 overview of, 46, 46–47 modalities, 48 somatic and visceral components, 47 spinal cord cross section, anterior and posterior roots, 47 peripheral nerves nerve fibers, classification of, 48–49, 49t organization of, 48, 48 sensory receptors adaptation, 50–51, 51 classification of, 49–50, 50 proprioceptors, 52–54, 53 receptor potentials, 49, 49 skin receptors, 51, 51–52 Peripheral sensitization, 320b Peripheral vision, 310 Perivascular space, 40, 40 Permeability, Phasic, noradrenergic neurons, 227 Photopic vision, 294 Photoreceptor cells, 293–294, 294 Photoreceptor layer, 292, 293 Photoreceptors, 50 Phototransduction, 292, 293, 295, 296 Pia mater, 39, 40, 77, 78 Pigment epithelial layer, retina, 291–292, 293 Piriform area, 398 Pitch, 205 Pituitary hormones regulation, 367 Plasma composition, 38t Plexiform layer, retina, 292, 293 Poikilothermia, 369 Polydendrocytes, 6, 7, 18 Polymodal C fibers, 404 Pons, 34, 67, 93 abducens nucleus, 153 anterior surface (basal pons), 98, 98–99 posterior surface (roof), 99 Pontine and rostral medullary reticular formation, 143 Pontine micturition center (PMC), 67 Pontine nuclei, 34 Pontine storage center (PSC), 67 Pontocerebellar fibers, 34 Pontomedullary junction, 99, 200, 222 Portal system, 366 Postcentral gyrus, 29, 250–251 Posterior cerebral artery (PCA) basal ganglia, blood supply, 325, 326, 326t blood supply, cerebral cortex, 263, 266, 267, 267 Posterior column–medial lemniscus pathway, 119 anatomy, 120–122, 121, 122 lesions, 122–123, 123 Posterior horn ascending sensory tracts, 124 spinal cord, 120 ventricular system, 36 Posterior inferior cerebellar arteries, 114 blood supply, cerebellum, 343, 344, 344t Posterior limb, of internal capsule, 140 Posterior lobe syndrome, 341b Posterior median sulcus, 75 Posterolateral sulcus, 75 Postganglionic fibers, 63 sympathetic, 65 Postsynaptic densities, Posttraumatic stress disorder (PTSD), 229 Postural adjustments, 143 movement, 138 Postural stability, 138, 142 Potential gradient, Precentral gyrus, 28, 248 Predictive saccade, 161, 161 Prefrontal association areas, 29 Prefrontal cortex, 253 serotonergic neuron, 230 Prefrontal cortices, 280, 281 Preganglionic parasympathetic fibers, 306 Preganglionic sympathetic neurons, 65 Pretectal area, 166 Pretectal nucleus, 306, 306 Primary auditory cortex, 209, 214 Primary cortical areas, cerebral cortex, 247 auditory, 251, 252 motor, 248–250, 249 olfactory system, 253 sensory, 250, 250–251 visual, 251, 251–252 Primary somatosensory cortex, 122 Primary visual cortex, 303 Projection fibers, 33 cerebral cortex, 246, 246 Proprioception, 120 Proprioceptive information, 129 Proprioceptors, 50, 52–54, 53, 118, 128 Prosencephalon, 25 Prosody, 258 Prosopagnosia, 257 Prostaglandins, 409 Pseudounipolar cells, 179 Pseudounipolar neurons, 120 Pterygopalatine, 182 Ptosis, 235b PTSD (see Posttraumatic stress disorder (PTSD) ) Pudendal nerve, 67, 69, 71 Pulvinar auditory processing, 282 complex, thalamus, 272 medial pulvinar, 281 nucleus, lesion, 288 visual processing, 282 Pupil, 290 Pupillary light reflex, optic reflexes, 306, 306–307 Pupillodilator reflex, optic reflexes, 307, 307 Purkinje neuron, 341–342, 342, 346 Putamen, basal ganglia, 312, 312 Pyramids, 34, 96 decussation, 34, 140, 141 motor control system, 353–354, 354t neurons, 242 tracts, 140 R Radial glia, Raphe nuclei, serotonergic systems, 230, 230 Rapid eye movements, 159 Receptive fields, 51 Receptive/sensory aphasia, 259 Receptor adaptation, 51 rapidly adapting, 51 slowly adapting, 50 cells, 401 potentials, 49 Rectum fullness, 59 Rectus muscles, 151, 151, 152, 152 Red nucleus, 142, 144, 349, 349 Red-cyan cells, 305 5/9/2011 9:23:10 PM 432 Red-green cells, 304, 304 Reflexive saccades, 160, 160–161 Refraction, light, 290 Regulatory inputs (modulators), thalamus, 273 Reissner (vestibular) membrane, 204 Relay center, 153 Relay nuclei, thalamus limbic relay nuclei, 279–281, 280 motor relay nuclei, 277–279, 278 sensory relay nuclei, 275–276, 276–277 Release inhibiting hormones, 365 Remyelination, 18 Renshaw cells, 82, 83 Resistance, 11, 12 Respiratory group, anterior, 233 Rest-and-digest system, 61 Resting membrane potential, 9–10 Reticular formation, 142, 193, 360 lateral zone, 225, 225 medial zone, 225, 225 nuclei, 33 Reticular nucleus, thalamus, 283–284, 284 Reticulospinal tract, 138, 142–144, 144, 149 Retina, 282 ganglion cells, 291 layers, 291–294, 293 photoreceptor cells, 293–294, 294 phototransduction, 293, 295, 296 specialization, 291, 292 Retinohypothalamic fibers, 361 Retinotopic columns, 303 Retinotopic organization, 300 visual cortex, 252 Retrograde transport, Reward circuitry addiction, 389–390 dopamine and saliency, 390–391, 391 dopamine and stress, 391 Reward functions, amygdala, 388–389 Rexed laminae, 82, 82t Rhombencephalon, 25 Ribbon synapse, 296 Right frontal cortex, middle frontal gyrus, 172 Rods, retinal layers, 291, 293–294 Rotational acceleration, balance, 216–218, 217, 218 Rubrospinal tract, 138, 142 Ruffini endings, 52 S Saccades reflexive saccades, 160, 160–161 volitional saccades, 161, 161–162 wiring diagram for, 159 Saccule, 216, 218, 220 Sagittal sinus inferior, 39 superior, 39 Saliency, pain, 415–416 Salivatory nucleus inferior, 110, 190 superior, 108, 182 Salty taste, 401 Satiety center, hypothalamus, 370 Scala media, 202 Scala tympani, 202 Scala vestibuli, 202 Schwann cells, 6–7 Sclera, 290 SCN (see Suprachiasmatic nucleus (SCN) ) Scotopic vision, 293 SCP (see Superior cerebellar peduncle (SCP) ) Semantic memory, 384 Semantic processing, 260 Semicircular canals, 215 Seminal emission, 71 Sensitization pain, 407 pain processing, 412 Sensory endings Krebs_Index.indd 432 Index type Ia and II, 53 type Ib, 53 Sensory homunculus, 250, 250 Sensory receptors adaptation, 50–51, 51 classification of, 49–50, 50 proprioceptors, 52–54, 53 receptor potentials, 49, 49 skin receptors, 51, 51–52 Sensory relay nuclei, thalamus, 275–276, 276–277 Septal nuclei, anatomy, 378, 381–382 Septum pellucidum, 36 Serotonergic systems, reticular formation pain, 231 raphe nuclei, 230, 230 sudden infant death syndrome, 231 Serotonin, 20 Sexual responses, visceral reflex systems, 69–71, 70 Short-term memory, 383–384, 384 SIDS (see Sudden infant death syndrome (SIDS) ) Sigmoid sinus, 40 Silent nociceptors, 408 Sinuses, confluence of, 40 Skin receptors, 51, 51–52 Sleep–wake cycle, 371–372 Smell (see Olfactory system) Smooth pursuit eye movements, 162, 162–163 Solitary tract, 182, 188 Soma, Somatic afferents, 65 Somatosensory areas, primary and secondary, 220 Somatosensory cortex, 250, 413 Somatotopic arrangement, 140, 178, 179, 180, 181 Somatotopy, 248 Sound, 205 Sour taste, 401 Spasticity, 350b Special somatic afferent (SSA) fibers, 101, 108, 174 hearing and balance, 199 Special visceral afferent (SVA) fibers, 101, 108, 110, 174, 181, 186 facial (CN VII) nerve, 182 glossopharyngeal (CN IX) nerve, 188–189 Special visceral efferent (SVE) fibers, 101, 106, 110, 111, 174, 175 facial (CN VII) nerve, 181, 184 glossopharyngeal (CN IX) nerve, 190 vagus (CN X) nerve, 193 Specific inputs (drivers), thalamus, 273 Spinal accessory nucleus, 111, 194 Spinal arteries anterior, 92, 114, 116 posterior, 114 Spinal border cells, 130, 136 Spinal cord 31 segments, 74 anterior (ventral) horn, 73 blood supply to, 87, 87–88 conduit function, 73 cross section of, 73 discriminative touch and proprioception, 92 dorsal and ventral roots, 74 gray and white matter, 36 internal structure of gray matter, 82–84 white matter, 84–85, 86, 87 intrinsic functions, 73 length, 35 organization, 35, 36 overview of, 74 posterior and anterior rootlets, 35 posterior (dorsal) horn, 73 reflexes stretch (myotatic), 88–89, 89 withdrawal, 89, 90 spinal nerve, 75 surface anatomy of anterior column, 77 lateral column, 77 meningeal coverings of, 77, 77–78, 78 posterior column, 76 spinal nerves, 78–79, 81 Spinal ganglia, 35, 78, 119, 120 Spinal motor neurons, excitability of, 144 Spinal nerves, 35, 75 anterior and posterior rami, 78 posterior and anterior roots, 78 Spinal nucleus and tract of V, 176 of trigeminal nerve, 106 Spinal reflexes, 139 arcs, 120 Spinal tract and nucleus of V, 178–179, 179, 180 Spinal trigeminal nucleus, 97, 110, 177, 198 Spinal trigeminal tract, 308 Spines, Spinocerebellar tracts, 85, 120 anterior, 128, 130, 131, 132 cuneocerebellar tract, 128–130, 130 lesions of, 133 posterior, 97, 128, 129 proprioceptive and exteroceptive information, 127 rostral, 128, 132, 132–133 Spinocerebellum, 337 Spinohypothalamic pathway, 414 Spinolimbic pathway, 414 Spinomesencephalic tract, 413–414 Spino-ponto-spinal reflex mechanism, 68 Spinoreticular fibers, 59 Spinoreticular system, visceral afferents, 59 Spinoreticular tract, 414 Spinothalamic tract, 85, 123, 178, 413, 422 Spiral ganglion, 209 Splanchnic nerves, 63 Splenium, 244–245, 245 Stapedius muscle, 201 Stapes, in middle ear, 201 Stellate cells, cerebellar cortex, 342, 342 Stem cells, Stereocilia, 204, 217 Stereopsis, 303 Sternocleidomastoid muscle, 194, 195 STN (see Subthalamic nucleus (STN) ) Strabismus, 236b Straight sinus, 40 Stretch (myotatic) reflex, 88–89, 89 Stria terminalis, 361, 380 Stria vascularis, 203 Striatum, 278, 278, 312 Striola, 218 S-type cones, 294, 304 Subarachnoid cisterns, 38 Subarachnoid hemorrhage, 41 Subarachnoid space, 40, 41, 78 Subcallosal gyrus, 376, 377 Subcortical structures, limbic system, 376, 378 Subdural space, 40, 41 Subiculum, 378 Submandibular ganglia, 182 Submucosal plexus (of Meissner), 63 Substance P, pain processing, 412 Substantia gelatinosa, 178 Substantia nigra (SN), 225, 313, 315, 355 Subthalamic fasciculus, 317 Subthalamic nucleus (STN), 312, 313, 313 Subthalamus, 33 Sudden infant death syndrome (SIDS), 231 Sulci, 28, 75 Sulcus limitans, 101 Superior cerebellar peduncle (SCP) afferent tracts, 333, 334 efferent tracts, 333, 334, 335 spinocerebellar connections, 337 Suprachiasmatic nucleus (SCN), 361, 371 Supraoculomotor area (SOA), 167 Sustentacular cells, olfactory system, 396 Sweat glands, 369 5/9/2011 9:23:10 PM Index Sweet taste, 401 Sympathetic chain, 307 Sympathetic efferents, 65 Sympathetic fibers, 71 Sympathetic ganglia, 65 Sympathetic nervous system, 58, 60, 62–63, 63 Sympathetic visceromotor neurons, 67 Synapses, Synaptic cleft, Synaptic input, 179–180 Synaptic targets, pain processing, 410–411, 411, 424 Synaptic transmission chemical synapses, 14, 14 electrical synapses, 13–14, 14 signal transduction EPSP and IPSP, 15 ionotropic receptors, 16 metabotropic receptors, 16 temporal summation, 14, 16, 16 types of receptors, 17 Synaptically evoked potential, 14 T Tabes dorsalis, 122b, 123 Tactile agnosia, 251 Target neurons, for lateral corticospinal tract, 140 Taste, 252–253 (see also Gustatory system) buds, 400 circumvallate papillae, 401 foliate papillae, 401 fungiform papillae, 400 pore, 401 receptor cells, 401 SVA fibers, 110, 188 Tears production, 184 Tectorial membrane, 204 Tectospinal tract, 138, 142, 144, 146 Tectum, 94, 94 Tegmentum, 94, 94, 220, 224 of midbrain, 153 Telencephalon, 25, 27 Temperature gradient, 165 regulation lesions, 368–369, 369 sweat glands, 369 Temporal gyrus, 282, 282 superior, 30, 251, 252 Temporal lobe cerebral cortex primary sensory areas, 253 temporal association areas, 257, 257 epilepsy, 392b ventral stream, 303 Temporal summation, 211 Temporospatial summation, 5, 16 Tendinous ring, 151, 151 Tensor tympani, 201 Tentorium cerebelli, 39 Thalamic reticular nucleus (TRN), 273, 283 Thalamohypothalamic fibers, 361 Thalamus, 33 anatomy, 271, 272–273 blood supply, 284, 285 driver inputs, 273 nuclei association nuclei, 281–282, 281–282 intralaminar nuclei, 282–283, 283 relay nuclei, 274–281, 276–278, 280 reticular nucleus, 283–284, 284 pain syndrome, 287 Thermal and mechanical stimulation, C fibers, 124 Thermally gated ion channels, 10 Thermoreceptors, 50 Third branchial arch, 190, 193 Third ventricle, 36 Third-order neurons, 122 Thirst center, hypothalamus, 371 Thoracic viscera, 59 Krebs_Index.indd 433 433 Tongue gustatory system, 400 taste distribution, 401 Tonic firing, thalamic neurons, 273, 275, 286 inhibition, basal ganglia, 316 noradrenergic neurons, 227 Tonotopic arrangement, 252 Tonotopy, 205 Tonsillar herniation, 233, 330b Tract of Lissauer, 178 Tractus solitarius, 403 Transient receptor potential (TRP) channels, 409 Transthalamic connections, 281, 281 Transverse sinus, 40 Trapezius muscles, 194, 195 Trapezoid body, medial nucleus, 211 Trigeminal chemoreception, 404 Trigeminal chief sensory nucleus, 106 Trigeminal ganglion, 106 Trigeminal meniscus, 178 Trigeminal (CN V) nerve, 40, 98, 106, 108, 177t, 310, 423 chief sensory nucleus, 176 mandibular division, 176 maxillary division, 176 modalities and functions of, 175 motor component of mid-pons, location of, 182 tracts associated with, 182 motor nucleus, 176 ophthalmic division of, 176 sensory component of chief sensory nucleus of, 177–178, 178 mesencephalic nucleus of, 179–180, 180, 181 spinal tract and, 178–179, 179, 180 Trigeminal nuclear complex, 182 Trigeminothalamic tract, 178–179, 179 posterior, 178 Tripartite synapse, TRN (see Thalamic reticular nucleus (TRN) ) Trochlea, 151 Trochlear (CN IV) nerve, 100, 106, 106 eye movements control, 152, 153, 155 TRPV1 receptor, 408 Truncal movement, cerebellum, 337 Truncal stability, 139 Tuber cinereum, 358, 358 Tufted cells, 397 Tympanic membrane, 200, 201 U Umami taste, 403 UMN (see Upper motor neurons (UMNs) ) Uncinate fasciculus, 243, 244 Uncus, limbic system, 377 Unmyelinated axons, 11 Upper limb, flexors of, 144 Upper motor neurons (UMNs), 73, 138, 148 basal ganglia, 311, 311 cortical motor system, 348–349, 349 lesions, 350b, 354, 354t red nucleus, 349, 349 reticular formation, 349, 349 vestibular nuclei, 349, 349 Urethral sphincters external, 67 innervation, 67 internal, 67 Utricle, 216, 218, 220 Uveal tract, 290 V Vagal ganglion, 192 Vagus (CN X) nerve, 59, 65, 96, 110, 111, 192t dorsal motor nucleus of, 65 inferior vagal (nodose) ganglion, 190 motor component of general visceral efferents, 193 special visceral efferents, 193 sensory component of general sensory afferents, 191–192 general visceral afferents, 192–193 superior ( jugular) vagal ganglion, 190 Vallate papillae, 401 Vasodepressor, 65 Vasodilation, 190 Vasopressin, 364 fear conditioning, 388 regulation, 364–365 Vasopressor, 65 Venous hemorrhage, 41 Venous sinuses, 39 Ventral amygdalofugal fibers, 361, 380–381 Ventral pathway, 303 Ventral posterolateral (VPL) nuclei, 122, 275, 276, 286 Ventral posteromedial (VPM) nucleus, 275, 276 ipsilateral, 189 of thalamus, 178, 187, 192 Ventral striatum, 358 Ventral tegmental area (VTA), 225–227, 226, 389 Ventral tier, 272 Ventricular system, 37, 94, 94 CSF, 35–39, 38, 38t lateral ventricles, 36 Ventromedial hypothalamus, 370–371 Vergence centers, 167, 170 optic reflexes, 308 Vermis, 35, 329 Vertebral arteries, 41, 112 Vertebral–basilar system, 41 Vertical gaze, 166, 166 Vesical plexus, 67 Vestibular (scarpa) ganglion, 218 Vestibular information, 162 Vestibular nuclei, 142, 154, 163, 349, 349 lateral and medial, 220 Vestibular nystagmus, 164, 164, 165 Vestibular organ, 163 Vestibular system, 150 Vestibule, 215, 216, 216 Vestibulocerebellum, 336 Vestibulocervical reflex, 220 Vestibulocochlear (CN VIII) nerve, 98, 108–109, 218 hearing and balance, 199 Vestibuloocular reflex (VOR), 155, 220 contralateral abducens and oculomotor, 163 horizontal canal, 163 wiring diagram for, 163 Vestibulospinal reflex, 220, 221 Vestibulospinal tract, 138, 142–143, 144, 147 lateral, 142, 143, 154 medial, 142, 154, 220 Viral infection, Bell palsy, 185 Visceral afferents, 65 Visceral motor (parasympathetic) nucleus, of CN III, 153 Visceral nervous system afferents and efferents, 58, 69 motor system craniosacral outflow of, 64t enteric system, 63, 63–64 hypothalamic input to, 64, 64 neurotransmitter activation of, 60, 61 parasympathetic system, 60, 61, 62 structure of, 60 sympathetic system, 60, 62–63, 63 pelvic splanchnic nerves, 72 reflex systems bladder function, control of, 65–69, 66, 68, 72 blood pressure control, 65, 65 pathways, 59 regulation of, 65 sexual responses, 69–71, 70 sensory afferents, 72 pain, 59 physiological functions, 59, 59 in spinal cord, 84 5/9/2011 9:23:10 PM 434 Visceral sensations, 188 Visual agnosia, 252 Visual association area, 252 Visual cortex, 251, 251–253 association, 282 Visual field, 299, 301, 301–302, 302b Visual pathway bipolar cells, 296–298, 297 ganglion cell, 298–299, 299 geniculate nuclei, lateral, 299, 300–301 optic chiasm and tract, 299–300, 300 optic radiations, 301, 301–302, 302b Visual salience, 282 Visual stimuli, 164 Visual system calcarine cortex, 289 clinical visual deficits, 302b color vision color information processing, 304, 304–305 influences behavior, 305 cortical processing dorsal pathway, 303–304 primary visual cortex, 303 ventral pathway, 303 eye, 289 cornea, 290, 290 pupil, 290 optic reflexes accommodation, 306, 307–308 corneal blink reflex, 308, 308 Krebs_Index.indd 434 Index pupillary light reflex, 306, 306–307 pupillodilator reflex, 307, 307 retina ganglion cell layer, 292, 293 inner limiting membrane, 292, 293 inner nuclear layer, 292, 293 inner plexiform layer, 292, 293 nerve fiber layer, 292, 293 outer limiting membrane, 292, 293 outer nuclear layer, 292, 293 outer plexiform layer, 292, 293 photoreceptor cells, 293–294, 294 photoreceptor layer, 292, 293 phototransduction, 293, 295, 296 pigment epithelial layer, 291–292, 293 specialization, 291, 292 visual pathway bipolar cells, 296–298, 297 ganglion cell, 298–299, 299 geniculate nuclei, lateral, 299, 300–301 optic chiasm and tract, 299–300, 300 optic radiations, 301, 301–302, 302b Visuospatial working memory, 282, 282 Vitamin A-linked photopigment (opsin), 294 Vitreous body, 290 Voiding, 68–69 Volitional saccades, 161, 161–162 Voltage, 11 Voltage-gated ion channels, Voluntary movement, 138 W Wallenberg syndrome, 235b Warm water caloric testing, 166 Water balance regulation, hypothalamus, 371 Watershed area, 263 Wernicke aphasia, 259 Wernicke area, 29, 214 auditory association area, 252 language processing, classical model, 258 Whiplash injury, 405 White commissure, anterior, 413 White communicating ramus, 63 White matter, 27, 29, 32–33, 33, 36 anterior (ventral) column, 85, 86 and gray matter, 27, 29, 36 lateral column, 85 posterior (dorsal) column, 85, 87 tracts, 262 Wide dynamic range (WDR) neurons, 410, 411 Wind-up, pain processing, 411, 412 Wiring circuit, basal ganglia, 316–319, 316–319 Withdrawal reflex, 89, 90, 416 Working memory, prefrontal cortex, 254 Z Zonule fibers, 290 5/9/2011 9:23:10 PM Krebs_Index.indd 435 5/9/2011 9:23:10 PM ... nuclei: serotonergic Figure 12. 1 Overview of the reticular formation in the brainstem 22 3 Krebs_Chap 12. indd 22 3 5/9 /20 11 8:45:49 PM 22 4 12 Brainstem Systems and Review network of cells that influences... Figure 12. 12 Infolink Krebs_Chap 12. indd 23 3 See Lippincott’s Illustrated Reviews: Pharmacology Neural control of emesis GI = gastrointestinal 5/9 /20 11 8:46:01 PM 23 4 12 Brainstem Systems and Review. .. cerebellar artery Krebs_Chap 12. indd 23 5 5/9 /20 11 8:46: 02 PM 23 6 12 Brainstem Systems and Review Boxes 12. 3 and 12. 4 describe the deficits that may result from occlusion of branches of the posterior cerebral