¢ Groove appears in ectoderm to fuse to form neurol tube bụ 2oth
day after conception Neural tube eventually forms the CNS
¢ During 5** week, modified:
¢ Forebrain: telencephalon and diencephalon ¢ Midbrain: unchanged
¢ Hindbrain: metencephalon and myelencephalon
¢ Part of ectoderm where fusion occurs becomes neural crest
¢ Neural crest forms ganglia of PNS
Trang 4Embrvwonic Deuelopment
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Three Five Adult
primary secondary derivatives
vesicles vesicles of
Wall Cavity Walls Cavities
Prosen- / Telen- /“Ñ-ZàCerebral Lateral
f Ẩ\ aphalon — KA @/ hemisphere ventricles
/}(forebrain ' —\-Thalamus Third
( ( idbrai ) HN \ 77-Hypothalamus ventricle
: imidbrain) cephalon—{ 7 Midbrain Aqueduct
Trang 5Embrvwonic Deuelopment
¢ Telencephalon grows disproportionately forming 2 the hemispheres of the cerebrum
¢ Ventricles and central canal become filled with
cerebral spinal fluid (CSF)
¢ CNS composed of gray and white matter
¢ Gray matter consists of neuron cell bodies and dendrites ¢ White matter (myelin) consists of axon tracts
www.cambodiamed.com
Trang 6Cerebrum
¢ Only structure of the telencephalon
¢ Largest portion of brain (80% mass)
¢ Responsible for higher mental functions ¢ Corpus callosum:
Trang 7Ce | e lor er mm (continued)
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Motor areas involved Central sulcus
with the control of - Sensory areas
voluntary muscles xe ~~ involved with
SZ cutaneous and
Frontah “<2 ™® other senses
ope | | Parietal lobe Motor - General _ speech e Ự, "Vf / A, 7 * II YY ff, ⁄ _ (Broca's | ` Z ) | Lateral 227, nal au) i) sulcus lm Th ó Auditory area Combining
Interpretation of sensor visual
experiences, memory o images, visual
visual and auditory | recognition of
patterns Temporal objects
Trang 8Cerebral Cortex
e Characterized by numerous convolutions
© Elevated folds: gyri
© Depressed groves: sulci
@ Frontal lobe:
© Anterior portion of each cerebral hemisphere
â Precentral gyri:
 Contains upper motor neurons
¢ Involved in motor control
® Body regions with the greatest number of motor
innervation are represented by largest areas of motor
Trang 9€Cerebral Certex Copyright © The McGraw-Hill Companies, Inc Permission required for reproduction or display \ Central sulcus _ NEG 4 oP | > Sensory area —\Lower / PS TƯ _/Trunk ` | ' Úp Ps _ THũmb, arm f Pelvis | /a
fingers, ` Upper ku h ower
Trang 10€Cerebral Certex
¢ Parietal lobe:
¢ Primary area responsible for perception of somatesthetic sensation
Trang 11€Cerebral Certex ¢ Occipital Lobe: ¢ Primary area responsible for vision and coordination of eye movements ¢ Insula:
¢ Implicated in memory encoding
¢ Integration of sensory information with visceral
responses
¢ Coordinated cardiovascular response to stress
Trang 12Visualizing the Brain ¢ X-ray computed tomography (CT):
¢ Complex computer manipulations of data obtained from x-ray absorption by tissues of different densities
° Soft tissue
¢ Positron-emission tomography (PET):
¢ Radioisotopes that emit positrons are injected into blood stream
¢ Collision of positron and electron result in emission of gamma rays
¢ Pinpoint brain cells that are most active
¢ Brain metabolism, drug distribution
¢ Magnetic resonance imaging (MRI):
¢ Protons (H*) respond to magnetic field, which align the protons
¢ Emit a radio-wave signal when stimulated
Trang 14EEG Patterns
Alpha:
c Recorded from parietal and occipital regions
Person is awake, relaxed, with eyes closed
10-12 cycles/sec
Beta:
c S$trongest from frontal lobes near precentral gyrus
Produced by visual stimuli and mental activity Evoked activity 13-25 cycles/sec Theta: c Emitted from temporal and occipital lobes Common in newborn Adult indicates severe emotional stress 5-8 cycles/sec Delta:
« Emitted in a general pattern
Common during sleep and awake infant
In awake adult indicate brain damage
Trang 15EEG Sleep Patterns
¢ 2 types of EEG patterns during sleep:
¢ REM (rapid eye movement):
¢ Dreams occur
¢ Low-amplitude, high-frequency oscillations ¢ Similar to wakefulness (beta waves)
¢ Non-Rem (resting):
¢ High-amplitude, low-frequency waves (delta waves) ¢ Superimposed on these are sleep spindles:
¢ Waxing and waning bursts of 7-14 cycles/sec ¢ Last for 1-3 sec
Trang 16Basal Nuclei (basal ganglia)
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° Mosses of gray motter Motor cerebral corte
composed of neuronal cell
bodies located deep within
white matter Claustrum | | Thalamus ⁄
¢ Contain: Basal Lent Putamen Pa das
¢ Corpus striatum: ¢ Caudate nucleus P nuclel InucleuslGlobus .` Corpus _ |Lentiform pallidu ˆ 4 ¢ Lentiform nucleus: striatum [ƒ8bÔ
Trang 17€Cerebrel Laterelizetien Copyright © The McGraw-Hill Companies, Inc Permission required for reproduction or display e Cerebral dominance: « Specialization of one hemisphere ° Left hemisphere: "More odept in language œnd analytical abilities ° Damage: te ˆÌ
¢ Severe speech problems ; WF Ith g
Trang 18Language
Broca’s area:
¢ Involves articulation of speech
¢ In damage, comprehension of speech in unimpaired Wernicke’s area:
¢ Involves language comprehension
¢ In damage, language comprehension is destroyed, but speech is rapid without any meaning Angular gyrus: ¢ Center of integration of auditory, visual, and somatesthetic information ¢ Damage produces aphasias Arcuate fasciculus:
¢ To speak intelligibly, words originating in Wernicke’s area must be
Trang 19-_ lmportơnt in the neurdl bosis of
emotional states are
hypothalamus and limbic
system
e Limbic system:
c Group of forebrain nuclei and fiber tracts that form a ring around the brain stem
* Center for basic emotional drives
© Closed circuit (Papez circuit):
© Fornix connects hippocampus
to hypothalamus, which projects to the thalamus which sends
fibers back to limbic system
Trang 20Emotien Til: Mettiuetieon (continued)
¢ Areas or the hypothalamus and limbic system are
involved in feelings and behaviors ¢ Aggression: ¢ Amygdala and hypothalamus ¢ Fear: ¢ Amygdala and hypothalamus °Ổ Feeding:
¢ Hypothalamus (feeding and satiety centers)
¢ Sexual drive and behavior:
¢ Hypothalamus and limbic system
¢ Goal directed behavior (reward and punishment):
Trang 21¢ Short-term:
¢ Memory of recent events
¢ Medial temporal lobe:
¢ Consolidates short term into long term memory
¢ Hippocampus is critical component of memory
¢ Acquisition of new information, facts and events requires both the medial temporal lobe and
hippocampus
Trang 22Long-Term Memor
¢ Consolidation of short-term memory into long-term memory
¢ Requires activation of genes, leading to protein synthesis and formation of new synaptic connections
¢ Altered postsynaptic growth of dendritic spines in area of contact
¢ Cerebral cortex stores factual information:
¢ Visual memories lateralized to left hemisphere
¢ Visuospatial information lateralized to right hemisphere
¢ Prefrontal lobes:
¢ Involved in performing exact mathematical calculations
Trang 23Long-Term Potentiation
° Type of synaptic learning
« Synapses that are 1* stimulated at high frequency will subsequently exhibit increased excitability
° In hippocampus, glutamate is NT
a Requires activation of the NMDA receptors for glutamate ¢ Glutamate and glycine or D-serine binding and partial
depolarization are required for opening of channels for Ca2* and Nat’
° May also involve presynaptic changes:
© Binding of glutamate to NMDA receptors and simultaneous depolarization, open receptor channels for Ca"
- Ca’ causes long-term potentiation in postsynaptic neuron, release of NO from postsynaptic neuron
- NO acts as a retrograde messenger, causing release of NT
Trang 24Neuronel $tem Cells in Learning
œnd Memor
¢ Neural stem cells:
¢ Cells that both renew themselves through mitosis and produce differentiated neurons and neuroglia
¢ Hippocampus has been shown to contain stem cells (required for long-term memory)
¢ Neurogenesis:
¢ Production of new neurons
Trang 25Thalœmu‡ and Epithaleamu$
-_ Tholqamu:s:
2 Composes 4/5 of the diencephalon
- Forms most of the walls of the 3" ventricle
« Acts as relay center through which all sensory information (except olfactory) passes to the cerebrum
¢ Lateral geniculate nuclei:
¢ Relay visual information
¢ Medial geniculate nuclei:
* Relay auditory information
¢ Intralaminar nuclei:
- Activated by many sensory modalities
¢ Projects to many areas
= Promotes alertness and arousal from sleep
° Epithalamus contains:
« Choroid plexus where CSF is formed
« Pineal gland which secretes melatonin
Trang 26Hypothalamus
¢ Contains neural centers for hunger, thirst, and body temperature
¢ Contributes to the regulation of sleep,
wakefulness, emotions, sexual arousal, anger, fear,
pain, and pleasure
¢ Stimulates hormonal release from anterior pituitary
¢ Produces ADH and oxytocin
Trang 27¢ Posterior pituitary:
¢ Stores and releases ADH (vasopressin) and oxytocin
Trang 28¢ Contains: ¢ Corpora quadrigemina: ¢ Superior colliculi: ¢ Involved in visual reflexes ¢ Inferior colliculi: ¢ Relay centers for auditory information ¢ Cerebral peduncles: ¢ Composed of ascending and descending fiber tracts ¢ Substantia nigra: ¢ Required for motor coordination ¢ Red nucleus:
¢ Maintains connections with cerebrum and cerebellum
Trang 29¢ Metencephalon:
¢ Pons:
¢ Surface fibers connect to cerebellum, and deeper fibers are part of motor and sensory tracts
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¢ Contains several nuclei associated with
cranial nerves V, VI, VII
¢ Contains the apneustic and
pneumotaxic respiratory centerss
¢ Cerebellum:
¢ Receives input from proprioceptors
¢ Participates in coordination of Midbrain~
movement Pons-
¢ Necessary for motor learning, Brain stem Pneumotaxic area
coordinating different joints during respiratory Apneustic area movement, and limb movements centers Rhythmicity area
Reticular formation—\ _ Medulla oblongata~
Trang 30
n in fa yy a@ i Sy (continued)
Myelencephalon (medulla oblongata):
All descending and ascending fiber tracts between
spinal cord and brain must pass through the medulla
¢ Nuclei contained within the medulla include VIII, IX, X, XI, XIl ¢- Pyramids:
- Fiber tracts cross to contralateral side
Vasomotor center:
- Controls autonomic innervation of blood vessels
Cardiac control center:
- Regulates autonomic nerve control of heart
Regulates respiration with the pons
|
|
|
Trang 31¢ Reticular Formation:
¢ Complex network of nuclei and nerve fibers within
medulla, pons, midbrain, thalamus and hypothalamus
¢ Functions as the reticular activating system (RAS)
¢ Non specific arousal of cerebral cortex to incoming sensory information
Trang 32Ascending Spinal Tracts
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e nvev sensor 4V, ostcentral gyrus
- xen h1 i Th Ñ
cutaneous receptors, Thư |
proprioceptors and WiE đề eral R t visceral receptors to | py cerebral cortex cổ | về al y w _ {axons of second-order a a ; ~~ spinothalamic
° Sensory fiber tract | Medulla \ | tract (axons of
decussation may occur (Z_ oblongata —Fascicul tus 4p Va © second-order
Telok iar) =
cord sensory neurons) jem Pain
Joint stretch receptor receptor
(proprioceptor)
Spinal cord (not part of
asciculus gracilis spinothalamic
cons of first-order | ⁄ j tract) nsory neurons) ey tm _
Trang 33De¿cending $pinal Treaet$
¢ Pyramidal (corticospinal)
tracts descend directly without synaptic
interruption from cerebral
cortex to spinal cord
¢ Function in control of fine
movements that require dexterity ¢ Reticulospinal tracts (extrapyramidal): ¢ Influence movement indirectly
¢ Gross motor movement
Trang 34Cranial and Spinal Nerves
° Cranial nerves:
© 2 pairs arise from neuron cell bodies in forebrain © 10 pairs arise from the midbrain and hindbrain
Roman numerals refer to the order in which the nerves are positioned from front of the brain to the back
« Most are mixed nerves containing both sensory and motor fibers e Spinal nerves: © 31 pairs grouped into 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and | coccygeal « Mixed nerve that separates near the attachment of the nerve to spinal cord
Produces 2 roots to each nerve
Trang 35Reflex Are
Unconscious motor WWW .carmbodiamed com
response to a sensory Copyright © The MoGraw-Hill Companies, Inc Permission required for reproduction or displa
stimulus
: : Cell
Stimulation of sensory Dorsal root body of Dorsal
receptors evoRes APs that ganglion neuron root SG ; Sensor are conducted into spinal » ngù†nn ` Dorsal cord a: aa tk Association
¢ Synapses with association neuron _ |
neuron, which synapses (interneuron) — with somatic motor White —_
neuron matter :
Conducts impulses to Tay youre
muscle and stimulates a Spinal ⁄ Ventra “Effector (muscle)
reflex contraction cord
¢ Brain is not directly
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