Do toe do dan truyen than kinh de phat hien thtfOng ton TKNV va vi tri cua thtfOng ton.
1. Nguyen ly chung
Co the la moi trtfdng dan dien ki'ch thich vao mot diem cua day than kinh se tao ra dtfpc mot xung dong lan doc theo spi true den tan cung than kinh va dien the hoat dong nay co the gian tiep ghi dtfpc tren da thong qua cac dien ctfc be mat. Ghi thdi gian dan truyen xung dong ta se danh gia dtfpc tinh trang dan truyen cua day than kinh.
Vdi phtfOng phap ghi dien the hoat dong neu tren, ngtfdi thay thuoc co the tham kham dtfpc tat ca cac day than kinh nam d nhtfng noi co the kich thich dien dtfpc (vi du TK chay, TK. mac, TK. hien ngoai, TK. tru, TK. gitfa).
Ben canh ky thuat do toe do dan truyen dung de tham kham phan than cua cac day than kinh, con co mot so
phtfOng phap nghien ctfu phan goc cua chung (phan xa
H, song F, phan xa nhay mat).
2. PhtfOng phap do toe do dan truyen than kinh
a. Phiictng phap do toe do dan truyen van dong
- Kich thich: kich thich vao cac diem doc theo dtfdng di cua day than kinh b&ng xung vuong co do dai 0,5 giay, ctfdng do tang den mtfc thu dtfpc bien do dap tfng ctfc dai.
- Ghi: dien ctfc be mat dat tai khoi co co day than kinh dinh tham dd chi phoi.
- Tmh toe do d in truyen than kinh.
Lj: thdi gian tiem tang de xuat hien dap ting R l khi kich thich vi tri A cua day than kinh (ms)
L2: thdi gian tiem tang de xuat hien dap ting R2 khi kich thich vi tri B cua day than kinh (ms)
D: khoang cach gitia hai diem A va B (mm) V: toe do dan truyen tti B den A (m/s). Theo cong thtic:
D V = ---
L 2 - L 1
Ta tinh dUdc toe do dan truyen than kinh hoac qua he computer ta biet dupe ket qua. Vi du do toe do dan truyen cua day than kinh gitia: diem kich thich d nep khuyu co thdi gian dan truyen xung tti nep khuyu den cho dam kim vao cO doi chieu ngon cai la 8,6miligiay; diem kich thich d cd tay co thdi gian dan truyen xung tti co tay den cho dam kim vao cd doi chieu ngon cai la 4msec thi thdi gian dan truyen tti nep khuyu den co tay la 243,8mm thi toe do dan truyen la 243,8; 4,6 = 53 met moi giay.
Theo Bouche (1983), toe do dan truyen than kinh binh thudng cua day than kinh gitia tti 48 - 50 met/giay cua day than kinh tru la 42 - 45met/giay.
So do 2.1. Do toe do dan truyen than kinh van dong - Nhan dinh:
Giam toe do dan truyen va keo dai thdi gian tiem tang phan anh thiidng ton myelin
Giam bien do cac dap ting phan anh thiidng ton sdi true
b. Phtfcfng phap do toe do dan truyen cam giac
Chi can kich thich tai mot diem la do dUdc van toe dan truyen cua day than kinh cam giac. Co hai cach do:
- Cach do thuan chieu vdi xung cam giac
(orthodromic): dat dien ciic kich thich d ngon chi va dien ciic ghi d goc chi.
- Cach do ngUdc chieu vdi xung cam giac
(antidromic): ta phai doi dien ciic ghi thanh dien ciic kich thich va ngiidc lai.
Sau do ta do khoang cach tii ndi kich thich den noi dat dien cUc. Theo cong thilc :
D
V = ---t t
ta tinh dupe van toe dan truyen hoac qua he thong computer cua may ta se dUdc ket qua.