Toj.su
Faoliyati olii asab az
faoliyati vohidi sokhtori
va funksionalii on, yane
neyron ibtido megirad. Funksiyai neyron az intiqoli
impulshoi asabi iborat ast. Impulshoi asabi yo hayajoni
asabi shakli makhsusi jarayoni susti bioelektriki mebo-
shad, ki dar hududi organizm ba sifati noqili akhbor
khidmat mekunad. Neyron doimo zakhirai muayyani barqi
dorad, ki on dar holati oromii organizm ba 50 milli-
volt (mV) barobar buda, potensiali membrani nomida
meshavad. Dar holati hayajon quvvai barqii yadroi neyron
ba kanori on mayl karda, dar natija tanosubi potensiali
barqii yadro va membrana tagyir meyobad. Dar in zamina
quvvai elektrikie hosil meshavad, ki ba 110 mV barobar
buda, qobil ast har guna amali uzvhoi organizmro faol
gardonad.
Hamaguna tasiroti muhit (mekhaniki, kimyovi, fi-
ziki va g.) dar retseptorho shakl digar karda, ba impul-
shoi asabi mubaddal megardand va mahz dar hamin shakl az
uzvhoi kanori ba sistemai markazii asab va az onjo ba
efektorho rasonida meshavand. Impulshoi asabi guyo «za-
boni» umumii robitai tamomi sokhtorhoi sistemai asab
meboshand. Surati harakati impulshoi asabi az tipi
nakhhoi asabi va shakli akhbor vobastagi dorad. Masalan,
nakhhoi asabii intiqoldihandai dard onro bo surati 1 –
30 m dar yak soniya meguzaronand. Dar nakhhoi asabii hara-
katdihanda boshand surati impulshoi asabi ba 60 to 120
m dar yak soniya barobar ast.
Impulshoi asabie, ki dar neyronho hosil meshavand,
asosi energetikii faoliyati olii asabro tamin mena-
moyand. Sistemai asab dar holati hayajoni doimi qaror
doshta nametavonad va az in ru hayajon dar faoliyati
olii asab ravandi yagona nabuda, ravandi baraksi on –
bozdori niz mavjud ast. Hamin tavr du ravandi asabi:
hayajon va bozdoriro farq mekunand. Bo navbat hamdigarro
ivaz namudani in ravandho mutadili va tanosubi
funksiyahoi olii asabro nigoh medorad. Agar ravandi
hayajon vujud namedosht, faoliyati sistemai asab umuman
imkonnopazir mebud, va agar ravandi bozdori namebud on
goh hujayrahoi asabi dar zeri tasiri hayajoni purquvvat
nobud meshudand.
Jorishavii ravandhoi asabi ba chunin qonunhoi aso-
sii faoliyati olii asab tobe ast:
Qonuni irradiatsiya (pahnshavi) va konsentratsiya
(jamshavi), ki muvofiqi on hayajoni dar natijai tasiri
yagon angezanda ba vujudomada dar yak qita naistoda, dar
mintaqahoi gunoguni qishri magzi sar pahn meshavad (ir-
radiatsiya). Masalan, odam az musiqi ba vajd omada, sar
va andomashro mejunbonad va poy mekubad, yane hayajon
avval dar markazi darki musiqi ba vujud omada, sipas ba
mintaqahoi harakati pahn shud. Hamzamon dar hududi
markazi hayajon ravandi bozdori ba amal omada, hayajonro
mahdud menamoyad va mutamarkaz mekunad (konsentratsiya).
Hudi ravandi bozdori niz avval pahn va bad jam mesha-
vad.
Qonuni induksiyai baynihami. Muvofiqi in qonun,
agar dar yagon mintaqai qishri magzi sar hayajon ba vujud
oyad, on goh dar mintaqai hamsoya ravandi bozdori faol
megardad (induksiyai manfi) va yo baraks, agar dar yak
qitai qishr bozdori ba amal oyad, ongoh dar mintaqai
hamsoya hayajon avj megirad (induksiyai musbi). Masalan,
kudak pesh az khob injiqI mekunad va megiryad. In hodisa-
ro chunin sharh dodan mumkin ast, ki bozdorii dar marka-
zi khob ba vujudomada dar
hayajonro faol menamoyad.
Hayajon va bozdo-
riro dar qishri nim-
kurrhoi magzi sar for-
matsiyai retikulyari ba
tanzim medarorad. On
dar qismi tana yo kundai
magzi sar joygir buda,
bo angushti khurdi panja
barobar ast. Dar in
qita miqdori kaloni
hujayrahoi asabii do-
roi shokhahoi daroz jam
omadaand, ki majmui
onho shabakai zichi
hujayraviro ba vujud
ovardaast. Hudi nomi
in sokhtori asabi niz az
injost, ki manoyash tashkilai shabakavi meboshad. For-
matsiyai retikulyari yak nav manbai energiya baroi
sokhtorhoi qishrii magz ast. On impulshoi asabii az
uzvhoi kanori oyandaro korkard namuda, ba qishr mefiri-
stad. Funksiyai formatsiyai retikulyariro dar misoli ze-
rin didan mumkin ast. Tasavvur mekunem, ki shakhse zangi
muhimi telefoniro intizor ast, vale khudash az telefon
dur, masalan dar oshkhona qaror dorad. Dar atrof sadoi
suhbati hamsoyaho, az tireza sadoi kucha va moshinho ba
gush merasad. Bo vujudi on ki hamai in sadoho bo rohhoi
asabii khos to ba markazhoi shunavoii magz rafta mera-
sand, odam ba onho etibor namedihad, zero in tasirot
pesh az ba markazhoi muvofiq rasidan tavassuti format-
siyai retikulyari meguzarand. Az in sokhtor ba vositai
rohhoi gayrikhos ba markazhoi shunavoi impulshoi asabie
firistoda meshavand, ki tasiri bozdoranda dorand. In
tasirot hassosii magzro nisbati sadohoi gayriasosi
past megardonad. Va ana sadoi zangi telefon. Bo vujudi
on ki sado nihoyat past buda, aniq nest, ki az telefon ast yo
az joi digar, magz zud ba on aksulamal zohir mekunad.
Odam ba tarafi sado nigoh mekunad, ba sui on qadam
meguzorad va gayra. CHaro na sadoi balandi kucha, balki
sadoi nihoyat past va bazur shunidashavandai telefon
hayajonro ba vujud meovarad? Zero dar in holat format-
siyai retikulyari tavassuti rohhoi gayrikhos impulshoi
muvofiq firistoda hassosii magzrro afzoish medihad.
Az khulosai dar bolo ovardashuda pay burdan mumkin
ast, ki akhboroti az uzvhoi his ba magz dokhilshavanda dar
qishr tahlil karda meshavand. Faoliyati tahlilii magz
imkoniyat medihad, ki masalan, mo kalimahoi «shir» va
«rish»- ro az hamdigar farq kunem, harchand, ki tarkibi
ovozii onho yakkhela ast. Protsesi tahlili akhbor hanuz az
retseptor ogoz shuda, zina ba zina to markazhoi qishri
idoma meyobad. Paiham shakl, zudi, quvva, mazmun va digar
khususiyathoi tasirot tahlil karda meshavad. Mahz tavas-
suti chunin tahlili hamajoniba mo metavonem «pahluhoi»
sukhan va nozukihoi bayonro dark namoem. Tahlil tasiri
angezanda bo amali tarkib aloqamand ast, akhborot dar
sokhtorhoi asabi na tanho tahlil, balki tarkibro niz az
sar meguzaronand. Mahz tavassuti ama-
li tarkib az tasiroti parokanda ob-
razhoi tomi ashyo va hodisaho ba vujud
meoyand, ki darki purrai vaziyati
olami atrofro tamin mekunand.
Faoliyati tahlili – tarkibii magzi
sar bo kori analizatorho aloqamand ast. Muallifi in
istiloh olimi I. P. Pavlov (1849-1936) meboshad. Anali-
zator gufta, olim sistemai nisbatan mustaqili organi-
kiro mefahmid, ki korkardi makhsusi akhboroti az jonibi
uzvi alohidai his qabulshudaro dar tamomi darajahoi on
tamin menamoyad. Hamin tavr, analizator chunin dast-
gohi asabiest, ki tahlili amiqi bo tarkib aloqamandi
tasiroti muhitro ba amal mebarorad. Analizator az se
qism iborat ast: 1) qismi qabulkunanda – retseptor; 2)
qismi guzaronanda – nakhhoi asabii markazshitob va 3)
qismi markazi – sohai muvofiqi qishr.
Tahlil va tarkibi tasirot, ki dar analizator
anjom doda meshavad, dar qishri magzi sar dogi
lagjandai hayajonro ba vujud meovarad.
Sahmi buzurgro dar fahmishi on, ki kori magzi sar
va faoliyati olii asab bo zuhuroti psikhiki va raftor chi
guna aloqamand ast, fiziologi rus I. M. Sechenov (1829-
1905) guzoshtaast. U soli 1863 risolai «Reflekshoi magzi
sar» – ro ba chop rasonid, ki minbad zaminai
tadqiqothoi ziyod dar samti omuzishi mekhanizmhoi
faoliyati olii asab gardid. Dertar I. P. Pavlov
aqidahoi I. M. Sechenovro inkishof doda, mekhanizmi
shakl giriftoni raftori navro dar hayvonot kashf kard,
ki bo nomi «reflekshoi sharti» mashhur ast.
Mafhumi «refleks» az zamoni Rene Dekart (1596-
1650) hamchun javobi organizm ba angezanda malum ast,
vale asosi ilmii on, hamchunin mekhanizmi hosilshavii
reflekshoi aloqamand bo tagyiroti sharoithoi zist va
muhiti hayotii mavjudotro kashf karda, olim bo hamin ba
paydoishi ilmi nav – fiziologiyai faoliyati olii asab
zamina guzosht. Pavlov dar tajribahoi khud bo sagho
oshkor sokht, ki hangomi ba tavri mutavozi (paraleli) va
takrori peshnihod namudani angezai baroi sagho
beahamiyat va angezai ahamiyatnok, on ba angezai beahami-
yat niz amali javobii ba angezai ahamiyatnok khosbudaro
zohir menamoyad. Hosilshavii chunin raftor ham dar hay-
vonot va ham dar inson ba mavjudiyati shartu sharoiti
muayyan (dar misoli dodashuda peshnihodi paralelii an-
gezahoi ahamiyatnok va beahamiyat) vobasta ast, az in ru
olim in guna aksulamalro «reflekskhoi sharti» nomida,
asosi fiziologii onro hamchun paydoshavii aloqahoi
muvaqqatii asabi sharh dod. Ba sifati mafhumi mukholif,
olim mafhumi «reflekshoi gayrisharti» – ro peshnihod
namud, ki dar zeri on aksulamalhoi dar sathi modarzodi
shakl giriftai organizmro mefahmid. Vaqte ki odam li-
muro chashida didaast va khususiyathoi mazzai onro medo-
nad, hangomi az dur didani on niz dar komi khud turshi
ehsos mekunad, shakhse, ki bekhabar khuroki vayronshudaro
istemol karda, dilbehuzuri ehsos kardaast, dar navbati
digar tanho didani on khohishi qay kardanro ba vujud
meovarad. In misolho namunai reflekshoi sharti mebo-
shand. Hangomi ravshanii baland nimpush kardani chash-
mon, atsazani hangomi ba rohi nafas aftidani jismi be-
gona, judo shudani ashk dar holati mudati ziyod kushoda
nigoh doshtani chashmon va monandi inho misolhoi re-
flekshoi gayrishartand.
Rohe, ki hangomi amali refleksho bo on hayajoni
asabi meguzarad, kamonaki reflektori nomida shudaast,
zero tasviri skhematikii on shakli kamon yo qavsro dorad.
Skhemai kamonaki reflektorii nisbatan sodda chunin
ast: nakhi asabii markazshitob tasiroti az jonibi ret-
septor kabulshuda va ba impulsi asabi tabdildodashudaro
ba markazhoi reflektorii SMA mebarad, ki on dar in jo
tahlil shuda javob ba angezanda hosil meshavad. Javobi
hosilshudaro nakhhoi asabii markazgurez ba effektorho –
uzvhoi harakati mebarand. Hamin tavr hayajon az uzvhoi
kanori ba markaz va az on joy boz ba periferiya barme-
gardad, vale na ba uzvhoi qabulkunanda, yane on na davra,
balki kamonro hosil mekunad. Kamonaki reflektori
amali ham reflekshoi sharti va ham gayrishartiro sharh
medihad. Ammo agar rohi guzarishi hayajon hangomi re-
flekshoi gayrisharti dar sathi modarzodi shaklgirad,
pas hangomi reflekshoi sharti on aloqahoi asabii dar
asosi tasiri takrorii angezanda bavujudomada ast.
Aloqahoi asabi dar asosi takrori bisyorkarata shakl
girifta, mustahkam megardand. Robitai baynihamii in
aloqaho, ki sistemai onhoro tashkil medihad hamchunin
dar asosi takror ustuvor meshavad va asosi raftori oda-
tii odamro tashkil medihand. CHunin sistemai aloqahoi
muvaqqatii shartiro, ki asosi on taqsimoti ustuvori
markazhoi hayajon va bozdori dar qishri magzi sar mebo-
shad, I. P. Pavlov stereotipi dinamiki nomidaast.
I. P. Pavlov faoliyati sharti – reflektorii qishr-
ro faoliyati signalii magz nomid. Zero faolkunandai
in faoliyat angezahoe meboshand, ki ba sifati signalho
khizmat mekunand. Angezahoe, ki az mukhiti atrof ba uzvhoi
hissii odam tasir merasonand, signalhoi darajai yakum yo
sistemai signalii yakum nomida shudand. On baroi odam va
aksari hayvonot umumi ast. Dar barobari in angezaho,
nutq niz baroi odam ba sifati signali khabarrasonanda
baromad karda metavonad va nutq az jonibi olim hamchun
signali darajai duyum yo sistemai signalii duyum baho do-
da shud.
