Role of the nucleus of the optic tract of monkeys on optokinetic nystagmus and optokinetic after-nystagmus: Effects of lesions

$90

18. Motor system II. Oculomotor control NEURONS OF THE OCULOMOTORNUCLEI IN THE HEREDITARY MICROPHTHALMIC RAT: A GOLGI STUDY KOICHI TANAKA, KATSUMI OTANI and SHOEI SUGITA. The T h i r d Department o f Anatomy, School o f Medicine,

Neurons o f

the

oculomotor,

examined by the Golgi method. diameter,

and m o s t o f

microphthalmic

trochlear, In t h i s

the

and

rats,

abducens

strain of rat,

extraocular

and 15 normal

Chiba U n i v e r s i t y ,

muscles

weighing

nuclei

in

the e y e b a l l do n o t

I-8-I

the

Inohana,

mlcrophthalmic

attach

to

90-110 g (50 days o l d ) ,

the

eyeball.

The b r a i n s were removed and impregnated with

modification

the Golgi-Cox method,

and embedded in

of

or s a g i t t a l

several primary dendrites

that

plane.

Neurons o f

celloidin.

at

X600 m a g n i f i c a t i o n

using

circumference o f the neuron along with i n t e r f a c e d to a personal computer. in the

normal

microphthalmic

and the mutant

the

X-Y

rat.

tapering.

ROLE OF THE NUCLEUS

However,

OF THE OPTIC

under deep a tungstate were cut

the normal

the

smaller

in

The number o f

TRACT

AFTER-NYSTAGMUS:EFFECTS

system.

primary

The a r e a

nuclei.

and

a digitizer

in the areas o f the somata

area and circumference

OF MONKEYS

had

The c o n t o u r o f the neuron was

charting

difference

the t h r e e

at

rat

and the d e n d r i t e s were

the area o f the somata were measured using

t h e r e are fewer s y n a p t i c inputs to the neurons c o n t r o l l i n g

OPTOKINETIC

in

directions.

pantograph

There was no s i g n i f i c a n t

r a t were s i g n i f i c a n t l y

sections

nuclei

less than t h a t in the normal r a t ,

s p a r s e l y branched and t r a v e l e d long d i s t a n c e s with l i t t l e outlined

Serial

these t h r e e

r a d i a t e d and a r b o r i z e d in a l l

d e n d r i t e s in the mutant r a t was s l i g h t l y

were

Sixteen

were s a c r i f i c e d

sodium p e n t o b a r b i t a l .

the coronal

rat

is reduced to about o n e - t h i r d in

anesthesia with 150 ~m in

Chiba 280

of

the

neurons in

These r e s u l t s

the

suggest

that

eye movement in the microphthalmic

rat.

ON O P T O K I N E T I C

NYSTAGMUS

AND

OF LESIONS

T O M O H I K O H A S E G A W A , K O J I H A R A D A ~ T A K A O I K A R A S H I * a n d ~ S A O KATO* D e p a r t m e n t of Otolaryngology, Yamagata U n i v e r s i t y School of M e d i c i n e , Z a o , Y a m a g a t a , J a p a n . # D e p a r t m e n t of O t o l a r y n g o l o g y , S t . M a r i a n n a University School of Medicine, Sugao,Miyamae-ku,Kawasaki,Japan. The slow phase stimulus

velocity

velocity

slow rise to st@ady-state. storage"mechanism nystagmus(OKAN). (NOT) were

In this

placed

unilaterally

acid(l-3ul).In

remaining

NOT lesion.

Other

induced

caused

leaving

the rapid rise

that

lly influenced

monkeys

NOTs were

on the lesion

of the charge

by NOT lesions,in

is unaffected.

NOTs were

side,leaving partially

were

after-

of the optic

monkeys.

totally

damaged,the

intact.

slow In the

slow rise and OKAN

to the e x p a n s i o n

The results

in ipsilateral

0.1%

destroyed,no rise

tract

NOT lesions

or by injecting

the rapid

proportion

normal.

and OKAN

of a "velocity

in the nucleus

knife

in

a subsequent

of optokinetic

in 6 Fuscata

side,in

eye m o v e m e n t s

and vestibular

whose

to steps

rise,and

the activation

side by surgical

a loss of the slow rise

the dynamics

nystagmus

examined

in response rapid

the production

of lesions

on the lesion

whose

reduced

lesions

of OKN were

the three

three m o n k e y s

selectively

with

on the left

rise or OKAN was p r o d u c e d

were

The slow rise reflects

study,effects

two components

nystagmus(OKN)

into two c o m p o n e n t s : a

and is associated

upon

kainic

of optokinetic

can be divided

showed

slow-phase

nystagmus

intact.

These

findings

of the v e l o c i t y

storage

mechanism

of the

that NOT velocity

indicate

are d i f f e r e n t i a -

that OKN and OKAN are a b o l i s h e d , w h i l e

vestibular