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POTENTIAL RELATED TO NO-GO REACTION IN GO/NO-GO DISCRIMINATIVE HAND MOVEMENT ON DIFFERENT AUDITORY STIMULI IN THE MONKEY. HISAE GEMBA, AND KAZUO SASAKI, I n s t i t u t e f o r Brain Research, Facul ty of Medicine, Kyoto Un ivers i ty , Sakyo-ku, Kyoto 606, Japan.

Monkeys M~caca fuscata) were t ra ined for reac t ion - t ime hand movements wi th d i s c r i m i n a t i v e go/no-go aud i to ry s t imu l i , and f i e l d po ten t i a l s were recorded wi th e lectrodes implanted in various cor t ices. Tones of I000 Hz and 2000 Hz were used as go and no-go s t imu l i . They were given to a monkey fo r I0 ms (or 500 ms) in a random order and at a random in te rva l of 5.0-10.0 s. When the monkey l i f t e d a lever by hand w i th in 500 ms a f t e r the s t a r t of go s t imu l i , i t was rewarded, whereas i t could get no reward on no-go s t imu l i , e i t he r by l i f t i n g or not l i f t i n g the lever. A surface- negative, dep th -pos i t i ve po ten t ia l was recorded s p e c i f i c a l l y on the no-go t r i a l in the dorsal bank of the p r i nc ipa l sulcus, j u s t as fo r movement wi th d i s c r i m i n a t i v e v isual s t imu l i (I). The po ten t ia l s ta r ted about 70-80 ms a f t e r onset of no-go s t imu l i , l as t ing fo r about 50-100 ms. The same monkeys were also t ra ined fo r reac t ion - t ime hand movement wi th d i s c r i m i n a t i v e go/no-go v isua l s t imu l i , and were examined wi th the same electrodes. Green and red l i gh t s (500 ms durat ion) were used as go and no-go s t imu l i . In the same monkey, the po ten t ia l re la ted to no-go react ion on d i s c r i m i n a t i v e aud i to ry s t imu l i was recorded in the ros t ra l par t of the dorsal bank of the p r i nc ipa l sulcus, and the po ten t i a l on v isual s t imu l i was in the caudal par t of the same bank. These f ind ings suggest that the dorsal bank of the p r i nc ipa l sulcus is re la ted to higher i n t eg ra t i ve funct ions such as d i sc r im ina t ion , judgement, suppression, etc., and that d i f f e r e n t loc i in th i s c o r t i c a l area are ac t i ve in the funct ions on sensory s t imu l i of d i f f e r e n t modal i t ies . I. Exp. Brain Res., 64 (1986) 603-606.

ACTIVITIES OF SWALLOWING-RELATED NEURONS IN THE CAT MEDULLA OBLONGATA. UMEZAKI, T., MATSUSE, T., HORI, T.

AND KIYOHARA, T. Dept. P h y s i o l . , Saga Medical School , Sa~a 840-01 Japan Many e x p e r i m e n t s on b r a i n stem l e s i o n and s t i m u l a t i o n have s u g g e s t e d t h a t the neurons in the n u c l e u s of

t he s o l i t a r y t r a c t (NTS) and the a d j a c e n t r e t i c u l a r f o r m a t i o n (RF) p l a y a c a r d i n a l r o l e in c e n t r a l programm-

ing of swal lowing . We i n v e s t i g a t e d the u n i t a c t i v i t y of m e d u l l a r y neurons , which were a c t i v a t e d o r t h o d r o - m i c a l l y by s t i m u l a t i o n of the i p s i l a t e r a l s u p e r i o r l a r y n g e a l ne rve (SLN), d u r i n g r e f l e x swa l l owing e l i c i t e d

by wa te r p o u r i n g i n t o the pharynx in the a n e s t h e t i z e d c a t . The m e d u l l a r y neu rons which changed a c t i v i t y on swa l l owing were c l a s s i f i e d i n t o t h r e e types . Type 1 neu rons a r e s e n s o r y neu rons r e l a y i n g SLN a f f e r e n t

i n p u t s . They were r e c o r d e d a lmost e x c l u s i v e l y in the i n t e r s t i t i a l subnuc leus of the NTS j u s t l a t e r a l to th, t r a c t u s s o l i t a r i u s (TS), and were a c t i v a t e d m o n o s y n a p t i c a l l y by i p s i l a t e r a l SLN s t i m u l a t i o n . They i n v a r i a - b ly r e sponded to mechan i ca l s t i m u l a t i o n o f p h a r y n g e a l mucosa, such as wa te r p o u r i n g , r e g a r d l e s s of t he oc -

c u r r e n c e of r e f l e x swa l lowing . Type II neu rons were l o c a t e d in the p a r v o c e l l u l a r d i v i s i o n of the m e d u l l a r y RF (mainly v e n t r a l and v e n t r o l a t e r a l to the NTS), and r e c e i v e d p o l y s y n a p t i c i n p u t s from the i p s i l a t e r a l SLN.

Neuronal a c t i v i t i e s of 67 % of them were t r a n s i e n t l y a c t i v a t e d a round the b e g i n n i n g of an EMG a c t i v i t y of the t h y r o h y o i d muscle d u r i n g swal lowing , and the r e m a i n i n g 33 % were i n h i b i t e d d u r i n g swa l lowing . These r e -

f l e x - i n d u c e d a c t i v i t i e s of type II neurons were obse rved even a f t e r the swa l lowing movement d i s a p p e a r e d in the c u r a r i z e d c o n d i t i o n . They a re p r o b a b l y invo lved in c e n t r a l programming of swal lowing . Type III neu rons

were motoneurons i n n e r v a t i n g swa l lowing muscles , wi th an a n t i d r o m i c r e sponse to i p s i l a t e r a l r e c u r r e n t l a r y n - gea l ne rve s t i m u l a t i o n .