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Activity of hand movement-related neuorns in the posterior parietal cortex of monkeys
$46 RESPONSE PROPERTIES AND MORPHOLOGICAL FEATURES OF NON-PYRAMIDAL NEURONS IN THE CAT PARIETAL CORTEX TETSURO YAMAMOTO, AKIO SAMEJIMA~ AND HIROSHI OKA DEPARTMENT OF PHYSIOLOGY, FUKUI MEDICAL SCHOOL, FUKUI 9 1 O - l l ,
JAPAN
E l e c t r o p h y s i o l o g i c a ] and morphological s t u d i e s on non-pyramidal neurons in the cat p a r i e t a l c o r t e x were performed under p e n t o b a r b i t a l a n e s t h e s i a ( i n i t i a l dose o f 35mg/kg, i . p . and a d d i t i o n a l dose o f 5-10mg/kg, i . v . every 2 h o u r s ) . A f t e r craniotomy, s t i m u l a t i n g e l e c t r o d e s were i n s e r t e d i n t o the b i l a t e r a l c e r e b e l l a r n u c l e i ( C N ) , the i p s i l a t e r a l t hal ami c VA and LP and the i p s i l a t e r a l pontine nuclei(PN). ] n t r a c e l l u l a r r e c o r d i n g was performed with a glass m i c r o e l e c t r o d e f i l l e d w i t h 5~ HRP d i s s o l v e d in 0.2M K - a c e t a t e . A f t e r checking the e l e c t r o p h y s i o l o g i c a l f e a t u r e s , HRP was i n j e c t e d i o n t o p h o r e t i c a l l y with an anodal c u r r e n t pulse( 2-5nA in i n t e n s i t y , 300ms in d u r a t i o n and l-2Hz). A t o t a l number of lO non-pyramidal neurons from v a r i o u s c o r t i c a l l a y e r s were recovered with HRP s t a i n i n g . Six o f these neurons were analyzed on t h e i r responsiveness to s t i m u l a t i o n o f the CN, VA, LP and PN. The l a t e n c i e s o f CN-EPSPs were 3.0-5.7ms, those o f VA-EPSPs were l.O-2.4ms and those o f LP EPSPs were 1.5-2.0ms. The thalamic EPSPs from both VA and LP s t i m u l a t i o n were considered to be o f a monosynaptic nature from t h e i r s h o r t l a t e n c ] e s and the s p a t i a l summation by double shock s t i m u l i at a s h o r t i n t e r v a l . A neuron located in l a y e r V-VI r ecei ved a r e c u r r e n t EPSP by PN s t i m u l a t i o n . M o r p h o l o g i c a l a n a l y s i s r e v e a l e d t h a t neurons s t a i n e d with HRP were c l a s s i f i e d i n t o t h r e e groups by t h e i r soma d e n d r i t i c morphology and axonal t r a j e c t o r y , i . e . , basket c e l l ( m u l t i p o l a r c e l l ) , b i t u f t e d c e l l and spiny or s p a r s e l y spinous s t e l l a t e c e l l . Basket c e l l s were located in l a y e r s I I , I l l , V and VI. These neurons had long h o r i z o n t a l axon c o l l a t e r a l s w i t h presumed p e r i c e l l u l a r s y n a p t i c nests. The t e r r i t o r i e s o f the axon c o l l a t e r a l s were as l a r g e as 34mm in the m e d i o l a t e r a l plane. An e l e c t r o n mic r oscopi c exami nat i on confirmed t h a t the f i n e s t r u c t u r e o f the soma and d e n d r i t e was s i m i l a r to t h a t o f GAD-positive neurons r e p o r t e d in o t h e r cortices. The stem axon was myelinated, and t h i s is c o n s i s t e n t with the f i n d i n g o f the l i g h t microscopic o b s e r v a t i o n o f HRP s t a i n i n g neurons. Concerning neurons u n c h a r a c t e r i z e d electrophysiologically, a s p a r s e l y spinous neuron located in a deeper p a r t o f l a y e r I I showed a l o c a l i z e d axonal r e g i o n , which seems to correspond t o the s o - c a l l e d double bouquet c e l l s . Another spiny neuron ]n l a y e r VI had a s i m i l a r axonal t r a j e c t o r y to p r o j e c t i n g neurons. The p r e s e n t study shows t h a t the i n t r a c o r t i c a l network o f the presumed i n h i b i t o r y i n t e r n e u r o n s spread much w i d e r ( 3 4mm) than t h a t of the c o r t i c a l column(O.5-1mm). The monosynaptic a c t i v a t i o n o f i n t e r n e u r o n s by thalamic s t i m u l a t i o n may be due to axon r e f l e x in some p a r t , whech a c t i o n should be f u r t h e r s t u d i e d . ACTIVITY MONKEYS.
OF H A N D
MOVEMENT-RELATED
NEUORNS
IN T H E P O S T E R I O R
PARIETAL
CORTEX
OF
MASATO TAIRA, HIDEO SAKATA, HIDETOSHI SHIBUTANI, SEIICHIRO M I N E .I A. P. GEORGOPOULOS*2; D~p. Neurophysiol., Tokyo Met. Inst. of Neuro~ci., 2-6 M u s a s h i d a i F u c h u T o k y o 183; Dep. of N e u r o s u r g e r y , C h i b a Univ., C h i b a ; ~ J o h n s H o p k i n s U n i v . Med. Sch. The p a r i e t a l a s s o c i a t i o n cortex is known to be c o n c e r n e d with v i s u a l l y guided m o v e m e n t of the hand as w e l l as with p e r c e p t i o n of space and body. M o u n t c a s t l e et al. (1975) r e c o r d e d c e l l s r e l a t e d to r e a c h a n d m a n i p u l a t i o n in t h i s r e g i o n . In o r d e r to s t u d y t h e i r f u n c t i o n a l characteristics, we a n a l y z e d the activity of neurons in the inferior p a r i e t a l l o b u l e of J a p a n e s e m a c a q u e monkeys during motor t a s k s u s i n g a v a r i e t y of m a n i p u l a n d a ; a l e v e r , a s m a l l knob, a s m a l l k n o b in a g r o o v e a n d a p u s h b u t t o n . F i r s t , the m o n k e y f i x a t e d a s m a l l r e d l i g h t in f r o n t a n d pressed a key. W h e n the light turned green, it r e l e a s e d the key and reached to the m a n i p u l a n d u m and h e l d it for one or two seconds. This task i n c l u d e d three epochs : t h e "set" period, t h e " r e a c h i n g " a n d the " m a n i p u l a t i o n " p e r i o d . We r e c o r d e d 236 neurons in the posterior p a r i e t a l cortex, of which sixty-eight showed a c t i v i t i e s r e l a t e d to hand movement. M o s t of the c e l l s were l o c a l i z e d in the deeper part of the posterior bank of the i n t r a p a r i e t a l sulcus. Three types of a c t i v i t y changes in relation to the e p o c h s of t h e t a s k s w e r e o b s e r v e d . 19 of 68 c e l l s s h o w e d an i n c r e a s e in a c t i v i t y d u r i n g " r e a c h i n g " ; 41 c e l l s s h o w e d an i n c r e a s e d u r i n g b o t h "reaching" and "manipulation"; and the r e m a i n i n g 8 c e l l s started to increase their a c t i v i t y f r o m the "set" p e r i o d . N o n e of t h e s e n e u r o n s w e r e a c t i v a t e d d u r i n g t h e fixation task without reach and manipulation; n o r d i d t h e y r e s p o n d to p a s s i v e joint movement. Most of these c e l l s (28/44) showed d i f f e r e n c e s in a c t i v i t y among different m a n i p u l a n d a used. The m a j o r i t y of reach and m a n i p u l a t i o n neurons tested (14/18) w e r e l e s s a c t i v e d u r i n g m o v e m e n t in t h e d a r k t h a n in t h e l i g h t , s h o w i n g the effect of the v i e w of the m o v i n g hand. These findings suggest that a group of c e l l s in t h i s r e g i o n p a r t i c i p a t e in t h e c o n t r o l of m o v e m e n t s of t h e h a n d u n d e r visual guidance, and they are selective in r e g a r d to t h e p a t t e r n of m o v e m e n t of the hand and fingers.
JAPAN
E l e c t r o p h y s i o l o g i c a ] and morphological s t u d i e s on non-pyramidal neurons in the cat p a r i e t a l c o r t e x were performed under p e n t o b a r b i t a l a n e s t h e s i a ( i n i t i a l dose o f 35mg/kg, i . p . and a d d i t i o n a l dose o f 5-10mg/kg, i . v . every 2 h o u r s ) . A f t e r craniotomy, s t i m u l a t i n g e l e c t r o d e s were i n s e r t e d i n t o the b i l a t e r a l c e r e b e l l a r n u c l e i ( C N ) , the i p s i l a t e r a l t hal ami c VA and LP and the i p s i l a t e r a l pontine nuclei(PN). ] n t r a c e l l u l a r r e c o r d i n g was performed with a glass m i c r o e l e c t r o d e f i l l e d w i t h 5~ HRP d i s s o l v e d in 0.2M K - a c e t a t e . A f t e r checking the e l e c t r o p h y s i o l o g i c a l f e a t u r e s , HRP was i n j e c t e d i o n t o p h o r e t i c a l l y with an anodal c u r r e n t pulse( 2-5nA in i n t e n s i t y , 300ms in d u r a t i o n and l-2Hz). A t o t a l number of lO non-pyramidal neurons from v a r i o u s c o r t i c a l l a y e r s were recovered with HRP s t a i n i n g . Six o f these neurons were analyzed on t h e i r responsiveness to s t i m u l a t i o n o f the CN, VA, LP and PN. The l a t e n c i e s o f CN-EPSPs were 3.0-5.7ms, those o f VA-EPSPs were l.O-2.4ms and those o f LP EPSPs were 1.5-2.0ms. The thalamic EPSPs from both VA and LP s t i m u l a t i o n were considered to be o f a monosynaptic nature from t h e i r s h o r t l a t e n c ] e s and the s p a t i a l summation by double shock s t i m u l i at a s h o r t i n t e r v a l . A neuron located in l a y e r V-VI r ecei ved a r e c u r r e n t EPSP by PN s t i m u l a t i o n . M o r p h o l o g i c a l a n a l y s i s r e v e a l e d t h a t neurons s t a i n e d with HRP were c l a s s i f i e d i n t o t h r e e groups by t h e i r soma d e n d r i t i c morphology and axonal t r a j e c t o r y , i . e . , basket c e l l ( m u l t i p o l a r c e l l ) , b i t u f t e d c e l l and spiny or s p a r s e l y spinous s t e l l a t e c e l l . Basket c e l l s were located in l a y e r s I I , I l l , V and VI. These neurons had long h o r i z o n t a l axon c o l l a t e r a l s w i t h presumed p e r i c e l l u l a r s y n a p t i c nests. The t e r r i t o r i e s o f the axon c o l l a t e r a l s were as l a r g e as 34mm in the m e d i o l a t e r a l plane. An e l e c t r o n mic r oscopi c exami nat i on confirmed t h a t the f i n e s t r u c t u r e o f the soma and d e n d r i t e was s i m i l a r to t h a t o f GAD-positive neurons r e p o r t e d in o t h e r cortices. The stem axon was myelinated, and t h i s is c o n s i s t e n t with the f i n d i n g o f the l i g h t microscopic o b s e r v a t i o n o f HRP s t a i n i n g neurons. Concerning neurons u n c h a r a c t e r i z e d electrophysiologically, a s p a r s e l y spinous neuron located in a deeper p a r t o f l a y e r I I showed a l o c a l i z e d axonal r e g i o n , which seems to correspond t o the s o - c a l l e d double bouquet c e l l s . Another spiny neuron ]n l a y e r VI had a s i m i l a r axonal t r a j e c t o r y to p r o j e c t i n g neurons. The p r e s e n t study shows t h a t the i n t r a c o r t i c a l network o f the presumed i n h i b i t o r y i n t e r n e u r o n s spread much w i d e r ( 3 4mm) than t h a t of the c o r t i c a l column(O.5-1mm). The monosynaptic a c t i v a t i o n o f i n t e r n e u r o n s by thalamic s t i m u l a t i o n may be due to axon r e f l e x in some p a r t , whech a c t i o n should be f u r t h e r s t u d i e d . ACTIVITY MONKEYS.
OF H A N D
MOVEMENT-RELATED
NEUORNS
IN T H E P O S T E R I O R
PARIETAL
CORTEX
OF
MASATO TAIRA, HIDEO SAKATA, HIDETOSHI SHIBUTANI, SEIICHIRO M I N E .I A. P. GEORGOPOULOS*2; D~p. Neurophysiol., Tokyo Met. Inst. of Neuro~ci., 2-6 M u s a s h i d a i F u c h u T o k y o 183; Dep. of N e u r o s u r g e r y , C h i b a Univ., C h i b a ; ~ J o h n s H o p k i n s U n i v . Med. Sch. The p a r i e t a l a s s o c i a t i o n cortex is known to be c o n c e r n e d with v i s u a l l y guided m o v e m e n t of the hand as w e l l as with p e r c e p t i o n of space and body. M o u n t c a s t l e et al. (1975) r e c o r d e d c e l l s r e l a t e d to r e a c h a n d m a n i p u l a t i o n in t h i s r e g i o n . In o r d e r to s t u d y t h e i r f u n c t i o n a l characteristics, we a n a l y z e d the activity of neurons in the inferior p a r i e t a l l o b u l e of J a p a n e s e m a c a q u e monkeys during motor t a s k s u s i n g a v a r i e t y of m a n i p u l a n d a ; a l e v e r , a s m a l l knob, a s m a l l k n o b in a g r o o v e a n d a p u s h b u t t o n . F i r s t , the m o n k e y f i x a t e d a s m a l l r e d l i g h t in f r o n t a n d pressed a key. W h e n the light turned green, it r e l e a s e d the key and reached to the m a n i p u l a n d u m and h e l d it for one or two seconds. This task i n c l u d e d three epochs : t h e "set" period, t h e " r e a c h i n g " a n d the " m a n i p u l a t i o n " p e r i o d . We r e c o r d e d 236 neurons in the posterior p a r i e t a l cortex, of which sixty-eight showed a c t i v i t i e s r e l a t e d to hand movement. M o s t of the c e l l s were l o c a l i z e d in the deeper part of the posterior bank of the i n t r a p a r i e t a l sulcus. Three types of a c t i v i t y changes in relation to the e p o c h s of t h e t a s k s w e r e o b s e r v e d . 19 of 68 c e l l s s h o w e d an i n c r e a s e in a c t i v i t y d u r i n g " r e a c h i n g " ; 41 c e l l s s h o w e d an i n c r e a s e d u r i n g b o t h "reaching" and "manipulation"; and the r e m a i n i n g 8 c e l l s started to increase their a c t i v i t y f r o m the "set" p e r i o d . N o n e of t h e s e n e u r o n s w e r e a c t i v a t e d d u r i n g t h e fixation task without reach and manipulation; n o r d i d t h e y r e s p o n d to p a s s i v e joint movement. Most of these c e l l s (28/44) showed d i f f e r e n c e s in a c t i v i t y among different m a n i p u l a n d a used. The m a j o r i t y of reach and m a n i p u l a t i o n neurons tested (14/18) w e r e l e s s a c t i v e d u r i n g m o v e m e n t in t h e d a r k t h a n in t h e l i g h t , s h o w i n g the effect of the v i e w of the m o v i n g hand. These findings suggest that a group of c e l l s in t h i s r e g i o n p a r t i c i p a t e in t h e c o n t r o l of m o v e m e n t s of t h e h a n d u n d e r visual guidance, and they are selective in r e g a r d to t h e p a t t e r n of m o v e m e n t of the hand and fingers.