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Amygdaloid neuronal responses to taste stimuli in rhesus monkey
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12. Chemical senses, olfaction and taste A M Y G D A L O I D N E U R O N A L R E S P O N S E S TO T A S T E S T I M U L I IN R H E S U S M O N K E Y . Z O L T A N K A R A D I * , T H O M A S R. S C O T T * t Y U T A K A O O M U R A t H I T O 0 N I S H I N O t L A S Z L O L E N A R D * A N D SHUJI AOU*, N a t i o n a l I n s t i t u t e for P h y s i o l o g i c a l S c i e n c e s , O k a z a k i 444, J a p a n . Despite the l a r g e a m o u n t of d a t a c o n c e r n i n g n e u r o n s of the a m y g d a l o i d body (AMY) in r e g u l a t i o n of f e e d i n g , l i t t l e is k n o w n a b o u t t h e i r s p e c i f i c f u n c t i o n in p r o c e s s i n g e n d o g e n o u s and e x o g e n o u s c h e m i c a l i n f o r m a t i o n . The p r e s e n t e x p e r i m e n t recorded extracellular single neuron activity of the AMY in awake and anesthetized rhesus monkeys during microelectrophoretic application of n e u r o c h e m i c a l s and d u r i n g g u s t a t o r y s t i m u l a t i o n . Less t h a n I/5 of the 370 AMY n e u r o n s t e s t e d r e s p o n d e d to a b r o a d v a r i e t y of tastes. Two t h i r d s of the g l u c o s e - s e n s i t i v e (GS) c e l l s c h a n g e d in a c t i v i t y to gustatory stimuli. These taste-responding GS-neurons were characteristically sensitive to noradrenaline. O n l y a b o u t I/3 of the glucose-insensitive (GIS) cells, e s p e c i a l l y s e n s i t i v e to d o p a m i n e , r e s p o n d e d to t a s t a n t s . GS- and GIS-neurons also v a r i a b l y c h a n g e in activity during conditioned alimentary bar press task. Thus, t h e s e two sets of A M Y c e l l s seem to have specific functional organization: they display distinct catecholamine sensitivity, and differentially integrate feeding related external sensory i n f o r m a t i o n w i t h b o t h e n d o g e n o u s and e x o g e n o u s c h e m i c a l s i g n a l s .
FUNCTIONAL SIGNIFICANCE OF DESCENDING FIBER CONNECTIONS FROM RAT CORTICAL GUSTATORY AREA TO THE PARABRACHIAL NUCLEUS° YOSHITAKA KIY01~TSU*I~ TAKASHIYANANOT02~RYUJI NATSU0*2~ T ~fUJI KITAI~JRA*3~ Departments of Dental A n e s t h2e s i o l o ~ Oral PhySiology and Oral Surgery I, Faculty of Dentistry, Osaka University, 1-8 Yamadaoka, Suita, Osaka 565, Japan. We ~tudied; cen~rifugal:mffects from the cortical gustatory area (CGA) on neural activities of %he parabrachial nucleus (PBN). Electrophysiological experiments were done in Wistar male rats anesthetized with urethane. Tracing of anterograde and retrograde transport of WCA-HRP showed that both corticoparabrachial (CGA-PBN) and parabrachiocortieal fibers passed through the dorsal tegmental area (DTA). Lesions of the DTA or PBN diminished salivary secretion induced by electrical stimulation of the CGA. Injection of glutamate into the PBN elicited copious salivary section. These findings suggest that some PBN neurons receive inputs from the CGA and send axons to the lower brain stem for salivary secretion. Of 46 PBN neurons which responded to taste stimuli, 9 (19%) showed facilitatory (F), 3 (7%) inhibitory (I), 6 (13%) F-I, and I I-F responses to single shock electrical stimulation of the ipsilateral CGA. Repetitive stimulation of the CGA induced F responses in l0 (31%) and I responses in 4 (13%). A~out 70% of affected PBN neurons were relay neurons to the thalamic taste area, central nucleus of the amygdala, or CGA. These results show that CGA-PBN fibers pass through the DTA, mediate cortically induced salivary section and affect about 40% of taste-responsive PBN neurons, with a facilitatory effect predominant.
ANINAL CONDITION IN ODOR-STIMULATION EXPERIMENTS. YOICBI OGAWAAND FUMIAKI MOTOKIZAWA, Department of Physiology, Nara Medical College, Kashihara, Nara 634, Japan. To establish an adequate condition in odor-stimulation experiment, we investigated the effects of anesthesia and respiratory a c t i v i t y on single unit a c t i v i t y in cat o l f a c t o r y bulb. Cats were anesthetized with sodium pentobarbital or urethane-chloralose solution (urethane 150 mg/ml and chloralose 10 mg/ml). In each case, two d i f f e r e n t anesthetic levels were distinguished on the basis of t h e i r effect on recovery curve of f i e l d potentials in the o l f a c t o r y bulb evoked by stimulation of the lateral o l f a c t o r y t r a c t . Low and high doses of sodium pentobarbital were defined as less than 15 and more than 25 mg/kg, respectively. For urethane-chloralose, low and high doses were less than 1.5 and more than 2.5 ml/kg. The cats respired spontaneously through the nose or a tracheotomy tube. Consequently, eight d i f f e r e n t conditions were examined. A total of 505 units were recorded in 56 animals. Respiratory modulation of unit a c t i v i t y was detected only under nasal respiration. In sodium pentobarbital anesthesia, respiratory modulation was reduced with the high dose. Mean discharge rates were less with the high d o s e than the low dose under both nasal and tracheal respiration. On the other hand, urethane-chloralose had no dose-related effects on pattern and rate of spontaneous discharge. The s e n s i t i v i t y of o l f a c t o r y units to pure a i r or amyl acetate was e×amined under tracheal respiration. For both anesthetic drugs, there was no marked difference in mechano- and o d o r - s e n s i t i v i t y between high and low dose. Thus, the depth of anesthesia influences the spontaneous a c t i v i t y of cat o l f a c t o r y bulb neurons, but not the s e n s i t i v i t y of the neurons to pure a i r and amyl acetate.
12. Chemical senses, olfaction and taste A M Y G D A L O I D N E U R O N A L R E S P O N S E S TO T A S T E S T I M U L I IN R H E S U S M O N K E Y . Z O L T A N K A R A D I * , T H O M A S R. S C O T T * t Y U T A K A O O M U R A t H I T O 0 N I S H I N O t L A S Z L O L E N A R D * A N D SHUJI AOU*, N a t i o n a l I n s t i t u t e for P h y s i o l o g i c a l S c i e n c e s , O k a z a k i 444, J a p a n . Despite the l a r g e a m o u n t of d a t a c o n c e r n i n g n e u r o n s of the a m y g d a l o i d body (AMY) in r e g u l a t i o n of f e e d i n g , l i t t l e is k n o w n a b o u t t h e i r s p e c i f i c f u n c t i o n in p r o c e s s i n g e n d o g e n o u s and e x o g e n o u s c h e m i c a l i n f o r m a t i o n . The p r e s e n t e x p e r i m e n t recorded extracellular single neuron activity of the AMY in awake and anesthetized rhesus monkeys during microelectrophoretic application of n e u r o c h e m i c a l s and d u r i n g g u s t a t o r y s t i m u l a t i o n . Less t h a n I/5 of the 370 AMY n e u r o n s t e s t e d r e s p o n d e d to a b r o a d v a r i e t y of tastes. Two t h i r d s of the g l u c o s e - s e n s i t i v e (GS) c e l l s c h a n g e d in a c t i v i t y to gustatory stimuli. These taste-responding GS-neurons were characteristically sensitive to noradrenaline. O n l y a b o u t I/3 of the glucose-insensitive (GIS) cells, e s p e c i a l l y s e n s i t i v e to d o p a m i n e , r e s p o n d e d to t a s t a n t s . GS- and GIS-neurons also v a r i a b l y c h a n g e in activity during conditioned alimentary bar press task. Thus, t h e s e two sets of A M Y c e l l s seem to have specific functional organization: they display distinct catecholamine sensitivity, and differentially integrate feeding related external sensory i n f o r m a t i o n w i t h b o t h e n d o g e n o u s and e x o g e n o u s c h e m i c a l s i g n a l s .
FUNCTIONAL SIGNIFICANCE OF DESCENDING FIBER CONNECTIONS FROM RAT CORTICAL GUSTATORY AREA TO THE PARABRACHIAL NUCLEUS° YOSHITAKA KIY01~TSU*I~ TAKASHIYANANOT02~RYUJI NATSU0*2~ T ~fUJI KITAI~JRA*3~ Departments of Dental A n e s t h2e s i o l o ~ Oral PhySiology and Oral Surgery I, Faculty of Dentistry, Osaka University, 1-8 Yamadaoka, Suita, Osaka 565, Japan. We ~tudied; cen~rifugal:mffects from the cortical gustatory area (CGA) on neural activities of %he parabrachial nucleus (PBN). Electrophysiological experiments were done in Wistar male rats anesthetized with urethane. Tracing of anterograde and retrograde transport of WCA-HRP showed that both corticoparabrachial (CGA-PBN) and parabrachiocortieal fibers passed through the dorsal tegmental area (DTA). Lesions of the DTA or PBN diminished salivary secretion induced by electrical stimulation of the CGA. Injection of glutamate into the PBN elicited copious salivary section. These findings suggest that some PBN neurons receive inputs from the CGA and send axons to the lower brain stem for salivary secretion. Of 46 PBN neurons which responded to taste stimuli, 9 (19%) showed facilitatory (F), 3 (7%) inhibitory (I), 6 (13%) F-I, and I I-F responses to single shock electrical stimulation of the ipsilateral CGA. Repetitive stimulation of the CGA induced F responses in l0 (31%) and I responses in 4 (13%). A~out 70% of affected PBN neurons were relay neurons to the thalamic taste area, central nucleus of the amygdala, or CGA. These results show that CGA-PBN fibers pass through the DTA, mediate cortically induced salivary section and affect about 40% of taste-responsive PBN neurons, with a facilitatory effect predominant.
ANINAL CONDITION IN ODOR-STIMULATION EXPERIMENTS. YOICBI OGAWAAND FUMIAKI MOTOKIZAWA, Department of Physiology, Nara Medical College, Kashihara, Nara 634, Japan. To establish an adequate condition in odor-stimulation experiment, we investigated the effects of anesthesia and respiratory a c t i v i t y on single unit a c t i v i t y in cat o l f a c t o r y bulb. Cats were anesthetized with sodium pentobarbital or urethane-chloralose solution (urethane 150 mg/ml and chloralose 10 mg/ml). In each case, two d i f f e r e n t anesthetic levels were distinguished on the basis of t h e i r effect on recovery curve of f i e l d potentials in the o l f a c t o r y bulb evoked by stimulation of the lateral o l f a c t o r y t r a c t . Low and high doses of sodium pentobarbital were defined as less than 15 and more than 25 mg/kg, respectively. For urethane-chloralose, low and high doses were less than 1.5 and more than 2.5 ml/kg. The cats respired spontaneously through the nose or a tracheotomy tube. Consequently, eight d i f f e r e n t conditions were examined. A total of 505 units were recorded in 56 animals. Respiratory modulation of unit a c t i v i t y was detected only under nasal respiration. In sodium pentobarbital anesthesia, respiratory modulation was reduced with the high dose. Mean discharge rates were less with the high d o s e than the low dose under both nasal and tracheal respiration. On the other hand, urethane-chloralose had no dose-related effects on pattern and rate of spontaneous discharge. The s e n s i t i v i t y of o l f a c t o r y units to pure a i r or amyl acetate was e×amined under tracheal respiration. For both anesthetic drugs, there was no marked difference in mechano- and o d o r - s e n s i t i v i t y between high and low dose. Thus, the depth of anesthesia influences the spontaneous a c t i v i t y of cat o l f a c t o r y bulb neurons, but not the s e n s i t i v i t y of the neurons to pure a i r and amyl acetate.