Discrimination of conspecific vocal sounds by chimpanzees

S14

EFFERENT CONNECTIONS FROM THE AUDITORY CORTEX TO THE INFERIOR COLLICULUS IN RATS. JUNSEI HORIKAWA*, YUTAKA HOSOKAWA*, TOMO0 HOMMA*, SUSUMU ITO*, AND KEIICHI MURATA, Department of Neurophyslnlogy, Medical Research Institute, Tokyo Medical and Dental University, 2-3-i0, Kandasorugadal, Chiyodaku, Tokyo I01, Japan.

Efferent c o n n e c t i o n s f r o m t h e p r i m a r y a u d i t o r y c o r t e x (AI) t o t h e i n f e r i o r collleulus (IC) were s t u d i e d in Wlstar r a t s ( 2 0 0 - 3 S O g) a n e s t h e t i z e d w l t h Nembutal (40 m g / k g initial; 5 mg/kg/hr suppIesentary doses), using three methods: 1)lntracellular r e c o r d i n g s f r o m IC n e u r o n s with electrical s t i m u l a t i o n o f AI a n d m e d l a i g e n l c u I a t e b o d y (MGB), 2) I n J e e t l o n s o f RRP i n t o t h e AI o r IC e x t r a c e I l u l a r l y , a n d 3) l n t r a c e l l u l a r HRP l a b e l l l n g s o f t h e IC n e u r o n s . R e c o r d i n g s a n d I n j e c t i o n s were made b y g i a s s c a p i l l a r y e l e c t r o d e s f i l i e d w i t h 1 M K - e l t r a t e o r HRP(3~ o r lO%)-contalned 0 . 5 M gCi a n d T r l s b u f f e r ( S 0 - 1 0 0 M Ohm). The b r a i n s were p e r f u s e d , fixed, sliced a t 4 0 - 6 0 u m t h i c k n e s s a n d s t a i n e d by t h e DAB (NI and Co e n h a n c e m e n t ) m e t h o d . From t h e p r e s e n t s t u d i e s , t h e a f f e r e n t p a t h w a y s f r o m t h e IC t o t h e l p s l l a t e r a i MGB, a n d f r o m t h e MGB t o the Ipsllateral AI, and the efferent pathways from the AI to the Ipsllateral MGB, to the Ipsilateral IC, and to the contralateral IC indirectly via commisural connections, were confirmed. There were no efferents from the MGB to the IC. IC neurons receiving the efferents from the AI tended to be located in the external nucleus and dorsal cortex of the IC, and responded wlth EPSP(70~), IPSP(IO~) and EPSP followed by IPSP {20%) to AI stimulation with latencies of 2-8 ms.

DISCRIMINATION OF C O N S P E C I F I C V O C A L S O U N D S BY C H I M P A N Z E E S . SHOZO KOJIMA, Primate R e s e a r c h I n s t i t u t e , K y o t o U n i v e r s i t y , K a n r i n , I n u y a m a , A i c h i , 484, Japan. The p e r c e p t i o n of v o c a l sounds, grunt, w h i m p e r and squeak, of the c h i m p a n z e e w a s s t u d i e d in two y o u n g f e m a l e c h i m p a n z e e s . U s u a l l y , g r u n t s are v o c a l i z e d w h e n chimpanzees are excited and tile r e l a t i o n to a v e r s i v e e m o t i o n is not clear. Whimpers and squeaks are related to mild and strong aversive emotion, respectively. T h e s e \ o c a l s o u n d s have h a r m o n i c s t r u c t u r e and f o r m a n t s . In the present experiment, harmonic sounds or formants which are important for the perception o~ these \oeal s o u m t ~ ~ver'e identified. For this purpose, each harmonic sound or formant of these xocal sounds was deleted by a digital filter and the c h i m p a n z e e s w e r e r e q u i r e d to d i s c r i m i n a t e these f i l l e r e d s o u n d s from e a c h o r i g i n a l sound. A r e a c t i o n t i m e t a s k was e m p l o y e d . Discrimination performance and r e a c t i o n times w e r e r e c o r d e d . The r e s u l t s s h o w e d that the c h i m p a n z e e s had difficulty in discrimination of l o w e r h a r m o n i c s o u n d s or f o r m a n t s u n d e r 2 or 3 kHz from the o r i g i n a l vocal sounds, w h i c h i n d i c a t e s that the low frequenc3 c o m p o n e n t s w e r e i m p o r t a n t for" the p e r c e p t i o n of v o c a l sounds. The relationship between these results and the W - s h a p e d a u d i t o r y s e n s i t i v i t y function of the c h i m p a n z e e is d i s c u s s e d . A p r e l i m i n a r y e x p e r i m e n t on ear ( h e m i s p h e r i c } a d v a n t a g e was conducted. The c h i m p a n z e e s s h o w e d a t e n d e n c y of right ear (]eft h e m i s h e r e ) a d v a n t a g e for d i s c r i m i n a t i o n b e t w e e n g r u n t s and w h i m p e r s .

5. Behaviour REGULATION OF AMINO ACID INGESTION IN RAT. EIICHI TABUCHI , TAKETOSHI ONO, KUNIO TORII *I AND KENICHIRO MURAMOTO 2, Dept. Physiol., Fac. Med., Toyama Med.

and Pharmaceu.

Univ., Toyama,

iA~inomoto

Co.,

Inc.,

Central Research Laboratories,

Yokohama, 2Dept. Electrical Engineering~ Toyama National Collese of Technolosy~ Toyama, Japan. In general, lysine,

rats prefer to ingest monosodium L-glutamate

one of the essential amino acids, prefer

to ingest

(MSG), however,

lysine and saline.

rats deficient in In the present

study, while feeding the same rats a diet containing gluten plus 20% purified egg protein or the some diet deficient in lysine, we investigated the volumes and consumption patterns of 8 kinds ol solutions (MSG, lysine, glycine, threonine, histidine, arginine, saline and water), which the rats freely ingested.

Amino acid deficient rats changed

their preference

amino acid, but to the other amino acids or solutions.

not only

to the deficient

Thus, rats may voluntarily maintain their

homeostasis, i.e. protein metabolism and osmotic pressure in their body, when possible.