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Functional differentiation in cerebral vocalization nuclei
$7 FUNCTIONAL DIFFERENTIATION
MASAO MAEKAWA* Mibu, Tochigi,
IN C E R E B R A L V O C A L I Z A T I O N NUCLEI
and NOZOMU SAITO, 321-02
Dept.
of Physiol.,
Dokkyo Univ. Med.
Sch.,
The cerebral v o c a l i z a t i o n center in canary, the caudal nucleus of the ventral h y p e r s t r i a t u m (HVc) and the robust nucleus of the a r c h i s t r i a t u m (RA), is well d e v e l o p e d and r e s p o n s i b l e for song ontogeny. The HVc is d i f f e r e n t i a t e d during song o n t o g e n y and develops in the h y D e r s t r i a t u m later than the RA, w h i c h develops in the archistriatum. Both nuclei r e c e i v e synaptic p r o j e c t i o n s from cerebral a u d i t o r y center, field L (Kelley? 1979). A u d i t o r y unit responses of h a l o t h a n e a n e s t h e t i z e d canaries were r e c o r d e d in both nuclei, including each border area. W i t h i n the HVc including its b o r d e r J area (termed "SH") were found auditory responsive units, while the RA r e s p o n d e d e x c l u s i v e l y in its b o r d e r area (termed "SA") but not in the nucleus itself. Most auditory neurons in the "SH" r e s p o n d e d with a phasic pattern to pure tone, while all auditory neurons in the "SA" r e s p o n d e d w i t h a tonic pattern. I n t r a c e l l u l a r recordings of the "SH" neurons showed s]ow spike p o t e n t i a l whose d e p o l a r i z a t i o n e l i c i t e d the burst discharge of fast spikes and was followed by h y p e r p o l a r i z a t i o n . The slow spike was a s s u m e d to be of intrinsic e l e c t r o g e n e s i s rather than synaptic, and underlay the phasic response of the "SH" neuron. The phasic response was e l i c i t e d by the e l e c t r i c a l stimulation of field L and Nif (nucleus interface) w h i c h send m o n o s y n a p t i c projections to the HVc. The latencies of the response from field L and Nil were 8±1.5 msec and 4.5±1 msec, respectively. A slow s p i k e caused by the e l e c t r i c a l stimulation of field L was similar to that of the auditory response. The intrinsic slow spike of auditory n e u r o n s in the "SH" may be triggered by e x t r i n s i c synaptic input from field L, w h i c h is a m a j o r auditory center of the cerebrum. The slow spike of the auditory response may c h a r a c t e r i z e the "SH" neuron of the HVc w h i c h functions as a v o c o - a u d i t o r y a s s o c i a t i o n area and, in turn, controls the motor d r i v i n g center, the RA, by m o n o s y n a p t i c innervation.
VOWEL PERCEPTION IN A CHIMPANZEE SHOZO KOJIMA, P r i m a t e Aichi, 484 Japan
Research
Institute,
gyoto
University.
Kanrin,
Inuyama,
The discrimination of vowels was investigated in a female chimpanzee and two human subjects. The voice stimuli used were five natural and synthesized Japanese vowels (male voices) a n d 12 n a t u r a l non-nasal French vowels (female voices). A reaction time task was employed, in which the chimpanzee pressed a key when a lamp was illuminated. One of the vowels was presented through headphones every second. The vowel was repeated 2-6 times and then changed to another vowel. The chimpanzee was trained to release her right hand from the key as quickly as possible when she detected the change. The dependent variable was a reaction time (the maximum reaction time was 1.000 sec). Longer reaction times were expected when members of a vowel pair were similar to each other. Reaction time data were analyzed by a non-metric multidimensional scaling method and cluster analyses. Chimpanzee data were compared with those of the human subjects. The main empirical difference between the chimpanzee and the human subjects, which ~as observed in all vowel sets, was that the reaction times for discriminating [i] from [u] were longer for the chimpanzee. The result is interesting because [i] and [u] are basic vowels in virtually all human languages, and these vowels are easy for humans to discriminate (Peterson & Barney, 1952). The relation of the present result to a prior measurement of this chimpanzee's auditory sensitivity (Kojima. 1984) was discussed. The chimpanzee showed a decrease in auditory sensitivity to 2 - 4 KHz t o n e s ( 4 KHz d i p ) . The first formant frequency of these vowels is similar and it is 300-350 Hz. The frequency of the second formant of [i] is greater than 2 KHz. Thus. it may be difficult for the chimpanzee to hear the second formant frequency of [i] and to discriminate between [i] and [u].
MASAO MAEKAWA* Mibu, Tochigi,
IN C E R E B R A L V O C A L I Z A T I O N NUCLEI
and NOZOMU SAITO, 321-02
Dept.
of Physiol.,
Dokkyo Univ. Med.
Sch.,
The cerebral v o c a l i z a t i o n center in canary, the caudal nucleus of the ventral h y p e r s t r i a t u m (HVc) and the robust nucleus of the a r c h i s t r i a t u m (RA), is well d e v e l o p e d and r e s p o n s i b l e for song ontogeny. The HVc is d i f f e r e n t i a t e d during song o n t o g e n y and develops in the h y D e r s t r i a t u m later than the RA, w h i c h develops in the archistriatum. Both nuclei r e c e i v e synaptic p r o j e c t i o n s from cerebral a u d i t o r y center, field L (Kelley? 1979). A u d i t o r y unit responses of h a l o t h a n e a n e s t h e t i z e d canaries were r e c o r d e d in both nuclei, including each border area. W i t h i n the HVc including its b o r d e r J area (termed "SH") were found auditory responsive units, while the RA r e s p o n d e d e x c l u s i v e l y in its b o r d e r area (termed "SA") but not in the nucleus itself. Most auditory neurons in the "SH" r e s p o n d e d with a phasic pattern to pure tone, while all auditory neurons in the "SA" r e s p o n d e d w i t h a tonic pattern. I n t r a c e l l u l a r recordings of the "SH" neurons showed s]ow spike p o t e n t i a l whose d e p o l a r i z a t i o n e l i c i t e d the burst discharge of fast spikes and was followed by h y p e r p o l a r i z a t i o n . The slow spike was a s s u m e d to be of intrinsic e l e c t r o g e n e s i s rather than synaptic, and underlay the phasic response of the "SH" neuron. The phasic response was e l i c i t e d by the e l e c t r i c a l stimulation of field L and Nif (nucleus interface) w h i c h send m o n o s y n a p t i c projections to the HVc. The latencies of the response from field L and Nil were 8±1.5 msec and 4.5±1 msec, respectively. A slow s p i k e caused by the e l e c t r i c a l stimulation of field L was similar to that of the auditory response. The intrinsic slow spike of auditory n e u r o n s in the "SH" may be triggered by e x t r i n s i c synaptic input from field L, w h i c h is a m a j o r auditory center of the cerebrum. The slow spike of the auditory response may c h a r a c t e r i z e the "SH" neuron of the HVc w h i c h functions as a v o c o - a u d i t o r y a s s o c i a t i o n area and, in turn, controls the motor d r i v i n g center, the RA, by m o n o s y n a p t i c innervation.
VOWEL PERCEPTION IN A CHIMPANZEE SHOZO KOJIMA, P r i m a t e Aichi, 484 Japan
Research
Institute,
gyoto
University.
Kanrin,
Inuyama,
The discrimination of vowels was investigated in a female chimpanzee and two human subjects. The voice stimuli used were five natural and synthesized Japanese vowels (male voices) a n d 12 n a t u r a l non-nasal French vowels (female voices). A reaction time task was employed, in which the chimpanzee pressed a key when a lamp was illuminated. One of the vowels was presented through headphones every second. The vowel was repeated 2-6 times and then changed to another vowel. The chimpanzee was trained to release her right hand from the key as quickly as possible when she detected the change. The dependent variable was a reaction time (the maximum reaction time was 1.000 sec). Longer reaction times were expected when members of a vowel pair were similar to each other. Reaction time data were analyzed by a non-metric multidimensional scaling method and cluster analyses. Chimpanzee data were compared with those of the human subjects. The main empirical difference between the chimpanzee and the human subjects, which ~as observed in all vowel sets, was that the reaction times for discriminating [i] from [u] were longer for the chimpanzee. The result is interesting because [i] and [u] are basic vowels in virtually all human languages, and these vowels are easy for humans to discriminate (Peterson & Barney, 1952). The relation of the present result to a prior measurement of this chimpanzee's auditory sensitivity (Kojima. 1984) was discussed. The chimpanzee showed a decrease in auditory sensitivity to 2 - 4 KHz t o n e s ( 4 KHz d i p ) . The first formant frequency of these vowels is similar and it is 300-350 Hz. The frequency of the second formant of [i] is greater than 2 KHz. Thus. it may be difficult for the chimpanzee to hear the second formant frequency of [i] and to discriminate between [i] and [u].