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1811 Auditory integration in the song control nucleus of the zebra finch
S206 1809 ~srol..
OPTICAL RECORDING OF SPATIOTFMPORAL ACTIVITY OF GUINEA PIG AUDITORY CORTEX IN RESPONSE TO FM SOUNDS. JUNSFI HORI.KAWA. YUT~O NASU Med. Res. Inst.. Tokvo Med. and Vo 101. Japa
Spatiotemporal activity patterns of the primary auditory cortex (field A) of guinea pigs in response to frequencymodulated (FM) sounds were studied using an optical recording instrument (12 x 12 photodiode array) and a voltagesensitive dye RH795. The animals were anesthetized with Nembutal. Sound stimuli were presented to the ear contralateral to the recording side. The frequency of the FM sounds swept linearly either upward from 4 to 16 kHz or downward from 16 to 4 kHz and the sweep rate was varied from 12 kHz/25 ms to 12 w200 ms. The excitatory responses in field A to slow-sweep FM sounds (512 kHz/100 ms) moved crossing the isofrequency bands according to the frequency change in the FM sounds. The direction of the response movement along the cortex to upward FM sounds was just opposite to those to downward FM sounds. However, the responses to fast-sweep upward- or downward-FM sounds (>12 kHz/lOO ms) moved obliquely crossing the isofrequency bands and disappeared halfway during stimulation. These results suggest that the inter-isofrequency-band interaction of excitation and inhibition in the auditory cortex plays an important role for information processing of time-varying signals like FM sounds.
1810
EFFECT OF INTERAURAL TIME DIFFERENCE ON NEURAL ACTIVITY PA-l-TERNS OF THE GUINEA PIG AUDITORY CORTEX OBSERVED BY OPTICAL RECORDING. YUTAKA HOSOKAWA, JUNSEI HORIKAWA, MASAHIRO NASU, IKUO TANIGUCHI. Dept. of Neurophysiol., Medical Res. Inst., Tokyo Medical and Dental Univ., Tokyo, 101, Japan Effect of interaural time difference (ITD) on neural activity of the guinea pig auditory cortex was studied by optical recording with a 12 x 12 photodiode array. Guinea pigs (280-4509) were anesthetized with sodium pentobarbital (30 mg/kg). The exposed cortex was stained with a voltage-sensitive dye (RH795). Optical signals were recorded and transformed into sequential two-dimensional images. When both ears were stimulated dichotically by tone bursts, excitatory optical signals appeared in both anterior (A) and dorsocaudal (DC) fields of the auditory cortex. Increase of ipsilateral leads from 0 to IO ms resulted in gradual decrease of the amplitude of the excitatory responses. Strong inhibition was observed in field DC and the ventral portion of field A. The ipsilateral lead inducing large inhibition was much longer than the value (80~s) calculated from the interaural distance of the guinea pig. These results and our previous results that the ipsilateral inhibition is sensitive to the interaural intensity difference (IID) indicate that IID is more important than ITD for sound localization in the guinea pig.
1811 321-02,
AUDITORY INTEGRATION MASAO MAEEANA. Dent. Japan.
IN THE SONG CONTROL NUCLEUS OF THE ZEBRA FINCH. f Dokkvo Univ. Sch. of Med., Mibu. Tochiqi,
of Phvsiol.
The zebra finch song includes harmonic structures in which one or more harmonics are usually suppressed. Neurons in the robust nucleus of the archistriatum (RA), one of song control nuclei, respondselectivelytoaspecific harmonicsuppressionpattern (suppression pattern-selective neurons) as well as in the lateral portion of the magnocellular nucleus of the anterior neostriatum (1MAN). However, most of the suppression pattern-selective neurons in the RA respond to the long call in which all harmonics are present or second harmonic is suppressed, while in the lMAN, most of them respond to the long call in which first or third harmonic is suppressed. The difference may come from the integration of auditory inputs from 1MAN and the higher vocal center (HVC) within the RA. To find the integrationof these two inputs within the RA, werecorded single unit auditory responses to harmonic suppression patterns in the RA of the adult male zebra finches which receives electriclesionsof bilaterallMAN.Types ofsuppressionpattern-selectiveneurons intheRAofthelMANlesionedbirds weredifferentfromthose ofnormalbirds. Theseresults suggest that auditory inputs from the 1MAN and HW are integrated within the RAto process song note patterns.
OPTICAL RECORDING OF SPATIOTFMPORAL ACTIVITY OF GUINEA PIG AUDITORY CORTEX IN RESPONSE TO FM SOUNDS. JUNSFI HORI.KAWA. YUT~O NASU Med. Res. Inst.. Tokvo Med. and Vo 101. Japa
Spatiotemporal activity patterns of the primary auditory cortex (field A) of guinea pigs in response to frequencymodulated (FM) sounds were studied using an optical recording instrument (12 x 12 photodiode array) and a voltagesensitive dye RH795. The animals were anesthetized with Nembutal. Sound stimuli were presented to the ear contralateral to the recording side. The frequency of the FM sounds swept linearly either upward from 4 to 16 kHz or downward from 16 to 4 kHz and the sweep rate was varied from 12 kHz/25 ms to 12 w200 ms. The excitatory responses in field A to slow-sweep FM sounds (512 kHz/100 ms) moved crossing the isofrequency bands according to the frequency change in the FM sounds. The direction of the response movement along the cortex to upward FM sounds was just opposite to those to downward FM sounds. However, the responses to fast-sweep upward- or downward-FM sounds (>12 kHz/lOO ms) moved obliquely crossing the isofrequency bands and disappeared halfway during stimulation. These results suggest that the inter-isofrequency-band interaction of excitation and inhibition in the auditory cortex plays an important role for information processing of time-varying signals like FM sounds.
1810
EFFECT OF INTERAURAL TIME DIFFERENCE ON NEURAL ACTIVITY PA-l-TERNS OF THE GUINEA PIG AUDITORY CORTEX OBSERVED BY OPTICAL RECORDING. YUTAKA HOSOKAWA, JUNSEI HORIKAWA, MASAHIRO NASU, IKUO TANIGUCHI. Dept. of Neurophysiol., Medical Res. Inst., Tokyo Medical and Dental Univ., Tokyo, 101, Japan Effect of interaural time difference (ITD) on neural activity of the guinea pig auditory cortex was studied by optical recording with a 12 x 12 photodiode array. Guinea pigs (280-4509) were anesthetized with sodium pentobarbital (30 mg/kg). The exposed cortex was stained with a voltage-sensitive dye (RH795). Optical signals were recorded and transformed into sequential two-dimensional images. When both ears were stimulated dichotically by tone bursts, excitatory optical signals appeared in both anterior (A) and dorsocaudal (DC) fields of the auditory cortex. Increase of ipsilateral leads from 0 to IO ms resulted in gradual decrease of the amplitude of the excitatory responses. Strong inhibition was observed in field DC and the ventral portion of field A. The ipsilateral lead inducing large inhibition was much longer than the value (80~s) calculated from the interaural distance of the guinea pig. These results and our previous results that the ipsilateral inhibition is sensitive to the interaural intensity difference (IID) indicate that IID is more important than ITD for sound localization in the guinea pig.
1811 321-02,
AUDITORY INTEGRATION MASAO MAEEANA. Dent. Japan.
IN THE SONG CONTROL NUCLEUS OF THE ZEBRA FINCH. f Dokkvo Univ. Sch. of Med., Mibu. Tochiqi,
of Phvsiol.
The zebra finch song includes harmonic structures in which one or more harmonics are usually suppressed. Neurons in the robust nucleus of the archistriatum (RA), one of song control nuclei, respondselectivelytoaspecific harmonicsuppressionpattern (suppression pattern-selective neurons) as well as in the lateral portion of the magnocellular nucleus of the anterior neostriatum (1MAN). However, most of the suppression pattern-selective neurons in the RA respond to the long call in which all harmonics are present or second harmonic is suppressed, while in the lMAN, most of them respond to the long call in which first or third harmonic is suppressed. The difference may come from the integration of auditory inputs from 1MAN and the higher vocal center (HVC) within the RA. To find the integrationof these two inputs within the RA, werecorded single unit auditory responses to harmonic suppression patterns in the RA of the adult male zebra finches which receives electriclesionsof bilaterallMAN.Types ofsuppressionpattern-selectiveneurons intheRAofthelMANlesionedbirds weredifferentfromthose ofnormalbirds. Theseresults suggest that auditory inputs from the 1MAN and HW are integrated within the RAto process song note patterns.