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Optical imaging of auditory cortical activity of the guinea pig
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4. Auditory system ELECTRON MICROSCOPIC OBSERVATION OF CALCITONIN GENE-RELATED P E P T I D E LIKE 1Mk4UNK)REACTIVITY IN TIRE ORGANS OF CORTI OF THE RAT HIROMICHI KURIYAMA t , SADAO SH1OSAKA 2 . , MIWAKO SEK1TANI 2 , TOSHIO YAIV~SHITA t , TAD/hMI KIJvlA~----~ AND MASAYA " T O ~ , Department of Otorhinolaryngology, Kansai Medical C o l l e g e 1, D e p a r t m e n t of Neuroanatomy, Biomedical Research C e n t e r 2, and Department of A n a t o m y a, O s a k a U n i v e r s i t y Medical School, 4-3-57 Nakanoshima, Kitaku, Osaka 530, Japan, Calcitonin gene-related peptide (CGRP)-like immunoreactive (CGRP-IR) nerve terminals in the organs of Corti of rats were studied by electron microscopy, In the inner spiral bundles, the CGRP-IR fibers showed a direct contact mainly with non~immunoreactive afferent fibers. Some C G R P - I R n e r v e e n d i n g s in the inner spiral bundles formed contacts directly with inner hair cells. In the outer spiral bundles, OGRP-IR f i b e r s formed synaptic contacts exclusively with outer hair cells. It should be noted that the number of synapses o f CGRP n e r v e endings with outer hair cells varied depending upon the sub-low: a falling gradient in the number occurred along the inner-outer axis. Our results suggest t h a t OGRP a c t s a s an e f f e r e n t neuromodulator in the organ of Corti.
GABAERGIC INHIBITION SHAPES NEURONAL SELECTIVITY TO INTERAURAL TIME DIFFERENCE. ICHIRO FUJITA1,2, AND MA$AKAZU KONISHI*2, 1: Frontier Research Program. RIKEN Institute. Hirosawa 2-1. Wako. Saitama 351-01. Jaoan. 2: Division of Biology 216-76. California Institute of Technology. Pasadena. California 91126. U.S.A. Interaural time difference (ITD) is the principal cue for the barn owl to locate the horizontal position of sound. Neuronal selectivity to ITD first appears in the nucleus laminaris which projects to a lemniscal nucleus and the central nucleus "core" of the inferior colliculus (ICc). The ICc in turn projects to the lateral shell of the central nucleus (IC1) and to the external nucleus of the inferior colliculus (ICx). Sharpness of ITD tuning improves in the ICc and ICx. ICx neurons resolve phase ambiguity when they are stimulated with noise bursts (Takahashi and Konishi, J. Neurosci., 6: 3413-3422, 1986). All these nuclei contain GABAergic cell bodies, terminals or both (Carr, Fujita and Konishi, J. Comp. Neurol., 286: 190-207, 1989). Iontophoretic application of bicuculline methiodide (BMI, a selective GABA antagonist) decreased ITD selectivity in ICc, IC1 and ICx neurons. ICx neurons became phase ambiguous in the presence of BMI. These actions of BMI were cancelled by simultaneous application of GABA. The results suggest that GABAergic inhibition contributes to the sharpening of ITD tuning and the elimination of phase ambiguity.
O P T I C A L I M A G I N G O F A U D I T O R Y C O R T I C A L ACTIVITY O F T H E G U I N E A PIG. H A S H I M O T O t T. Inst. Med. Dent. Engiru, Tokyo Meal. Dent. Univ.t chiyoda-ku, Tokyo 101
Optical techniques were applied to the detection of a pattern of population activity of the auditory cortex under light anesthesia (Keta mine hydrochloz-ide ). A video method for imaging the fluorescence of a voltage-sensitive dye (RH41 4) was contrived to map neuronal activity in response to sound stimulation. The fluorescent im age was s a m pled through a tim e window by a shutter opened in synchrony with stimulus presentation and transferred to a Newvicon TV camera. The background i m a g e with no stimulation was subtracted from the video i m a g e and the difference i m a g e was integrated in the f r a m e memory of an i m a g e processor. The integrated optical i m a g e was recorded sequentially along with the time lapse fro m stim ulus init/ation. Excitation foci responding to a natural call of the animal were found in the optical record. The signal-to-noise ratio of the present image was not good enough to analyze the temporal pattern of the cortical response.
4. Auditory system ELECTRON MICROSCOPIC OBSERVATION OF CALCITONIN GENE-RELATED P E P T I D E LIKE 1Mk4UNK)REACTIVITY IN TIRE ORGANS OF CORTI OF THE RAT HIROMICHI KURIYAMA t , SADAO SH1OSAKA 2 . , MIWAKO SEK1TANI 2 , TOSHIO YAIV~SHITA t , TAD/hMI KIJvlA~----~ AND MASAYA " T O ~ , Department of Otorhinolaryngology, Kansai Medical C o l l e g e 1, D e p a r t m e n t of Neuroanatomy, Biomedical Research C e n t e r 2, and Department of A n a t o m y a, O s a k a U n i v e r s i t y Medical School, 4-3-57 Nakanoshima, Kitaku, Osaka 530, Japan, Calcitonin gene-related peptide (CGRP)-like immunoreactive (CGRP-IR) nerve terminals in the organs of Corti of rats were studied by electron microscopy, In the inner spiral bundles, the CGRP-IR fibers showed a direct contact mainly with non~immunoreactive afferent fibers. Some C G R P - I R n e r v e e n d i n g s in the inner spiral bundles formed contacts directly with inner hair cells. In the outer spiral bundles, OGRP-IR f i b e r s formed synaptic contacts exclusively with outer hair cells. It should be noted that the number of synapses o f CGRP n e r v e endings with outer hair cells varied depending upon the sub-low: a falling gradient in the number occurred along the inner-outer axis. Our results suggest t h a t OGRP a c t s a s an e f f e r e n t neuromodulator in the organ of Corti.
GABAERGIC INHIBITION SHAPES NEURONAL SELECTIVITY TO INTERAURAL TIME DIFFERENCE. ICHIRO FUJITA1,2, AND MA$AKAZU KONISHI*2, 1: Frontier Research Program. RIKEN Institute. Hirosawa 2-1. Wako. Saitama 351-01. Jaoan. 2: Division of Biology 216-76. California Institute of Technology. Pasadena. California 91126. U.S.A. Interaural time difference (ITD) is the principal cue for the barn owl to locate the horizontal position of sound. Neuronal selectivity to ITD first appears in the nucleus laminaris which projects to a lemniscal nucleus and the central nucleus "core" of the inferior colliculus (ICc). The ICc in turn projects to the lateral shell of the central nucleus (IC1) and to the external nucleus of the inferior colliculus (ICx). Sharpness of ITD tuning improves in the ICc and ICx. ICx neurons resolve phase ambiguity when they are stimulated with noise bursts (Takahashi and Konishi, J. Neurosci., 6: 3413-3422, 1986). All these nuclei contain GABAergic cell bodies, terminals or both (Carr, Fujita and Konishi, J. Comp. Neurol., 286: 190-207, 1989). Iontophoretic application of bicuculline methiodide (BMI, a selective GABA antagonist) decreased ITD selectivity in ICc, IC1 and ICx neurons. ICx neurons became phase ambiguous in the presence of BMI. These actions of BMI were cancelled by simultaneous application of GABA. The results suggest that GABAergic inhibition contributes to the sharpening of ITD tuning and the elimination of phase ambiguity.
O P T I C A L I M A G I N G O F A U D I T O R Y C O R T I C A L ACTIVITY O F T H E G U I N E A PIG. H A S H I M O T O t T. Inst. Med. Dent. Engiru, Tokyo Meal. Dent. Univ.t chiyoda-ku, Tokyo 101
Optical techniques were applied to the detection of a pattern of population activity of the auditory cortex under light anesthesia (Keta mine hydrochloz-ide ). A video method for imaging the fluorescence of a voltage-sensitive dye (RH41 4) was contrived to map neuronal activity in response to sound stimulation. The fluorescent im age was s a m pled through a tim e window by a shutter opened in synchrony with stimulus presentation and transferred to a Newvicon TV camera. The background i m a g e with no stimulation was subtracted from the video i m a g e and the difference i m a g e was integrated in the f r a m e memory of an i m a g e processor. The integrated optical i m a g e was recorded sequentially along with the time lapse fro m stim ulus init/ation. Excitation foci responding to a natural call of the animal were found in the optical record. The signal-to-noise ratio of the present image was not good enough to analyze the temporal pattern of the cortical response.