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Optical imaging of tonotopical organization in the auditory cortex of guinea pigs
S247 16-01
AMPULLA PRESSURE CHANGES OF THE HORIZONTAL SEMICIRCULAR CANAL IN PIGEONS DURING CALORIC STIMULATION. YOSHIRO WADA, HIROYUKI SUZUKI AND SATORU WATANABE, Department of Equilibrium Adaptation Research, Division of Hiqher Nervous Control, Research Institute of Environmental Medicine, Naqoya University, Naqoya 464-01, Japan It is difficult to explain the mechanism of caloric nystagmus under microgravity by convection theory only. One of the other theories is an occurrence of a relative volume change due to temperature changes. As the volume change must lead to a of the horizontal the ampulla pressure we tried to measure pressure change, (Columba livid) using an improved servo micropipette semicircular canal in pigeons The system (Micropressure system Model 900, WPI) following caloric stimulation. horizontal semicircular canal placed in the horizontal plane which was the least effective position for convection. The main result was that the ampulla pressure was raised following cold calorization and vice versa. The relationship between the was almost linear within the range of and caloric stimulation ampulla pressure temperature in these experiments. Next, we tried to observe the ampulla pressure under some different head positions or artificial perilymphatic fistula.
16-02
OPTICAL GUINEA
IMAGING PIGS.
OF IKUO
TONOTOPICAL TANIGUCHI,
ORGANIZATION JUNSEI
IN
HORIKAWA,
MASAHIRO NASU, Dept. of Neurophysiology, Medical Research and Dental University, 2-3-10 Kanda-surugadai, Chiyoda-ku,
THE
AUDITORY
TOSHIO
Institute, Tokyo
101,
CORTEX
OF AND Medical
MORIYAMA
Tokyo Japan
The sound-evoked neural activity in the guinea pig auditory cortex was studied by optical recording with the aid of voltage-sensitive dye, RH 795. The animals were anesthetized with intraperitoneal Nembutal (30 mg/kg). The auditory cortex was exposed and stained for 90 min with RH 795. Changes in light intensity induced by sounds at various frequencies and pressure levels were recorded with a 12 x 12 array of photodiodes. The amplitudes of the responses were transformed to sequential spatio-temporal patterns. Tonotopical organization was found in two subdivisions of the auditory cortex, fields A and DC. The frequency gradients in fields A and DC had a mirror-image relationship. This agrees with results obtained by microelectrode techniques. However, the tonotopic response observed in our study was transient. The strong activity that focally began in field A propagated in two directions; dorsally along the iso-frequency bands in field A, and caudally toward field DC. These results suggest that at the onset of sounds, neural signals first entered field A, and then processing were transferred from field A to field DC. The latter is probably a hierarchically higher center.
16-03
OPTICAL IMAGING OF AUDITORY CORTICAL ACTIVITY IN THE GUINEA PIG. HASHIMOTO, T. Inst.Med. Dent. Engin., Tokyo Med. Dent. Univ. Chiyoda-ku, Tokyo 101, Japan
The pattern of population activity of the auditory cortex in response to sound stimulation was with a newly developed video method imaging the epi-fluorescence of a voltage-sensitive dye(RH795). The animals were lightly anesthetizedwith Ketamine hydrochloride. The fluorescent images were sampled through a time window by an electronic shutter opened in synchrony with the stimulus presentations.The background images were subtracted from the responsive images and the difference image was integrated in the video frame memory. The excitation foci in the optical record in response to a natural call of the animal were analyzed in correlation with a spectrographic survey of sound stimuli. The spatio-temporal patterns of auditory cortical activity in responsetothe speciesspecific repertoire of the animal's vocalizationwere found. For further analysis of excitation foci a sinusoidal click train and "terminal-analog"speech-like sounds were used as the simpler model of animal's vocalized sound. The stripe pattern of excitation found in the optical records would be due to the columnar structure in the auditory cortex. The time series of the optical records would play an important role in analyzing the global functional structure and the population activity of the auditory cortex in response to sound stimulation.
mapped
AMPULLA PRESSURE CHANGES OF THE HORIZONTAL SEMICIRCULAR CANAL IN PIGEONS DURING CALORIC STIMULATION. YOSHIRO WADA, HIROYUKI SUZUKI AND SATORU WATANABE, Department of Equilibrium Adaptation Research, Division of Hiqher Nervous Control, Research Institute of Environmental Medicine, Naqoya University, Naqoya 464-01, Japan It is difficult to explain the mechanism of caloric nystagmus under microgravity by convection theory only. One of the other theories is an occurrence of a relative volume change due to temperature changes. As the volume change must lead to a of the horizontal the ampulla pressure we tried to measure pressure change, (Columba livid) using an improved servo micropipette semicircular canal in pigeons The system (Micropressure system Model 900, WPI) following caloric stimulation. horizontal semicircular canal placed in the horizontal plane which was the least effective position for convection. The main result was that the ampulla pressure was raised following cold calorization and vice versa. The relationship between the was almost linear within the range of and caloric stimulation ampulla pressure temperature in these experiments. Next, we tried to observe the ampulla pressure under some different head positions or artificial perilymphatic fistula.
16-02
OPTICAL GUINEA
IMAGING PIGS.
OF IKUO
TONOTOPICAL TANIGUCHI,
ORGANIZATION JUNSEI
IN
HORIKAWA,
MASAHIRO NASU, Dept. of Neurophysiology, Medical Research and Dental University, 2-3-10 Kanda-surugadai, Chiyoda-ku,
THE
AUDITORY
TOSHIO
Institute, Tokyo
101,
CORTEX
OF AND Medical
MORIYAMA
Tokyo Japan
The sound-evoked neural activity in the guinea pig auditory cortex was studied by optical recording with the aid of voltage-sensitive dye, RH 795. The animals were anesthetized with intraperitoneal Nembutal (30 mg/kg). The auditory cortex was exposed and stained for 90 min with RH 795. Changes in light intensity induced by sounds at various frequencies and pressure levels were recorded with a 12 x 12 array of photodiodes. The amplitudes of the responses were transformed to sequential spatio-temporal patterns. Tonotopical organization was found in two subdivisions of the auditory cortex, fields A and DC. The frequency gradients in fields A and DC had a mirror-image relationship. This agrees with results obtained by microelectrode techniques. However, the tonotopic response observed in our study was transient. The strong activity that focally began in field A propagated in two directions; dorsally along the iso-frequency bands in field A, and caudally toward field DC. These results suggest that at the onset of sounds, neural signals first entered field A, and then processing were transferred from field A to field DC. The latter is probably a hierarchically higher center.
16-03
OPTICAL IMAGING OF AUDITORY CORTICAL ACTIVITY IN THE GUINEA PIG. HASHIMOTO, T. Inst.Med. Dent. Engin., Tokyo Med. Dent. Univ. Chiyoda-ku, Tokyo 101, Japan
The pattern of population activity of the auditory cortex in response to sound stimulation was with a newly developed video method imaging the epi-fluorescence of a voltage-sensitive dye(RH795). The animals were lightly anesthetizedwith Ketamine hydrochloride. The fluorescent images were sampled through a time window by an electronic shutter opened in synchrony with the stimulus presentations.The background images were subtracted from the responsive images and the difference image was integrated in the video frame memory. The excitation foci in the optical record in response to a natural call of the animal were analyzed in correlation with a spectrographic survey of sound stimuli. The spatio-temporal patterns of auditory cortical activity in responsetothe speciesspecific repertoire of the animal's vocalizationwere found. For further analysis of excitation foci a sinusoidal click train and "terminal-analog"speech-like sounds were used as the simpler model of animal's vocalized sound. The stripe pattern of excitation found in the optical records would be due to the columnar structure in the auditory cortex. The time series of the optical records would play an important role in analyzing the global functional structure and the population activity of the auditory cortex in response to sound stimulation.
mapped