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Role of Mammalian Auditory Cortex in the Perception of Elementary Sound Properties
Department of Neuroscience, University of Pennsylvania, Philadelphia, Pennsylvania 19104 Talwar, Sanjiv K., Pawel G. Musial, and George L. Gerstein. Role of Mammalian Auditory Cortex in the Perception of Elementary Sound Properties. J. Neurophysiol. 85: 2350-2358, 2001. Studies in several mammalian...
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Published in: | Journal of neurophysiology 2001-06, Vol.85 (6), p.2350-2358 |
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Main Authors: | , , |
Format: | Article |
Language: | English |
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Online Access: | Get full text |
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Summary: | Department of Neuroscience, University of Pennsylvania,
Philadelphia, Pennsylvania 19104
Talwar, Sanjiv K.,
Pawel G. Musial, and
George L. Gerstein.
Role of Mammalian Auditory Cortex in the Perception of Elementary
Sound Properties. J. Neurophysiol. 85: 2350-2358, 2001. Studies in several mammalian species have
demonstrated that bilateral ablations of the auditory cortex have
little effect on simple sound intensity and frequency-based behaviors.
In the rat, for example, early experiments have shown that auditory
ablations result in virtually no effect on the rat's ability to either
detect tones or discriminate frequencies. Such lesion experiments,
however, typically examine an animal's performance some time after
recovery from ablation surgery. As such, they demonstrate that the
cortex is not essential for simple auditory behaviors in the
long run. Our study further explores the role of cortex in basic
auditory perception by examining whether the cortex is normally
involved in these behaviors. In these experiments we
reversibly inactivated the rat primary auditory cortex (AI) using the
GABA agonist muscimol, while the animals performed a simple auditory
task. At the same time we monitored the rat's auditory activity by
recording auditory evoked potentials (AEP) from the cortical surface.
In contrast to lesion studies, the rapid time course of these
experimental conditions preclude reorganization of the auditory system
that might otherwise compensate for the loss of cortical processing. Soon after bilateral muscimol application to their AI region, our rats
exhibited an acute and profound inability to detect tones. After a few
hours this state was followed by a gradual recovery of normal hearing,
first of tone detection and, much later, of the ability to discriminate
frequencies. Surface muscimol application, at the same time,
drastically altered the normal rat AEP. Some of the normal AEP
components vanished nearly instantaneously to unveil an underlying
waveform, whose size was related to the severity of accompanying
behavioral deficits. These results strongly suggest that the cortex is
directly involved in basic acoustic processing. Along with observations
from accompanying multiunit experiments that related the AEP to AI
neuronal activity, our results suggest that a critical amount of
activity in the auditory cortex is necessary for normal hearing. It is
likely that the involvement of the cortex in simple auditory
perceptions has hitherto not been clearly |
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ISSN: | 0022-3077 1522-1598 |
DOI: | 10.1152/jn.2001.85.6.2350 |