Responses to Sound
The response properties of sensory areas are thought by many neurophysiologists to be arranged neatly along maps (somatotopic, retinotopic, and tonotopic maps) and parcelled into columns within which all units share some common properties. There have been two approaches to this organization. In one, the order of the arrangement is stressed (e.g., Hubel and Wiesel 1979, Mountcastle 1979) while the other approach stresses the statistical nature of the arrangement (e.g., Creuzfeldt 1978, Towe 1975). The debate between these approaches has been especially prolonged in the case of the auditory cortex because its organization has resisted the experimental approaches for detection of order more than the somatosensory or visual areas. The reader is referred to Merzenich et al. (1975), Imig and Adrian (1977), and Middlebrooks et al. (1980) for examples of work stressing the order in the cortex and to Evans et al. (1965), Abeles and Goldstein (1970), Goldstein and Abeles (1975) for works stressing the statistical nature of the order. These global properties of the arrangement of the auditory cortex are related to our study of local cortical circuits only indirectly. If the tonotopic mapping of the auditory cortex is very strict, we expect that when measuring the activity of a group of cells, all the cells would respond to tones of similar pitch. If the columnar parcellation of the auditory cortex is very strict, we expect to find strong correlations between neighbors when a stimulus is applied. These arguments may lead one to believe that when we record from a group of neurons while applying an adequate stimulus the whole group would respond in unison.
KeywordsFiring Rate Auditory Cortex Cortical Network Common Input Medial Geniculate Body
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