Journal of Neuroscience, Vol 12, 3651-3664, Copyright © 1992 by Society for Neuroscience
Visual projections routed to the auditory pathway in ferrets: receptive fields of visual neurons in primary auditory cortex
AW Roe, SL Pallas, YH Kwon and M Sur
Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge 02139.
How does cortex that normally processes inputs from one sensory modality
respond when provided with input from a different modality? We have
addressed such a question with an experimental preparation in which retinal
input is routed to the auditory pathway in ferrets. Following neonatal
surgical manipulations, a specific population of retinal ganglion cells is
induced to innervate the auditory thalamus and provides visual input to
cells in auditory cortex (Sur et al., 1988). We have now examined in detail
the visual response properties of single cells in primary auditory cortex
(A1) of these rewired animals and compared the responses to those in
primary visual cortex (V1) of normal animals. Cells in A1 of rewired
animals differed from cells in normal V1: they exhibited larger receptive
field sizes and poorer visual responsivity, and responded with longer
latencies to electrical stimulation of their inputs. However, striking
similarities were also found. Like cells in normal V1, A1 cells in rewired
animals exhibited orientation and direction selectivity and had simple and
complex receptive field organizations. Furthermore, the degree of
orientation and directional selectivity as well as the proportions of
simple, complex, and nonoriented cells found in A1 and V1 were very
similar. These results have significant implications for possible
commonalities in intracortical processing circuits between sensory
cortices, and for the role of inputs in specifying intracortical circuitry.
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