Interlaminar Interactions in the Cat Visual Cortex (Laminae, Columns)
Schwark, Harris Daniel
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Permalink
https://hdl.handle.net/2142/77641
Description
Title
Interlaminar Interactions in the Cat Visual Cortex (Laminae, Columns)
Author(s)
Schwark, Harris Daniel
Issue Date
1985
Department of Study
Biology
Discipline
Biology
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Biology, Animal Physiology
Language
eng
Abstract
One component of the vertical organization of visual cortex is the projection of cells in supragranular layers to cells in the infragranular layers. By recording from cells in the infragranular layers during synaptic inactivation of layers 1-3, I have examined the possibility that this projection may confer certain receptive field properties upon cells in the deep cortical layers. I have found that cells in layer 5 and 6 which remain active in the absence of supragranular layer activity retain their specificities for stimulus orientation, direction, and length.
Supragranular layers were inactivated either reversibly, by cooling the cortical surface, or permanently, by making a cryogenic lesion. In both types of experiment the temperature of the brain surface was controlled with a copper plate attached to a Peltier device and positioned between the dura mater and the cortical surface. The effects of cooling or lesion were monitored throughout the vertical extent of the cortex with a linear array of 15 lacquer-coated tungsten microelectrodes. Receptive field properties were assessed using moving bar stimuli.
Following destruction of the supragranular layers by freezing, most neurons in layers 5 and 6 retained their specificities for stimulus orientation, direction, and length. No neurons in layers 5 or 6 were silenced as a result of inactivation of the supragranular layers by cooling, indicating that the sample of neurons under the lesions was unbiased. These results demonstrate that, within a cortical column, the projection from the supragranular layers is not required for continued specificity for stimulus orientation, direction, and length by infragranular layer neurons, and suggest that these properties may arise through local synaptic interactions within laminae.
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