Journal of Neuroscience, Vol 15, 4868-4874, Copyright © 1995 by Society for Neuroscience
Differential properties of cells in the feline primary visual cortex providing the corticofugal feedback to the lateral geniculate nucleus and visual claustrum
KL Grieve and AM Sillito
Department of Visual Science, Institute of Ophthalmology, London, United Kingdom.
We have examined the responses of 141 layer VI cells in the feline visual
cortex. Within this group we compared the responses of a subpopulation of
cells checked for connectivity by electrical stimulation in the dLGN and
the visual claustrum. The antidromically identified corticogeniculate
projecting cells had relatively short receptive fields, as judged from
length response curves, measured quantitatively, and were located at the
"short" end of the receptive field length spectrum seen in the general
population. Of the 17 corticogeniculate projecting cells, 71% were S type
cells, which were typically monocular and directionally selective, with
relatively long latencies following electrical stimulation. The remaining
29% were C type cells, also directionally selective, but with a wider
spread of ocular dominance preferences and shorter latencies following
electrical stimulation. S and C type subpopulations did not differ in their
receptive field lengths. The mean receptive field length for this
subpopulation was 2.2 degrees +/- 0.27, the shortest field being 1 degrees
and the longest 5 degrees. The five layer VI cells activated by electrical
stimulation from electrodes within the dorsocaudal (visual) claustrum all
had much longer receptive field lengths than the corticogeniculate
population, often 10 degrees or longer and were monocular and directionally
selective S type cells. These data indicate that the information carried in
the corticogeniculate stream (and that from layer VI directly to layer IV
carried by axon collaterals) is relatively tightly focused in spatial terms
whilst the less spatially focused, long receptive field output from layer
VI projects to the claustrum.
Previous Article | Next Article
