Journal of Neuroscience, Vol 1, 83-93, Copyright © 1981 by Society for Neuroscience
Does laminar position determine the receptive field properties of cortical neurons? A study of corticotectal cells in area 17 of the normal mouse and the reeler mutant
V Lemmon and AL Pearlman
The neocortex of the reeler (rl) mutant mouse develops abnormally; as a
result, the orderly arrangement of cells in laminae containing neurons of
similar size and configuration is severely disrupted. The reeler mutant
thus offers an opportunity to study the role played by laminar position in
establishing the interneuronal connections of the cortex. Since the
receptive field properties of neurons in the primary visual cortex (area
17) are determined by these complex interconnections, a study of receptive
field properties provides a useful way to test whether functionally
important connections are altered by abnormal cell position. We chose the
corticotectal (CT) cells of area 17 for this analysis because they have
distinctive receptive field properties and can be identified positively by
antidromic stimulation with electrodes in the superior colliculus. In
addition, CT cells are located in a single lamina (layer V) in the visual
cortex of normal mice, but are distributed from surface to white matter in
the reeler visual cortex. We characterized the receptive fields of
identified CT cells in area 17 of normal mice and reeler mutants and
studied several properties of these cells quantitatively. Corticotectal
cells in the visual cortex of the normal mouse have high rates of
spontaneous activity and large receptive fields that are neither oriented
nor directional; they respond to moving stimuli over a wide range of
stimulus velocities, have high peak velocity sensitivities, and show very
little spatial summation. Corticotectal cells in the visual cortex of the
reeler mutant do not differ significantly in these characteristics,
although CT cells with extremely large receptive fields are encountered
somewhat more frequently in reeler cortex. These findings indicate that the
detailed connections which determine the receptive field properties of CT
cells are properly established in the reeler mutant mouse despite the
markedly abnormal positions of CT cells in reeler visual cortex.