Journal of Neuroscience, Vol 1, 578-584, Copyright © 1981 by Society for Neuroscience
Morphology of physiologically identified W-cells in the C laminae of the cat's lateral geniculate nucleus
LR Stanford, MJ Friedlander and SM Sherman
The projections from the retina through the lateral geniculate nucleus to
the visual cortex in the cat are comprised of three parallel, independent
pathways. These three pathways involve, respectively, W-, X- , and Y-cells
in the retina and the lateral geniculate nucleus. In this study, we
investigated the morphology of those neurons in the C laminae of the
lateral geniculate nucleus that receive input from retinal W- cells.
Micropipettes filled with horseradish peroxidase (HRP) were used to record
the responses of single geniculate neurons identified as W-, X-, or
Y-cells. Five W-cells in the C laminae then were stained intracellularly by
impalement of the cell with the microelectrode followed by iontophoresis of
HRP. Each of these neurons has a small to medium size soma and fine
dendrites oriented roughly parallel to the plane of the geniculate laminar
borders. These geniculate W-cells differ among themselves mainly in the
detail of their dendritic processes. Three of these cells have virtually no
dendritic appendages, while the other two have complex appendages not
previously reported among neurons in the C laminae. Also, the degree of
horizontal orientation of the dendrites differs considerably among these
cells. Overall, the morphology of these W-cells is generally consistent
with the class 4 cell briefly described by Guillery (Guillery, R. W. (1966)
J. Comp. Neurol. 128: 21-50), and consequently, our data indicate that
class 4 neurons are the morphological correlate of neurons physiologically
classified as W-cells. Since greater morphological detail is presented by
these HRP-filled cells than by previous Golgi- impregnated preparations, we
can describe more completely the morphology of class 4 cells.