The different parts of the neocortex receive fibers from definite cell masses in the dorsal thalamus. Injury to a cortical area results in retrograde degeneration of the thalamic center the fibers of which end in the area destroyed. Associated with the degeneration of the nerve elements there occur profound vascular changes. This was first noticed in the dorsal nucleus of the lateral geniculate body after extirpation of the visual cortex.1 The vascular changes consisted of enlargement of the afferent vessels, apparent increase in their number, thickening of the capillary network and heightened permeability of the vascular walls.
The present study is an attempt to find whether there are such vascular changes in other thalamic nuclei after destruction of their respective cortical fields. I used albino rats as subjects. The projection of the thalamic centers on the cortex in this animal has been worked out by Lashley,2 Clark,3