Effects of strabismus on development of cortico-geniculate projections in the kitten.

In six kittens reared with surgically induced strabismus, three each of convergent and divergent types, we studied 208 striate cortex cells. Of these, 22 were identified as projecting to the dorsal lateral geniculate nucleus (LGN) on the basis of antidromic activation from LGN and of histological localization within cortical layer VI. We classified these cortico-geniculate cells according to their axonal conduction velocities which in normal cats, are generally grouped into slow, intermediate, or fast categories. Proportions and mean conduction velocities of slow and fast groups were approximately the same as in the normal cat, but the intermediate group was almost entirely missing with only one cell classified as such. Our results suggest that development of the intermediate group, which has previously been implicated in functional binocular vision, may be impaired selectively by strabismus.