PLASTICITY OF SPINY STELLATE CELLS IN CAT VISUAL-CORTEX OF NORMAL ANDVISUALLY DEPRIVED ANIMALS

We studied the relationships between the system of ocular dominance co lumns and the dendritic morphology of cells in layer 4 in cat visual c ortex of normal and visually deprived animals. Geniculocortical axons from the ipsilateral eye were anterogradely labeled in vivo by injecti ng the fluorescent tracer DiI into layer A of the lateral geniculate n ucleus. Subsequent intracellular staining in slice preparations allowe d us to visualize simultaneously the dendritic arborizations of indivi dual cells and the termination pattern of thalamic afferents. Our resu lts show that the dendritic fields of spiny stellate cells in normal a nimals are biased away from the neighboring column. The dendritic fiel ds of pyramidal cells in layer 4 were not influenced by the presence o f a columnar border. This specific effect for spiny stellate cells was more pronounced in strabismic animals, were the normal eye alignment is disrupted and the input from the two eyes becomes more asynchronous . Monocular deprivation weakened the influence of the segregated input on the dendritic fields. Spiny stellate cells in the columns of the o pen eye had the tendency to confine their dendrites to the same column . However, spiny stellate cells in the columns of the deprived eye exh ibited the opposite effect, their dendrites had a bias towards the nei ghboring column of the open eye. These results demonstrate that the de ndritic fields of cortical neurons are shaped by patterns of afferent input. Our observation further indicate that the effects of visual dep rivation on geniculocortical axons are accompanied by structural chang es of their cortical target cells.