Distinctive neurophysiological properties of embryonic trigeminal and geniculate neurons in culture.
Development of membrane properties of layer IV neocortical neurons, which receive thalamic inputs, and other layer neurons, which receive cortical inputs, were studied in organotypic cocultures of a rat visual cortical slice with either a block of the lateral geniculate nucleus or another cortical slice. In all types of cells, the membrane time constant, input resistance and spike width decreased markedly with days in culture whereas maximum rate of rise of the spike increased. Except for layer V/VI neurons, spike height and resting potentials also tended to increase during development. These changes were more prominent in superficial neurons regardless of afferent connectivity. The results suggest that the membrane properties of cortical neurons develop primarily based on laminar specificity.