Influence of subcortical neurons on the functional development of cerebral neocortex in tissue culture.

The role of subcortical input and/or output pathways in the development of cortical networks was examined in organotypic tissue cultures derived from neonatal mouse brain. Comparisons were made between cultures of cerebral neocortex grown with large amounts of subcortical tissue and those that were completely isolated or included small amounts of subcortical tissue. Extracellular electrophysiological recordings showed differences in excitability and spatial distribution of responses elicited by electrical stimulation of the dorsal edge of cerebral neocortex. Cultures with proportionately greater amounts of subcortical tissue showed enhanced cortical excitability and also displayed a sharper columnar arrangement than was evident in explants that were completely isolated from subcortical influences. The data suggest that subcortical inputs and/or target fields may provide signals that influence the progressive functional development of cerebral neocortical circuitry.