The processing and encoding of information in the visual cortex.

Our knowledge of the response properties of visual cortical neurons has increased steadily since the original studies of Hubel and Wiesel in the 1960s. By comparison, an understanding of the neural mechanisms responsible for these properties has proved more elusive. Models for the mechanisms involved in even the most basic responses, such as the orientation tuning of simple cells in the primary visual cortex of the cat, remain controversial. Recent studies, however, are providing further support for a simple model (first suggested by Hubel and Wiesel), in which it is hypothesized that the response properties of simple cells in layer 4 of the cortex are dominated by the convergence of highly specific thalamic inputs.