Integrative action in the cat's lateral geniculate body.

It has often been asked whether the lateral geniculate body contributes to the integration of incoming visual impulses or is a mere 'way-station' in the pathway from retina to cortex. While perhaps less complex than the retina or cortex, the geniculate is histologically far from the simple structure that the term 'way-station' would imply (O'Leary, 1940; Glees, 1941). The presence of extensive dendritic arborizations, the profuse ramifications of incoming optic-tract fibres, and the existence of shortaxon cells, all suggest that there may be something more than a 1: 1 transmission of impulses from optic nerve to optic radiations. The retinal region over which a cell in the visual system can be influenced (excited or inhibited) by light is called the receptive field of that cell. Largely through the work of Kuffler (1953), retinal ganglion cells in the cat are known to have a well defined, concentric, receptive field arrangement. Up to now receptive fields of cells in the dorsal lateral geniculate have received very little attention, although recent work (Hubel, 1960) has suggested that they too, are concentrically arranged. In the present work receptive fields in the optic tract and lateral geniculate body are compared. This provides a sensitive means of detecting and studying any modification of the visual input to the lateral geniculate.