Properties of cells projecting rostrally from the superficial layers of the cats superior colliculus.

Cells projecting rostrally from the cat's superior colliculus were identified by antidromic activation from the posterior thalamus. These cells occurred principally in the stratum griseum superficiale and stratum opticum, although some were also encountered in deeper laminae. The rostrally projecting neurons of the superficial laminae formed a heterogeneous group with respect to axonal conduction velocity, receptive field dimensions and special response properties, such as directional and velocity sensitivity. No correlation was detected between receptive field size and estimated axonal conduction velocity in these units. Cells with the smallest receptive fields, were rarely excited antidromically from the thalamus.