The effect of background illumination on the responses of the neurons of the cat's superior colliculus to moving stimuli.

The influence of background illumination on unitary neuronal responses of cat's superior colliculus to moving stimuli were investigated. Diverse types of neurons responding to background illumination were observed: Neurons which did not change their activity during background illumination; neurons in which the response to moving stimuli during background light was facilitated; cells in which the spatiotemporal dispersion of the peak of evoked response was narrowed with light adaptation; cells in which activity was suppressed during background illumination; and neurons in which the specific response was changed to an unspecific one (and vice versa) during background illumination. The background illumination itself did not evoke any response in the cell, and the suggestion was put forward that subthreshold influences could modulate the evoked activity of the neuron.