The vertebrate retina is known to mediate both visual and non-image-forming photic responses. With the use of statistical analyses of sections immunohistochemically labelled with a polyclonal antiserum against the activated form of protein CREB (p-CREB), a transcription factor which participates in some neural responses to stimuli, we have observed that the piriform cortex of both wild-type and retinally degenerate (rd) mice respond to light stimulation independently of the circadian time in which the stimulus was given. Responses in visually blind (rd/rd) mice corroborate the hypothesis that there must be neural connections between the retina and cortical brain areas other than those involved in image processing, and strongly support the idea that since these mice lack rods and cones, the melanopsin retinal ganglion cells could mediate this non-visual light input.