Circadian rhythms in Mexican blind cavefish Astyanax mexicanus in the lab and in the field.

Biological clocks have evolved as an adaptation to life on a rhythmic planet, synchronising physiological processes to the environmental light-dark cycle. Here we examine circadian clock function in Mexican blind cavefish Astyanax mexicanus and its surface counterpart. In the lab, adult surface fish show robust circadian rhythms in per1, which are retained in cave populations, but with substantial alterations.

Abnormal axons in the albino optic tract.

Purpose: There have been suggestions that the misrouting of axons at the optic chiasm leading to the abnormal ratio of crossed to uncrossed axons in the optic tract of albinos is a consequence of abnormal timing of ganglion cell axon outgrowth. The sequence of genesis of ganglion cell classes and their axon outgrowth is correlated with the deep-to-superficial distribution of their axons by size in the mammalian optic tract. Optic tract axon order in albino and normally pigmented ferrets was, therefore, examined to determine whether an abnormal pattern of retinal ganglion cell genesis and axon outgrowth is evident in albinos.

Protein kinase C immunoreactivity in the pigmented and albino rat retina.

The albino retina is abnormal. The central region is under-developed and some cell populations are reduced or increased in number. Not least of these anomalies is the deficit in the rod population in hypopigmented rodents and carnivores.

Interaction of color and geometric cues in depth perception: when does "red" mean "near"?

Luminance and color are strong and self-sufficient cues to pictorial depth in visual scenes and images. The present study investigates the conditions under which luminance or color either strengthens or overrides geometric depth cues. We investigated how luminance contrast associated with the color red and color contrast interact with relative height in the visual field, partial occlusion, and interposition to determine the probability that a given figure presented in a pair is perceived as "nearer" than the other.