Circadian Photoreception - Photoreceptive Cells of the Mammals - Assignment Example

In order to explore the photoreception in a mole rat who is found to be completely blind. The blindness of Spalax was evident from the incomplete and regressed visual pathways. Also, an open behavioral reaction to light and lack of visual cortical potentials validate its blindness. However, the molecular and structural probes of the subcutaneous eye (atrophied) indicate retina performs an operational role in light perception, as well as the entrainment of thermoregulatory rhythms and circadian locomotors by ambient light, evidences a capability for photoperiodic detection.

It has been reported that rigorous regression of tectal and thalamic structures concerned in motion and form perception is joined to exclusive hypertrophy of structures assisting photoperiodic functions. So the study provides an imperative to link the ocular regressions (the differential expansion and reduction) found in Spalax as an outcome of adaptation to the underground environment. Since the view prevailing suggested that the ocular regression consequences from nonselective or negative evolutionary processes.

The study concludes that the photoperiodic system, maintaining appropriate thermoregulatory and reproductive responses, has been exclusively expanded, while the acute metabolic load of keeping a visible eye along with the non-operational ‘image forming sensory system renders the inherent evolutionary drift for their structural regression. Therefore, ocular regression, paired with selective advancement of photoperiodic pathways, presents a single facet of a distinctive range of adaptations evolved within the subterranean mammals to meet environmental restraints enforced by the underground environment (Cooper, Herbin, and Nevo 159).