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Title: Aberrant light directly impairs mood and learning through melanopsin-expressing neurons
Journal: Nature (2012) 491:594
Link: https://doi:10.1038/nature11673
Comments: Brain manages the light information in two ways: image forming and non-image forming visual information. Retinal ganglion cell (RGC) will give rise to the optic nerve to conduct visual information from the retina to the brain. Recent studies revealed that intrinsically photosensitive RGCs (ipRGCs) play a central role in non-image forming visual functions with expression of photopigment melanopsin, while majority of the image forming information will be processed by optic cells with photopigment rhodopsin
Current study addressed the effect of light on mood and cognitive functions using mice. Aberrant light such as light schedule with quite short period (e.g., 7 hours rather than 24 hours), mice exhibited depressive-like behaviors (anhedonia-like phenotype and enhanced immobility in sucrose preference and forced swim tests, respectively) with increased corticosterone response. This change was associated with impairment of spatial memory as revealed by Morris water maze test as well as reduced long term potentiation observed in the hippocampus.
In human psychiatry, the effect of light on mood has been known by the example of seasonal for of depression (seasonal affective disorder, SAD). Evidences provided by this study may provide a neural substrate underlying the pathophysiology underlying the SAD.
