Violet light modulates the central nervous system to regulate memory and mood

Light stimuli from the external environment serves as a signal. Photoreceptors receive photons at the outer nuclear layer of the retina. Non-visual photoreceptors, such as opsin5 (also known as OPN5 or neuropsin), are expressed in the retinal ganglion cells (RGCs) and hypothalamus to regulate the circadian cycle and body temperature. Here, we show that violet light (VL) stimuli received by OPN5-positive RGCs are transmitted to the habenula brain region. VL improves memory in aged mice and simultaneously increases neural architecture-related genes such as oligodendrocyte-related genes in the hippocampus. In addition, VL improves depressive-like behaviors in the social defeat stress model in an OPN5 dependent manner. Following VL exposure, cFos activation is observed at the nucleus accumbens (NAc) and the paraventricular thalamic nucleus (PVT). Taken together, the results indicate that violet light modulates brain function such as memory and mood by transmitting the signal from RGCs to the habenula region in the brain. ### Competing Interest Statement K. T. reports he is the CEO of Tsubota Laboratory, Inc. K. T., M. H. and Y. M. owns the unlisted stocks of Tsubota Laboratory, Inc., a company developing devices related to violet light. R. A. L. has a sponsored research agreement with BIOS Lighting and, in collaboration with BIOS Lighting, has submitted patent application 41906194/PCT/US21/17681, Lighting Devices to Promote Circadian Health. Y. H. is an employee of the Tsubota Laboratory Inc. Tsubota Laboratory, Inc. consigns the experiment to N. S., P. G. M. H. and K. O. Other authors declare no conflicts of interest associated with this manuscript.