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

Abstract

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.

Ventral striatal dopamine encodes unique properties of visual stimuli in mice

“…We cannot, however, rule out the involvement of UV-sensitive non-visual opsins in our observed findings, such as neuropsin ( Opn5 ), which is maximally activated by 380 nm light (Tarttelin et al, 2003). Neuropsin-expressing retinal ganglion cells project to multiple limbic regions (Sasaki et al, 2021), and this opsin promotes thermogenesis via intrinsically light-sensitive glutamatergic neurons in the preoptic area (Zhang et al, 2020). While melanopsin-expressing ipRGCs are hypothesized to engage VTA outputs via a disynaptic circuit involving the preoptic area (Zhang et al, 2021), we found that Opn4 knockout had no effect on the ability of light to evoke LNAc dopamine.…”