Special CSB Seminar – Doctor Samer Hattar, Chief and Senior Investigator, Section on Light and Circadian Rhythms (SLCR), NIH/National Institute of Mental Health

The discovery of atypical mammalian photoreceptors that are distinct from
the classical rod and cone photoreceptors opened new avenues for light
research. The non-rod/non-cone photoreceptors belong to retinal ganglion
cells (RGCs) and express the photopigment melanopsin rendering them
intrinsically photosensitive RGCs or ipRGCs for short. We showed that
these cells project widely in the brain and are in position to control
many essential behaviors, which include circadian rhythms and sleep.
Recently, we found that ipRGCs also have a direct influence on mood and
learning & memory. In this presentation, I am going to present unpublished
data where my lab uncovered a new brain region that is essential for the
direct light effects on mood. I will present anatomical and functional
evidence that this region is both necessary and sufficient for mood
regulation by light. These studies open new avenues to understand major
depressive mechanisms, especially the ones related to seasonal changes.