Light Affects Mood and Learning through Distinct Retina-Brain Pathways

Cell. 2018 Sep 20;175(1):71-84.e18. doi: 10.1016/j.cell.2018.08.004. Epub 2018 Aug 30.


Light exerts a range of powerful biological effects beyond image vision, including mood and learning regulation. While the source of photic information affecting mood and cognitive functions is well established, viz. intrinsically photosensitive retinal ganglion cells (ipRGCs), the central mediators are unknown. Here, we reveal that the direct effects of light on learning and mood utilize distinct ipRGC output streams. ipRGCs that project to the suprachiasmatic nucleus (SCN) mediate the effects of light on learning, independently of the SCN's pacemaker function. Mood regulation by light, on the other hand, requires an SCN-independent pathway linking ipRGCs to a previously unrecognized thalamic region, termed perihabenular nucleus (PHb). The PHb is integrated in a distinctive circuitry with mood-regulating centers and is both necessary and sufficient for driving the effects of light on affective behavior. Together, these results provide new insights into the neural basis required for light to influence mood and learning.

Keywords: aberrant light cycle; circadian rhythms; ipRGCs; learning; mood; perihabenular nucleus; suprachiasmatic nucleus; ventromedial prefrontal cortex.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, N.I.H., Intramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Affect / physiology
  • Affect / radiation effects*
  • Animals
  • Brain / physiology
  • Circadian Rhythm
  • Learning / physiology
  • Learning / radiation effects*
  • Light*
  • Mice
  • Mice, Inbred C57BL
  • Phototherapy / methods
  • Retina / metabolism
  • Retina / physiology
  • Retinal Ganglion Cells / metabolism
  • Retinal Ganglion Cells / physiology
  • Retinal Ganglion Cells / radiation effects
  • Signal Transduction / physiology
  • Suprachiasmatic Nucleus / metabolism
  • Vision, Ocular / physiology
  • Visual Pathways / metabolism
  • Visual Perception / physiology