Dim artificial light at night alters immediate early gene expression throughout the avian brain

Artificial light at night (ALAN) is a pervasive pollutant that alters physiology and behavior. However, the underlying mechanisms triggering these alterations are unknown, as previous work shows dim levels of ALAN may have masking effect, bypassing central clock. Light stimulates neuronal activity in numerous brain regions which could turn activate downstream effectors regulating physiological response. In present study, taking advantage immediate early gene (IEG) expression proxy for activity, we determined activated response to ALAN. We exposed zebra finches (1.5 lux) analyzed 24 throughout brain. found overall two different IEGs, cFos ZENK, birds were significantly from inactive night. Additionally, ALAN-exposed had IEG active during day several areas associated with vision, movement, learning memory, pain processing, hormone regulation. These results give insight into mechanistic pathways responding underlie downstream, well-documented behavioral changes.