Fig. 1.

Microinjection of ifenprodil inhibits the magnitude of light-induced phase shifts in the circadian rhythm in wheel-running activity. Histograms plot the mean phase shift of hamsters in DD that received a treatment of either vehicle (200nl) plus light or ifenprodil (200nl, 2mg/ml) plus light. Other groups included hamsters treated with vehicle or ifenprodil alone. Light treatments (15min, 150 lux) were delivered at either CT 13.5 (left panel) or CT 19. The vehicle or drug treatments were delivered immediately prior to light. The placement of the canula into the SCN region was histologically confirmed. N = 6-8 for all points; error bars represent SEM. Values were analyzed with t-test and asterisks indicates significance at P < 0.05.