Figure 3.

Irradiation impairs CFC produced via a single context-shock pairing. (A) Fear conditioning was produced by placing the mouse in the conditioning chamber and delivering one footshock 180 s later (Delayed shock). One control group received context exposure but no shock. The other control group received a footshock within 10 s of being placed in the chamber (Immed. shock). Mice were returned to the conditioning chamber on the following day to assess context-elicited fear. The two control groups exhibited negligible levels of freezing in the context test (B) and did not differ from each other, and, therefore, were combined as one control group. There was no effect of irradiation in the control groups, but among mice receiving the delayed shock, irradiated mice exhibited significantly less context-elicited fear than sham mice. Neither irradiation nor the shock latency (immediate versus delayed) affected the unconditioned response to shock, operationalized as the mouse's velocity of locomotion during the shock (C). *p < .01