PAVLOVIAN FEAR CONDITIONING IN MICE ANESTHETIZED WITH HALOTHANE

Pavlovian fear conditioning was employed to investigate learning durin g general anesthesia. Mice were given three CS-UCS presentations while anesthetized with halothane. The CS was a 10-s tone and the UCS a 0.4 -mA shock delivered intramuscularly to the hindlimbs via needle electr odes. Anesthetized control groups received either CS only, UCS only, o r CS followed by a 3-min delayed UCS. Strength of fear conditioning wa s assessed by measuring duration of suppression of drinking induced by tone presentation in a test session conducted 24 h after training. Re sults showed that mice trained under anesthesia exhibited a significan t amount of conditioned suppression relative to the anesthetized contr ol groups. These results show that Pavlovian fear conditioning can occ ur under halothane anesthesia.