Figure 2.

Experimental protocol summary and footshock sensitivity level assay. A, Schematic representation showing experimental associative fear conditioning assay and timeline for examining acquisition (encoding) versus expression (recall) phases of associative olfactory fear memory. B, C, Behavioral sensitivity assay demonstrating that although subthreshold (0.4 mA) footshock stimuli produce neither conditioned freezing behavior (B) nor conditioned suppression of exploratory behavior (C), presentation of a suprathreshold (0.8 mA) footshock level produces significant levels of freezing (B) and suppression of exploratory behavior (C). Error bars represent SEM for this and all subsequent figures. For this and all subsequent figures, *p < 0.05; **p < 0.01.