Mice were habituated to the startle chambers for 5–10 min on three separate days. On the day of testing, mice were first exposed to 15 startle-alone (105-dB noise burst) trials (leaders), before being presented with ten odor + startle trials randomly intermingled with ten startle-alone trials. The odor + startle trials consisted of a 10-s odor presentation co-terminating with a 50-ms, 105-dB noise burst. For each mouse, an OPS score was computed by subtracting the startle response in the first odor + startle trial from the startle response in the last startle-alone leader. This OPS score was then divided by the last startle-alone leader and multiplied by 100 to yield the percent OPS score (% OPS) reported in the results. Mice were exposed to the acetophenone-potentiated startle (acetophe-none + startle) and propanol-potentiated startle (propanol + startle) procedures on independent days in a counter-balanced fashion.