Control conditions in the fear-potentiated startle response paradigm.

In the present study, the fear-potentiated startle response paradigm was modified in order to investigate the decrease in control startle levels often observed after administration of anxiolytic drugs. The within-animal comparison of control startle amplitudes and fear-potentiated startle amplitudes normally used was replaced by a between-animal comparison. Moreover, the experimental design was extended with an additional control group, a no-shock group. The anxiolytics diazepam and chlordiazepoxide were used as pharmacological tools. The main findings were that both benzodiazepines dose-dependently reduced control startle amplitudes and no-shock startle amplitudes equally, suggesting that shock-associated contextual cues are not responsible for the drug-induced decrease in control startle amplitudes in the fear-potentiated startle response paradigm.