Figure 8.

Central administration of NPY enhances the extinction to the contextual component of fear-potentiated startle. A, A comparison of noise-alone startle was made among values from three days of the behavioral procedure shown here: (1) baseline (startle amplitude measured before fear conditioning, (2) Pre-Ext test (startle amplitude measured after fear conditioning, before extinction training), and (3) Post-Ext test (startle amplitude measured after extinction training). B, In the vehicle group, startle response increases from baseline to Pre-Ext and then remains constant, corresponding to the development and maintenance of contextual fear. However, in the NPY group startle response increases from baseline to Pre-Ext and then decreases to levels comparable to baseline during the Post-Ext test. This pattern corresponds to extinction of contextual fear [significant main effect of test session (F _(2,59) = 6.545, p < 0.01); error bars indicate ±SEM; *p < 0.05].