Fig. (3) UCR diminution within the fMRI signal response. Significant diminution of the unconditioned fMRI signal response was observed within the prefrontal cortex (PFC) and anterior insula during test trials. UCR amplitude within these brain regions was reduced when the UCS followed the CS+ (i.e. CS+UCS trials) and CS− (i.e. CS−UCS trials) compared to when the UCS was presented alone. There was no difference on CS+UCS versus CS−UCS trials. Graphs reflect the mean amplitude (% signal change) of all voxels within volumes of activation. Error bars reflect SEM after adjusting for between-subject variance (Loftus and Masson, 1994). Asterisk indicates significant difference.