| In one study, pre-pulse inhibition (PPI) and affective modulation (AM) of startle blink, and electrodermal activity (EDA) were used to assess response to angry, happy and neutral faces in normal comparison (NC,N = 12), socially phobic (SP,N = 12) and schizotypal subjects (SZ,N = 12). Attention was directed to facial features (2 tasks, one with stimuli inverted), age, angry and happy expressions in five counter-balanced tasks with white noise bursts delivered at 120 and 3800ms following image onset. Results extend previous literature by demonstrating attentional modulation of PPI for visual stimuli, sensitivity of PPI to task difficulty, and disruption of AM by attention to emotional stimulus characteristics. SP reported heightened state anxiety and both SP and SZ endorsed heightened trait anxiety. SP displayed enhanced PPI to social versus non-social stimuli and showed an attentional bias for angry and happy versus neutral faces which did not vary with attentional modulation. Female SP produced elevated, delayed startle blinks and impaired emotion detection, consistent with depressive response patterns, although they did not report concurrent depression. SZ displayed attentional modulation of PPI for happy versus angry faces, but produced impaired AM and decreased PPI to happy faces suggesting reduced sympathetic arousal to happy faces. SZ produced atypical PPI in tasks with multidimensional social information. In a second study in the same subjects, N100, P200 and P300 components were measured in six counter-balanced tasks in response to angry, happy and neutral faces serving as context, target and non-target stimuli with emotion (happy, angry, neutral) or feature detection instructions (2 tasks, one with stimuli inverted). Results extend previous literature by demonstrating P200 sensitivity to affective versus neutral contexts, N100 sensitivity to emotional valence, and RT, N100 and P300 sensitivity to stimulus orientation. SP had enhanced N100 amplitude to neutral targets in angry versus happy contexts, but male SZ had delayed P200 to affective faces, consistent with impaired affective discrimination. Across targets and non-targets, SP had larger P300 to angry faces and SZ had reduced P300 to happy faces. SP and SZ self-reported similar levels of impaired social function and social anxiety, but this research suggests the groups differ in underlying information processing mechanisms. |
