FUNCTIONAL MRI STUDY OF SPECIFIC ANIMAL PHOBIA USING AN EVENT-RELATED EMOTIONAL COUNTING STROOP PARADIGM

Background: Emotional interference tasks may be useful in probing anterior cingulate cortex (ACC) function to understand abnormal attentional control in individuals with specific phobia. Methods: In a 3T functional MRI study, individuals with specific phobias of the animal subtype (SAP, n = 12) and healthy comparison (HC) adults (n = 12) completed an event-related emotional counting Stroop task. Individuals were presented phobia-related, negative, and neutral words and were instructed to report via button press the number of words displayed on each trial. Results: Compared to the HC group, the SAP group exhibited greater rostral A CC activation (i.e., greater response to phobia-related words than neutral words). In this same contrast, HCs exhibited greater fight amygdala and posterior insula activations as well as greater thalamic deactivation than the SAP group. Both groups exhibited anterior cingulate, dorsomedial prefrontal cortex, inferior frontal gyrus/insula, and amygdala activations as well as thalamic deactivation. Psychophysiological interaction analysis highlighted a network of activation in these regions in response to phobia-related words in the SAP group. Conclusions: Taken together, these findings implicate a circuit of dysfunction, which is linked to attention abnormalities in individuals with SAP Depression and Anxiety 26:796-805, 2009. Published 2009 Wiley-Liss, Inc.(dagger)