Neural Mechanisms of Automatic and Direct Processing of Phobogenic Stimuli in Specific Phobia
Received 27 January 2005; received in revised form 24 May 2005; accepted 15 June 2005. published online 03 September 2005.
Background
The study aimed to identify brain activation during direct and automatic processing of phobogenic stimuli in specific phobia.
Methods
Responses to phobia-related and neutral pictures (spiders and mushrooms) were measured by means of event-related functional magnetic resonance imaging during two different tasks. In the identification task, subjects were asked to identify the object (spider or mushroom). In a demanding distraction task, subjects had to match geometric figures displayed in the foreground of the pictures.
Results
Phobics showed greater responses to spiders versus mushrooms in the left amygdala, left insula, left anterior cingulate gyrus (ACC), and left dorsomedial prefrontal cortex (DMPFC) during the identification task and in the left and right amygdala during the distraction task. All of these activations were also significantly increased compared to control subjects who did not show stronger brain activation to spiders versus mushrooms under any task condition.
Conclusions
Our findings propose specific neural correlates of automatic versus direct evaluation of phobia-relevant threat. While the amygdala, especially the right amygdala, seems to be crucially involved in automatic stimuli processing, activation of areas such as the insula, ACC and DMPFC is rather associated with direct threat evaluation and requires sufficient attentional resources.
aDepartment of Biological and Clinical Psychology, Friedrich-Schiller-University, Jena, Germany
bInstitute of Diagnostic and Interventional Radiology, Friedrich-Schiller-University, Jena, Germany
Address reprint requests to Thomas Straube, Ph.D., Department of Biological and Clinical Psychology, Friedrich-Schiller-University, Am Steiger 3 // 1, D-07743 Jena, Germany
ABSTRACT