fMRI of emotion: some clinical applications at 3 Tesla.

INTRODUCTION It is well known that amygdala is a key point nervous structure in the emotional limbic system. When, for instance, the situation becomes dangerous for the individual, the amygdala comes into play and, by the activation of a series of pathways (conscious and unconscious), may trigger biologic and behavioural responses, which enable the individual to cope with the danger and to survive it (fight or flight). The emotional system output acts through both the classic somatic motor system and its own motor pathways (the emotional motor system), which act in parallel to promote the correct behavioural response. The advent of functional Magnetic Resonance Imaging (fMRI) allowed a better definition of the activity of these limbic structures, not only in the normal population, but also in some clinical applications. At our Neuroscience Department we applied fMRI to two very different pathologies: panic disorder and ulcerative colitis. PANIC DISORDERS. Aim. Panic disorder (PD) is an anxiety disorder characterized by recurring severe panic attacks and chronic hyperarousal. It has been shown that, in normal population, amygdala activates in response to fearful faces even if presented below the threshold of conscious visual perception. Our aim was to establish whether the amygdala was engaged by the two different presentations of fearful faces and whether its responses were different in PD patients and controls. Materials and Methods. 13 PD patients and 15 healthy volunteers underwent two passive viewing tasks during a 3T fMRI scanning: 1) presentation of faces with fearful vs neutral expressions (17 ms, subliminar stimulus) using a backward masking procedure; 2) presentation of the same faces vs neutral expressions (200 ms, consciously perceived stimulus), whose spatial frequency contents had been manipulated by low-pass filtering (low spatial frequencies, LSF). Results. Whereas controls showed a bilateral activation for fearful masked faces and left amygdala activation for the LSF condition, patients failed to show any activation within the amygdala in both conditions. Conclusions. Findings showed that the chronic hyperarousal in PD patients is correlated with a reduced amygdala activation to potentially threatening visual stimuli, thus becoming maladaptive. Therapeutic approaches should consider not only the clearly visible overreaction to harmless stimuli, but also the hyporeaction to real danger that chronic PD patients might have developed over time. ULCERATIVE COLITIS. Aim. The aim of this study was to investigate the emotional system in patients suffering from Ulcerative Colitis (UC). To this aim, we focused on Amygdala, perigenual Anterior Cingulate Cortex (pACC), anterior part of Middle Cingulate Cortex (aMCC) and medial Prefrontal Cortex (mPFC), the main nervous structures crucially involved in the emotional processing. We used fMRI to evaluate the changes in Blood Oxigenation Level Dependent (BOLD) signal induced by single and repeated visual emotional stimulations, within the aforesaid limbic structures, in patients with mild UC in clinical remission, compared to healthy people. Materials and Methods. We tested 10 UC patients having mild disease in clinical remission and 10 healthy Control subjects by 3T fMRI, during a visual emotional stimulation (by using International Affective Picture System (IAPS) images). Two identical visual emotional stimulations were repeated for each subject in the same session, in order to study amygdala, pACC, aMCC and mPFC ROI-based BOLD signal changes in the 1st response (1st Trial) and habituation (2nd Trial). A repeated measures ANOVA was used for the statistical analysis of the results. Results. UC patients showed a different emotional activation pattern with respect to Control subjects. In the 1st Trial, UC patients showed a significantly lower bilateral fMRI BOLD signal in all the limbic structures examined, with respect to the Control group. In the 2nd Trial, the Control...