Subregional amygdala functional connectivity: normative maps and influence of oral citalopram in healthy volunteers

Amygdalar functional connectivity (fc) is important in emotional regulation, potentially predicting behavioural traits such as harm avoidance. The amygdala is a highly heterogeneous structure; even at a typical fMRI resolution of 3 mm³ its subareas are located distinctly. We used×3×3 cytoarchitectonic probability maps (CAPM, post-mortem validated) to study the fc of three amygdala subregions in healthy volunteers during processing of semantically congruent and incongruent emotional image/word pairs before and after 4 days of oral citalopram (1.5 Telsa, EPI, 360 volumes). Seed extraction was performed using non-overlapping maximum probability maps (Eickhoff et al., 2005) and auto-regression maps were generated with covariation for affine motion parameters and globals. 2nd level random effect analyses were conducted to define common and differenzial fc of the subregions, with additional comparisons to the non-differentiated amygdala defined on standard parcellation of the Colin27 brain (Tzourio-Mazoyer et al., 2002). After 4 days of oral citalopram, activation related to conflict processing was reduced in the parahippocampal/fusiform gyri (corrected cluster p<0.05). Amygdala subregions showed differenzial fc, e.g. specifically to the subgenual cingulate, brainstem or striate. Effects of citalopram hereon will be reported. Our peliminary conclusion is that consideration of differenzial fc of the amygdala may increase specifity and power of studies on limbic activation.