Δ9-tetrahydrocannabinol (THC) has been shown to modulate anxiety and facilitate the extinction of fear by inhibiting amygdala reactivity. Since functional coupling between the amygdala and prefrontal cortex (PFC) is implicated in affective processes, it is possible that THC affects amygdala-PFC functional connectivity, in ways that differ across amygdala subregions: basolateral (AMYG-BL), centromedial (AMYG-CM), and superficial (AMYG-SF). The aim of the study was to examine the effects of THC on functional connectivity between amygdala subregions and the PFC during socio-emotional threat in healthy adults using a double-blind, placebo-controlled, within-subjects design. Sixteen subjects completed a functional magnetic resonance imaging (fMRI) task designed to probe amygdala responses to social threat. Amygdala subregion-PFC functional connectivity was compared between THC and placebo using generalized psychophysiological interaction (gPPI) analyses. Findings indicated that THC enhanced AMYG-BL and AMYG-SF connectivity to the rostral anterior cingulate/medial PFC. These effects, including THC’s potential ability to reduce threat perception or enhance socio-emotional regulation, may help understand the neurocircuitry of affect.
Published by Oxford University Press on behalf of CINP 2014. This work is written by (a) US Government employee(s) and is in the public domain in the US.