Hippocampus and human emotion control: a novel fMRI sequence shows hippocampal contribution within the Approach-Avoidance Task.

Abstract

The hippocampus has been consistently implicated in spatial navigation and memory consolidation. Recently, anterior hippocampal sub-fields CA1 and CA3 have been involved in emotional action tendencies, like approach and avoidance behaviour. However, it remains unclear whether those sub-fields are also involved in supporting control over those emotional action tendencies. To study what neurophysiological substrates is involved in emotion regulation, which is the ability to control impulsive reactions, traditionally the approach-avoidance task (AAT) has been employed. Although the emotion control literature has shown network of different brain areas interacting when participants had to control their emotions, those studies could not test whether CA1/CA3 was part of the emotion control brain network. The current study tests this possibility, using a novel flow-sensitive high resolution fMRI sequence in thirty-eight participants performing AAT, a task where participants approached or avoided visually displayed emotional faces (happy or angry) by pulling or pushing a joystick. Approaching angry and avoiding happy faces (incongruent condition) requires rapid application of cognitive control to override prepotent habitual action tendencies to approach appetitive or to avoid aversive situations. A ROI analysis was employed, encompassing the the anterior prefrontal cortex (aPFC), amygdala (BLA), and anterior hippocampus. Moreover, single-subject beta values were extracted from peak-voxel CA1 and CA3 and were analysed through a Bayesian statistics. Results showed replication previous findings for the aPFC and BLA, hence validating the sensitivity of the novel fMRI sequence. However, single-subject beta- values analysis did not confirm the presence of neither CA sub-fields contribution within AAT. Despite such findings, results at the group level show congruency- related activation within the anterior hippocampus, hence potentially revealing small and distributed anterior hippocampal contribution in the emotion regulation network