Disrupting the Right Inferior Frontal Gyrus Increases Social Brain Activity During Emotion Recognition

Neuroimaging research has pinpointed a specialized social brain network responsible for emotion recognition and social cognition. This network, which engages in activities such as facial expression analysis and deducing others' mental states, can be disrupted by damage to the right inferior frontal gyrus (IFG), a top-down control region within this network.

To explore the impact of temporarily interrupting the right IFG on the broader social brain, researchers combined transcranial magnetic stimulation (TMS) with functional magnetic resonance imaging (fMRI). The study included 20 participants who underwent two scanning sessions during a delayed match-to-sample emotion recognition task.

In this task, happy or fearful facial expressions were preceded by congruent or incongruent word cues. Before each scan, TMS was applied over the right IFG or a control site on the vertex (with balanced session order across participants). The results revealed that TMS to the IFG heightened neural activity in various regions of the social brain network, including the bilateral temporal pole, precuneus, and medial prefrontal cortex (mPFC).

This finding demonstrates that inhibiting the IFG's top-down control mechanisms changes neural processing in distant nodes of the social brain network. The study's implications are discussed in the context of how people recognize and interpret the emotions of others.