The contribution of the left inferior frontal gyrus in affective processing of social groups

Abstract

We investigated the contribution of the pars opercularis of the left inferior frontal gyrus (LIFGop) in representing knowledge about social groups. We asked healthy individuals to categorize words preceded by semantically congruent or incongruent primes while stimulating the LIFGop. Previous studies showing an involvement of the LIFGop both in processing social stimuli and negative valence words led us to predict that its stimulation would affect responses to negative social category words. Compared to the Vertex as control site, the stimulation of the LIFGop increased the speed of categorization of negative social groups, and disrupted the semantic priming effect for negative words overall. Within the framework of recent theories of semantic memory, we argue that the present results provide initial evidence of the representation of social groups being characterized by affective properties, whose processing is supported by the LIFGop.

Electrophysiological Correlates of Social Group Representations in Affective Priming

“…These results contribute to explaining previous findings associating the damage and stimulation of areas commonly involved in processing affective information with the specific representation of social groups (Piretti et al, 2015;Suran et al, 2019). Although the reason and the nature for such reliance is still debated (Meteyard, Cuadrado, Bahrami, & Vigliocco, 2012), we propose that the greater association with affective processing when representing social groups could derive from the repeated engagement in empathetic (Barsalou, 2008) and evaluative responses (Piretti et al, 2015) when the meaning of these concepts is acquired and rehearsed.…”

Disrupting inferior frontal cortex activity alters affect decoding efficiency from clear but not from ambiguous affective speech

“…In fact, repetitive TMS over the left IFC revealed perturbed social perception while social cognition was preserved, with slower reaction times observed for emotion recognition (Keuken, Hardie et al 2011). A similar TMS procedure targeting the pars opercularis of the left IFG led to faster categorization of negative social groups and disrupted semantic priming for negative words, as opposed to TMS over the vertex (Suran, Rumiati et al 2019). These two studies emphasize the importance of the target location for a TMS procedure-and add nuance to IFC subparts functioning and specificity-by pointing toward slower or faster responses according precise IFC disruption in the pars orbitalis (Keuken, Hardie et al 2011) or opercularis (Suran, Rumiati et al 2019), respectively.…”

“…In fact, repetitive TMS over the left IFC revealed perturbed social perception while social cognition was preserved, with slower reaction times observed for emotion recognition (52). A similar TMS procedure targeting the pars opercularis of the left IFG led to faster categorization of negative social groups and disrupted semantic priming for negative words, as opposed to TMS over the vertex (35). These two studies emphasize the importance of the target location for a TMS procedure-and add nuance to IFC subparts functioning and specificity-by pointing toward slower or faster responses according precise IFC disruption in the pars orbitalis (52) or opercularis (35), respectively.…”

“…The cTBS procedure targeting the IFC led to an altered functioning of this region and affected decisional processes of the participants during the affect classification task. This target region was chosen because it was found active during the processing of affective voices in the CG, and it is a commonly found activation peak across many studies on voice processing, categorization, and classification (Schirmer and Kotz 2006, Frühholz and Grandjean 2012, Frühholz and Grandjean 2013, Suran, Rumiati et al 2019, Grandjean 2020). The cTBS procedure had an impact on both behavioral decisions and cerebral processing.…”