Theta-gamma phase amplitude coupling serves as a marker of social cognition and visual working memory deficits in individuals with elevated autistic traits

It has been thought that coordination of briefly maintained information (working memory) and social cognition (mentalizing) rely on different brain mechanisms. However, the dorsomedial prefrontal cortex (DMPFC) seems to control the mentalizing and the visual working memory networks. We aimed to show (1) that visual working memory and social cognition share the same neural communication mechanism (i.e., interregional phase-amplitude coupling) and (2) that this mechanism is behaviorally relevant. We analyzed electrical brain activity from 98 volunteers who differed in the extent of (subclinical) autistic personality traits. Participants performed a social, visual and verbal working memory task, each implemented in a low and a high cognitive load version. We analyzed how slow rhythmical brain activity in the DMPFC controls distributed posterior regions associated with working memory and mentalizing via phase-amplitude coupling. First, individuals with low autistic personality traits use slow rhythmical brain activity in the DMPFC to precisely tune communication with posterior brain areas depending on the effort necessary in the visual and social tasks. Second, individuals with high autistic personality traits struggle in fine-tuning this mechanism, which is associated with difficulties in efficiently adapting brain activity to the difficulty level of a visual working memory task; and they demonstrate problems with efficiently synchronizing the relevant cortical network in a social cognition task. While these findings suggest a unified function of brain oscillations in cognitive coordination between social and visual tasks, they could also explain why individuals with high autistic personality traits can have difficulties with demanding cognitive processing and mentalizing.