The Involvement of the Posterior Cerebellum in Reconstructing and Predicting Social Action Sequences

Abstract

Recent advances in social neuroscience have highlighted the critical role of the cerebellum and especially the posterior cerebellar Crus in social mentalizing (i.e., theory of mind). Research in the past 5 years has provided growing evidence supporting the view that the posterior cerebellum builds internal action models of our social interactions to predict how other people's actions will be executed, and what our most likely responses to these actions will be. This paper presents an overview of a series of fMRI experiments on novel tasks involving a combination of (a) the learning or generation of chronological sequences of social actions either in an explicit or implicit manner, which (b) require social mentalizing on another person's mental state such as goals, beliefs, and implied traits. Together, the results strongly confirm the central role of the posterior cerebellar Crus in identifying and automatizing action sequencing during social mentalizing, and in predicting future action sequences based on social mentalizing inferences about others. This research program has important implications: It provides for the first time (a) fruitful starting points for diagnosing and investigating social sequencing dysfunctions in a variety of mental disorders which have also been related to cerebellar dysfunctions, (b) provides the necessary tools for testing whether non-invasive neurostimulation targeting the posterior cerebellum has a causal effect on social functioning, and (c) whether these stimulation techniques and training programs guided by novel cerebellar social sequencing insights, can be exploited to increase posterior cerebellar plasticity in order to alleviate social impairments in mental disorders.

The role of the cerebellum in sequencing and predicting social and non-social events in patients with bipolar disorder

“…Indeed, a larger cluster of significant GM reduction was evidenced in the right Crus II, a region known to be involved in mentalizing processes, primarily when a high level of abstraction is in demand ( van Overwalle and Mariën, 2016 ; van Overwalle et al, 2020 ). Several fMRI studies on healthy subjects have acknowledged the activation of the posterior cerebellum, specifically the Crus I and II, together with cerebral areas known to be part of the social brain during social mentalizing both when the tasks required and did not require sequential processing ( van Overwalle and Mariën, 2016 ; van Overwalle et al, 2022 ). Together with functional activation, cerebellar Crus II and mentalizing brain regions have been found to be effectively connected by closed loops, further demonstrating the cerebellar modulation of advanced social processing ( van Overwalle et al, 2020 ).…”

“…More recently, the role of the cerebellum as a sequential and prediction processor has also been investigated in the social domain, with a focus on Theory of Mind (ToM) skills. In this domain, the construction of internal models reflects the correct implementation of the sequence of social actions, thus allowing people to predict one’s own and others’ behaviors and reactions, and to adjust unexpected events when violations from predicted scenarios are met to finally adjust social interaction accordingly by modulating cerebral cortex activity ( Clausi et al, 2019 ; Heleven et al, 2019 ; van Overwalle et al, 2019a , b , 2022 ). The contribution of lobules Crus I and II has been evidenced for those functions, which is consistent with the widespread connections the posterior cerebellum has with areas in the cerebral cortex involved in high-order functions ( van Overwalle and Mariën, 2016 ; van Overwalle et al, 2022 ).…”

The Cerebellum Is a Key Structure in the Neural Network for Mentalizing: An MRI Study in the Behavioral Variant of Frontotemporal Dementia

“…The present RS-fMRI study provides the first evidence of altered FC within cerebellar and cerebral networks related to mentalizing in patients with bvFTD. The importance of the cerebellum in social/mentalizing functions has been recently acknowledged [ 12 , 53 , 54 ]. Several fMRI studies have documented the activation of specific cerebellar areas, such as Crus I and Crus II, during classic mirror tasks [ 53 ], and belong to the salience network (SN) and to the default mode network (DMN) [ 17 , 18 ].…”

Can transcranial direct current stimulation (tDCS) of the cerebellum improve implicit social and cognitive sequence learning?

“…Extending this hypothesis to the social domain, researchers propose that the cerebellum contributes to mentalizing by building internal models of repeated social sequences, and then automatizes and adjusts these models according to the current reality during social interactions ( Van Overwalle et al, 2019 ; Van Overwalle et al, 2021 ). To illustrate, during daily social interactions, in some cultures we gradually learn that people we are close to, typically smile at us, stretch out their arms and hug us when we greet them.…”