The traditional view on the cerebellum is that it controls motor behavior. Although recent work has revealed that the cerebellum supports also nonmotor functions such as cognition and affect, only during the last 5 years it has become evident that the cerebellum also plays an important social role. This role is evident in social cognition based on interpreting goal-directed actions through the movements of individuals (social “mirroring”) which is very close to its original role in motor learning, as well as in social understanding of other individuals’ mental state, such as their intentions, beliefs, past behaviors, future aspirations, and personality traits (social “mentalizing”). Most of this mentalizing role is supported by the posterior cerebellum (e.g., Crus I and II). The most dominant hypothesis is that the cerebellum assists in learning and understanding social action sequences, and so facilitates social cognition by supporting optimal predictions about imminent or future social interaction and cooperation. This consensus paper brings together experts from different fields to discuss recent efforts in understanding the role of the cerebellum in social cognition, and the understanding of social behaviors and mental states by others, its effect on clinical impairments such as cerebellar ataxia and autism spectrum disorder, and how the cerebellum can become a potential target for noninvasive brain stimulation as a therapeutic intervention. We report on the most recent empirical findings and techniques for understanding and manipulating cerebellar circuits in humans. Cerebellar circuitry appears now as a key structure to elucidate social interactions.

This meta-analysis explores the role of the posterior cerebellum Crus I/II in social mentalizing. We identified over 200 fMRI studies via NeuroSynth that met our inclusion criteria and fell within bilateral Crus II areas related to “sequencing” during mentalizing (coordinates ±24 -76 -40; from earlier studies) and mere social “mentalizing” or self-related emotional cognition (coordinates ±26 -84 -34; from NeuroSynth), located in the cerebellar mentalizing network of Buckner et al. (2011). A large majority of these studies (74%) involved mentalizing or self-related emotional cognition. Other functions formed small minorities. This high incidence in Crus II compares very favorably against the lower base-rate for mentalizing and self-related emotions (around 35%) across the whole brain as revealed in NeuroSynth. In contrast, there was much less support for a similar role of Crus I (coordinates -40 -70 -40 from earlier “sequencing” studies) as only 35% of the studies were related to mentalizing or self-related emotions. The present findings show that a domain-specific social mentalizing functionality is supported in the cerebellar Crus II. This has important implications for theories of the social cerebellum focusing on sequencing of social actions, and for cerebellar neurostimulation treatments.

Recent research has indicated that the cerebellum is responsible for social judgments, such as making trait attributions. The present study investigated the function of the posterior cerebellum in supporting sequence learning linked to trait inferences about persons. We conducted a memory paradigm that required participants to learn a given temporal order of six behavioral sentences that all implied the same personality trait of the protagonist. We then asked participants to infer the trait of the person and to recall the correct order of the sentences and to rate their confidence in their trait judgments and retrieval accuracy. Two control conditions were created: a nonsocial comparison control, involving six nonsocial sentences implying a feature of an object, and a nonsocial nonsequential reading baseline condition. While learning the specific sequence of the sentences, the posterior cerebellum (Crus 2) was more activated for social trait-related sequencing than nonsocial object-related sequencing. Also, given a longer duration to learn the sequences, the precuneus and posterior cingulate cortex were more activated when participants attempted to retrieve the sequences linked to social traits. In addition, confidence in retrieving the correct order of the social sequences modulated the posterior cerebellum (Crus 1) given a longer duration to learn. Our findings highlight the important function of the posterior cerebellum in supporting an active process of sequencing trait-implying actions.

Highlights• The posterior cerebellar Crus is involved in sequence-based social navigation, along with the parahippocampal gyrus and social cortical areas.• Crus II is recruited during memorizing social and non-social sequential trajectories• Crus I is specifically recruited to memorize social trajectories.• Cerebellar Crus I and II, and lobules VI are recruited when reproducing social and nonsocial sequencing trajectories.

Can we predict the future by reading others´ minds? This study explores whether attributing others’ personality traits facilitate predictions about their future actions and the temporal order of these future actions. Prior evidence demonstrated that the posterior cerebellar Crus is involved in identifying the temporal sequence of social actions and the person’s traits they imply. Based on this, we hypothesized that this area might also be recruited in the reverse process, that is, knowledge of another person’s personality traits supports predictions of temporal sequences of others’ actions. In this study, participants were informed about the trait of a person, and then had to select actions that were consistent with this information and arrange them in the most likely temporal order. As hypothesized, the posterior cerebellar Crus 1 and 2 were strongly activated when compared to a control task which involved only the selection of actions (without temporal ordering) or which depicted non-social objects and their characteristics. Our findings highlight the important function of the posterior cerebellar Crus in the prediction of social action sequences in social understanding.