Social Cerebellum and action sequences
Frank Van Overwalle (1) and Kim van Dun (2)
(1) VUB; (2) Universiteit van Hasselt
Social neuroscience has made significant progress in understanding the neural correlates of social cognition, including mentalizing, or our ability to read other persons’ mental state. However, this research has focused predominantly on the cerebral cortex subserving mentalizing processes. Nevertheless, the cerebellum might be more critical to social cognition than assumed so far. But what might be the role of the cerebellum in social cognition? It has traditionally been assumed that the cerebellum only supports motor processing, and that its main function was to learn movement sequences that underpin motor skills. Specifically, the cerebellum was assumed to construct internal models involving sequences of movements in order to automate and fine-tune motor processes, and to check whether an anticipated movement is aligned with current behavior. With respect to social cognition, in analogy with motor behavior, it has been proposed that the cerebellum supports learning and automatization of social action sequences in internal models of social interaction. These internal models allow humans to better anticipate action sequences during social interaction in an intuitive way, to continuously check whether an anticipated action sequence aligns with current behavior, and where necessary, to adjust these actions rapidly and continuously. The contributions in the present symposium provide novel evidence for this sequencing hypothesis of the social cerebellum with respect to explicit and implicit learning of sequencing of social actions in healthy and patient groups, and how cerebellar stimulation might modulate the working of this social sequencing function and improve our understanding of the underlying mechanisms.
Speaker 1: Novel fMRI, patient and TMS findings on the role of the cerebellum in social action sequences
Elien Heleven (1), Kim van dun (2) and Frank Van Overwalle (1)
(1) VUB; (2) Universiteit Hasselt
An increasing number of studies highlighted the importance of the cerebellum in social functioning, most often the posterior part (i.e., Crus 1 and 2). One hypothesis states that the basic function of the cerebellum -- to develop internal models of sequences involving motor elements for the planning and execution of movements -- extended during evolution to the development of internal models of purely mental element which facilitates event sequence processing. We developed new sequencing tasks to investigate cerebellar involvement in the processing of different types of sequences, in which participants generated the correct chronological order of new or well known event stories. The results of an fMRI study on healthy subjects, showed strong posterior cerebellar activation during order generation for all event types compared to passive viewing or reading events, and even more so for new social events compared to routine (non-) social events. Currently, we are investigating the effects of neurostimulation on the posterior cerebellum on task performances in healthy subjects for our sequencing tasks. In an other study, we are investigating performances of cerebellar patients on these tasks. Preliminary results will be presented at the conference.
Speaker 2: The posterior cerebellum supports the explicit sequence learning linked to trait attribution
Min Pu (1), Elien Heleven (1), Jeroen Delplanque (1), Noémie Gibert (2), Qianying Ma (1), Giulia Funghi (3) and Frank Van Overwalle (1)
(1) VUB; (2) University of Montpellier, France; (3) Sapienza University of Rome, Italy
Recent research has indicated that the cerebellum contributes to 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 non-social comparison control, involving six non-social sentences implying a feature of an object, and a non-social non-sequential reading baseline condition. While learning the specific sequence of the sentences, the posterior cerebellum (Crus II) was more activated for social trait-related sequencing than non-social object-related sequencing. Level of metacognitive confidence in successfully retrieving the sequences modulated the posterior cerebellum (Crus I) as well as the left frontal cortex. Our findings highlight the important function of the posterior cerebellum in supporting an active process of sequencing trait-implying actions.
Speaker 3: The posterior cerebellum supports implicit learning of true and false belief sequence
Qianying Ma (1), Min Pu (1), Elien Heleven (1) and Frank Van Overwalle (1)
Sequences exist in numerous motor, cognitive and social skills, and learning sequences help people to execute and predict efficient and adaptive behaviors. Besides evidence for cerebellar contribution to motor and cognitive sequence learning, recent studies documented posterior cerebellar activation in multiple social cognition tasks in which sequences play a critical role (e.g. generating the chronological order of a social story). Here, we investigated the function of the cerebellum when people learn regularities in a social context implicitly. In particular, we used a novel social implicit sequence learning task, combining elements from false belief and serial reaction time tasks. Participants learned that protagonists were offered flowers at four locations. The protagonists’ beliefs concerning the flowers were true or false, respectively, depending on their orientation towards the scene (true belief: flowers could be seen) or away from it (false belief: protagonists believe that everything was as before). Participants then had to indicate as fast as possible how many flowers were given according to the protagonists’ perspective. Unbeknown to the participants, there was a sequence tied to the two protagonists and their belief orientations. As predicted, the results revealed that the posterior cerebellum was activated during belief sequence learning, and was also involved in detecting violations when the learned belief sequence was disrupted by a random sequence. Together, our results highlight contributions of the posterior cerebellum in the implicit formation of internal representations of new belief sequences at the learning phase and in the detection of sequential violations.
Speaker 4: Cerebellar stimulation with TMS and tDCS
Kim van Dun (1) and Mario Manto (1)
Improving brain functions by modulating neuronal excitability with noninvasive brain stimulation (NIBS) techniques such as tDCS and TMS is an exciting new research domain. Since the cerebellum is connected with cortical regions subserving motor, cognitive and affective functions via cerebellothalamocortical pathways, it might be an interesting target. A literature study showed that the cerebellum is involved in motor functioning and cognition in a similar manner, although the impact is more subtle in the latter. Although only a handful of experimental studies exist, there is also evidence that cerebellar stimulation might modulate emotional processing and early perceptual processing. The involvement of the cerebellum in social cognition is gradually becoming accepted, especially in mentalizing and mirroring. However, studies employing NIBS and functional imaging data are lacking. In addition, cerebellar stimulation might be a useful aid in the rehabilitation of social behavior in patients by restoring the cerebellocerebral functional connectivity. Several studies have shown that repeated sessions of cerebellar stimulation may exert long-lasting positive effects on motor, cognitive, and affective defects. The cerebellum is strongly connected to the motor and associative regions of the cerebrum via closed loops running in parallel, allowing communication in both directions. In addition, the cerebellum has the highest density of neurons and has a dense cortical cellularity, making it very susceptible to NIBS (van Dun & Manto, 2018; van Dun, Overwalle, Manto, & Marien, 2018). Therefore, the cerebellum may act as a window upon functional connectivity networks (van Dun, Bodranghien, Manto, & Mariën, 2017). However, in order to use TMS and tDCS as standard (clinical) practice techniques, it is crucial to learn more about the working mechanisms and impact of the different stimulation protocols. Factors such as duration of the stimulation, the shape of the electrodes, and montage (location of electrodes) need to be taken into account to optimize electrical/magnetic stimulation over the cerebellum in order to obtain effective cerebellar neuromodulation.