The plasticity of the mirror system: How reward learning modulates cortical motor simulation of others

Abstract

Cortical motor simulation supports the understanding of others' actions and intentions. This mechanism is thought to rely on the mirror neuron system (MNS), a brain network that is active both during action execution and observation. Indirect evidence suggests that (alpha/beta) mu suppression, an electroencephalographic (EEG) index of MNS activity, is modulated by reward. In this study we aimed to test the plasticity of the MNS by directly investigating the link between (alpha/beta) mu suppression and reward. 40 individuals from a general population sample took part in an evaluative conditioning experiment, where different neutral faces were associated with high or low reward values. In the test phase, EEG was recorded while participants viewed videoclips of happy expressions made by the conditioned faces. Alpha/beta mu suppression (identified using event-related desynchronisation of specific independent components) in response to rewarding faces was found to be greater than for non-rewarding faces. This result provides a mechanistic insight into the plasticity of the MNS and, more generally, into the role of reward in modulating physiological responses linked to empathy.

The functions of imitative behaviour in humans

“…Rather, imitation is heavily modulated by social factors, including gaze, affiliative goals and many other social factors. Neuroimaging studies similarly show that mechanisms of imitation are closely linked to and modulated by social brain systems (Wang, Ramsey & Hamilton, ) and reward systems (Trilla Gros, Panasiti & Chakrabarti, ). Such modulation likely reflects the intimate links between mechanisms of imitation and other social mechanisms, which could be built by either learning or genetics and which enable imitation to be used as a tool for simulation, social learning and social connections.…”

Autistic Traits Moderate the Impact of Reward Learning on Social Behaviour

“…First, the strength of conditioning was correlated to the number of ball tosses directed to the PosC face. Evaluative conditioning has already been seen to influence different proxy metrics related to empathy such as spontaneous mimicry of happy faces [Sims et al, ], or human hands [Haffey et al, ], cortical motor simulation [Trilla Gros, Panasiti, & Chakrabarti, ] and frontostriatal connectivity [Sims et al, ]. Importantly, evaluative conditioning is thought to contribute to several important phenomena in social psychology like stigmatization, and ingroup favoritism effect [Walther, Nagengast, & Trasselli, ] which respectively determine the way we categorize the social world and the way we favour some individuals (in‐group members) with respect to others (out‐group members).…”

Supressão de ritmo mu durante exposição a estímulos associados a ansiedade social

“…O papel dos neurônios espelho no comportamento empático seria o de permitir uma representação interior de ações, movimentos e, principalmente, de intenções. De fato, parece que a supressão do ritmo mu, em indivíduos normais, é mais intensa quando os mesmos são expostos a figuras de faces expressando aprovação ou recompensa em comparação a faces expressando reprovação, sugerindo que a atividade empática possa modular mecanismos de avaliação de recompensa e ameaças de natureza social 5 . Comportamentos ligados a noção de moralidade também tem sido descritos como relacionados a atividade deste grupo de neurônios.…”

“…Como é observado em momentos de ausência de atividade motora, ou seja, sobre uma área não ativa, o ritmo mu foi inicialmente considerado como reflexo de um estado de repouso similar ao descrito para o ritmo alfa clássico 4 . Este ponto de vista tem sofrido mudanças recentemente a partir de relatos de supressão de ritmos do tipo alfa durante a realização de atividades cognitivas 5 . A dessincronização do EEG é vista como o resultado da ativação de vias tálamo-corticais e o consequente aumento da atividade cortical, ao passo que sua sincronização se correlaciona com a redução da atividade cortical 1 .…”