Differential Mirror Neuron System (MNS) Activation During Action Observation with and without Social-Emotional Components in Autism: A Meta-Analysis of Neuroimaging Studies

Abstract

Background Impaired imitation has been found to be an important factor contributing to social communication deficits in individuals with autism spectrum disorder (ASD). It has been hypothesized that the neural correlate of imitation, the mirror neuron system (MNS), is dysfunctional in ASD, resulting in imitation impairment as one of the key behavioral manifestations in ASD. Previous MNS studies produced inconsistent results, leaving the debate of whether mirror neurons are “broken” in ASD unresolved. Methods This meta-analysis aimed to explore the differences in MNS activation patterns between typically developing (TD) and ASD individuals when they observe biological motions with or without social-emotional components. Effect-size signed differential mapping (ES-SDM) was adopted to synthesize the available fMRI data. Results ES-SDM analysis revealed hyperactivation in the right inferior frontal gyrus and left supplementary motor area in ASD during observation of biological motions. Subgroup analysis of experiments involving the observation of stimuli with or without emotional component revealed hyperactivation in the left inferior parietal lobule and left supplementary motor during action observation without emotional components, whereas hyperactivation of right inferior frontal gyrus was found during action observation with emotional components in ASD. Subgroup analyses of age showed hyperactivation of bilateral inferior frontal gyrus in ASD adolescents, while hyperactivation in the right inferior frontal gyrus was noted in ASD adults. Meta-regression within ASD individuals indicated that right cerebellum crus I activation increased with age, while left inferior temporal gyrus activation decreased with age. Limitations This meta-analysis is limited in its generalization of the findings to individuals with ASD by the restricted age range, heterogeneous study sample, and the large within-group variation in MNS activation patterns during object observation. Furthermore, we only included action observation studies which might limit the generalization of our results to the imitation deficits in ASD. In addition, the relatively small sample size for individual studies might also potentially overestimate the effect sizes. Conclusion The MNS is impaired in ASD. The abnormal activation patterns were found to be modulated by the nature of stimuli and age, which might explain the contradictory results from earlier studies on the “broken mirror neuron” debate.

Unique deficit in embodied simulation in autism: An fMRI study comparing autism and developmental coordination disorder

“…The TD and DCD groups may have suffered from ceiling and floor effects respectively in motor scores, making it difficult to find correlations within those groups. Thus previously reported discrepancies, with some studies showing differential activity in the IFGop in ASD while others found no differences (for reviews, see Chan & Han, 2020;Yates & Hobson, 2020), may be explained by heterogeneity in motor ability across TD and ASD groups as well as within the ASD group, which prior studies did not assess. We investigated differences in IFGop activity in ASD not only when processing facial expressions, but also hand actions.…”

“…Activity in the IFGop is involved in social cognition, emotion processing, and empathy (for reviews, see de Waal & Preston, 2017;Jeon & Lee, 2018). Interestingly, several ASD studies show differential functioning in the IFGop during imitation and/or action observation tasks compared to TD peers (Dapretto et al, 2006;Kana, Wadsworth, & Travers, 2011;Williams, 2008), though there have been discrepant findings (for reviews, see Chan & Han, 2020;Yates & Hobson, 2020). However, to date no fMRI studies have considered how motor impairment impacts IFGop activity in ASD, or if IFGop impairment is unique to ASD.…”

Neurones miroirs, substrat neuronal de la compréhension de l’action?

“…Compte tenu en outre du développement important de la littérature relative aux neurones miroirs, une compréhension précise des propriétés et des fonctions présumées de ces neurones paraît primordiale pour éviter les simplifications abusives. Par ailleurs, le développement de nouvelles approches expérimentales tant chez l'animal que chez l'homme, devrait permettre de renforcer les différents modèles relatifs aux phénomènes complexes qui impliquent les neurones miroirs, telle que l'imitation [106,107], l'empathie [108], la coordination sociale [109][110][111] ou encore l'autisme [112].…”

Alone Again: Altered Activation in the Observation Execution System during Synchronization in High Loneliness Individuals

“…Similar hyperactivation of the OE was found in multiple studies in ASD. For a recent review refer to (Chan & Han, 2020). Moreover, previous studies showed that lonely people have a reduction in fractional atrophy of white matter tracts linked to the IFG (Tian et al, 2014) as well as decreased white matter density in the IPL (Nakagawa et al, 2015), which may further reduce the effectiveness of the OE system.…”