The mirror neuron system (MNS) theory has played a central role in attempts to understand the social deficits observed in autism spectrum disorders (ASD). These cells, first described in primates, activate during both the execution and observation of an action, suggesting a neural bridge between perception and action—a key mechanism for empathy, imitation, and social understanding. In the article by Martineau et al. (2010), this hypothesis was tested using functional neuroimaging (fMRI) in adults with high-functioning autism, revealing important nuances in brain activation during the observation and execution of manual movements.
The study recruited seven individuals with ASD and eight typically developed controls, all right-handed, and applied a paradigm in alternating blocks of observation, execution, and rest, focusing on the perception of hand flexion-extension movements. The data showed that, during motor execution, both groups activated the contralateral primary motor area, as expected. However, only the group with ASD showed additional activation in the ipsilateral cerebellum, suggesting a greater attentional load or functional cerebellar dysfunction, although without anatomical changes detected by structural imaging (Martineau et al., 2010).
The most surprising finding emerged from the observation condition. In contrast to controls, who primarily activated the left intraparietal sulcus and bilateral occipital regions—areas expected for visual-motor processing—individuals with autism showed atypical activation in the bilateral inferior frontal gyrus (pars opercularis), a core region of the MNS. This hyperactivation, more intense than in controls during simple observation of human movement, contradicts the hypothesis of an underactivation of the system in ASD, as observed in previous studies with children (Dapretto et al., 2006), and suggests a possible compensation or alternative pattern of perceptual-motor processing (Martineau et al., 2010).
This exacerbated activation of the MNS in autistic individuals during action observation, especially in the pars opercularis, is interpreted by the authors as a marker of atypical — not necessarily deficient — functioning of this system. This may reflect a different interpretation of the observed action. For neurotypical individuals, the simple gesture in the video might seem trivial; for individuals with ASD, however, it could carry a differentiated motor or social meaning, sufficient to intensely engage the MNS. This idea corroborates the notion that MNS activity in autism can be modulated by the degree of familiarity and identification with the observed stimulus, as already proposed by Oberman et al. (2008).
Furthermore, it was observed that, during observation, individuals with ASD activated regions such as the central and postcentral sulci—classical components of the motor and somatosensory cortex—that were not engaged in controls. This may indicate a tendency of the autistic brain to process social stimuli in a more concrete motor or sensory way, instead of integrating them into more abstract social networks. Also noteworthy is the absence of differential activation in the precuneus in individuals with ASD, a region associated with self-reference and social awareness—another indication of dysfunction in networks related to theory of mind and social introspection in autism (Martineau et al., 2010).
In summary, the study by Martineau et al. offers a relevant contribution to the debate on the role of the mirror neuron system in autism spectrum disorders. By demonstrating that not only is there activation of this system in adults with ASD, but that it can be amplified under certain perceptual conditions, the authors challenge the simplistic conception of a simply hypoactive MNS. Instead, they suggest that MNS functioning in autism is qualitatively distinct—a functional reorganization that can both contribute to and limit social skills. This perspective points to the need for more individualized approaches in therapies aimed at social rehabilitation in autism, in addition to reinforcing the importance of understanding the neural correlates of action perception and empathy as dynamic and contextual processes.
Reference:
MARTINEAU, Joëlle et al. Atypical activation of the mirror neuron system during perception of hand movement in autism. Brain Research, vol. 1320, p. 168–175, 2010. DOI: https://doi.org/10.1016/j.brainres.2010.01.035.
