The hypothesis that mirror neurons (MN) constitute the common neural basis of social cognition has gained increasing interest in social neuroscience. In an article published by Schmidt et al. (2021), the authors sought empirical evidence to support this hypothesis by investigating, based on functional neuroimaging (fMRI), the activation of brain regions during imitation, empathy and theory of mind (ToM) tasks. This study contributes significantly to the consolidation of the embodied simulation model, according to which we understand the mental and emotional states of others by automatically simulating their actions in our own neural motor circuits.
The starting point was the identification, in previous studies with primates, of neurons that activate both during the execution and observation of an action. In the human brain, structures such as the inferior frontal gyrus (particularly Brodmann area 44), the inferior parietal cortex (IPL), the posterior superior temporal sulcus (pSTS), the amygdala and the fusiform gyrus have been associated with this mirror neuron system (MNS). The authors advance by demonstrating, through shared voxel (sVx) analyses, that these same regions are activated not only in each task individually, but jointly in the different conditions of social cognition evaluated. This suggests a common functional core between the various components of social cognition, overcoming previous methodological limitations that relied on averages across participants or different experimental paradigms.
It is also worth noting that the study methodology is refined by using the same stimuli (facial expressions of fear and anger) in the three tasks evaluated, which reduces possible biases related to the nature of the stimuli. This standardization allowed for a more accurate comparison between the tasks. Robust results were obtained both in the conjunction analysis between tasks and in the individual analysis within each participant. More than 80% of the individuals presented significantly shared voxels between the three tasks in the target regions, especially in the inferior frontal gyrus, IPL and pSTS, even with unsmoothed data — a technical advance that improves spatial resolution and avoids dilution of subtle neural signals.
It is important to mention that although the results do not directly prove the existence of mirror neurons in the human brain — since fMRI indirectly measures neural activity via BOLD signal — the data strongly converge on the existence of a distributed functional mirroring process in a social neural network. This network appears to integrate motor, emotional and perceptual components, reinforcing the view that the human social brain operates in an embodied, contextual and multifaceted manner.
The study also reveals that different subprocesses of empathy (cognitive vs. affective) and theory of mind partially activate distinct regions. For example, affective empathy was more linked to activation of the left temporoparietal cortex (TPJ), while cognitive empathy engaged more executive control. These distinctions help to refine the understanding of the functional specificities of each component of social cognition, without invalidating the hypothesis of a shared neural substrate.
In summary, the findings presented by Schmidt et al. (2021) provide convergent evidence, with high ecological and methodological validity, that there is a common neural system underlying imitation, empathy, and theory of mind—processes central to human social interaction. This conclusion reinforces the proposal that embodied simulation is a fundamental mechanism of social cognition and highlights the mirror neuron system as a key player in the neurofunctional understanding of social behavior.
Reference:
SCHMIDT, SNL; HASS, J.; KIRSCH, P.; MIER, D. The human mirror neuron system—A common neural basis for social cognition? Psychophysiology, vol. 58, n. 5, e13781, 2021. DOI: https://doi.org/10.1111/psyp.13781.
