The research conducted by Portugalskaya, Levenchik and Pavlenko (2021) sheds light on the complex relationship between the activity of the mirror neuron network (ZSM, from the Russian “зеркальная система мозга”), language perception processes, and cognitive and affective traits such as intelligence and empathy. Using a robust experimental approach based on electroencephalography (EEG), the study explores how sentences with different levels of semantic coherence modulate brain rhythms associated with ZSM, revealing an intricate interplay between linguistic, motor and socio-emotional aspects of the brain.
The ZSM is composed of neural networks that are activated both during the execution of actions and during the observation or imagination of these actions. Traditionally associated with social cognition—especially empathy, imitation, and learning—this network also appears to be involved in the perception and understanding of language, especially language that describes motor actions. The hypothesis that the evolution of human language benefited from the reuse of motor circuits, mediated by mirror neurons, is supported by the findings of this research.
Using EEG with spectral analysis (including wavelet transforms), the authors recorded the cortical activity of 25 healthy adults while they listened to poem fragments with coherent sentences (“I raise my hands and I raise my head”) and incoherent sentences (“I run around my hands and I run around my head”). A significant desynchronization of the mu rhythm (9.7–12.0 Hz)—a classic marker of ZSM activation—was observed in the central and temporal regions of the neocortex during perception of the coherent sentence, especially 0.3–0.5 s after the end of the key expression. In contrast, nonsense sentences induced synchronization of these rhythms, suggesting involvement of cognitive inhibition networks and greater semantic processing load.
Interestingly, the degree of mu rhythm desynchronization—and thus the putative activation of the ZSM—correlated positively with the level of verbal intelligence. Individuals with higher scores on the Wechsler test showed a greater reduction in mu rhythm amplitude when listening to the coherent sentence. This finding suggests that efficient processing of action language may more intensively recruit motor circuits in individuals with higher linguistic cognitive ability.
On the other hand, the response to nonsensical sentences was more modulated by empathy levels. Participants with high scores on empathy scales (especially in the emotional and affective identification domains) showed less synchronization of the mu rhythm when hearing incoherent sentences, which may indicate a more efficient and faster neural response to incongruent content. Thus, the study provides support for the idea that empathy—as a component of the “social brain”—also influences how we interpret language, even when it violates semantic expectations.
It is important to emphasize that the authors do not assume that the desynchronization of the mu rhythm reflects exclusively the activation of mirror neurons, but rather of broader motor networks, with possible functional overlap. The complexity of the bidirectional connections between the auditory and motor cortex, as well as sensorimotor integration mechanisms, may contribute to the observed effects. Nevertheless, the data corroborate the functional hypothesis that the ZSM participates in the semantic-motor mapping of language, particularly in action contexts.
These findings invite us to reconsider the traditional boundaries between linguistic, motor, and social cognition, emphasizing the interdependence of cortical networks in the human communicative experience. As a neuroscientist, I note that these results reinforce a trend observed in several recent studies: language, far from being an exclusively symbolic or phonological process, involves mental simulations anchored in motor and affective systems. This paradigm encourages integrative approaches to understanding the brain mechanisms of meaning, with potential clinical applications in language and empathy disorders, such as those in autism spectrum disorders.
Reference:
PORTUGAL’SKAIA, AA; LEVENCHIK, GY; PAVLENKO, VB Activity of the brain’s mirror neuron network during speech perception and its relationship with the level of intelligence and empathy. Uchyonye Zapiski Krymskogo Federal’nogo Universiteta imeni VI Vernadskogo. Biology. Khimia, v. 7, n. 1, p. 156–168, 2021. DOI: 10.37279/2413-1725-2021-7-1-156-168.
