Marco Iacoboni

Previous studies using functional magnetic resonance imaging and transcranial magnetic stimulation (TMS) explored the relationships between linguistic processing and motor resonance, i.e. the activation of the motor system while perceiving others performing an action. These studies have mainly investigated a specific linguistic domain, i.e. semantics, whereas phonology has been largely neglected. Here we used single‐pulse TMS to compare the effects of semantic and phonological processing with motor resonance effects. We applied TMS to the primary motor hand area while subjects observed object‐oriented actions and performed semantic and phonological tasks related to the observed action. Motor evoked potentials were recorded in two hand muscles, one of them more involved in the execution of the observed actions than the other one, at three different timepoints (0, 200 and 400 ms after stimulus onset). The results demonstrated increased corticospinal excitability that was muscle‐specific (i.e. restricted to the hand muscle involved in the observed action), hemisphere‐specific (left), and time‐specific (400 ms after stimulus onset). The results suggest an additive effect of independent semantic and phonological processing on motor resonance. The novel phonological effect reported here expands the links between language and the motor system and is consistent with a theory of shared control for hand and mouth. Furthermore, the timing of the semantic effect suggests that motor activation during semantic processing is not an ‘epiphenomenon’ but rather is essential to the construction of meaning.

This article traces the contributions of mirror neuron theories in neuroscience to debates on literature and related theories of mimesis or, as Erich Auerbach defined it, the representation of reality. The “ensemble” descriptor used for the visualization technologies on which we currently depend to chart the neuronal firing in the human brain is also an apt term for an additional translational issue between structure and what one might call the philosophical domain. The most carefully established data of brain activity is empirically confirmable on the micro level. Moving from it to the so-called “higher order” or more complex issues of meaning and use by humans, not least in cultural life, requires in effect a translation from micro evidence to ensemble evidence. Within the neurosciences, such translational processes are objects of seduction and suspicion at once. Yet an “ensemble” principle is not only active in brain mapping evidence, but in the “single brain” to “social brain” evidence field for neural mirroring. The brain in isolation represents only a slice of the field of the dialogic brain, the brain performing social cognition of others, the brain bringing the other’s existence into the individual’s embodied space through the individual’s internal simulation. This essay moves from the concept of the social brain to the suggestion of an ontological priority of representation in the mirror neuron paradigm. Is literature itself a relative of brain mirroring processes, and thus a form of biomimesis? And if we recognize literature and other representational processes as a part of “the human ensemble,” should we also recognize the capacity of literature and other art forms to mimetically influence our performance of physiological being?

There is a convergence between cognitive models of imitation, constructs derived from social psychology studies on mimicry and empathy, and recent empirical findings from the neurosciences. The ideomotor framework of human actions assumes a common representational format for action and perception that facilitates imitation. Furthermore, the associative sequence learning model of imitation proposes that experience-based Hebbian learning forms links between sensory processing of the actions of others and motor plans. Social psychology studies have demonstrated that imitation and mimicry are pervasive, automatic, and facilitate empathy. Neuroscience investigations have demonstrated physiological mechanisms of mirroring at single-cell and neural-system levels that support the cognitive and social psychology constructs. Why were these neural mechanisms selected, and what is their adaptive advantage? Neural mirroring solves the “problem of other minds” (how we can access and understand the minds of others) and makes intersubjectivity possible, thus facilitating social behavior.

It has been suggested that cortical neural systems for language evolved from motor cortical systems, in particular from those fronto-parietal systems responding also to action observation. While previous studies have shown shared cortical systems for action – or action observation - and language, they did not address the question of whether linguistic processing of visual stimuli occurs only within a subset of fronto-parietal areas responding to action observation. If this is true, the hypothesis that language evolved from fronto-parietal systems matching action execution and action observation would be strongly reinforced. We used functional magnetic resonance imaging (fMRI) while subjects watched video stimuli of hand-object-interactions and control photo stimuli of the objects and performed linguistic (conceptual and phonological), and perceptual tasks. Since stimuli were identical for linguistic and perceptual tasks, differential activations had to be related to task demands. The results revealed that the linguistic tasks activated left inferior frontal areas that were subsets of a large bilateral fronto-parietal network activated during action perception. Not a single cortical area demonstrated exclusive – or even simply higher - activation for the linguistic tasks compared to the action perception task. These results show that linguistic tasks do not only share common neural representations but essentially activate a subset of the action observation network if identical stimuli are used. Our findings strongly support the evolutionary hypothesis that fronto-parietal systems matching action execution and observation were co-opted for language, a process known as exaptation.

In primates, ventral premotor and rostral inferior parietal neurons fire during the execution of hand and mouth actions. Some cells (called mirror neurons) also fire when hand and mouth actions are just observed. Mirror neurons provide a simple neural mechanism for understanding the actions of others. In humans, posterior inferior frontal and rostral inferior parietal areas have mirror properties. These human areas are relevant to imitative learning and social behavior. Indeed, the socially isolating condition of autism is associated with a deficit in mirror neuron areas. Strategies inspired by mirror neuron research recently have been used in the treatment of autism and in motor rehabilitation after stroke. Ann Neurol 2007