Automatic ultrarapid activation and inhibition of cortical motor systems in spoken word comprehension – New publication in PNAS

New article "Automatic ultrarapid activation and inhibition of cortical motor systems in spoken word comprehension" by Yury Shtyrov et al. published in Proceedings of the National Academy of Sciences. Abstract

Shtyrov, Y., Butorina, A., Nikolaeva, A., & Stroganova, T. (2014). Automatic ultrarapid activation and inhibition of cortical motor systems in spoken word comprehension. Proceedings of the National Academy of Sciences. doi: 10.1073/pnas.1323158111

Significance

The mechanisms through which our brain generates complex cognitive percepts from simple sensory and motor events remain unknown. An important question is whether the basic brain structures controlling movements and perceptions directly participate in higher-order cognitive processes such as language comprehension. Using neurophysiology, we found ultrarapid (starting at ∼80 ms) activations in the human motor cortex in response to unattended action-related verbs and nouns, with words related to different body parts activating corresponding body representations. Accompanying this category-specific activity was activation suppression by words with area-incompatible meaning, demonstrating operation of the neurophysiological principles of lateral/surround inhibition in language processing. These instant activations and deactivations emerging for words of different types in the absence of attention advocate automatic involvement of neural sensorimotor circuits in language comprehension.

Abstract

To address the hotly debated question of motor system involvement in language comprehension, we recorded neuromagnetic responses elicited in the human brain by unattended action-related spoken verbs and nouns and scrutinized their timecourse and neuroanatomical substrates. We found that already very early on, from ∼80 ms after disambiguation point when the words could be identified from the available acoustic information, both verbs and nouns produced characteristic somatotopic activations in the motor strip, with words related to different body parts activating the corresponding body representations. Strikingly, along with this category-specific activation, we observed suppression of motor-cortex activation by competitor words with incompatible semantics, documenting operation of the neurophysiological principles of lateral/surround inhibition in neural word processing. The extremely early onset of these activations and deactivations, their emergence in the absence of attention, and their similar presence for words of different lexical classes strongly suggest automatic involvement of motor-specific circuits in the perception of action-related language.