Brain Signatures of Meaning Access in Action Word Recognition

TLDR

Action words are thought to be represented by distributed neuronal ensembles that bind language and action information across cortical areas, explaining the observed spatiotemporal dynamics of word meaning access. The study aimed to test whether action words trigger rapid spreading of activity from language to sensorimotor areas by using fast neurophysiological imaging to reveal spatiotemporal patterns for words with different action‑related meanings. High‑density magnetoencephalography recorded brain activity while subjects listened to face‑ or leg‑related action words during a distraction task. Source localization revealed early activation in superior temporal and inferior frontocentral areas (130–146 ms), with face‑word stimuli producing stronger frontocentral activation and leg‑word stimuli stronger superior central activation at 170 ms, and correlations between frontocentral source strength and semantic ratings confirmed that meaning access in action word recognition is an early automatic process reflected by spatiotemporal signatures.

Abstract

The brain basis of action words may be neuron ensembles binding language- and action-related information that are dispersed over both language- and action-related cortical areas. This predicts fast spreading of neuronal activity from language areas to specific sensorimotor areas when action words semantically related to different parts of the body are being perceived. To test this, fast neurophysiological imaging was applied to reveal spatiotemporal activity patterns elicited by words with different action-related meaning. Spoken words referring to actions involving the face or leg were presented while subjects engaged in a distraction task and their brain activity was recorded using high-density magnetoencephalography. Shortly after the words could be recognized as unique lexical items, objective source localization using minimum norm current estimates revealed activation in superior temporal (130 msec) and inferior frontocentral areas (142-146 msec). Face-word stimuli activated inferior frontocentral areas more strongly than leg words, whereas the reverse was found at superior central sites (170 msec), thus reflecting the cortical somatotopy of motor actions signified by the words. Significant correlations were found between local source strengths in the frontocentral cortex calculated for all participants and their semantic ratings of the stimulus words, thus further establishing a close relationship between word meaning access and neurophysiology. These results show that meaning access in action word recognition is an early automatic process ref lected by spatiotemporal signatures of word-evoked activity. Word-related distributed neuronal assemblies with specific cortical topographies can explain the observed spatiotemporal dynamics reflecting word meaning access.