Acquisition of New Word Meaning. MEG Study
Embodied cognition theory implies that speech is largely based on the body motor and sensory experience. The question, which is crucial for understanding the origin of language, is how our brain transforms sensory-motor experience and gets access to word semantic representation. We developed an auditory-motor experimental procedure that allowed investigating neural underpinning of word meaning acquisition by way of associative "trial-and-error" learning paradigm that mimics basic aspects of natural language learning. Participants were presented with eight pseudowords; four of them were assigned to specific body part movements during learning blocks – through commencing actions by one of participant’s left or right extremities and receiving a feedback. The other pseudowords did not require actions and were used as controls. Magnetoencephalogram was recorded during passive listening of the pseudowords before and after learning blocks. The cortical sources of the magnetic evoked responses were reconstructed using distributed source modeling. Learning of novel word meaning through word-action association selectively increased neural specificity for these words in the auditory parabelt areas responsible for spectrotemporal analysis, as well as in articulatory areas, both located in the left hemisphere. The extent of neural changes was linked to the degree of language learning, specifically implicating the physiological contribution of the left perisylvian cortex in the speech learning success.