Neurophysiological Mechanisms of Word Meaning Acquisition

The current study used trial-and-error learning paradigm to establish new associations between pseudowords and actions. We addressed two questions: when and where processes associated with lexicality learning take place in the human brain, and how newly formed associations influence phonological processing of pseudowords. Participants were presented with eight pseudowords; during learning, four of them were assigned to specific body part movements. MEG was recorded during passive listening to the pseudowords before and after learning. The cortical sources of the magnetic evoked responses were reconstructed. Phase-locked neural response selectively increased for pseudowords with acquired association compared with control pseudowords. Using data-driven approach, we localized activation into the left hemisphere within both low-tier (STS), and higher-tier (intraparietal sulcus, temporal pole) structures involved in speech processing. Differential effects were observed within 150-350 ms.