ИСТИНА

A stable association between words and objects or events underlies human speech. Today it is rather challenging for neuroscience to describe how lexicality is established in the human brain, and how phonological word representations relate to lexicality. The current study aimed to use trial-and-error learning paradigm to establish new associations between pseudowords and actions. We addressed two questions: when and where processes associated with lexicality take place in the human brain, and how newly formed associations influence phonological processing of pseudowords. Participants were presented with eight pseudowords; during learning blocks, four of them were assigned to specific body part movements 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 to the pseudowords before and after learning blocks. The cortical sources of the magnetic evoked responses were reconstructed using distributed source modeling. Phase-locked neural response selectively increased for pseudowords that acquired association compared with control pseudowords. Using data-driven approach, we localized significant differential activation into the left hemisphere, including insula, Broca's complex, intraparietal sulcus and anterior STS-MTG. Differential activation started 150 ms after the uniqueness point. These areas can be viewed as both low-tier (STS), and higher-tier (intraparietal sulcus, temporal pole) structures involved in speech processing. Our results evidence active involvement of a phonological loop in semantic access during initial world learning, which agrees with Lieberman’s motor theory of speech perception.