Authors:

SHTYROV, Y., Nikulin, V.. & PULVERMULLER, F.

Reference:

Year of publication:

2010

CBU number:

7236

Abstract:

Contrary to traditional research into long-term memory formation that concentrates on learning-induced changes over days or weeks of practice, we looked into immediate plastic changes caused in the brain by passive perceptual learning. Our subjects were presented with spoken words and pseudowords in passive oddball experiments (~150 rare deviant and ~800 frequent standard trials). Monosyllabic stimuli in each block differed only in their final consonant, and both acoustic and lexical contrasts were kept constant across conditions. The subjects' EEG was recorded using high-density whole-scalp array. We then scrutinised evoked responses on a trial-by-trial basis, and investigated changes in these responses over the experimental session. Whereas the brain response to deviant words was large throughout the experiment (A weak trend towards an amplitude decline over time), that to deviant pseudowords increased dramatically, being small at the start and large at the end of a 15 minute experimental session. Robustness of pre-existing word memory traces with moderate habituation of their activation as opposed to the apparent formation of new memory circuits for previously unknown pseudowords appear to be the most likely causes of these effects. As to our knowledge, this is the first report of a neurophysiological manifestation of rapid word learning as it is well-known to take place in infancy and in second language acquisition. We discuss implications of this new finding for the neurobiological theory of language and the underlying brain dynamics at the neuronal circuit level.