Rapid Cortical Plasticity Underlying Novel Word Learning

Abstract

Humans are unique in developing large lexicons as their communication tool. To achieve this, they are able to learn new words rapidly. However, neural bases of this rapid learning, which may be an expression of a more general cognitive mechanism, are not yet understood. To address this, we exposed our subjects to familiar words and novel spoken stimuli in a short passive perceptual learning session and compared automatic brain responses to these items throughout the learning exposure. Initially, we found enhanced activity for known words, indexing the ignition of their underlying memory traces. However, just after 14 min of learning exposure, the novel items exhibited a significant increase in response magnitude matching in size with that to real words. This activation increase, as we would like to propose, reflects rapid mapping of new word forms onto neural representations. Similar to familiar words, the neural activity subserving rapid learning of new word forms was generated in the left-perisylvian language cortex, especially anterior superior-temporal areas. This first report of a neural correlate of rapid learning suggests that our brain may effectively form new neuronal circuits online as it gets exposed to novel patterns in the sensory input. Understanding such fast learning is key to the neurobiological explanation of the human language faculty and learning mechanisms in general.

Flexible, rapid and automatic neocortical word form acquisition mechanism in children as revealed by neuromagnetic brain response dynamics

“…In contrast, the activation seen in the present study for novel word forms with both native and non-native phonology indicates response enhancement which not only counteracts but overrides any repetition-related suppression. Although not directly comparable, these results tentatively support previous findings in adults (e.g., Shtyrov et al, 2010;Yue, Bastiaanse, & Alter, 2014;Kimppa et al, 2015Kimppa et al, , 2016: similarly to the findings with adults, we observed an increase of activation to novel word forms in the left temporal region, which may be indicative of adults and children utilising at least partially similar networks for rapid formation of memory traces for novel word forms. As previous studies indicate that the language lateralisation is fully established by the age of 5 years (or earlier), with only minimal changes later in development (Weiss-Croft & Baldeweg, 2015), this response enhancement in the left temporal region is highly indicative of reliance on a neural network tuned for native language processing.…”

“…On the basis of visual inspection, three peaks were identified: 91, 317, and 452 ms from stimulus onset. As in previous studies (Shtyrov et al, 2010, Yue, Bastiaanse & Alter, 2014Kimppa et al, 2015) showing rapid lexical acquisition effects at latencies around ~50-120 ms, we a priori focussed on the first two peaks as they fall fell within 200 ms after the disambiguation points (see Figure 1, and the Stimuli section above). Ad hoc, we also analysed the peak at 452ms as well to verify that no similar effects were present at a later stage.…”

Proficiency and sentence constraint effects on second language word learning

“…Although many studies have found that one-time acquisition occurs during word learning (Borovsky et al, 2010(Borovsky et al, , 2012Shtyrov, 2011;Shtyrov, Nikulin, & Pulvermüller, 2010), more evidence suggests that we still need practice and repetition to consolidate and refine word learning (Medina et al, 2011;Mestres-Missé et al, 2007Munro, Baker, McGregor, Docking, & Arciuli, 2012;Ramscar et al, 2013). Studies on children's word learning found that repetition of context (stories or non-target words) is better in facilitating word learning than an equal number of varied contexts (Axelsson & Horst, 2014;Williams & Horst, 2014).…”

Competition from unseen or unheard novel words: Lexical consolidation across modalities

“…Indeed, Saffran, Newport, Aslin, Tunick, and Barrueco (1997) found young adults and first-grade children to be equally skilled at segmenting and storing novel words from a string of nonsense syllables in an incidental learning task. More recently, Shtyrov, Nikulin, and Pulvermüller (2010) reported a neurophysiological counterpart of these behavioural findings on the early stages of word learning. After as little as 14 min of passive listening, neural response patterns to novel words became qualitatively identical to those elicited by existing words, suggesting that memories of the novel words had been established.…”