ERPs reflecting frequency of unattended spoken words: a neuronal index of connection strength in lexical memory circuits?
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1
MRC Cognition and Brain Sciences Unit, United Kingdom
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2
Cognitive Brain Research Unit, University of Helsinki, Finland
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3
University of St. Petersburg, Russia, Russia
How are words represented in the brain and can these representations be qualitatively assessed? Recent research demonstrates that neurophysiological signatures of individual words can be measured when subjects do not focus their attention on speech. These automatic activations, manifest as negative deflections of ERPs, can appear surprisingly early (within ~200 ms) and are based on robust connections within neuronal circuits encoding individual words that ignite even when attentional resources are scarce. A critical prediction of this framework is that words with high frequency of occurrence have especially strongly connected underlying memory circuits and should thus yield more negative ERPs compared with rarer words. We tested this prediction by presenting our subjects, in passive non-attend conditions, with acoustically matched high- and low-frequency words. Two experiments were performed using Finnish and Russian native speakers and stimuli. Using factorial and correlation analyses, we found that already at 100-150 ms after the stimulus information was available response amplitude was modulated by the words’ lexical frequency. Topographic mapping and source analysis suggested that this early automatic frequency effect originates from the left inferior-frontal cortex. Latency differences between ERPs to low- and high-frequency words suggested faster access to more frequent lexical entries. Our results support the account of word memory traces as interconnected neuronal circuits, and suggest that speed and magnitude of their activation are determined by their internal connection strength, which, in turn, is determined by everyday language use. Funding: Supported by MRC, Helsinki Univ., St.Petersburg Univ., Russian Ministry of Education & Science (goskontrakt №02.740.11.5148).
Keywords:
EEG,
Language
Conference:
XI International Conference on Cognitive Neuroscience (ICON XI), Palma, Mallorca, Spain, 25 Sep - 29 Sep, 2011.
Presentation Type:
Poster Presentation
Topic:
Poster Sessions: Neural Bases of Language
Citation:
Shtyrov
YY,
Kimppa
L,
Boricheva
D,
Pulvermuller
F,
Alexandrov
A and
Kujala
T
(2011). ERPs reflecting frequency of unattended spoken words: a neuronal index of connection strength in lexical memory circuits?.
Conference Abstract:
XI International Conference on Cognitive Neuroscience (ICON XI).
doi: 10.3389/conf.fnhum.2011.207.00298
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Received:
22 Nov 2011;
Published Online:
28 Nov 2011.
*
Correspondence:
Dr. Yury Y Shtyrov, MRC Cognition and Brain Sciences Unit, Cambridge, United Kingdom, yury.shtyrov@cfin.au.dk