Language switching decomposed through MEG and evidence from bimodal bilinguals

Esti Blanco-Elorrieta, Karen Emmorey, Liina Pylkkänen

Research output: Contribution to journalArticle

Abstract

A defining feature of human cognition is the ability to quickly and accurately alternate between complex behaviors. One striking example of such an ability is bilinguals' capacity to rapidly switch between languages. This switching process minimally comprises disengagement from the previous language and engagement in a new language. Previous studies have associated language switching with increased prefrontal activity. However, it is unknown how the subcomputations of language switching individually contribute to these activities, because few natural situations enable full separation of disengagement and engagement processes during switching. We recorded magnetoencephalography (MEG) from American Sign Language-English bilinguals who often sign and speak simultaneously, which allows to dissociate engagement and disengagement. MEG data showed that turning a language "off" (switching from simultaneous to single language production) led to increased activity in the anterior cingulate cortex (ACC) and dorsolateral prefrontal cortex (dlPFC), while turning a language "on" (switching from one language to two simultaneously) did not. The distinct representational nature of these on and off processes was also supported by multivariate decoding analyses. Additionally, Granger causality analyses revealed that (i) compared with "turning on" a language, "turning off" required stronger connectivity between left and right dlPFC, and (ii) dlPFC activity predicted ACC activity, consistent with models in which the dlPFC is a top-down modulator of the ACC. These results suggest that the burden of language switching lies in disengagement from the previous language as opposed to engaging a new language and that, in the absence of motor constraints, producing two languages simultaneously is not necessarily more cognitively costly than producing one.

Original languageEnglish (US)
Pages (from-to)9708-9713
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume115
Issue number39
DOIs
StatePublished - Sep 25 2018

Keywords

  • Bilingualism
  • Bimodal bilinguals
  • Executive control
  • Language switching
  • Magnetoencephalography

ASJC Scopus subject areas

  • General

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