Can bilingualism increase neuroplasticity of language networks in epilepsy?

Alena Stasenko; Adam Schadler; Erik Kaestner; Anny Reyes; Mirella Díaz-Santos; Monika Połczyńska; Carrie R McDonald

doi:10.1016/j.eplepsyres.2022.106893

Can bilingualism increase neuroplasticity of language networks in epilepsy?

Epilepsy Res. 2022 May:182:106893. doi: 10.1016/j.eplepsyres.2022.106893. Epub 2022 Mar 4.

Authors

Alena Stasenko¹, Adam Schadler², Erik Kaestner², Anny Reyes³, Mirella Díaz-Santos⁴, Monika Połczyńska⁵, Carrie R McDonald⁶

Affiliations

¹ Center for Multimodal Imaging and Genetics, University of California, San Diego, CA, USA; Department of Psychiatry, University of California, San Diego, CA, USA. Electronic address: astasenko@ucsd.edu.
² Center for Multimodal Imaging and Genetics, University of California, San Diego, CA, USA; Department of Psychiatry, University of California, San Diego, CA, USA.
³ Center for Multimodal Imaging and Genetics, University of California, San Diego, CA, USA; Department of Psychiatry, University of California, San Diego, CA, USA; San Diego State University/University of California San Diego Joint Doctoral Program in Clinical Psychology, San Diego, CA, USA.
⁴ Department of Neurology, David Geffen School of Medicine at UCLA, University of California, Los Angeles, CA, USA; Mary S. Easton Center for Alzheimer's Disease Research, University of California, Los Angeles, CA, USA; Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine at UCLA, University of California, Los Angeles, CA, USA.
⁵ Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine at UCLA, University of California, Los Angeles, CA, USA.
⁶ Center for Multimodal Imaging and Genetics, University of California, San Diego, CA, USA; Department of Psychiatry, University of California, San Diego, CA, USA; San Diego State University/University of California San Diego Joint Doctoral Program in Clinical Psychology, San Diego, CA, USA; Department of Radiation Medicine and Applied Sciences, University of California, San Diego, CA, USA.

Abstract

Individuals with left temporal lobe epilepsy (TLE) have a higher rate of atypical (i.e., bilateral or right hemisphere) language lateralization compared to healthy controls. In addition, bilinguals have been observed to have a less left-lateralized pattern of language representation. We examined the combined influence of bilingual language experience and side of seizure focus on language lateralization profiles in TLE to determine whether bilingualism promotes re-organization of language networks. Seventy-two monolingual speakers of English (21 left TLE; LTLE, 22 right TLE; RTLE, 29 age-matched healthy controls; HC) and 24 English-dominant bilinguals (6 LTLE, 7 RTLE, 11 HC) completed a lexical-semantic functional MRI task and standardized measures of language in English. Language lateralization was determined using laterality indices based on activations in left vs right homologous perisylvian regions-of-interest (ROIs). In a fronto-temporal ROI, LTLE showed the expected pattern of weaker left language lateralization relative to HC, and monolinguals showed a trend of weaker left language lateralization relative to bilinguals. Importantly, these effects were qualified by a significant group by language status interaction, revealing that bilinguals with LTLE had greater rightward language lateralization relative to monolingual LTLE, with a large effect size particularly in the lateral temporal region. Rightward language lateralization was associated with better language scores in bilingual LTLE. These preliminary findings suggest a combined effect of bilingual language experience and a left hemisphere neurologic insult, which may together increase the likelihood of language re-organization to the right hemisphere. Our data underscore the need to consider bilingualism as an important factor contributing to language laterality in patients with TLE. Bilingualism may be neuroprotective pre-surgically and may mitigate post-surgical language decline following left anterior temporal lobectomy, which will be important to test in larger samples.

Keywords: Bilingualism; Functional magnetic resonance imaging (fMRI); Language lateralization; Laterality; Neuroplasticity; Temporal lobe epilepsy.

Publication types

Research Support, N.I.H., Extramural

MeSH terms

Brain Mapping
Epilepsy, Temporal Lobe* / surgery
Humans
Language
Multilingualism*
Neuronal Plasticity

Abstract

Publication types

MeSH terms

Grants and funding