Reorganising language: Neuroplasticity after left-hemisphere stroke through right-hemisphere recruitment

Summary

The left hemisphere (LH) of the brain is dominant for language function in the majority of the population. Yearly, over one million people worldwide suffer LH-damage due to stroke and remain permanently impaired in language functioning. Patients with LH-damage may show global right-hemisphere (RH) activity for language, but little is known about RH-recruitment during language use. My project aims at a fundamental understanding of dynamic RH-recruitment in LH-stroke, i.e., during language use at the actual millisecond timescale of language processes. Understanding the mechanisms of RH-recruitment is important for neurolinguistic and neuroscience theory as well as for clinical applications. I will recruit (premorbidly right-handed) patients with stroke-induced damage to the LH and matched controls. I will employ two well-established experimental paradigms that measure word-production processes and advanced neuroimaging techniques to examine structural and functional aspects of RH-recruitment during language use. This approach is unprecedented in the study of language neuroplasticity. For function, I will employ magnetoencephalography to measure the brain’s electrophysiological signal, a direct measure of neuronal activity with millisecond temporal-resolution. Neuronal operations leave behind particular fingerprints in the electrophysiological signal, allowing one to track language processes in different brain areas. Using these neuronal fingerprints, I will examine whether the new RH-language system in patients is capable of performing the same neuronal operations as the language-dominant LH of matched controls. For structure, I will employ tractography on diffusion-weighted imaging data to estimate the integrity of the corpus-callosum fibres, connecting different areas in the two hemispheres. I will assess whether poor integrity of different parts of the corpus callosum imposes structural constraints on RH-recruitment. My results will elucidate structure-function relationships that shape brain organisation and will help refine existing anatomical models of language function. Additionally, they will contribute to developing personalised language-treatment strategies that make maximal use of a patient’s neuroplastic potential.

Details

Project number

451-17-003

Main applicant

Dr. V. Piai

Affiliated with

Radboud Universiteit Nijmegen, Donders Institute for Brain, Cognition and Behaviour, Centre for Cognition

Team members

Dr. V. Piai

Duration

01/11/2017 to 31/08/2020