Multi-factorial modulation of hemispheric specialization and plasticity for language in healthy and pathological conditions: A review
Cortex. 2017-01-01; 86: 314-339
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1. Cortex. 2017 Jan;86:314-339. doi: 10.1016/j.cortex.2016.05.013. Epub 2016 Jun 7.
Multi-factorial modulation of hemispheric specialization and plasticity for
language in healthy and pathological conditions: A review.
Tzourio-Mazoyer N(1), Perrone-Bertolotti M(2), Jobard G(3), Mazoyer B(3), Baciu
(1)IMN UMR 5293, CNRS, France; IMN UMR 5293, Université de Bordeaux, France; IMN
GIN UMR 5293, CEA, France. Electronic address: .
(2)Univ. Grenoble Alpes, LPNC, Grenoble, France; CNRS, LPNC, UMR 5105, Grenoble,
(3)IMN UMR 5293, CNRS, France; IMN UMR 5293, Université de Bordeaux, France; IMN
GIN UMR 5293, CEA, France.
This review synthesizes anatomo-functional variability of language hemispheric
representation and specialization (hemispheric specialization for language, HSL)
as well as its modulation by several variables (demographic, anatomical,
developmental, genetic, clinical, and psycholinguistic) in physiological and
pathological conditions. The left hemisphere (LH) dominance for language,
observed in approximately 90% of healthy individuals and in 70% of patients, is
grounded by intra-hemispheric connections mediated by associative bundles such as
the arcuate fasciculus and inter-hemispheric transcallosal connections mediated
by the corpus callosum that connects homotopic regions of the left and right
hemispheres (RH). In typical brains, inter-hemispheric inhibition, exerted from
the LH to the RH, permits the LH to maintain language dominance. In pathological
conditions, inter- and intra-hemispheric inhibition is decreased, inducing
modifications on the degree of HSL and of language networks. HSL evaluation is
classically performed in clinical practice with the Wada test and
electro-cortical stimulation, gold standard methods. The advent of functional
neuroimaging has allowed a more detailed assessment of the language networks and
their lateralization, consistent with the results provided by the gold standard
methods. In the first part, we describe anatomo-functional support for HSL in
healthy conditions, its developmental course, its relationship with cognitive
skills, and the various modulatory factors acting on HSL. The second section is
devoted to the assessment of HSL in patients with focal and drug-resistant
epilepsy (FDRE). FDRE is considered a neurological model associated with patterns
of language plasticity, both before and after surgery: FDRE patients show
significant modification of language networks induced by changes mediated by
transcallosal connections (explaining inter-hemispheric patterns of language
reorganization) or collateral connections (explaining intra-hemispheric patterns
of language reorganization). Finally, we propose several predictive and
explicative models of language organization and reorganization.
Copyright © 2016 Elsevier Ltd. All rights reserved.
PMID: 27321148 [Indexed for MEDLINE]