What is right-hemisphere contribution to phonological, lexico-semantic, and sentence processing? Insights from a meta-analysis
NeuroImage. 2011-01-01; 54(1): 577-593
DOI: 10.1016/j.neuroimage.2010.07.036
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1. Neuroimage. 2011 Jan 1;54(1):577-93. doi: 10.1016/j.neuroimage.2010.07.036. Epub
2010 Jul 23.
What is right-hemisphere contribution to phonological, lexico-semantic, and
sentence processing? Insights from a meta-analysis.
Vigneau M(1), Beaucousin V, Hervé PY, Jobard G, Petit L, Crivello F, Mellet E,
Zago L, Mazoyer B, Tzourio-Mazoyer N.
Author information:
(1)Groupe d’Imagerie Neurofonctionnelle, UMR CI-NAPS 6232, CNRS CEA, GIP Cyceron,
Caen, France.
To evaluate the relative role of left and right hemispheres (RH) and describe the
functional anatomy of RH during ortholinguistic tasks, we re-analyzed the 128
papers of a former left-hemisphere (LH) meta-analysis (Vigneau et al., 2006). Of
these, 59 articles reported RH participation, providing 105 RH language contrasts
including 218 peaks compared to 728 on the left, a proportion reflecting the LH
language dominance. To describe inter-hemispheric interactions, in each of the
language contrasts involving both hemispheres, we distinguished between
unilateral and bilateral peaks, i.e. having homotopic activation in the LH in the
same contrast. We also calculated the proportion of bilateral peaks in the LH.
While the majority of LH peaks were unilateral (79%), a reversed pattern was
observed in the RH; this demonstrates that, in contrast to the LH, the RH works
in an inter-hemispheric manner. To analyze the regional pattern of RH
participation, these unilateral and bilateral peaks were spatially clustered for
each language component. Most RH phonological clusters corresponded to bilateral
recruitment of auditory and motor cortices. Notably, the motor representation of
the mouth and phonological working memory areas were exclusively
left-lateralized, supporting the idea that the RH does not host phonological
representations. Right frontal participation was not specific for the language
component involved and appeared related to the recruitment of attentional and
working memory areas. The fact that RH participation during lexico-semantic tasks
was limited to these executive activations is compatible with the hypothesis that
active inhibition is exerted from the LH during the processing of meaning. Only
during sentence/text processing tasks a specific unilateral RH-temporal
involvement was noted, likely related to context processing. These results are
consistent with split-brain studies that found that the RH has a limited lexicon,
with no phonological abilities but active involvement in the processing of
context.
Copyright © 2010 Elsevier Inc. All rights reserved.
DOI: 10.1016/j.neuroimage.2010.07.036
PMID: 20656040 [Indexed for MEDLINE]