Variation in homotopic areas’ activity and inter-hemispheric intrinsic connectivity with type of language lateralization: an FMRI study of covert sentence generation in 297 healthy volunteers.

Nathalie Tzourio-Mazoyer, M. Joliot, D. Marie, B. Mazoyer
Brain Struct Funct. 2015-05-27; 221(5): 2735-2753
DOI: 10.1007/s00429-015-1068-x

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1. Brain Struct Funct. 2016 Jun;221(5):2735-53. doi: 10.1007/s00429-015-1068-x. Epub
2015 May 27.

Variation in homotopic areas’ activity and inter-hemispheric intrinsic
connectivity with type of language lateralization: an FMRI study of covert
sentence generation in 297 healthy volunteers.

Tzourio-Mazoyer N(1)(2)(3), Joliot M(4)(5)(6), Marie D(4)(5)(6), Mazoyer
B(4)(5)(6).

Author information:
(1)Groupe d’Imagerie Neurofonctionelle UMR 5296, Université de Bordeaux, Case 71,
146, rue Léo Saignat, 33000, Bordeaux, France. .
(2)CNRS, GIN, UMR 5296, 33000, Bordeaux, France. .
(3)CEA, GIN, UMR 5296, 33000, Bordeaux, France. .
(4)Groupe d’Imagerie Neurofonctionelle UMR 5296, Université de Bordeaux, Case 71,
146, rue Léo Saignat, 33000, Bordeaux, France.
(5)CNRS, GIN, UMR 5296, 33000, Bordeaux, France.
(6)CEA, GIN, UMR 5296, 33000, Bordeaux, France.

We investigated the regional correlates of differences in hemispheric
lateralization in 297 healthy volunteers [including 153 left-handers (LH)]
previously classified into three types of language lateralization according to
their hemispheric functional lateralization index measured with fMRI during
covert sentence production versus word list production (PRODSENT-LIST): 250
leftward asymmetrical Typicals, 10 rightward asymmetrical Strong-atypicals (only
LH), and 37 Ambilaterals with weak lateralization. Using a functionally driven
homotopic atlas (AICHA), we compared patterns of regional asymmetry during
PRODSENT-LIST in these three groups. Among the 192 homotopic regions of interest
(hROIs) of the AICHA atlas, 58 exhibited a significant effect of the type of
lateralization on their BOLD signal variation during PRODSENT-LIST. The analyses
of patterns of asymmetry of these 58 hROIs showed that (1) hROIs asymmetries in
Strong-atypicals were significantly negatively correlated with those observed in
Typicals, which indicates that their regional pattern of rightward asymmetries
was comparable to the regional pattern of leftward language asymmetries of
Typicals; (2) right- and left-handed Typicals had identical profiles, whereas
left-handed Ambilaterals exhibited reduced leftward asymmetry as compared
either to right-handed Ambilaterals or to Typicals. Moreover, left-handed
Ambilaterals pattern of hROIs asymmetries significantly positively correlated
with those of both Typicals and Strong-atypicals. In 291 of the participants, we
tested the hypothesis that differences in language lateralization were associated
with differences in inter-hemispheric connectivity during resting state by
measuring their regional homotopic inter-hemispheric intrinsic connectivity
coefficient (rHIICC) in 36 of the 58 hROIs known to be connected via the corpus
callosum. Mean rHIICCs were negatively correlated with task-induced functional
asymmetries, suggesting that enhanced inter-hemispheric cooperation at rest
translates into increased inter-hemispheric cooperation during language
production. In addition, the left-handed Ambilaterals exhibited a significantly
larger rHIICC compared with right-handed Ambilaterals and Typicals, confirming a
difference in inter-hemispheric organization in this group.

DOI: 10.1007/s00429-015-1068-x
PMID: 26013303 [Indexed for MEDLINE]


Auteurs Bordeaux Neurocampus