Strong rightward lateralization of the dorsal attentional network in left-handers with right sighting-eye: An evolutionary advantage

Laurent Petit (1) , Laure Zago (1) , Emmanuel Mellet (1) , Gaël Jobard (1) , Fabrice Crivello (1) , Marc Joliot (1) , Bernard Mazoyer (1) , Nathalie Tzourio-Mazoyer (1)

1 GIN - UMR 5296 - Groupe d'Imagerie Neurofonctionnelle

Hemispheric lateralization for spatial attention and its relationships with manual preference strength and eye preference were studied in a sample of 293 healthy individuals balanced for manual preference. Functional magnetic resonance imaging was used to map this large sample while performing visually guided saccadic eye movements. This activated a bilateral distributed cortico-subcortical network in which dorsal and ventral attentional/saccadic pathways elicited rightward asymmetrical activation depending on manual preference strength and sighting eye. While the ventral pathway showed a strong rightward asymmetry irrespective of both manual preference strength and eye preference, the dorsal frontoparietal network showed a robust rightward asymmetry in strongly left-handers, even more pronounced in left-handed subjects with a right sighting-eye. Our findings brings support to the hypothesis that the origin of the rightward hemispheric dominance for spatial attention may have a manipulo-spatial origin neither perceptual nor motor per se but rather reflecting a mechanism by which a spatial context is mapped onto the perceptual and motor activities, including the exploration of the spatial environment with eyes and hands. Within this context, strongly left-handers with a right sighting-eye may benefit from the advantage of having the same right hemispheric control of their dominant hand and visuospatial attention processing. We suggest that this phenomenon explains why left-handed right sighting-eye athletes can outperform their competitors in sporting duels and that the prehistoric and historical constancy of the left-handers ratio over the general population may relate in part on the hemispheric specialization of spatial attention.

Mots clés: right hemisphere; eye movements; fMRI; eyedness; handedness; spatial attention; humans; hemispheric dominance; humans r r

Domaines: Neurosciences

Laurent Petit, Laure Zago, Emmanuel Mellet, Gaël Jobard, Fabrice Crivello, et al.. Strong rightward lateralization of the dorsal attentional network in left-handers with right sighting-eye: An evolutionary advantage. Human Brain Mapping, 2015, 36 (3), pp.1151-64. ⟨10.1002/hbm.22693⟩. ⟨hal-01197157⟩