Strong rightward lateralization of the dorsal attentional network in left-handers with right sighting-eye: An evolutionary advantage
Hum. Brain Mapp.. 2014-11-19; 36(3): 1151-1164
Read on PubMed
1. Hum Brain Mapp. 2015 Mar;36(3):1151-64. doi: 10.1002/hbm.22693. Epub 2014 Nov 19.
Strong rightward lateralization of the dorsal attentional network in left-handers
with right sighting-eye: an evolutionary advantage.
Petit L(1), Zago L, Mellet E, Jobard G, Crivello F, Joliot M, Mazoyer B,
(1)Université Bordeaux, GIN, UMR5296, Bordeaux, France; CNRS, GIN, UMR5296,
Bordeaux, France; CEA, GIN, UMR5296, Bordeaux, France.
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.
© 2014 Wiley Periodicals, Inc.
PMID: 25409934 [Indexed for MEDLINE]