The role of left fronto-parietal tracts in hand selection: Evidence from neurosurgery
Cortex. 2020-04-01; :
DOI: 10.1016/j.cortex.2020.03.018
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Strong right-hand preference on the population level is a uniquely human feature,
although its neural basis is still not clearly defined. Recent behavioural and
neuroimaging literature suggests that hand preference may be related to the
orchestrated function and size of fronto-parietal white matter tracts
bilaterally. Lesions to these tracts induced during tumour resection may provide
an opportunity to test this hypothesis. In the present study, a cohort of
seventeen neurosurgical patients with left hemisphere brain tumours were
recruited to investigate whether resection of certain white matter tracts affects
the choice of hand selected for the execution of a goal-directed task (assembly
of jigsaw puzzles). Patients performed the puzzles, but also tests for basic
motor ability, selective attention and visuo-constructional ability,
preoperatively and one month after surgery. An atlas-based disconnectome analysis
was conducted to evaluate whether resection of tracts was significantly
associated with changes in hand selection. Diffusion tractography was also used
to dissect fronto-parietal tracts (the superior longitudinal fasciculus) and the
corticospinal tract. Results showed a shift in hand selection despite the absence
of any motor or cognitive deficits, which was significantly associated with
frontal and parietal resections rather than other lobes. In particular, the shift
in hand selection was significantly associated with the resection of dorsal
rather than ventral fronto-parietal white matter connections. Dorsal white matter
pathways contribute bilaterally to control of goal-directed hand movements. We
show that unilateral lesions, that may unbalance the cooperation of the two
hemispheres, can alter the choice of hand selected to accomplish movements.