Hemispheric Differences in Corticospinal Excitability and in Transcallosal Inhibition in Relation to Degree of Handedness

Davidson, Travis; Tremblay, François

doi:10.1371/journal.pone.0070286

Cited by 60 publications

(38 citation statements)

References 38 publications

(43 reference statements)

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“…However, various reports indicate that left-handers have reduced hemispheric lateralization and hence, the differences between populations varying in handedness might be complex (Solodkin et al, 2001). Regarding CS excitability at rest, for example, it seems unlikely that left-handers will show increased excitability in the right hemisphere since previous studies have reported a lower intensity required to reach rMT in M1 LEFT , relative to M1 RIGHT , in left- and right-handers (Davidson and Tremblay, 2013). Future assessment of left handers would allow a fuller characterization of the hemispheric similarities and differences in motor preparation and implementation.…”

Section: Discussionmentioning

confidence: 99%

“…One approach here has been to examine corticospinal (CS) excitability at rest, comparing motor-evoked potentials (MEPs) elicited by stimulation over the primary motor cortex of left or right hemisphere (M1 LEFT and M1 RIGHT respectively) (Davidson and Tremblay, 2013; Hammond et al, 2004). The results from this literature are inconsistent (Barber et al, 2012; Serrien et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

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Comparison of the two cerebral hemispheres in inhibitory processes operative during movement preparation

et al. 2016

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Neuroimaging and neuropsychological studies suggest that in right-handed individuals, the left hemisphere plays a dominant role in praxis, relative to the right hemisphere. However hemispheric asymmetries assessed with transcranial magnetic stimulation (TMS) has not shown consistent differences in corticospinal (CS) excitability of the two hemispheres during movements. In the current study, we systematically explored hemispheric asymmetries in inhibitory processes that are manifest during movement preparation and initiation. Single-pulse TMS was applied over the left or right primary motor cortex (M1LEFT and M1RIGHT, respectively) to elicit motor-evoked potentials (MEPs) in the contralateral hand while participants performed a two-choice reaction time task requiring a cued movement of the left or right index finger. In Experiments 1 and 2, TMS probes were obtained during a delay period following the presentation of the preparatory cue that provided partial or full information about the required response. MEPs were suppressed relative to baseline regardless of whether they were elicited in a cued or uncued hand. Importantly, the magnitude of these inhibitory changes in CS excitability was similar when TMS was applied over M1LEFT or M1RIGHT, irrespective of the amount of information carried by the preparatory cue. In Experiment 3, there was no preparatory cue and TMS was applied at various time points after the imperative signal. When CS excitability was probed in the cued effector, MEPs were initially inhibited and then rose across the reaction time interval. This function was similar for M1LEFT and M1RIGHT TMS. When CS excitability was probed in the uncued effector, MEPs remained inhibited throughout the RT interval. However, MEPs in right FDI became more inhibited during selection and initiation of a left hand movement, whereas MEPs in left FDI remained relatively invariant across RT interval for the right hand. In addition to these task-specific effects, there was a global difference in CS excitability across experiments between the two hemispheres. When the intensity of stimulation was set to 115% of the resting threshold, MEPs were larger when the TMS probe was applied over the M1LEFT than over M1RIGHT. In summary, while the latter result suggests that M1LEFT is more excitable than M1RIGHT, the recruitment of preparatory inhibitory mechanisms is similar within the two cerebral hemispheres.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Comparison of the two cerebral hemispheres in inhibitory processes operative during movement preparation

et al. 2016

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“…However, it is also possible that the corpus callosum serves to allow one hemisphere to inhibit processing within the other (Chiarello & Maxfield, 1996). A recent transcranial magnetic stimululation (TMS) study found evidence for more rapid transcallosal inhibition of motor cortex for mixed/weak as compared to strong/consistent handers (Davidson & Tremblay, 2013). It is unclear whether such findings can be generalized to other, more cognitive domains, but if weak handers have increased transcallosal inhibition a potential structural correlate of this might still be greater callosal volume for this group, an effect we did not observe.…”

Section: Discussionmentioning

confidence: 99%

“…It is posited that mixed/weak handers rely on greater crosstalk across hemispheres, and increased access to right hemisphere processes, than do consistent/strong handers (Prichard et al, 2013). Surprisingly, very little neurobiological evidence has been gathered to support this conjecture (but see Davidson & Tremblay, 2013). Instead, degree of handedness is used as a proxy variable for the extent of hemispheric interaction (Lyle & Orsborn, 2011; Sontam & Christman, 2012; Sontam et al, 2009) – that is, such handedness differences are taken as the evidence of variations in interhemispheric interaction.…”

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confidence: 99%

Neurostructural correlates of consistent and weak handedness

McDowell

Felton

Vazquez

et al. 2015

Laterality: Asymmetries of Body, Brain and Cognition

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Various cognitive differences have been reported between consistent and weak handers (Prichard, Propper, & Christman, 2013), but little is known about the neurobiological factors that may be associated with this distinction. The current study examined cortical structural lateralization and corpus callosum volume in a large, well-matched sample of young adults (N = 164) to explore potential neurostructural bases for this hand group difference. The groups did not differ in corpus callosum volume. However, at the global hemispheric level, weak handers had reduced or absent asymmetries for gray and white matter volume, cortical surface area, thickness, and local gyrification, relative to consistent handers. Group differences were also observed for some regional hemispheric asymmetries, the most prominent of which was reduced or absent gyrification asymmetry for weak handers in a large region surrounding the central sulcus and extending into parietal association cortex. The findings imply that variations in handedness strength are associated with differences in structural lateralization, not only in somatomotor regions, but also in areas associated with high level cognitive control of action.

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“…The procedures for TMS and MEP recordings has been described in details elsewhere [7,29]. Briefly, MEPs were recorded with participants comfortably seated using surface electrodes (DE-2.1, Delsys Inc., Boston, MA, USA) placed in a belly-tendon montage over the right first dorsal interosseous (FDI).…”

Section: Tms and Recordings Of Mepsmentioning

confidence: 99%

Lasting depression in corticomotor excitability associated with local scalp cooling

Tremblay

Remaud

Mekonnen

et al. 2015

Neuroscience Letters

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Hemispheric Differences in Corticospinal Excitability and in Transcallosal Inhibition in Relation to Degree of Handedness

Cited by 60 publications

References 38 publications

Comparison of the two cerebral hemispheres in inhibitory processes operative during movement preparation

Comparison of the two cerebral hemispheres in inhibitory processes operative during movement preparation

Neurostructural correlates of consistent and weak handedness

Lasting depression in corticomotor excitability associated with local scalp cooling

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