Asymmetry in the Human Motor Cortex and Handedness

Amunts, Katrin; Schlaug, Gottfried; Schleicher, Axel; Steinmetz, Helmuth; Dabringhaus, Andreas; Roland, Per E.; Zilles, Karl

doi:10.1006/nimg.1996.0073

Cited by 430 publications

(303 citation statements)

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“…All patients with tremor but one had tremor on the right, while three had no tremor on the left. Brain asymmetry due to lateralization [2,23] and consistent right-handedness of all patients may have also contributed to the asymmetry of findings. A structural asymmetry of the cerebellar hemispheres in association with handedness has been described, and seems to be more marked in right-handers [59].…”

Section: Discussionmentioning

confidence: 94%

Morphological differences in Parkinson’s disease with and without rest tremor

et al. 2009

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Section: Discussionmentioning

confidence: 94%

Morphological differences in Parkinson’s disease with and without rest tremor

et al. 2009

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“…The predominance of right hemisphere regions is also supported by evidence that the right hemisphere is specifically involved in grasping networks [Begliomini et al, 2008] and by studies showing that performing sequential movements with the NDH produces greater activations in the CL hemisphere (hence here the right hemisphere) as compared to the DH [Jäncke et al, 1998; Ng et al, 2008; Seong‐Gi et al, 1993]. It has been argued that the recruitment of the motor cortex of right‐handers increases when using their NDH and that the more skilled and more widely used cortex requires less effort and, hence, less recruitment and signal [Amunts et al, 1996; Jäncke et al, 1998; Ng et al, 2008]. Furthermore, in this study we looked at the network that is shared between the DH and NDH.…”

Section: Discussionmentioning

confidence: 99%

Differential involvement of cortical and cerebellar areas using dominant and nondominant hands: An FMRI study

Alahmadi

Pardini

Samson

et al. 2015

Human Brain Mapping

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Motor fMRI studies, comparing dominant (DH) and nondominant (NDH) hand activations have reported mixed findings, especially for the extent of ipsilateral (IL) activations and their relationship with task complexity. To date, no study has directly compared DH and NDH activations using an event‐related visually guided dynamic power‐grip paradigm with parametric (three) forces (GF) in healthy right‐handed subjects. We implemented a hierarchical statistical approach aimed to: (i) identify the main effect networks engaged when using either hand; (ii) characterise DH/NDH responses at different GFs; (iii) assess contralateral (CL)/IL‐specific and hemisphere‐specific activations. Beyond confirming previously reported results, this study demonstrated that increasing GF has an effect on motor response that is contextualised also by the use of DH or NDH. Linear analysis revealed increased activations in sensorimotor areas, with additional increased recruitments of subcortical and cerebellar areas when using the NDH. When looking at CL/IL‐specific activations, CL sensorimotor areas and IL cerebellum were activated with both hands. When performing the task with the NDH, several areas were also recruited including the CL cerebellum. Finally, there were hand‐side‐independent activations of nonmotor‐specific areas in the right and left hemispheres, with the right hemisphere being involved more extensively in sensori‐motor integration through associative areas while the left hemisphere showing greater activation at higher GF. This study shows that the functional networks subtending DH/NDH power‐grip visuomotor functions are qualitatively and quantitatively distinct and this should be taken into consideration when performing fMRI studies, particularly when planning interventions in patients with specific impairments. Hum Brain Mapp 36:5079–5100, 2015. © 2015 Wiley Periodicals, Inc.

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“…Cytoarchitectural features were relied upon for identification of cortical regions due to individual variation in their gross anatomical location (e.g., Amunts et al, 1996;Zilles et al, 1996;Petrides and Pandya, 1999;Rademacher et al, 2001). Cortical layers were analyzed separately as layers I, II, III, and V/VI.…”

Section: Identifying Cortical Regions and Layersmentioning

confidence: 99%

Cortical dopaminergic innervation among humans, chimpanzees, and macaque monkeys: A comparative study

et al. 2008

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In this study, we assessed the possibility that humans differ from other primate species in the supply of dopamine to the frontal cortex. To this end, quantitative comparative analyses were performed among humans, chimpanzees, and macaques using immunohistochemical methods to visualize tyrosine hydroxylase-immunoreactive axons within the cerebral cortex. Axon densities and neuron densities were quantified using computer-assisted stereology. Areas 9 and 32 were chosen for evaluation due to their roles in higher-order executive functions and theory of mind, respectively. Primary motor cortex (area 4) was also evaluated because it is not directly associated with cognition. We did not find an overt quantitative increase in cortical dopaminergic innervation in humans relative to the other primates examined. However, several differences in cortical dopaminergic innervation were observed among species which may have functional implications. Specifically, humans exhibited a sublaminar pattern of innervation in layer I of areas 9 and 32 that differed from that of macaques and chimpanzees. Analysis of axon length density to neuron density among species revealed that humans and chimpanzees together deviated from macaques in having increased dopaminergic afferents in layers III and V/VI of areas 9 and 32, but there were no phylogenetic differences in area 4. Finally, morphological specializations of axon coils that may be indicative of cortical plasticity events were observed in humans and chimpanzees, but not macaques. Our findings suggest significant modifications of dopamine's role in cortical organization occurred in the evolution of the apes, with further changes in the descent of humans.

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Asymmetry in the Human Motor Cortex and Handedness

Cited by 430 publications

References 0 publications

Morphological differences in Parkinson’s disease with and without rest tremor

Morphological differences in Parkinson’s disease with and without rest tremor

Differential involvement of cortical and cerebellar areas using dominant and nondominant hands: An FMRI study

Cortical dopaminergic innervation among humans, chimpanzees, and macaque monkeys: A comparative study

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