Interhemispheric differences of hand muscle representation in human motor cortex

Cicinelli, Paola; Traversa, R.; Bassi, Andrea; Scivoletto, Giorgio; Rossini, Paolo Maria

doi:10.1002/(sici)1097-4598(199705)20:5<535::aid-mus1>3.0.co;2-a

Cited by 141 publications

(69 citation statements)

References 27 publications

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“…That is, regions that show activity when stimulated may not necessarily be recruited when performing a unimanual task. Furthermore, our findings regarding contralateral representations are in line with previous TMS studies (Cicinelli et al 1997;Wassermann et al 1992;Wilson et al 1993). Previous work reports a lack of iMEPs (Bawa et al 2004;Carr et al 1994;Netz et al 1997) except for conditions in which the target muscle was contracted (Wassermann et al 1994;Ziemann et al 1999), although muscle contraction alters interhemispheric interactions (Nelson et al 2009).…”

Section: Discussionmentioning

confidence: 43%

“…Those that are more mixedhanded show the most bilateral M1 activity during the performance of a unimanual task (Dassonville et al 1997). Additionally, several studies have used transcranial magnetic stimulation (TMS) to investigate the relationship between handedness and motor cortical representations (Cicinelli et al 1997;Triggs et al 1999;Wassermann et al 1992;Wilson et al 1993). While most studies indicate that there is no difference between the motor cortical representations across the two hemispheres, the majority of studies have been limited to right-handed individuals (Cicinelli et al 1997;Wassermann et al 1992;Wilson et al 1993), although Triggs and colleagues (1999) did find asymmetries in the motor cortex between left-and righthanders.…”

Section: Organization Of Motor Cortex and Handednessmentioning

confidence: 99%

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Handedness, Dexterity, and Motor Cortical Representations

Taylor²,

Seidler

2011

Journal of Neurophysiology

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. Motor system organization varies with handedness. However, previous work has focused almost exclusively on direction of handedness (right or left) as opposed to degree of handedness (strength). In the present study, we determined whether measures of interhemispheric interactions and degree of handedness are related to contra-and ipsilateral motor cortical representations. Participants completed a battery of handedness assessments including both handedness preference measures and behavioral measures of intermanual differences in dexterity, a computerized version of the Poffenberger paradigm (PP) to estimate interhemispheric transfer time (IHTT), and they underwent transcranial magnetic stimulation (TMS) mapping of both motor cortices while we recorded muscle activity from the first dorsal interosseous muscle bilaterally. A greater number of ipsilateral motor evoked potentials (iMEPs) were elicited in less lateralized individuals with the number of iMEPs correlated with IHTT. There were no relationships between handedness or lateralization of dexterity and symmetry of contralateral motor representations, although this symmetry was related to IHTT. Finally, IHTT was positively correlated with multiple measures of laterality and handedness. These findings demonstrate that degree of laterality of dexterity is related to the propensity for exhibiting iMEPs and the speed of interhemispheric interactions. However, it is not clear whether iMEPs are directly mediated via ipsilateral corticospinal projections or are transcallosally transmitted. I N T R O D U C T I O NIt is known that handedness is related to the organization of the sensorimotor system. For example, there is some evidence to indicate that left-and right-handers may differ in corpus callosum morphology (Habib et al. 1991;Westerhausen et al. 2004;Witelson 1985) and organization of motor cortical representations (Amunts et al. 1996;Dassonville et al. 1997;Kim et al. 1993;Volkmann et al. 1998). These neuroanatomical differences have been linked to behavior as well with lefthanders typically having faster and more accurate interhemispheric transmission than right-handers (Cherbuin and Brinkman 2006a,b;Marzi et al. 1991). However, the majority of work investigating relationships between handedness, neuroanatomy, and behavior has evaluated direction of handedness (left vs. right) as opposed to degree of handedness (how strongly handed one is), although there is evidence to support the importance of the latter (Dassonville et al. 1997;Luders et al. 2010;Siebner et al. 2002;Solodkin et al. 2001). Organization of motor cortex and handednessMotor cortex physiology is related to handedness. For example, left-and right-handers show different functional activation patterns in the primary motor cortex (M1) when performing motor tasks. Right-handers show more asymmetrical activation in M1, predominantly in the dominant (left) hemisphere, whereas left-handers show more bilateral activity (Kim et al. 1993;Siebner et al. 2002). Those that are more mixedhanded show the most ...

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Section: Discussionmentioning

confidence: 43%

Section: Organization Of Motor Cortex and Handednessmentioning

confidence: 99%

Handedness, Dexterity, and Motor Cortical Representations

Taylor²,

Seidler

2011

Journal of Neurophysiology

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“…These findings are intriguing because in normal subjects stimulation levels necessary to evoke MEP responses are generally lower for the dominant hand (44,45, but see ref. 46). Furthermore, we observed no such asymmetry in the bilateral amputee AD, suggesting that in LB and CD it was not due to the bilateral amputation per se.…”

Section: Discussionmentioning

confidence: 54%

Re-emergence of hand-muscle representations in human motor cortex after hand allograft

Vargas

Aballéa

Rodrigues

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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The human primary motor cortex (M1) undergoes considerable reorganization in response to traumatic upper limb amputation. The representations of the preserved arm muscles expand, invading portions of M1 previously dedicated to the hand, suggesting that former hand neurons are reassigned to the control of remaining proximal upper limb muscles. Hand allograft offers a unique opportunity to study the reversibility of such long-term cortical changes. We used transcranial magnetic stimulation in patient LB, who underwent bilateral hand transplantation 3 years after a traumatic amputation, to longitudinally track both the emergence of intrinsic (from the donor) hand muscles in M1 as well as changes in the representation of stump (upper arm and forearm) muscles. The same muscles were also mapped in patient CD, the first bilateral hand allograft recipient. Newly transplanted intrinsic muscles acquired a cortical representation in LB's M1 at 10 months postgraft for the left hand and at 26 months for the right hand. The appearance of a cortical representation of transplanted hand muscles in M1 coincided with the shrinkage of stump muscle representations for the left but not for the right side. In patient CD, transcranial magnetic stimulation performed at 51 months postgraft revealed a complete set of intrinsic hand-muscle representations for the left but not the right hand. Our findings show that newly transplanted muscles can be recognized and integrated into the patient's motor cortex.amputation ͉ longitudinal ͉ plasticity ͉ reorganization ͉ TMS I t is now well established that the adult brain is highly influenced by changes occurring at the body's periphery. Evidence from human and animal models show that, when deprived of its afferent sensory input and/or its motor effectors, the primary sensory (S1) and motor (M1) cortical regions undergo plastic modifications (1-10).Traumatic upper limb amputation in humans produces lifelong consequences. Patients often report a global feeling that the missing body part is still present. This feeling is frequently associated with specific sensory and kinesthetic sensations and pain in the missing limb. Many patients further describe that the phantom limb can be moved voluntarily (review in refs. 11 and 12).Functional investigation of human M1 reorganization after amputation has demonstrated that instead of becoming inactive, the hand area is now activated during proximal limb movements (5,13,14), and that cortical stimulation of this region evokes contraction of proximal upper limb muscles (4, 9, 15, 16). Face and forearm motor representations that surround the representation of the missing hand have also been shown to expand into the de-efferented cortex (16,17), with the expansion of lip movements into the former hand area correlating positively with the amount of phantom limb pain (18). Studies employing TMS paired-pulse protocols have shown less intracortical inhibition in the region corresponding to the amputated limb when compared with the intact limb's region (19,20), suggest...

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“…In young adults, a mean difference of 5% (ranging between −10 and +15%) has been consistently found between the dominant (lower) and non-dominant MEP threshold (Triggs et al, 1997;Triggs et al, 1994;Triggs et al, 1999). Asymmetry appears to be present in cortical maps (larger maps on the dominant hemisphere) (Cicinelli et al, 1997); the CSP (shorter duration when the dominant motor cortex is stimulated) (Priori et al, 1999); and interhemispheric inhibition using the two-coil paired pulse paradigm (greater inhibition when the conditioning stimulus is delivered to the dominant hemisphere) (Netz et al, 1995). Reports show conflicting data as to whether there is functional asymmetry of SICI/ICF (Cicinelli et al, 2000;Civardi et al, 2000;Ilic et al, 2004;Maeda et al, 2002).…”

Section: Age-related Changes In Asymmetrymentioning

confidence: 99%

Transcranial magnetic stimulation in children

Garvey

Mall

2008

Clinical Neurophysiology

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Developmental disabilities (e.g. attention deficit disorder; cerebral palsy) are frequently associated with deviations of the typical pattern of motor skill maturation. Neurophysiologic tools, such as transcranial magnetic stimulation (TMS), which probe motor cortex function, can potentially provide insights into both typical neuromotor maturation and the mechanisms underlying the motor skill deficits in children with developmental disabilities. These insights may set the stage for finding effective interventions for these disorders. We review the literature pertaining to the use of TMS in pediatrics. Most TMS-evoked parameters show age-related changes in typically developing children and some of these are abnormal in a number of childhood-onset neurological disorders. Although no TMS-evoked parameters are diagnostic for any disorder, changes in certain parameters appear to reflect disease burden or may provide a measure of treatment-related improvement. Furthermore, TMS may be especially useful when combined with other neurophysiologic modalities (e.g. fMRI). However, much work remains to be done to determine if TMS-evoked parameters can be used as valid and reliable biomarkers for disease-burden, the natural history of neurological injury and repair, and the efficacy of pharmacological and rehabilitation interventions.

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Interhemispheric differences of hand muscle representation in human motor cortex

Cited by 141 publications

References 27 publications

Handedness, Dexterity, and Motor Cortical Representations

Handedness, Dexterity, and Motor Cortical Representations

Re-emergence of hand-muscle representations in human motor cortex after hand allograft

Transcranial magnetic stimulation in children

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