Long-term reorganization of motor cortex outputs after arm amputation

Röricht, Simone; Meyer, Bernd‐Ulrich; Niehaus, L.; Brandt, Stephan A.

doi:10.1212/wnl.53.1.106

Cited by 104 publications

(60 citation statements)

References 21 publications

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“…While the brains of subjects with amputation are nondisabled, significant reorganization occurs after the injury. After amputation, the human brain undergoes reorganization of the motor cortex in the areas previously designated to the missing limb [25][26][27]. It has been shown that areas previously delegated to the missing limb begin functioning with adjacent areas of the cortical map.…”

Section: Discussionmentioning

confidence: 99%

Feedforward control strategies of subjects with transradial amputation in planar reaching

Metzger

Dromerick²,

Schabowsky³

et al. 2010

JRRD

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Abstract-The rate of upper-limb amputations is increasing, and the rejection rate of prosthetic devices remains high. People with upper-limb amputation do not fully incorporate prosthetic devices into their activities of daily living. By understanding the reaching behaviors of prosthesis users, researchers can alter prosthetic devices and develop training protocols to improve the acceptance of prosthetic limbs. By observing the reaching characteristics of the nondisabled arms of people with amputation, we can begin to understand how the brain alters its motor commands after amputation. We asked subjects to perform rapid reaching movements to two targets with and without visual feedback. Subjects performed the tasks with both their prosthetic and nondisabled arms. We calculated endpoint error, trajectory error, and variability and compared them with those of nondisabled control subjects. We found no significant abnormalities in the prosthetic limb. However, we found an abnormal leftward trajectory error (in right arms) in the nondisabled arm of prosthetic users in the vision condition. In the no-vision condition, the nondisabled arm displayed abnormal leftward endpoint errors and abnormally higher endpoint variability. In the vision condition, peak velocity was lower and movement duration was longer in both arms of subjects with amputation. These abnormalities may reflect the cortical reorganization associated with limb loss.

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Section: Discussionmentioning

confidence: 99%

Feedforward control strategies of subjects with transradial amputation in planar reaching

Metzger

Dromerick²,

Schabowsky³

et al. 2010

JRRD

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“…TMS studies of M1 reorganization following peripheral injury have clearly established that the stimulation intensities required to evoke MEP responses are strongly affected by amputation-induced deafferentation (4,9). MEP latency reduction has also been described for stump muscles in amputees, correlating inversely with the extent of a given muscle's representation in M1 (4,19).…”

Section: Discussionmentioning

confidence: 99%

“…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)(2)(3)(4)(5)(6)(7)(8)(9)(10).…”

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confidence: 99%

“…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).…”

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confidence: 99%

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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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“…Previous studies have shown that limb amputation or deafferentation induces changes in primary sensory (S1) and motor (M1) cortices (reviewed by Chen et al, 2002), with evidence deriving from electroencephalography (Flor et al, 2000;Grüsser et al, 2001;Karl et al, 2001), transcranial magnetic stimulation (TMS) (Cohen et al, 1991;Pascual-Leone et al, 1996;Röricht et al, 1999;Mercier et al, 2006), magnetoencephalography (Flor et al, 1995), and functional magnetic resonance imaging (fMRI) (Lotze et al, 1999;Giraux et al, 2001;Grü sser et al, 2004). A remapping of cortical topography in upper limb amputees is consistently found, with enlargement and increased activation of the S1/M1 face area after stump stimulation (Ramachandran et al, 1992;Karl et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

Functional Expansion of Sensorimotor Representation and Structural Reorganization of Callosal Connections in Lower Limb Amputees

Simões¹,

Bramati²,

Rodrigues³

et al. 2012

J. Neurosci.

115

117

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Previous studies have indicated that amputation or deafferentation of a limb induces functional changes in sensory (S1) and motor (M1) cortices, related to phantom limb pain. However, the extent of cortical reorganization after lower limb amputation in patients with nonpainful phantom phenomena remains uncertain. In this study, we combined functional magnetic resonance (fMRI) and diffusion tensor imaging (DTI) to investigate the existence and extent of cortical and callosal plasticity in these subjects. Nine "painless" patients with lower limb amputation and nine control subjects (sex-and age-matched) underwent a 3-T MRI protocol, including fMRI with somatosensory stimulation. In amputees, we observed an expansion of activation maps of the stump in S1 and M1 of the deafferented hemisphere, spreading to neighboring regions that represent the trunk and upper limbs. We also observed that tactile stimulation of the intact foot in amputees induced a greater activation of ipsilateral S1, when compared with controls. These results demonstrate a functional remapping of S1 in lower limb amputees. However, in contrast to previous studies, these neuroplastic changes do not appear to be dependent on phantom pain but do also occur in those who reported only the presence of phantom sensation without pain. In addition, our findings indicate that amputation of a limb also induces changes in the cortical representation of the intact limb. Finally, DTI analysis showed structural changes in the corpus callosum of amputees, compatible with the hypothesis that phantom sensations may depend on inhibitory release in the sensorimotor cortex.

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Long-term reorganization of motor cortex outputs after arm amputation

Abstract: Reorganization of the motor system can be present more than 20 years after amputation. Furthermore, differential patterns of reorganized corticospinal output were found for different stump muscles, which might be due to varying amounts of ipsilateral corticospinal projections.

Cited by 104 publications

References 21 publications

Feedforward control strategies of subjects with transradial amputation in planar reaching

Feedforward control strategies of subjects with transradial amputation in planar reaching

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

Functional Expansion of Sensorimotor Representation and Structural Reorganization of Callosal Connections in Lower Limb Amputees

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