Behavioral and magnetoencephalographic correlates of plasticity in the adult human brain

Ramachandran, V. S.

doi:10.1073/pnas.90.22.10413

Cited by 272 publications

(136 citation statements)

References 41 publications

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“…This discovery suggests that the peripheral and central sensory pathways endured and remained viable after prolonged periods of postamputation disuse, which is compelling in light of evidence suggesting that although the subcortical topography of the limb afferents is maintained after amputation, spinal cord and brainstem afferents from adjacent residual limb and face sprout into and strongly reactivate territory once occupied by the missing limb (7-10). Interestingly, although both patients examined in this work report the presence of a phantom limb, neither patient has ever felt any evoked phantom-limb sensations elicited from tactile stimulation of the face or trunk (11)(12)(13). The reactivation of sensation generated relatively extensive evoked sensations of the missing limb in both patients.…”

Section: Discussionmentioning

confidence: 99%

Redirection of cutaneous sensation from the hand to the chest skin of human amputees with targeted reinnervation

Kuiken

Marasco

Lock

et al. 2007

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

250

182

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Amputees cannot feel what they touch with their artificial hands, which severely limits usefulness of those hands. We have developed a technique that transfers remaining arm nerves to residual chest muscles after an amputation. This technique allows some sensory nerves from the amputated limb to reinnervate overlying chest skin. When this reinnervated skin is touched, the amputees perceive that they are being touched on their missing limb. We found that touch thresholds of the reinnervated chest skin fall within near-normal ranges, indicating the regeneration of largefiber afferents. The perceptual identity of the limb and chest was maintained separately even though they shared a common skin surface. A cutaneous expression of proprioception also occurred in one reinnervated individual. Experiments with peltier temperature probes and surface electrical stimulation of the reinnervated skin indicate the regeneration of small diameter temperature and pain afferents. The perception of an amputated limb arising from stimulation of reinnervated chest skin may allow useful sensory feedback from prosthetic devices and provides insight into the mechanisms of neural plasticity and peripheral regeneration in humans.regeneration ͉ neural machine interface ͉ touch ͉ artificial limbs T he loss of an arm is a singularly debilitating injury. Improving the function of artificial arms remains a considerable challenge, especially for high-level amputations where the disability is greatest. A primary impediment to better function is that current prostheses provide very little sensory feedback. The amputees must rely primarily on vision to manipulate objects, and they cannot feel what they touch with motorized prosthetic hands. This limitation greatly increases the cognitive burden on the amputee and impedes the use of the artificial limb.We have developed a neural-machine interface called targeted reinnervation (TR) that provides enhanced motor control and the potential for meaningful sensation feedback for artificial arms (1-3). The amputated brachial plexus nerves that once provided motor control and sensory feedback in the missing limb are transferred to arm and chest muscles that remain after the amputation. Once reinnervated, these muscles produce electromyogram (EMG) signals that correspond to the original arm control signals sent from the brain down the brachial plexus nerves. This process provides improved and more intuitive control of a motorized artificial arm (4-6). The contractions of the reinnervated muscles function as biological amplifiers for the motor commands transmitted by the amputated arm nerves. Concurrently, the sensory nerve fibers in these amputated nerves appear to reinnervate the skin overlying the target muscles. When this reinnervated skin is touched, the amputee feels as if the missing hand is being touched. This skin reinnervation may provide a direct portal to the sensory pathways of the amputated arm and hand. It could potentially provide an amputee with the ability to feel what he touches with a pro...

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Section: Discussionmentioning

confidence: 99%

Redirection of cutaneous sensation from the hand to the chest skin of human amputees with targeted reinnervation

Kuiken

Marasco

Lock

et al. 2007

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

250

182

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“…This suggests that cortex has far more representational plasticity than previously believed. Indeed, recent studies have shown that cortex retains representational plasticity into adulthood (e.g., radical "remapping" of somatosensory cortex after amputation, in humans and in infrahuman primates-Merzenich, Recanzoni, Jenkins, Allard, & Nudo, 1988;Pons et al, 1991;Ramachandran, 1993; see also Greenough, Black, & Wallace, 1993;Greenough, McDonald, Parnisari, & Camel, 1986). Although one cannot entirely rule out the possibility that neurons are born "knowing" what kinds of representations they are destined to take on, the case for innate representations does not look very good right now.…”

Section: "It Is a Certain Wiring Of The Microcircuitry That Is Essentmentioning

confidence: 99%

From first words to grammar in children with focal brain injury

Bates

Thal

Trauner

et al. 1997

Developmental Neuropsychology

199

122

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The effects of focal brain injury are investigated in the first stages of language development, during the passage from first words to grammar. Parent report and/or free speech data are reported for 53 infants and preschool children between 10 -44 months of age. All children had suffered a single, unilateral brain injury to the left or right hemisphere, incurred before six months of age (usually in the pre-or perinatal period). This is the period in which we should expect to see maximal plasticity, but it is also the period in which the initial specializations of particular cortical regions ought to be most evident. In direct contradiction of hypotheses based on the adult aphasia literature, results from 10 -17 months suggest that children with righthemisphere injuries are at greater risk for delays in word comprehension, and in the gestures that normally precede and accompany language onset. Although there were no differences between left-vs. right-hemisphere injury per se on expressive language, children whose lesions include the left temporal lobe did show significantly greater delays in expressive vocabulary and grammar throughout the period from 10 -44 months. There were no specific deficits associated with left frontal damage, but there was a significant effect of frontal lobe injury to either hemisphere in the period from 16 -31 months, when normal children usually show a burst in vocabulary and grammar. This bilateral effect of frontal damage is independent of motor impairment. Hence there are specific effects of lesion site in early language development, but they are not consistent with the lesion-syndrome correlations observed in adults with homologous injuries, nor with the literature on acquired lesions in older children. Results are used to argue against innate localization of linguistic representations, and in favor of an alternative view in which innate regional biases in style of information processing lead to familiar patterns of brain organization for language under normal conditions, while permitting alternative patterns to emerge in children with focal brain injury. 3 FROM FIRST WORDS TO GRAMMAR IN CHILDREN WITH FOCAL BRAIN INJURYIn 1861, Paul Broca described a case of nonfluent aphasia with preserved comprehension, associated with damage to a region of left frontal cortex that now bears Broca's name. By 1874, Carl Wernicke had described a very different form of aphasia, a severe comprehension deficit with preserved fluency and melodic line (albeit with clear impairment of word retrieval). This syndrome was associated with damage to the posterior portion of the left temporal lobe, a region now referred to as Wernicke's area. The reliability and significance of these two complementary lesion-syndrome mappings have been called into question many times (Freud 1891(Freud /1953Goldstein, 1948;Head, 1963;Marie, 1906;Mohr et al., 1978), including recent studies using in vivo brain imaging which show that the classic lesion-syndrome correlations are violated at least 20% of the time (Basso, C...

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“…These changes have been associated with phantom phenomena, especially pain (Flor et al, 1995;Flor, 2002), implying that nonpainful phantom phenomena might not be associated with somatomotor plasticity , Lotze et al, 2001. Nevertheless, although phantom pain is seldom directly tested, and some authors deal with plasticity without pain (Giraux et al, 2001;Vargas et al, 2009), most focus on upper limb amputees who report phan-tom pain (Ramachandran, 1993;Flor et al, 1998;Lotze et al, 1999Lotze et al, , 2001MacIver et al, 2008).…”

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.

114

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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Behavioral and magnetoencephalographic correlates of plasticity in the adult human brain

Abstract: Recent behavioral and physiological evidence suggests that even brief sensory deprivation can lead to the rapid emergence of new and functionally effective neural connections in the adult human brain.

Cited by 272 publications

References 41 publications

Redirection of cutaneous sensation from the hand to the chest skin of human amputees with targeted reinnervation

Redirection of cutaneous sensation from the hand to the chest skin of human amputees with targeted reinnervation

From first words to grammar in children with focal brain injury

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

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