Adult brain plasticity - what is revealed is exciting, what is hidden is critical.
About: This article is published in Journal of Biosciences.The article was published on 2002-09-01. It has received 7 citations till now. The article focuses on the topics: Developmental plasticity.
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TL;DR: This review focuses on the methods that have evidence of associated cortical level reorganization, namely task-specific training, constraint-induced movement therapy, robotic training, mental imaging, and virtual training, which utilize principles of motor learning.
173 citations
Cites background from "Adult brain plasticity - what is re..."
..., 2003) and exclusively of cortex as Cortical plasticity (Jain, 2002)....
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...This ability of the brain and other parts of the central nervous system to reorganize itself is referred to as Neuroplasticity (Rossini et al., 2003) and exclusively of cortex as Cortical plasticity (Jain, 2002)....
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TL;DR: A comparison of the extents of deafferentation across the monkeys shows that even if the dorsal column lesion is partial, preserving most of the hand representation, it is sufficient to induce an expansion of the face representation.
Abstract: Adult brains undergo large-scale plastic changes after peripheral and central injuries. Although it has been shown that both the cortical and thalamic representations can reorganize, uncertainties exist regarding the extent, nature, and time course of changes at each level. We have determined how cortical representations in the somatosensory area 3b and the ventroposterior (VP) nucleus of thalamus are affected by long standing unilateral dorsal column lesions at cervical levels in macaque monkeys. In monkeys with recovery periods of 22-23 months, the intact face inputs expanded into the deafferented hand region of area 3b after complete or partial lesions of the dorsal columns. The expansion of the face region could extend all the way medially into the leg and foot representations. In the same monkeys, similar expansions of the face representation take place in the VP nucleus of the thalamus, indicating that both these processing levels undergo similar reorganizations. The receptive fields of the expanded representations were similar in somatosensory cortex and thalamus. In two monkeys, we determined the extent of the brain reorganization immediately after dorsal column lesions. In these monkeys, the deafferented regions of area 3b and the VP nucleus became unresponsive to the peripheral touch immediately after the lesion. No reorganization was seen in the cortex or the VP nucleus. A comparison of the extents of deafferentation across the monkeys shows that even if the dorsal column lesion is partial, preserving most of the hand representation, it is sufficient to induce an expansion of the face representation.
152 citations
Cites background from "Adult brain plasticity - what is re..."
...Adult brains retain a remarkable ability to change in response to injuries that interrupt transmission of peripheral inputs resulting from damage to the peripheral or central pathways (Jones, 2000; Chen et al., 2002; Jain, 2002; Kaas et al., 2008)....
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TL;DR: Using intracortical microstimulation (ICMS) it is shown that movements evoked in the whisker and the neck region of the rat motor cortex are highly sensitive to the depth of anaesthesia.
Abstract: The primary motor cortex of mammals has an orderly representation of different body parts Within the representation of each body part the organization is more complex, with groups of neurons representing movements of a muscle or a group of muscles In rats, uncertainties continue to exist regarding organization of the primary motor cortex in the whisker and the neck region Using intracortical microstimulation (ICMS) we show that movements evoked in the whisker and the neck region of the rat motor cortex are highly sensitive to the depth of anaesthesia At light anaesthetic depth, whisker movements are readily evoked from a large medial region of the motor cortex Lateral to this is a small region where movements of the neck are evoked However, in animals under deep anaesthesia whisker movements cannot be evoked Instead, neck movements are evoked from this region The neck movement region thus becomes greatly expanded An analysis of the threshold currents required to evoke movements at different anaesthetic depths reveals that the caudal portion of the whisker region has dual representation, of both the whisker and the neck movements The results also underline the importance of carefully controlling the depth of anaesthesia during ICMS experiments
79 citations
Cites background from "Adult brain plasticity - what is re..."
...…in the brain organization are seen when the system is subjected to an insult (injury or excessive stimulation that is outside the normal range encountered: Jain et al., 1998b; Jain, 2002), and reveal hidden or newly emergent properties of the brain such as due to new growth (Jain et al., 2000)....
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...system is subjected to an insult (injury or excessive stimulation that is outside the normal range encountered: Jain et al., 1998b; Jain, 2002), and reveal hidden or newly emergent properties of the brain such as due to new growth (Jain et al....
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TL;DR: The results show that deafferentations lead to a more widespread brain reorganization than previously known and show that reorganization in areas S2 and PV shares a common substrate with area 3b, but there are specific features that emerge in S 2 and PV.
Abstract: Transection of dorsal columns of the spinal cord in adult monkeys results in large-scale expansion of the face inputs into the deafferented hand region in the primary somatosensory cortex (area 3b) and the ventroposterior nucleus of thalamus. Here, we determined whether the upstream cortical areas, secondary somatosensory (S2) and parietal ventral (PV) areas, also undergo reorganization after lesions of the dorsal columns. Areas S2, PV, and 3b were mapped after long-term unilateral lesions of the dorsal columns at cervical levels in adult macaque monkeys. In areas S2 and PV, we found neurons responding to touch on the face in regions in which responses to touch on the hand and other body parts are normally seen. In the reorganized parts of S2 and PV, inputs from the chin as well as other parts of the face were observed, whereas in area 3b only the chin inputs expand into the deafferented regions. The results show that deafferentations lead to a more widespread brain reorganization than previously known. The data also show that reorganization in areas S2 and PV shares a common substrate with area 3b, but there are specific features that emerge in S2 and PV.
52 citations
Cites background from "Adult brain plasticity - what is re..."
...Perceptual consequences of plasticity It has been proposed (Ramachandran et al., 1992; Jain, 2002) that plasticity provides an anatomical and neurophysiological substrate for referred phantom sensations that are experienced by patients with amputation of a limb (Melzack, 1971; Katz and Melzack, 1990; Ramachandran, 1993) or spinal cord injury (Sweet, 1975; Ettlin et al....
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...The primary somatosensory cortex undergoes somatotopic reorganization after injuries to the peripheral or spinal pathways (Jones, 2000; Chen et al., 2002; Jain, 2002; Kaas et al., 2008)....
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...It has been proposed that somatotopic reorganization results in perceptual abnormalities such as phantom sensations, which are experienced by patients with spinal cord injuries or amputations (Ramachandran et al., 1992; Flor et al., 1995; Kaas et al., 1999; Jain, 2002)....
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...It has been proposed (Ramachandran et al., 1992; Jain, 2002) that plasticity provides an anatomical and neurophysiological substrate for referred phantom sensations that are experienced by patients with amputation of a limb (Melzack, 1971; Katz and Melzack, 1990; Ramachandran, 1993) or spinal cord…...
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TL;DR: Long-term sensory loss in adult monkeys does not change the overall topography of the movement representation in the motor cortex but results in changes in the details of movement representations.
Abstract: Long-term injuries to the dorsal columns of the spinal cord at cervical levels result in large-scale somatotopic reorganization of the somatosensory areas of the cortex and the ventroposterior nucleus of the thalamus. As a result of this reorganization, intact inputs from the face expand into the deafferented hand representations. Dorsal column injuries also result in permanent deficits in the use of digits for precision grip and a loss of fractionated movements of the digits. We determined whether the chronic loss of sensory inputs and the behavioral deficits caused by lesions of the dorsal columns in adult macaque monkeys affect organization of the motor cortex. The results show that, in the primary motor cortex, intracortical microstimulation evokes extension–flexion movements of the thumb at significantly fewer sites compared with the normal monkeys. There is a corresponding increase in the adduction–abduction movements. Furthermore, there is a significant increase in the thresholds of the currents required to evoke movements of the digits. Thus, long-term sensory loss in adult monkeys does not change the overall topography of the movement representation in the motor cortex but results in changes in the details of movement representations.
38 citations
Cites background from "Adult brain plasticity - what is re..."
...Reorganization of the motor cortex after sensory loss As for sensory systems (Merzenich et al., 1983; Kaas et al., 1990, 1997; Gilbert and Wiesel, 1992; Schwaber et al., 1993; Jain, 2002; Tandon et al., 2009), the primary motor cortex of adult mammals undergoes reorganization after neurons lose connections to their targets because of amputation of a limb, motor nerve injury, or a spinal cord injury....
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...…cortex after sensory loss As for sensory systems (Merzenich et al., 1983; Kaas et al., 1990, 1997; Gilbert and Wiesel, 1992; Schwaber et al., 1993; Jain, 2002; Tandon et al., 2009), the primary motor cortex of adult mammals undergoes reorganization after neurons lose connections to their targets…...
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References
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TL;DR: Mapping of the receptive fields of cells in the thalamus and cortex after section of the dorsal columns in the rat reveals evidence of functional reorganization in the central nervous system.
Abstract: Mapping of the receptive fields of cells in the thalamus and cortex after section of the dorsal columns in the rat reveals evidence of functional reorganization in the central nervous system.
359 citations
TL;DR: The authors examined sensory afferent terminations in the spinal cord and brainstem and determined the somatotopic organization of cortical area 3b in three adult monkeys with previous hand or forearm amputation, as veterinary treatment of forelimb injuries.
Abstract: Reorganization of somatosensory cortex after peripheral nerve damage typically has been attributed to cortical plasticity. Here we provide evidence that much of the large-scale cortical reorganization that occurs after a major loss of peripheral inputs reflects the sprouting or expansion of afferents from the remaining forelimb into deprived territories of the spinal cord and brainstem. We examined sensory afferent terminations in the spinal cord and brainstem, and determined the somatotopic organization of cortical area 3b in three adult monkeys with previous hand or forearm amputation, as veterinary treatment of forelimb injuries. In each monkey, the distribution of labeled sensory afferent terminations from the remaining parts of the fore-limb was much more extensive than the normal distribution of inputs from the forelimb, and extended into portions of the dorsal horn of the spinal cord and the cuneate nucleus of the brainstem related to the amputated hand. In the same animals, tactile stimulation of the forelimb activated much of the deprived hand representation in area 3b of cortex; the lateral portion of the deprived region in area 3B appeared to be reactivated by inputs from the face. These data provide important new evidence that one of the mechanisms subserving large scale reorganization in cortex is a relay of topographic changes that occur subcortically. Presumably, the expanded primary sensory inputs activate postsynaptic neurons that are normally driven by inputs from the hand so that the neurons now have receptive fields on the forearm. Since the topographic representation of the body is greatly magnified in the relay to cortex, the subcortical changes can result in dramatic cortical map changes.
308 citations
TL;DR: The results suggest that reorganization of sensory pathways occurs very soon after amputation in humans, potentially due to the unmasking of ordinarily silent inputs rather than sprouting of new axon terminals.
Abstract: We studied a patient after amputation of an arm and found that in less than 24 h stimuli applied on the ipsilateral face were referred in a precise, topographically organized, modality-specific manner to distinct points on the phantom. Functional magnetic resonance imaging (fMRI) performed one month later showed that brush-evoked activity in the brain demonstrates objective signal changes which correlate with perceptual changes in the phantom hand. This finding in humans corresponds to the observations of immediate plasticity in cortical pathways described in animals, including primates. The results suggest that reorganization of sensory pathways occurs very soon after amputation in humans, potentially due to the unmasking of ordinarily silent inputs rather than sprouting of new axon terminals.
224 citations
TL;DR: Sensory stimuli to the body are conveyed by the spinal cord to the primary somatosensory cortex, which is highly dependent on dorsal spinal column inputs, and other spinal pathways do not substitute for the dorsal columns even after injury.
Abstract: Sensory stimuli to the body are conveyed by the spinal cord to the primary somatosensory cortex. It has long been thought that dorsal column afferents of the spinal cord represent the main pathway for these signals, but the physiological and behavioural consequences of cutting the dorsal column have been reported to range from mild and transitory to marked. We have re-examined this issue by sectioning the dorsal columns in the cervical region and recording the responses to hand stimulation in the contralateral primary somatosensory cortex (area 3b). Following a complete section of the dorsal columns, neurons in area 3b become immediately and perhaps permanently unresponsive to hand stimulation. Following a partial section, the remaining dorsal column afferents continue to activate neurons within their normal cortical target territories, but after five or more weeks the area of activation is greatly expanded. After prolonged recovery periods of six months or more, the deprived hand territory becomes responsive to inputs from the face (which are unaffected by spinal cord section). Thus, area 3b of somatosensory cortex is highly dependent on dorsal spinal column inputs, and other spinal pathways do not substitute for the dorsal columns even after injury.
195 citations
TL;DR: The face afferents from the trigeminal nucleus of the brainstem sprout and grow into the cuneate nucleus in adult monkeys after lesions of the dorsal columns of the spinal cord or therapeutic amputation of an arm, which may underlie the large-scale expansion of the face representation into the hand region of somatosensory cortex that follows such deafferentations.
Abstract: Somatotopic maps in the cortex and the thalamus of adult monkeys and humans reorganize in response to altered inputs. After loss of the sensory afferents from the forelimb in monkeys because of transection of the dorsal columns of the spinal cord, therapeutic amputation of an arm or transection of the dorsal roots of the peripheral nerves, the deprived portions of the hand and arm representations in primary somatosensory cortex (area 3b), become responsive to inputs from the face and any remaining afferents from the arm. Cortical and subcortical mechanisms that underlie this reorganization are uncertain and appear to be manifold. Here we show that the face afferents from the trigeminal nucleus of the brainstem sprout and grow into the cuneate nucleus in adult monkeys after lesions of the dorsal columns of the spinal cord or therapeutic amputation of an arm. This growth may underlie the large-scale expansion of the face representation into the hand region of somatosensory cortex that follows such deafferentations.
190 citations