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Hand Representation (hand + representation)

Distribution by Scientific Domains
Life Sciences75%

Selected Abstracts

Reorganization of cortical hand representation in congenital hemiplegia

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 4 2009
Yves Vandermeeren
Abstract When damaged perinatally, as in congenital hemiplegia (CH), the corticospinal tract usually undergoes an extensive reorganization, such as the stabilization of normally transient projections to the ipsilateral spinal cord. Whether the reorganization of the corticospinal projections occurring in CH patients is also accompanied by a topographical rearrangement of the hand representations in the primary motor cortex (M1) remains unclear. To address this issue, we mapped, for both hands, the representation of the first dorsal interosseous muscle (1DI) in 12 CH patients by using transcranial magnetic stimulation co-registered onto individual three-dimensional magnetic resonance imaging; these maps were compared with those gathered in age-matched controls (n = 11). In the damaged hemisphere of CH patients, the representation of the paretic 1DI was either found in the hand knob of M1 (n = 5), shifted caudally (n = 5), or missing (n = 2). In the intact hemisphere of six CH patients, an additional, ipsilateral, representation of the paretic 1DI was found in the hand knob, where it overlapped exactly the representation of the non-paretic 1DI. In the other six CH patients, the ipsilateral representation of the paretic 1DI was either shifted caudally (n = 2) or was lacking (n = 4). Surprisingly, in these two subgroups of patients, the representation of the contralateral non-paretic 1DI was found in a more medio-dorsal position than in controls. The present study demonstrates that, besides the well-known reorganization of the corticospinal projections, early brain injuries may also lead to a topographical rearrangement of the representations of both the paretic and non-paretic hands in M1. [source]

Dynamic spatial cognition: Components, functions, and modifiability of body schema1

JAPANESE PSYCHOLOGICAL RESEARCH, Issue 3 2006
KAORU SEKIYAMA
Abstract:, There has been substantial progress towards the understanding of the classical notion of "body schema," with recent advances in experimental methodology and techniques. Mental rotation of the hands can be used as a tool to investigate body schema. Research has shown that implicit motor imagery (i.e., mental simulated movements) can be generated based on the body schema, by combining both stored and incoming sensory information. Multimodal stimulation of peripersonal space has also served as an experimental paradigm for the study of body schema. Perception of peripersonal space is based on body-part-centered space coding that is considered as a manifestation of the body schema, its function being to integrate visual, tactile, and proprioceptive information, and perhaps motor plans as well. By combining such experimental paradigms with neuroimaging and neurophysiological techniques, research has converged to show that the parietal association cortex and premotor cortex are important for the body schema. Multimodal perception of body parts and peripersonal space have been also studied in relation to prism adaptation and tool use effects, indicating a clear modifiability of the body schema. Following prolonged adaptation to reversed vision, a reversed hand representation can be added to the body schema like a tool. The stored component of the body schema may not be established well in young children. But once established it may not be deleted even after an arm is amputated, although it may be weakened. All of these findings help to specify properties of the body schema, its components, functions, and modifiabilities. [source]

Reorganization of cortical hand representation in congenital hemiplegia

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 4 2009
Yves Vandermeeren
Abstract When damaged perinatally, as in congenital hemiplegia (CH), the corticospinal tract usually undergoes an extensive reorganization, such as the stabilization of normally transient projections to the ipsilateral spinal cord. Whether the reorganization of the corticospinal projections occurring in CH patients is also accompanied by a topographical rearrangement of the hand representations in the primary motor cortex (M1) remains unclear. To address this issue, we mapped, for both hands, the representation of the first dorsal interosseous muscle (1DI) in 12 CH patients by using transcranial magnetic stimulation co-registered onto individual three-dimensional magnetic resonance imaging; these maps were compared with those gathered in age-matched controls (n = 11). In the damaged hemisphere of CH patients, the representation of the paretic 1DI was either found in the hand knob of M1 (n = 5), shifted caudally (n = 5), or missing (n = 2). In the intact hemisphere of six CH patients, an additional, ipsilateral, representation of the paretic 1DI was found in the hand knob, where it overlapped exactly the representation of the non-paretic 1DI. In the other six CH patients, the ipsilateral representation of the paretic 1DI was either shifted caudally (n = 2) or was lacking (n = 4). Surprisingly, in these two subgroups of patients, the representation of the contralateral non-paretic 1DI was found in a more medio-dorsal position than in controls. The present study demonstrates that, besides the well-known reorganization of the corticospinal projections, early brain injuries may also lead to a topographical rearrangement of the representations of both the paretic and non-paretic hands in M1. [source]

Motor cortex involvement during verbal versus non-verbal lip and tongue movements

HUMAN BRAIN MAPPING, Issue 2 2002
Riitta Salmelin
Abstract We evaluated left and right motor cortex involvement during verbal and non-verbal lip and tongue movements in seven healthy subjects using whole-head magnetoencephalography. The movements were paced by tone pips. The non-verbal tasks included a kissing movement and touching the teeth with the tongue. The verbal tasks comprised silent articulation of the Finnish vowel /o/, which requires mouth movement similar to that in the kissing task, pronouncing the same self-selected word repeatedly, and producing a new word for every tone pip. Motor cortex involvement was quantified by task-related suppression and subsequent rebound of the 20-Hz activity. The modulation concentrated to two sites along the central sulcus, identified as the motor face and hand representations. The 20-Hz suppression in the face area was relatively similar during all tasks. The post-movement rebound, however, was significantly left-lateralized during word production. In the non-verbal tasks, hand areas showed pronounced suppression of 20-Hz activity that was significantly diminished for the verbal tasks. The latencies of the 20-Hz suppression in the left and right face representations were correlated across subjects during verbal mouth movements. Increasing linguistic content of lip and tongue movements was thus manifested in spatially more focal motor cortex involvement, left-hemisphere lateralization of face area activation, and correlated timing across hemispheres. Hum. Brain Mapping 16:81,91, 2002. © 2002 Wiley-Liss, Inc. [source]