Somatic Motor and Sensory Representation in the Cerebral Cortex of Man as Studied by Electrical Stimulation

Penfield, Wilder; Boldrey, Edwin

doi:10.1093/brain/60.4.389

Cited by 3,682 publications

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“…1 The technique is su ciently sensitive to reveal mediolateral somatotopic progression on the scalp of proximal to distal muscles in a manner consistent with the known representation of the limb on the motor cortex. 2,3 The areas of the representations of muscles are consistent with ®ndings obtained following direct cortical stimulation, 4,5 yet evidence suggests that reorganization may occur in response to altered a erent input or neurological trauma.…”

Section: Introductionsupporting

confidence: 65%

Motor cortical mapping of proximal upper extremity muscles following spinal cord injury

Brouwer

Hopkins-Rosseel

1997

Spinal Cord

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Focal transcranial magnetic stimulation was used to map the motor cortical representations of the relaxed and gently contracted biceps brachii, deltoid and triceps muscles in 22 subjects comprised of 12 controls, ®ve subjects with complete and ®ve with incomplete cervical spinal cord lesions (SCI). Motor evoked potentials (MEPs) were rarely observed during the resting condition (3/30 muscles tested; SCI group) which precluded detailed analysis of these data. With background facilitation, the mean number of scalp stimulation sites producing MEPs varied according to muscle (P50.001); biceps yielded the largest maps and triceps the smallest. The cortical representations of proximal upper extremity muscles were largest for the control group and smallest for the incomplete SCI group although di erences were not signi®cant (P40.09). The optimal site of stimulation (that which produced the largest MEP) was always surrounded by an area producing submaximal MEPs, but was variable across subjects and groups. There was extensive overlap in the motor cortical representation areas corresponding to the three muscles of interest. Following maximal intensity stimulation at the optimal site, the mean MEP amplitudes (normalized) were largest for the biceps muscle and smallest or absent in triceps (P50.02). No di erences were detected between groups (P40.50). The threshold stimulus intensity was highest for those with incomplete SCI and lowest amongst control subjects (P50.05), with biceps then deltoid muscles generally having lower thresholds than triceps (P50.001). The ®ndings suggest that cortical map areas and MEP characteristics are not signi®cantly altered in gently contracting muscles innervated by nerve roots rostral to the lesion. Only activation thresholds are higher following SCI, particularly incomplete lesions, although there is no apparent association with sensorimotor function. The inability to elicit MEPs in the relaxed muscles of patients with SCI fail to support previous reports of expanded motor cortical representations associated with muscles innervated by roots rostral to the lesion.

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Section: Introductionsupporting

confidence: 65%

Motor cortical mapping of proximal upper extremity muscles following spinal cord injury

Brouwer

Hopkins-Rosseel

1997

Spinal Cord

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“…While effector-specific mapping of sensory and motor cortex is well established (Penfield and Boldrey 1949), similar mapping must be evaluated at the premotor cortex, which demonstrated the clearest activation differences in this study. The rostral ventral premotor cortex is an area that has demonstrated involvement in hand actions (Rizzolatti et al 2002).…”

Section: Discussionmentioning

confidence: 96%

Preparatory band specific premotor cortical activity differentiates upper and lower extremity movement

et al. 2007

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Event related desynchronization (ERD) allows evaluation of brain signals in multiple frequency dimensions. The purpose of this study was to determine left hemispheric non-primary motor cortex differences at varying frequencies of premovement ERD for similar movements by endeffectors of the upper and lower extremities. We recorded 32-channel electroencephalography (EEG) while subjects performed self-paced right ankle dorsiflexion and wrist extension. Electromyography (EMG) was recorded over the tibialis anterior and extensor carpi ulnaris. EEG was analyzed for premovement ERD within the alpha (8-12 Hz), low beta (13-18 Hz) and high beta (18-22 Hz) frequencies over the premotor, motor, and sensory areas of the left and mesial cortex from −1.5 to 0 s before movement. Within the alpha and high beta bands, wrist movements showed limited topography, but greater ERD over posterior premotor cortex areas. Alpha ERD was also significantly greater over the lateral motor cortex for wrist movements. In the low beta band, wrist movements provided extensive ERD differences to include the left motor and mesial/ lateral premotor areas, whereas ankle movements showed only limited ERD activity. Overall, alpha and high beta activity demonstrated distinctions that are consistent with mapping of wrist Correspondence to: Lewis A. Wheaton, lwheaton@grecc.umaryland.edu. and ankle representations over the sensorimotor strip, whereas the low beta representation demonstrated the clearest distinctions between the limbs over widespread brain areas, particularly the lateral premotor cortex. This suggests limited leg premovement activity at the dorsolateral premotor cortex. Low beta ERD may be reflect joint or limb specific preparatory activity in the premotor area. Further work is required to better evaluate the extent of this low beta activity for multiple comparative joints. NIH Public Access

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“…For example, Weber (1834Weber ( /1996 found that the perceived distance between two points of a compass changed as he moved them across his skin, feeling farther apart on regions of high tactile sensitivity compared to regions of lower sensitivity. Subsequent studies have replicated this pattern and suggest a systematic relation between perceived tactile distance and the spatial sensitivity of skin surfaces (e.g., Cholewiak, 1999;Taylor-Clarke et al, 2004;Anema, Wolswijk, Ruis, & Dijkerman, 2008;Miller, Longo, & Saygin, 2016), an effect known as Weber's illusion, suggesting that tactile distance perception preserves spatial distortions characteristic of the famous 'Penfield homunculus' (Penfield & Boldrey, 1937).…”

Section: Distortions Of Tactile Distance Perceptionmentioning

confidence: 89%

Mapping the internal geometry of tactile space.

Longo¹,

Голубова²

2017

Journal of Experimental Psychology: Human Perception and Perfor

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A large body of research has shown spatial distortions in the perception of tactile distances on the skin. For example, perceived tactile distance is increased on sensitive compared to less sensitive skin regions, and larger for stimuli oriented along the medio-lateral axis than the proximo-distal axis of the limbs. In this study we aimed to investigate the spatial coherence of these distortions by reconstructing the internal geometry of tactile space using multidimensional scaling (MDS). Participants made verbal estimates of the perceived distance between 2 touches applied sequentially to locations on their left hand. In Experiment 1 we constructed perceptual maps of the dorsum of the left hand, which showed a good fit to the actual configuration of stimulus locations. Critically, these maps also showed clear evidence of spatial distortion, being stretched along the medio-lateral hand axis. Experiment 2 replicated this result and showed that no such distortion is apparent on the palmar surface of the hand. These results show that distortions in perceived tactile distance can be characterized by geometrically simple and coherent deformations of tactile space. We suggest that the internal geometry of tactile space is shaped by the geometry of receptive fields in somatosensory cortex.

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Somatic Motor and Sensory Representation in the Cerebral Cortex of Man as Studied by Electrical Stimulation

Cited by 3,682 publications

References 0 publications

Motor cortical mapping of proximal upper extremity muscles following spinal cord injury

Motor cortical mapping of proximal upper extremity muscles following spinal cord injury

Preparatory band specific premotor cortical activity differentiates upper and lower extremity movement

Mapping the internal geometry of tactile space.

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