Brain topography
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Comparative Study
Scalp field potentials of human pain: spatial effects and temporal relation in finger stimulation.
In the present study, the spatial extent and temporo-spatial correlations of the human brain responses were investigated by electrically stimulating thumb (D1) and little finger (D5) under painful and non-painful intensity levels. High-density (124-ch) somatosensory evoked potentials (SEPs) were recorded (-50 to +450 ms) from 15 healthy male volunteers. Early (0-50 ms), and late phases (150-450 ms) of the responses were analyzed. ⋯ For the late phase, the AM potentials at N2 correlated with that of P2 for both D1 and D5 under painful stimulation. The focal effects in FA of contralateral early potential indicates a shallow dipole in the primary somatosensory area of SI, while the large spatial extent in AM indicates a deep dipole of the putative cingulum activation under painful stimulation. No correlation between early and late activities implied that both activations are operated independently at the early SI and late cingulate processing of evoked pain.
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Comparative Study
Topographic analysis of painful laser and sural nerve electrical evoked potentials.
A quantitative scalp topographic pattern analysis was used to compare evoked potentials elicited by painful laser (LEP) and electrical stimulation of the sural nerve (snSEP) in 22 healthy adults. The snSEP and LEP were separated into stable periods (consecutive time points having the same topographic pattern). The topographic pattern is dependent upon the number, location, orientation and relative magnitudes of the brain areas active at that time (source configuration). ⋯ These findings have important implications for the choice of evoking stimulus in investigations of pain processing in humans. For example, the sural nerve electrical stimulus will be preferred over the laser in studies of the anterior cingulate's role in cognitive processes related to pain, such as orienting attention, and/or in studies involving cognitive tasks that require the presentation of a large number of painful stimuli. The LEP N1 and N2 peaks, on the other hand, will be preferred in studies of the parietal operculum's role in pain sensation.