Neuroreport
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This review highlights recent developments in research on human cortical oscillations in the gamma-band range (30-100 Hz). Electroencephalography has demonstrated a role of these signals for cognitive functions including visual perception, attention, learning and memory. ⋯ Additional gamma-band activity has been found over the frontal cortex during top-down tasks. Oscillatory activity in the gamma range may serve to assess the temporal dynamics of cortical networks and their interactions.
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Comparative Study Clinical Trial
Functional connectivity changes with concentration of sevoflurane anesthesia.
Low-frequency oscillations (<0.08 Hz) have been detected in functional magnetic resonance imaging studies, and appear to be synchronized between functionally related areas. The effect of anesthetic agents on cortical activity is not completely characterized. ⋯ Across all volunteers, the number of significant voxels (p<2.5 x 10) in the functional connectivity maps was reduced by 78% for light anesthesia and by 98% for deep anesthesia, compared with the awake state. Additionally, significant correlations in the connectivity maps were bilateral in the awake state but unilateral in the light anesthesia state.
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Comparative Study
Potentiation of spinal N-methyl-D-aspartate-mediated nociceptive transmission by cocaine-regulated and amphetamine-regulated transcript peptide in rats.
The present study examined the effects of cocaine-regulated and amphetamine-regulated transcript peptide (CARTp) fragment 55-102, on N-methyl-D-aspartate (NMDA)-mediated nociceptive transmission in vivo and in vitro. In-vivo experiments were conducted in Sprague-Dawley rats to evaluate the effects of CARTp on thermal hyperalgesia induced by NMDA or alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA). Intrathecal NMDA (1, 2, 4 nmol) or AMPA (0.5, 1, 2 nmol) dose-dependently decreased the tail-flick latency. ⋯ The in-vitro effects of CARTp on NMDA-induced or AMPA-induced depolarizations in substantia gelatinosa neurons were studied in rat spinal cord slices. CARTp (100, 300 nM), which caused no significant change of membrane potentials, increased the amplitude of NMDA-induced depolarizations in substantia gelatinosa neurons with little effect on AMPA-induced depolarizations. The present study demonstrates that exogenously applied CARTp selectively facilitates NMDA receptor-mediated nociceptive transmission.