Journal of neurophysiology
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The pursuit of a physiological indicator of noxious stimulation is desirable as it has the potential to provide mechanistic information regarding acute pain and may ultimately improve pain management strategies. Currently, there are no specific neurophysiological markers of pain to evaluate treatments. Recent attempts to identify neural correlates of pain have focused on different neuroimaging modalities. The purpose of this review is to discuss common neuroimaging techniques and findings thus far.
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Parkinson's disease is associated with altered neural activity in the motor cortex. Chronic high-frequency deep brain stimulation (DBS) of the subthalamic nucleus (STN) is effective in suppressing parkinsonian motor symptoms and modulates cortical activity. However, the anatomical pathways responsible for STN DBS-mediated cortical modulation remain unclear. ⋯ The short-latency response occurs as a result of antidromic activation of the hyperdirect pathway comprising corticosubthalamic axons. However, the neural origins of intermediate- and long-latency responses remain elusive, and the dominant view is that these are produced through the orthodromic pathway (basal ganglia-thalamus-cortex). By combining in vivo electrophysiology with computational modeling, we demonstrate that antidromic activation of the cortico-thalamic-cortical pathway is sufficient to generate the intermediate- and long-latency cortical responses to STN DBS.
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Randomized Controlled Trial
Dose response of somatosensory cortex repeated anodal transcranial direct current stimulation on vibrotactile detection: a randomized sham-controlled trial.
This randomized sham-controlled trial investigated anodal transcranial direct current stimulation (tDCS) over the somatosensory cortex contralateral to hand dominance for dose-response (1 mA, 20 min × 5 days) effects on vibrotactile detection thresholds (VDT). VDT was measured before and after tDCS on days 1, 3, and 5 for low- (30 Hz) and high-frequency (200 Hz) vibrations on the dominant and nondominant hands in 29 healthy adults (mean age = 22.86 yr; 15 men, 14 women). Only the dominant-hand 200-Hz VDT displayed statistically significant medium effect size improvement for mixed-model analysis of variance time-by-group interaction for active tDCS compared with sham. ⋯ In conclusion, anodal tDCS at 1 mA, 20 min × 5 days on the dominant sensory cortex can modulate a linear improvement of dominant-hand high-frequency VDT but not low-frequency or nondominant-hand VDT. NEW & NOTEWORTHY Repeated weak anodal transcranial direct current stimulation (1 mA, 20 min) on the dominant sensory cortex provides linear improvement in dominant-hand high-frequency vibration detection thresholds. No effects were observed for low-frequency or nondominant-hand vibration detection thresholds.