Neuroreport
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Hyperbaric oxygen (HBO2) therapy induces analgesia in various conditions of pain in humans. In mice, HBO2 treatment evokes an acute antinociceptive response in the abdominal constriction test. ⋯ The antinociceptive effect was also significantly reduced in mice homozygous for a defective neuronal NOS gene. On the basis of these results, we conclude that neuronal NO is critical in the expression of the acute antinociceptive effect of HBO2.
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Event-related potentials were recorded to examine the electrophysiologic correlates of the evaluation of possible answers provided during a semantic, a numeric, and a figure inference task. We examined two conditions: the probe stimulus given was what participants initially generated (Correct answer) or it was unexpected and incorrect (Unexpected Incorrect answer). ⋯ The generator of N320 effect was localized near the anterior cingulate cortex. The N320 effect, therefore, reflects an expectation violation while participants performed semantic, numeric, or figure inference task.
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In an earlier study, we reported the antinociceptive effects of a special repetitive transcranial magnetic stimulation paradigm: continuous theta-burst stimulation (cTBS), when applied to human motor cortex. Here, we investigated whether the reduced subjective pain perception of 10 healthy individuals could be measured by changes in laser-evoked potentials, a reflection of pain related activations in the operculoinsular and midcingulate cortex. ⋯ However, both pain ratings and laser-evoked potential amplitudes were reduced after real and sham cTBS. When compared with sham stimulation, cTBS resulted in a significantly greater diminution of pain ratings and N2-P2 amplitudes on the hand contralateral to the site of motor cortex stimulation.
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Although a common pain response, whether swearing alters individuals' experience of pain has not been investigated. This study investigated whether swearing affects cold-pressor pain tolerance (the ability to withstand immersing the hand in icy water), pain perception and heart rate. In a repeated measures design, pain outcomes were assessed in participants asked to repeat a swear word versus a neutral word. ⋯ Swearing increased pain tolerance, increased heart rate and decreased perceived pain compared with not swearing. However, swearing did not increase pain tolerance in males with a tendency to catastrophise. The observed pain-lessening (hypoalgesic) effect may occur because swearing induces a fight-or-flight response and nullifies the link between fear of pain and pain perception.
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Percutaneous inoculation of mice with herpes simplex virus type-1 produces marked dynamic allodynia in the zosteriform dermatome. In this study, we examined the electrophysiological excitability of the wide-dynamic range neuron in the spinal dorsal horn and the tibial nerve in response to mechanical (brush, punctum, and pinch) stimuli in mice with herpetic allodynia. ⋯ The responses of the tibial nerve to all kinds of mechanical stimuli examined were decreased. These results suggest that dynamic allodynia in the affected dermatome is because of the increased excitability of wide-dynamic range neurons, but not primary afferents, to brush stimulation.