European journal of pain : EJP
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Slowing refers to the gradual decrease in conduction velocity evoked by repetitive electrical stimuli. The underlying mechanisms are still poorly understood, and its physiological/pathological relevance scarcely discussed; however, changes in axonal conduction properties might unmask abnormal nociceptor function and alter the encoding time window at the spinal cord. ⋯ Under our experimental conditions, slowing seems largely dependent on functional Ih . The marked decrease in slowing after axotomy in C-fibres fits with the increased expression of functional hyperpolarization-activated/HCN channel current and may underlie the analgesic effects of the specific Ih blocker ZD7288 previously described in neuropathic pain models.
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Brain areas involved in nociception have been repeatedly investigated. Therefore, brain responses to physiological pain conditions are well identified. The same is not true for allodynic pain in patients with neuropathic pain since the cortical reorganizations that are involved in the conversion of non-noxious stimuli into painful sensations still remain unknown. ⋯ The insular subdivision was inappropriately activated considering the innocuous nature of the stimulus, but adequately activated with regard to pain-evoked sensation. Subcortically, the hypothesis of reorganization at any level of the somatosensory and pain pathways underlying such insular activity was supported by the observed shift of thalamic activation from a lateral-posterior to an anterior-medial position.
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Schizophrenia patients display impaired recognition of their own emotions and those of others and deficits in several domains of empathy. The first-person experience of pain and observing others in pain normally trigger strong emotional mechanisms. We therefore hypothesized that schizophrenia patients would display impaired recognition and categorization of both their own pain and the pain of others. ⋯ Schizophrenic patients have a deficit of the identification and categorization of pain both in themselves and in others.
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Several functional magnetic resonance imaging (fMRI) studies use thermal pain stimuli to determine brain activation patterns during pain. Studies use either a standard temperature condition for all participants or an individualized temperature condition based on the individually determined pain threshold of the participant. The aim of the present study was to compare both conditions in the same participants. ⋯ The similar activation patterns between the two conditions suggest that it is not necessary to use individualized stimuli per se. The temperature of 46 °C appeared to be an adequate temperature for standardized stimulation to observe significant brain activations related to thermal pain.
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Randomized Controlled Trial
The role of excess subcutaneous fat in pain and sensory sensitivity in obesity.
Previous studies suggest pain sensitivity may be decreased in obesity, but it is unknown whether this is a global or a site-specific phenomenon related to the amount of excess fat. ⋯ Obese participants are less sensitive than non-obese individuals, but only on areas with excess subcutaneous fat.