Somatosensory & motor research
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Pressure evoked temporal summation of pain has been described with slow repetitions (<0.5 Hz) relative to what is recommended originally for assessing temporal pain summation (>1 Hz). This study examined temporal summation of pain by repeated computer-controlled pressure stimulation at high repetition rates with and without simultaneous active probe rotations for potential better efficiency. ⋯ An optimum of 500 ms repeated pressure stimulation at 1 Hz produced the most apparent temporal summation of pain sensation which further was enhanced during probe rotation. These findings suggest an optimized and novel method to improve the current procedures for assessing temporal summation of pressure-induced pain.
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The aim of this study was to investigate whether watching one's own face being touched in a reversal mirror condition modulates orofacial somatosensory sensitivity. A total of 37 healthy volunteers participated in a pilot study, the main study, and a control experiment. In the main experiment, 16 participants received seven different intensities of pinprick stimuli in the right infraorbital region. ⋯ The somatosensory sensitivity may be impaired when the location of stimulation is not in accordance with the perception. In conclusion, hypoesthetic effects of a reversal mirror were present for fixed force measures but not for threshold measures. Further studies are now needed to describe the potential implications for other somatosensory modalities and orofacial pain conditions.
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Test-retest reliability is important to establish for any diagnostic tool. The reliability of quantitative sensory testing (QST) in the trigeminal region has recently been described in Caucasians as well as differences in absolute thresholds and responses between Caucasians and Chinese. However, the test-retest reliability has not been determined in a Chinese population. ⋯ Test site and gender affect thermal thresholds substantially. The test-retest reliability of most thermal threshold measures were acceptable for assessing somatosensory function, however, innocuous thresholds appear to be associated with larger variability than noxious thresholds in a Chinese population.
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Hyperalgesia in different musculoskeletal structures including bones is a major clinical problem. An experimental bone hyperalgesia model was developed in the present study. Hyperalgesia was induced by three different weights impacted on the shinbone in 16 healthy male and female subjects. ⋯ Females developed more pronounced hyperalgesia reflected in reduced IPTs and PPTs (p < 0.05). Temporal summation was significantly (p < 0.05) facilitated after induction of hyperalgesia with the strongest facilitation in males. The developed bone pain and hyperalgesia model may provide the basis for studying this fundamental mechanism of bone-related hyperalgesia and be used for profiling compounds developed for this target.
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Neurological dysfunction after traumatic brain injury (TBI) is associated with pathology in cortical, subcortical, and brainstem nuclei. Our laboratory has reported neuropathology and microglial activation in the somatosensory barrel cortex (S1BF) and ventral posterior medial thalamus (VPM) after diffuse TBI in the rat, which correlated with post-injury whisker sensory sensitivity. The present study extends our previous work by evaluating pathology in whisking-associated sensory and motor brainstem nuclei. ⋯ In contrast, the VIIN showed non-significant neuropathology and reduced labeling of activated Iba1 microglia over 1 month post-injury. Together with our previous data, neuropathology and neuroinflammation in the whisker somatosensory pathway may contribute to post-injury sensory sensitivity more than the motor pathway. Whether these findings are direct results of the mechanical injury or consequences of progressive degeneration remains to be determined.