Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale
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Randomized Controlled Trial Comparative Study
A comparison of the effects of repetitive transcranial magnetic stimulation (rTMS) by number of stimulation sessions on hemispatial neglect in chronic stroke patients.
We investigated the effect of repetitive transcranial magnetic stimulation (rTMS) applied either during one session of stimulation, or by ten sessions of low-frequency stimulation over the left parietal cortex, on hemispatial neglect in stroke patients. We enrolled 34 subjects that had experienced a stroke. All subjects received 1,200 real rTMS over the left parietal cortex at an intensity of 90% of motor thresholds with 1 Hz. ⋯ The results showed no difference in baseline value between the single session group and the ten sessions group. Total ten sessions of low-frequency rTMS over the left parietal cortex, compared with the single session of rTMS, significantly improved hemispatial neglect in letter cancelation, line bisection, and Ota's task (P < 0.01). Finally, a total of ten sessions of low-frequency rTMS can be used in treatment by rTMS for patients suffering from hemispatial neglect after stroke.
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Self-consciousness is based on multisensory signals from the body. In full-body illusion (FBI) experiments, multisensory conflict was used to induce changes in three key aspects of bodily self-consciousness (BSC): self-identification (which body 'I' identify with), self-location (where 'I' am located), and first-person perspective (from where 'I' experience the world; 1PP). Here, we adapted a previous FBI protocol in which visuotactile stroking was administered by a robotic device (tactile stroking) and simultaneously rendered on the back of a virtual body (visual stroking) that participants viewed on a head-mounted display as if filmed from a posterior viewpoint of a camera. ⋯ Self-location depended on visuospatial viewpoint (first experiment) and visuotactile synchrony (second experiment). Our results show that the visuospatial viewpoint from which the virtual body is seen during FBIs modulates the subjective 1PP and that such viewpoint manipulations contribute to spatial aspects of BSC. We compare the present data with recent data revealing vestibular contributions to the subjective 1PP and discuss the multisensory nature of BSC and the subjective 1PP.
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Corticospinal and intracortical excitability of the quadriceps in patients with knee osteoarthritis.
Deficits in voluntary activation of the quadriceps muscle are characteristic of knee osteoarthritis (OA), contributing to the quadriceps weakness that is also a hallmark of the disease. The mechanisms underlying this central activation deficit (CAD) are unknown, although cortical mechanisms may be involved. Here, we utilize transcranial magnetic stimulation (TMS) to assess corticospinal and intracortical excitability in patients with knee OA and in a comparably aged group of healthy older adults, to quantify group differences, and to examine associations between TMS measures and pain, quadriceps strength, and CAD. ⋯ No associations were observed between CAD and measures of corticospinal or intracortical excitability. These data suggest against direct involvement of corticospinal or intracortical pathways within primary motor cortex in the mechanisms of CAD. However, pain is implicated in the neural mechanisms of quadriceps motor control in patients with knee OA.
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Within the context of low back pain, the measurement of deep abdominal anticipatory postural adjustments (APAs) during rapid limb movement has received much interest. There is dispute about the association between APAs and back pain. Moreover, there is limited evidence examining compensatory postural adjustments (CPAs) in back pain. ⋯ For the whole group, APA amplitudes were reduced post-standing during shoulder flexion (p = 0.005). Pain reported during standing was associated with the changes in APA amplitudes post-standing (rs = 0.43, p = 0.002). These findings support previous research using hypertonic saline injections to induce back pain that showed reduced APA amplitudes, and extends findings to suggest pain does not effect compensatory postural adjustments.
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The aims were to investigate (1) if temporomandibular disorders (TMD) patients with temporomandibular joint (TMJ) pain had different conditioned pain modulation (CPM) compared with healthy subjects and, (2) if clinical pain characteristics influenced CPM. Sixteen TMD pain patients and 16 age-matched healthy subjects were participated. A mechanical conditioning stimulus (CS) was applied to pericranial muscles provoking a pain intensity of 5/10 on a visual analogue scale. ⋯ In the patients, the relative PPT changes during CS were not significantly higher than baseline at TMJ (5.3 ± 3.8 %, P = 0.981) and masseter (-2.8 ± 4.8 %, P = 1.000) but significantly higher at forearm (12.3 ± 4.7 %, P = 0.039). No correlation was detected between TMD pain intensity and CPM effect (R = -0.261; P = 0.337) or between pain duration and CPM effect (R = -0.423; P = 0.103) at painful TMJ. These findings indicate that CPM is impaired in TMD pain patients especially at sites with chronic pain but not at pain-free sites and that the clinical pain characteristics do not influence CPM.