Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale
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Randomized Controlled Trial
A pharmaco-fMRI study on pain networks induced by electrical stimulation after sumatriptan injection.
Sumatriptan, a drug widely used to alleviate migraine headaches, has several somatosensory adverse effects, including tactile allodynia. To understand whether sumatriptan affects sensory and affective circuitries simultaneously, we investigated the responses of 12 healthy volunteers to electrical stimuli after infusion with either sumatriptan or saline. Using a double-blind crossover study design, we used functional magnetic resonance imaging (fMRI) to measure brain activation in different areas during electrical stimulation. ⋯ In contrast, activation following saline administration was observed primarily in the lateral pain system, including the primary sensory cortex, lateral SII, posterior insular cortex, anterior ACC, and lateral thalamus. Importantly, we found that VAS ratings and MPQ scores were increased after sumatriptan infusion, but not after saline administration. Our fMRI, VAS, and SF-MPQ findings suggest that sumatriptan plays a significant role in the affective dimension of pain and a minor role related to sensory discrimination.
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Randomized Controlled Trial
Features of cortical neuroplasticity associated with multidirectional novel motor skill training: a TMS mapping study.
Given the evidence that the primary motor cortex (MI) consists of subpopulations of upper motor neurons tuned to different directional parameters of a motor movement, this study hypothesized that novel motor skill training involving either a bidirectional or more complex multidirectional tongue-typing movement should produce distinct training-related features of tongue MI neuroplasticity in humans. Novel motor skill training consisted of tongue typing using custom-made intra-oral keypads for 30-min over two consecutive days. The bidirectional keypad consisted of three sensors positioned along the upper palatal midline as a 3 × 1 array, whereas the multidirectional keypad consisted of nine sensors arranged as a 3 × 3 array that was centred along the upper palatal midline. ⋯ Bidirectional and multidirectional training were associated with increases and decreases in a number of cortical motor map sites from where tongue activity could be evoked, however; multidirectional training was associated with a greater number of cortical motor map sites with increased excitability and a shift in the centre of gravity of the motor map. No effects of training were found on the FDI TMS-MEP stimulus-response curves. This study revealed distinct training-related features of tongue MI neuroplasticity and proposes that a greater amount of functionally related neuronal populations may be 'trained' by the inclusion of different and more complex directional parameters within a novel motor task.