Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale
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Transcranial direct current stimulation (tDCS) uses a weak electric current to modulate neuronal activity. A neurophysiologic outcome measure to demonstrate reliable tDCS modulation at the group level is transcranial magnetic stimulation engendered motor evoked potentials (MEPs). Here, we conduct a study testing the reliability of individual MEP response patterns following a common tDCS protocol. ⋯ Using this common protocol, we found the effects of tDCS on MEP amplitudes to be highly variable at the individual level. In addition, no significant effects of tDCS on MEP amplitude were found at the group level. Future studies should consider utilizing a more strict experimental protocol to potentially account for intra-individual response variations.
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Interactions between the hands are a collateral of simultaneous bimanual movements and can inform us about the functional asymmetries of the dominant and nondominant hemisphere-effector systems. Few studies on bimanual coordination have focused on discrete movement control, and even fewer have looked at this in the context of handedness. Using a novel bimanual paradigm in which both hands perform simultaneous target-directed movements, this study addressed interference between the hands in two groups of left-handed individuals. ⋯ The findings mirror the results of a previous study in right-handers. At the same time, interference was overall weaker in the left-handers, and not as exclusively dominant to nondominant as in the previous right-handed sample. The results not only confirm that hand control characteristics switch with handedness, but also shape interactions between the hands accordingly in left-handers.
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Autonomic dysregulation and heterogeneous symptoms characterize postural orthostatic tachycardia syndrome (POTS). This study evaluated the effect of high-resolution, relational, resonance-based, electroencephalic mirroring (HIRREM(®)), a noninvasive, allostatic neurotechnology for relaxation and auto-calibration of neural oscillations, on heart rate variability, brain asymmetry, and autonomic symptoms, in adolescents with POTS. Seven subjects with POTS (three males, ages 15-18) underwent a median of 14 (10-16) HIRREM sessions over 13 (8-17) days. ⋯ Use of HIRREM was associated with reduced sympathetic bias in autonomic cardiovascular regulation, greater symmetry and reduced amplitudes in temporal lobe high-frequency electrical activity, and a trend for reduced autonomic symptoms. Data suggest the potential for allostatic neurotechnology to facilitate increased flexibility in autonomic cardiovascular regulation, possibly through more balanced activity at regions of the neocortex responsible for autonomic management. Clinical trial registry "Tilt Table with Suspected postural orthostatic tachycardia syndrome (POTS) Subjects," Protocol Record: WFUBAHA01.
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Perceptual binding of multisensory events occurs within a limited time span known as the temporal binding window. Failure to correctly identify whether multisensory events occur simultaneously, what their temporal order is, or whether they should be causally bound can lead to inaccurate representations of the physical world, poor decision-making, and dangerous behavior. It has been shown that the ability to discriminate simultaneity, temporal order, and causal relationships among stimuli can become increasingly difficult as we age. ⋯ Simultaneity judgments in younger and older adults were indistinguishable. Positive correlations between TOJ and SJ as well as SJ and stream/bounce tasks were found in younger adults, which identify common (SJ) and distinct (TOJ, stream/bounce) neural mechanisms that sub-serve temporal processing of audiovisual information that is lost in older adults. We conclude that older adults have an extended temporal binding window for TOJ and stream/bounce tasks, but the temporal binding window in SJ is preserved, suggesting that age-related changes in multisensory integration are task specific and not a general trait of aging.
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Vestibular stimulation has been reported to alleviate central pain. Clinical and physiological studies confirm pervasive interactions between vestibular signals and somatosensory circuits, including nociception. However, the neural mechanisms underlying vestibular-induced analgesia remain unclear, and previous clinical studies cannot rule out explanations based on alternative, non-specific effects such as distraction or placebo. ⋯ This transient reduction in pain perception was associated with reduced amplitude of all LEP components, including the early N1 wave reflecting the first arrival of nociceptive input to primary somatosensory cortex. We conclude that cold left ear CVS elicits a modulation of both nociceptive processing and pain perception. The analgesic effect induced by CVS could be mediated either by subcortical gating of the ascending nociceptive input, or by direct modulation of the primary somatosensory cortex.