Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology
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Comparative Study
Somatosensory evoked potentials (SEPs) recorded from deep brain stimulation (DBS) electrodes in the thalamus and subthalamic nucleus (STN).
To examine the location of deep brain stimulation (DBS) electrode somatosensory evoked potentials (SEPs) and determine the generators of the median nerve SEPs recorded in thalamus and subthalamic nucleus (STN). ⋯ We propose that the thalamic SEP is generated by excitatory post-synaptic potentials in sensory relay neurons in nucleus ventrocaudalis. A small potential in STN at a similar latency, may be due to volume conduction from thalamus. Intraoperative and postoperative SEP recordings from DBS electrodes could be used to determine the optimal position of the contacts relative to the sensory pathways and the choice of contacts for chronic stimulation.
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Comparative Study
Effect of transcranial DC sensorimotor cortex stimulation on somatosensory evoked potentials in humans.
To study the after-effect of transcranial direct current stimulation (tDCS) over the sensorimotor cortex on the size of somatosensory evoked potentials (SEPs) in humans. ⋯ tDCS can modulate cortical somatosensory processing in humans and might be a useful tool to induce plasticity in cortical sensory processing.
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Comparative Study
Neonatal electrocortical brain activity and cerebral tissue oxygenation during non-acidotic, normocarbic and normotensive graded hypoxemia.
Neonates are commonly exposed to isolated hypoxemic episodes. In order to identify the risk of this, we correlated cerebral oxygen delivery and electrocortical brain activity during isolated graded and repetitive hypoxemia in 1-week-old piglets. ⋯ Acute isolated hypoxemia has to be sustained to induce neuronal hypofunction in normotensive animals. Hypoxic hypoxemia led to acute changes in neuronal activity, whereas cellular oxygenation remained unaffected.
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To investigate the possible contribution of the primary somatosensory area (SI) to pain sensation. ⋯ Since the N20 SEP component originates from the anterior bank of the post-central gyrus (area 3b), our result suggests that this part of SI does not participate in LEP generation. In fact, the previously published LEP sources in the SI area estimated from scalp recordings are about 10-17 mm posterior of the electrode in our patient, suggesting that they are more likely located in area 1, 2 or posterior parietal cortex.
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Clinical Trial
Effects of experimental muscle pain on mechanical properties of single motor units in human masseter.
Muscle pain is known to influence muscle activity but the details of its effects on the mechanical properties of single motor units (SMU) have not been described. We have recently reported a decreased firing rate of SMU in the human masseter muscle during painful contractions with a constant force output. Force output can be modulated by the SMU discharge rate in relation to the contractile properties of SMU. Therefore, the objective of the present study was to measure the mechanical properties of SMU in the masseter to clarify the mechanism which underlies the decrease in SMU firing rate during jaw-muscle pain. ⋯ Potentiation of twitch force could be a possible compensatory mechanism to maintain a constant force output during painful isometric contractions when SMU firing decreases. This finding therefore provides new information on the adaptation of motor function by muscle pain.