Mapping of somato-sensory evoked potentials (SEP): new findings suggesting the role of brain waves as a "temporal analyzer of the stimulus".
For a number of years we have been reporting a relationship between the mid components of the somato-sensory evoked potentials and basic brain waves. Recently we suggested that when the primary spike occurs it elicits a train consisting of beta, alpha, theta and delta single waves, originating at the same point in time and overlapping one with the other. The half periods of each of these waves are equal to the latencies of mid and late SEP components. Thus the latter are in fact the classical brain waves. They are present bilaterally but are of higher amplitude on the parietal region contralateral to the side of the stimulus applied to the median nerve. Presumably at that side the brain wave amplitude is increased by the delayed potentials due to the conduction of some components of the signal travelling in the thin myelinated fibers. Indeed this study revealed the presence of recurrent delayed positive and negative foci in the parietal region contralateral to the side of the stimulus in addition to the late vertex components. Thus brain waves contribute to the temporal analysis of the stimulus.
Liberson
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D000293:Adolescent; D000328:Adult; D002540:Cerebral Cortex / Q000502:physiology*; D004562:Electrocardiography; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005625:Frontal Lobe / Q000502:physiology; D006801:Humans; D008475:Median Nerve / Q000502:physiology; D009431:Neural Conduction / Q000502:physiology; D009434:Neural Pathways / Q000502:physiology; D009778:Occipital Lobe / Q000502:physiology; D010296:Parietal Lobe / Q000502:physiology; D011930:Reaction Time