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Chapter 16.2 Electroencephalography and the Neurophysiology of Sleep-wakefulness

BOOK TITLE: Understanding Medical Physiology: A Textbook for Medical Students

Author
1. Bijlani R.L.
ISBN
9788180612213
DOI
10.5005/jp/books/10999_105
Edition
3/e
Publishing Year
2004
Pages
8
Author Affiliations
1. All India Institute of Medical Sciences, New Delhi
Chapter keywords
physiological process, active electrodes, neurosurgery, potential difference, desynchronised activity, postsynaptic potentials, neuronal activity, alpha rhythm, subcortical transaction, power spectral analysis, frequency waveform, paradoxical sleep, gastrointestinal motility, proprioceptive impulses, mental equilibrium, electrical activity

Abstract

This chapter discusses electroencephalography and the neurophysiology of sleep-wakefulness, where electroencephalography is the technique that has been applied the most to the study of sleep-wakefulness. Electroencephalography involves recording the electrical activity of the brain with the help of surface electrodes placed on the scalp, and the record is called an electroencephalogm (EEG). To record an EEG, the electrodes are placed in the frontal, parietal, temporal and occipital regions according to a precisely defined system. Synchronous activity gets summated to give large waves. Asynchronous activity leads to simultaneous deflections in opposite directions, which cancel each other out. Alpha waves are typically recorded when a person is awake but inattentive. Beta waves are typically recorded when a person is awake and alert. EEG is often recorded for research or investigation of patients continuously for hours, and sometimes overnight. Three states of consciousness are wakefulness, dreamless sleep and dream sleep.

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