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(of an electroencephalogram), the replacement of time-ordered, synchronous high-amplitude (30-100 microvolts [μv ]) and slow (α and θ-activity) oscillations of biopotentials by less regular, low-amplitude (5-25 μV) and faster (β-activity) oscillations. The desynchronization of biopotentials in the cerebral cortex usually occurs in response to various stimuli (see Figure 1) but may be caused, for example, by some pharmaceuticals. Desynchronization is one version of the “activation reaction,” or the “waking reaction,” in which the leading role is played by influences exerted on the cortex of the formatio reticularis. Desynchronization also sets in during particular stages of sleep (the fast phase of sleep, or “fast” sleep). Desynchronization is a manifestation of the orientation reflex.

Figure 1. Human electroencephalogram. At rest a regular α-rhythm with a frequency of 10 periods per second is recorded on pickups from various regions of the brain (at left). In response to a light stimulus (the dark band at bottom) the α-rhythm is replaced by low-amplitude β-activity. Scale: 50 μV along the vertical, 1 sec along the horizontal.

Persistent desynchronization (a so-called flat electroencephalogram) is one indication of disruption of the activity of the central nervous system.


References in periodicals archive ?
His most prescriptive advice to performers urges tempo flexing, desynchronization of layers, breaking up of phrases, wilder rubato, and a generally "freer and more individualistic approach to the musical text" (see pp.
Shift workers, whom Kunz calls "a model for internal desynchronization," are known to experience increased morbidity and mortality for a number of diseases, including cardiovascular disorders and cancer.
Motor dysfunction in the neuroscience patient often involves desynchronization of the oropharyngeal musculature and impairment in swallowing.
Such difference of measured time, called the desynchronization correction, depends on the flight direction--with or opposite to Earth's rotation.
The most common desynchronization is that of a free-running rhythm.
Crossing time zones causes jet lag (known as transient desynchronization of the circadian rhythm to medical experts).
Wetlands are valued because they perform a variety of beneficial functions, such as nutrient transformation, hydrologic desynchronization, and pollutant and sediment retention (Kusler and Kentula 1994; Mitsch and Gosselink 1986; Whigham and others 1988).
The IRSG says marginal changes in world rubber consumption during the past two years are due to desynchronization in regional growth rates.
Drug-induced desynchronization of densely connected visual, motor, and association areas in mammalian brains, in contrast, would disturb all sorts of functions.
The desynchronization of biorhythms increases the risk of disease or dysfunction.
Desynchronization of a human's circadian rhythm by frequent shift rotation can lead to health disorders and the reduced level of vigilance discussed earlier.
1 "Oventricular desynchronization imposed by right ventricular apical pacing even when AV synchrony is preserved increases the risk of heart failure and AF in patients with SND and normal baseline QRS duration.