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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 ?
This agrees with the observed significant desynchronization activity reported above.
41] found desynchronization and full disclosure attacks in SASI protocol.
We could reframe his notion of a distended temporality to chart what Jonas's work can reveal only belatedly, with desynchronization but one feature of this structural deferral.
We observed that synchronization of epileptic spikes occurs in the preictal periods and dynamical desynchronization in the postictal periods.
Changes in event-related desynchronization and synchronization during the auditory oddball task in schizophrenia patients.
The limited level of intra-regional trade and financial integration also "certainly contribute" to business cycle desynchronization.
The activity of theta has been reported in episodic long-term and working memory; its oscillations seem to be responsible for the integration of top-down and bottom-up information during the encoding phase, while alpha desynchronization correlates with semantic memory performance (30,31)
Moreover, Stebelova et al19 observed in a study that STZ-induced diabetes resulted in lower melatonin levels in the pancreas, kidney and duodenum compared to the control, thus suggesting that the lower amplitude of melatonin in target organs induced by STZ might contribute to the desynchronization of daily rhythms and might also weaken the antioxidant capacity of tissues.
Movement-related desynchronization of alpha rhythms is lower in athletes than non-athletes: A high-resolution EEG study.
Kadri Taht & Melinda Mills, Nonstandard Work Schedules, Couple Desynchronization, and Parent-Child Interaction: A Mixed-Methods Analysis, 33 J.
Chronic stress leads to desynchronization of the HPA axis and subsequent imbalances in stress hormone levels, a critical feature of stress-related illness.
Bright Light Therapy Protects Women from Circadian Rhythm Desynchronization During Chemotherapy for Breast Cancer," by Ariel B.