alpha activity

Also found in: Dictionary, Thesaurus, Encyclopedia.
Related to alpha activity: alpha rhythm

alpha rhythm

A type of electrical activity in adults detected by EEG in the posterior brain, which may be abolished with visual stimulation and attenuated by thinking. Alpha rhythm (AR) is seen in relaxed adults with closed eyes; it has a frequency of 8–13 Hz over the occipital lobe and has bihemispheric asynchrony, where the non-dominant hemisphere has a greater wave amplitude. Focal CNS disease is accompanied by focally altered AR, which becomes diffuse in coma. 

AR is the EEG pattern that corresponds to the awake state; it is present in most, but not all, normal individuals, and is most consistent and predominant during relaxed wakefulness, particularly with reduction of visual input. AR has a range in each person: the low end is exhibited in drowsiness or sleep and the upper end with alertness. AR also varies with age: it is slower in children and older age groups relative to young and middle-aged adults.
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.

alpha activity

Sleep disorders The presence of alpha waves or alpha rhythm in an EEG. See Alpha rhythm.
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
Tackling creativity at its roots: Evidence for different patterns of EEG alpha activity related to convergent and divergent modes of task processing.
Jensen, "Modulation of posterior alpha activity by spatial attention allows for controlling a continuous brain-computer interface," Brain Topography, vol.
The higher the alpha activity before the passive training, the better the people learned.
Interestingly, Kubitz and colleagues (1996; 1997) observed decreases in alpha activity during exercise, while the present investigation observed increases in alpha activity.
A particular form of spatial reorganization of alpha activity is noted in tumor damage to mediobasal regions of the temporal lobe with the involvement of the hippocampus and close-lying structures in the pathological process.
One of the general findings from EEG research in this area has been that an increase in alpha activity, commonly seen as skill level increases, is not simply indicative of cortical deactivation, but is indicative of neural reorganization concomitant with the acquisition of more efficient, task-specific cognitive and motor processes (Nunez, 1995; Smith, McEvoy, & Gevins, 1999).
It is true that alpha activity is not solely modulated by visual activity but although we classified other dream activities the strongest correlation was found for visual imagery.
* Patients with Alzheimer's disease tend to show a slowing of alpha activity below 8 Hz, a decrease in alpha activity, a decrease in the alpha to theta ratio, an increase in theta activity, and an increase in delta activity.
It was expected that, in comparison with the HC individuals, the AC ones would show lower alpha activity while solving creative problems.
Gross alpha and beta activity in bone: For gross alpha activity in bone, there was a significant difference (ANOVA, p < 0.01) between locations.
Different patterns of occipital and sensory motor alpha activity were observed during kinaesthetic versus visual imaging in which greater relative occipital activation occurred during the latter task.