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At least 145 records · Page 8Linked to original sources
PubMed1975

Changes in alpha rhythm asymmetry during learning of verbal and visuospatial tasks.

Alpha activity in the two cortical hemispheres was examined during learning and overlearning of a verbal and a visuospatial task. Compared to a pretask baseline condition, the amount of alpha activity during the tasks was decreased. An increase in alpha activity was found from learning to overlearning in both tasks. A greater amount of alpha was found in the right hemisphere for both tasks. In addition, no difference in the degree of alpha asymmetry was found between the tasks. This was discussed in light of prior contrary findings. A significant positive correlation was found between change in learning rate and change in alpha asymmetry during the verbal task. An interpretation of this finding was offered in terms of the level of hemispheric activation reflecting the degree of task engagement.

Alpha Rhythm↗
PubMed2005

Expectancy of pain is influenced by motor preparation: a high-resolution EEG study of cortical alpha rhythms.

This high-resolution electroencephalographic (EEG) study on alpha event-related desynchronization (ERD) evaluated whether anticipatory activity precedes a sensorimotor interaction induced by concomitant painful stimuli and sensorimotor demand. An omitted-stimulus paradigm induced the expectancy of the painful stimulation at the left hand. In the experimental condition, the painful stimulation was associated with a visual go/no-go task triggering right-hand movements. Two control conditions manipulated the painful sensorimotor interaction variable. Compared with the control conditions, the expectancy of the painful sensorimotor interaction increased the high-band alpha EEG oscillations over the right primary sensorimotor cortex contralateral to the nociceptive stimuli and, to a lesser extent, over the centroparietal midline. These findings suggest that concomitant painful stimuli and simple sensorimotor go/no-go demands affect anticipatory activity as revealed by alpha ERD.

Adult↗
PubMed1987

[Sensory stimulation-induced alpha-rhythm asymmetry of schizophrenic patients].

Changes in the alpha-waves produced by the "Berger-reaction" and simultaneously occurring alpha-wave asymmetries were evaluated in 40 right-handed patients with acute paranoid hallucinatory schizophrenia treated without drugs and 55 right-handed controls. Compared to the controls the laterality of alpha-wave in the patients was shifted to the right and increased at the same time. The former change may be due to an increased reactivity of the right hemisphere, while the latter points to a disturbed relationship between the two hemispheres.

Acute Disease↗
PubMed1997

EEG-alpha rhythms and memory processes.

The results of several experiments indicate that alpha frequency varies as a function of memory performance. It was found that in samples of age matched subjects alpha frequency of good memory performers is about 1 Hz-higher than those of bad performers. The difference in alpha frequency between good and bad performers reaches a maximum during the retrieval of information, is much smaller during encoding and is minimal--but still significant--during a resting period. These results suggest that alpha frequency may be a permanent and not only a functional parameter that determines the speed with which information can be retrieved from memory. The calculation of changes in band power indicate further that the upper alpha band is particularly sensitive to semantic memory demands. The lower alpha band, on the other hand, seems to reflect attentional processes. These findings are discussed on the basis of a hypothesis which assumes that EEG frequencies within the alpha band stem at least in part from the thalamus and that the activity of thalamo-cortical networks reflects processes that are related to searching, accessing and retrieving information from (scmantic) long-term memory.

Alpha Rhythm↗
PubMed2005

Visually evoked phase synchronization changes of alpha rhythm in migraine: correlations with clinical features.

OBJECTIVE: This study aimed to compute phase synchronization of the alpha band from a multichannel electroencephalogram (EEG) recorded under repetitive flash stimulation from migraine patients without aura. This allowed examination of ongoing EEG activity during visual stimulation in the pain-free phase of migraine. METHODS: Flash stimuli at frequencies of 3, 6, 9, 12, 15, 18, 21, 24, and 27 Hz were delivered to 15 migraine patients without aura and 15 controls, with the EEG recorded from 18 scalp electrodes, referred to the linked earlobes. The EEG signals were filtered in the alpha (7.5-13 Hz) band. For all stimulus frequencies that we evaluated, the phase synchronization index was based on the Hilbert transformation. RESULTS: Phase synchronization separated the patients and controls for the 9, 24 and 27 Hz stimulus frequencies; hyper phase synchronization was observed in patients, whereas healthy subjects were characterized by a reduced phase synchronization. These differences were found in all regions of the scalp. CONCLUSIONS: During migraine, the brain synchronizes to the idling rhythm of the visual areas under certain photic stimulations; in normal subjects however, brain regions involved in the processing of sensory information demonstrate desynchronized activity. Hypersynchronization of the alpha rhythm may suggest a state of cortical hypoexcitability during the interictal phase of migraine. SIGNIFICANCE: The employment of non-linear EEG analysis may identify subtle functional changes in the migraine brain.

Adult↗
PubMed1991

Effects of cigarette smoking upon frequencies of EEG alpha rhythm and finger tapping.

Under the influence of nicotine, an increase in EEG alpha frequency as well as finger tapping speed has been reported from separate experiments, and it has also been shown that tapping and alpha frequencies may correlate in defined experimental settings. The present study aimed at the analysis of smoking effects using parallel recordings of both EEG and finger tapping. Twelve healthy subjects were tested in two sessions (smoking deprivation versus smoking). After smoking, both dominant alpha frequency (P less than 0.05) and tapping performance (P less than 0.001) were higher than during deprivation. In most subjects, the increase of both parameters developed in parallel, and during phases of very stable tapping the ratio of alpha and tapping frequencies was close to 2:1. Both frequencies correlated during the deprived (r = 0.6108, P = 0.035) as well as the smoking (r = 0.7009, P = 0.011) conditions. Results confirm earlier findings regarding the effect of smoking upon EEG and tapping, and the parallel changes of both parameters may be attributed to the pharmacological properties of nicotine. Besides possible peripheral and spinal effects of nicotine, the increase of tapping performance parallels the increased frequency of central nervous pacemakers.

Adult↗