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Digitale Medien

Mu and Beta Rhythm Topographies During Motor Imagery and Actual Movements (2000)

McFarland, Dennis J. ; Miner, Laurie A. ; Vaughan, Theresa M. ; [weitere]

Springer

Brain topography 12 (2000), S. 177-186

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ISSN: 1573-6792

Schlagwort(e): Sensorimotor cortex ; Mu rhythm ; Beta rhythm ; EEG ; Imagery

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Notizen: Abstract People can learn to control the 8-12 Hz mu rhythm and/or the 18-25 Hz beta rhythm in the EEG recorded over sensorimotor cortex and use it to control a cursor on a video screen. Subjects often report using motor imagery to control cursor movement, particularly early in training. We compared in untrained subjects the EEG topographies associated with actual hand movement to those associated with imagined hand movement. Sixty-four EEG channels were recorded while each of 33 adults moved left- or right-hand or imagined doing so. Frequency-specific differences between movement or imagery and rest, and between right- and left-hand movement or imagery, were evaluated by scalp topographies of voltage and r spectra, and principal component analysis. Both movement and imagery were associated with mu and beta rhythm desynchronization. The mu topographies showed bilateral foci of desynchronization over sensorimotor cortices, while the beta topographies showed peak desynchronization over the vertex. Both mu and beta rhythm left/right differences showed bilateral central foci that were stronger on the right side. The independence of mu and beta rhythms was demonstrated by differences for movement and imagery for the subjects as a group and by principal components analysis. The results indicated that the effects of imagery were not simply an attenuated version of the effects of movement. They supply evidence that motor imagery could play an important role in EEG-based communication, and suggest that mu and beta rhythms might provide independent control signals.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1023437823106

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Digitale Medien

Chronic exposure of primates to 60-Hz electric and magnetic fields: I. exposure system and measurements of general health and performance (1989)

Wolpaw, Jonathan R. ; Seegal, Richard F. ; Dowman, Robert

New York, NY [u.a.] : Wiley-Blackwell

Bioelectromagnetics 10 (1989), S. 277-288

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Details

ISSN: 0197-8462

Schlagwort(e): 60-Hz fields ; electric field ; magnetic field ; primate ; central nervous system ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Biologie , Physik

Notizen: We exposed pigtailed macaques (Macaca nemestrina) to electric (E) and magnetic (B) fields at strengths of 3 kV/m and 0.1 G, 10 kV/m and 0.3 G, and 30 kV/m and 0.9 G for three 21 day segments. These three exposure segments were preceded and followed by 21 day sham exposure segments. Additional animals received only sham exposure for five 21 day segments. Detailed description of the exposure chamber and field generation apparatus is given. We evaluated measures of animal well-being, including weight, blood chemistry, blood cell counts, and performance on a simple motor task, and performed postmortem examinations. Reliable and consistent results were obtained throughout data collection. None of the measures evaluated was significantly affected by E- and B-field exposures. Data obtained during actual exposure segments were not distinguishable from those obtained during the initial and final sham exposure segments, nor were they different from data obtained from the sham-exposed animals. Thus, field exposure had no apparent effects on general health or performance.

Zusätzliches Material: 5 Ill.