Cognitive tasks augment gamma EEG power.
OBJECTIVE
Gamma EEG oscillations are low amplitude rhythms in the 30-100 Hz range that correlate with cognitive task execution. They are usually reported using time-locked averaging of EEG during repetitive tasks. We tested the hypothesis that continuous gamma EEG would be measurable during mental tasks.


METHODS
We investigated sustained human gamma EEG oscillations induced by 8 cognitive tasks (Visual Checkerboard, Expectancy, Reading, Subtraction, Music, Expectancy, Word learning, Word recall, and a Video Segment) in 20 subjects using standard digital EEG recording and power spectral analysis.


RESULTS
All of the cognitive tasks augmented gamma power relative to a control condition (eyes open watching a blank computer screen). This enhancement was statistically significant at more than one scalp site for all tasks except checkerboard. The Expectancy, Learning, Reading and Subtraction tasks expressed the most impressive gamma response, up to 5 fold above the control condition and there was some task-related specificity of the distribution of increased gamma power, especially in posterior cortex with visual tasks.


CONCLUSIONS
Widespread gamma activation of cortical EEG can easily be demonstrated during mental activity.


CONCLUSIONS
These results establish the feasibility of measuring high frequency EEG rhythms with trans-cranial recordings, demonstrate that sustained gamma EEG activity correlates with mentation, and provides evidence consistent with the temporal binding model.
Fitzgibbon
S P
SP
Centre for Neuroscience and Department of Medicine (Neurology), Flinders University, P.O. Box 2100, Adelaide, SA, Australia.
Pope
K J
KJ
Mackenzie
L
L
Clark
C R
CR
Willoughby
J O
JO
D000328:Adult; D002540:Cerebral Cortex / Q000502:physiology; D003071:Cognition / Q000502:physiology*; D004569:Electroencephalography / Q000379:methods*; D005260:Female; D006801:Humans; D007858:Learning / Q000502:physiology; D008297:Male; D011939:Mental Recall / Q000502:physiology; D010775:Photic Stimulation / Q000379:methods; D011932:Reading; D018709:Statistics, Nonparametric