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Summary: High Gamma Power Is Phase-Locked
to Theta Oscillations in
Human Neocortex
R. T. Canolty,1
* E. Edwards,1,2
S. S. Dalal,3
M. Soltani,1,2
S. S. Nagarajan,3,4
H. E. Kirsch,5
M. S. Berger,6
N. M. Barbaro,5,6
R. T. Knight1,2,3,5,6
We observed robust coupling between the high- and low-frequency bands of ongoing electrical
activity in the human brain. In particular, the phase of the low-frequency theta (4 to 8 hertz)
rhythm modulates power in the high gamma (80 to 150 hertz) band of the electrocorticogram, with
stronger modulation occurring at higher theta amplitudes. Furthermore, different behavioral tasks
evoke distinct patterns of theta/high gamma coupling across the cortex. The results indicate that
transient coupling between low- and high-frequency brain rhythms coordinates activity in
distributed cortical areas, providing a mechanism for effective communication during cognitive
processing in humans.
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