( urce of the seizure so it could be remo...)Slow brain waves play key role in coordinating complex activity

Several hours of data from five different patients revealed that high-gamma activity was locked to the theta rhythm in many different areas of the brain. The stronger the theta wave, the stronger the coupling to high-gamma oscillations.

The pattern of coupling between theta and high-gamma also changed with the task. Patients listening to a list of words would show strong coupling in a particular set of brain regions, but when they then had to name pictures, a different set of brain areas would show strong coupling.

"We used to think that one little patch of cortex takes care of this function and another little patch takes care of that function, but now we see it's more about systems that are cooperating on one task, then they switch over and cooperate on another task," said UCSF's Kirsch. "On the fly you want to link these areas to do a task, and when the task is over, you want to decouple them and let them link up with someone else. Ryan has shown that the theta waves allow this coupling and uncoupling by locking into phase."

Knight and his colleagues continue to probe the connection between waves of different frequency in the brain and are building a more closely spaced grid of electrodes that can measure finer detail on the brain's surface. They also plan to combine brain grid recordings with recordings from individual neurons in the cortex to find out what really generates the brain waves that EEGs and ECoGs measure.