theta rhythm
theta wave

It plays a role in the generation of theta waves.

Also, theta waves are thought to be linked to learning and memory.

Then theta waves, 4-6 cycles per second, characterized by "imagery."

As he reached to shut off the machine, Rachel saw a theta wave appear on the screen.

Until she'd seen that theta wave, she'd believed David was as good as dead.

Thus, theta waves recorded from site above and below a generating layer have opposite signs.

But now he was deep in theta waves and under my control.

The spikes in the theta waves match the pulses of light.

And it triggers a highly abnormal spiking of theta waves in the brain.

In fact, I have to wonder whether your own theta waves aren't beginning to spike.