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You had surgery during which the brain waves in your brain’s cortex were measured.

The brain is located inside the head. It receives, processes and stores sensory impressions. The brain controls movements and various physical functions. The cortex is the outer layer of the brain.

Many of the brain’s processes involve mild electrical currents flowing to the nerve cells. Some of these currents can be measured. Measuring the brain waves in the cortex involves, first, opening up the cranial bone under anesthetic. A mesh with several sensors is then placed on the surface of the brain. Sensors may be small metal plates, for example.

The sensors are used to measure the brain waves in different areas of the brain. This enables the activity in specific parts of the brain’s cortex to be examined.

The brain waves are represented as lines or waves on a screen or on paper. When a seizure occurs, these lines or waves change. The measurements can also show where in the brain a seizure occurred.