The brain’s total electrical output is about 30 to 40 watts, enough to power a small household light bulb. Its electrical activity is generated by the cortex, thalamus, and the brain stem. The cortex contains 97% of the brain’s 100 billion neurons and is the primary source of electrical activity measured during neurofeedback. The thalamus is the subcortical structure that controls the rhythm of neuronal fi ring. It’s responsible for the generation of the brainwave frequencies or bandwidths called theta, alpha, and sensory motor rhythm (SMR). Delta is generated by the deeper levels of the cortex and beta by both the cortex and the brain stem (Thompson & Thompson, 2003).