Brain activity, conceptual artwork. The brain activity is represented by firing chemical synapses (green). Chemical synapses are junctions through which the cells of the nervous system signal to each other and they allow the neurons (nerve cells) of the central nervous system to form interconnected neural circuits. Intense brain activity could signify having thoughts and ideas, or even an epileptic attack. The cerebrum, the largest part of the brain, is seen here with the front of the brain at left. It is responsible for conscious thoughts and actions.