When you hear a good joke, this is the system that kicks in and produces the giggly face. - Michael S. Gazzaniga

As in any layered system, however, the system can become jeopardized if a core component that transfers information from one layer to another malfunctions. In the case of biological tissue, if the kinds of proteins that connect cells together are defective, then information may not be able to transfer from the individual-cell layer to the tissue layer, and the entire system could shut down. While not perfect, the layered design of biological systems is advantageous because it minimizes the number of points in the system that, if attacked, would result in catastrophic damage, and it limits the effects of attacks at other points.

enabled conscious experience itself — we humans enjoy mental states that arise from our underlying neuronal, cell-to-cell interactions. Mental states do not exist without those interactions. At the same time, they cannot be defined or understood by knowing only the cellular interactions. Mental states that emerge from our neural actions do constrain the very brain activity that gave rise to them. Mental states such as beliefs, thoughts, and desires all arise from brain activity and in turn can and do influence our decisions to act one way or another. Ultimately, these

Multi-modular brains have at their beck and call a tremendous number of paths to conscious experience. If one route gets destroyed, another may provide an alternate course. To stamp out consciousness, all modules leading to a conscious state must be shut down. Until this happens, intact modules will continue to pass information from one layer to another and induce a subjective feeling of experience. The contents of that conscious experience may be very different from normal, but consciousness remains. Visiting the neuropsychology clinic, we will see how various assaults on our brain affect consciousness and provide insights into how our brains are organized. It turns out that the endless fluctuations of our cognitive life, which are managed by our cortex, ride on a sea of emotional states, which are constantly being adjusted by our subcortical brain.