1. 1 Neuro-Electronic Interfacing 1. 1. 1 Nervous System Communication in the(human) bodyand the interaction with the environment is controlled by the nervous system. It can be divided into a central part, which - cludes the spinal cord, brainstem, cerebellum, and cerebrum, and a peripheral part, which includes all neuronal tissue outside the central part (Martini 2001). The latter provides the interface between the central nervous system and the internal and ext- nal environment of the body. Eye, ear, skin, and muscle sensors provide the nec- sary information. Via primary afferent neurons this information is transmitted to the central nervous system. Conversely,this system provides information to the - tor organs via theefferent fibers. Furthermore, the central nervous system is resp- sible for cognition, learning, and memory. Neurons are cells specialized for receiving information and transmitting signals to other neurons or to effector cells, such as muscles and glands (Levitan 1991). Like all other cells, neurons are enclosed by a cell membrane, which is a double layer of phospholipid molecules.
This bilayer, about 10 nm thick, serves as a barrier that - lows the cell to maintain an internal (cytoplasmic) composition far different from the composition of the extracellular fluid. It contains enzymes, receptors, and an- gens that play central roles in the interaction of thecell with other cells.