Information (neural impulses/action potentials) travel throughout your nervous system along a network of 3 types of neurons; sensory neurons, motor neurons, and interneurons. The interneurons are found in the CNS (the sensory and motor neurons are not) and receive input from about 2,000-10,000 motor neurons and transmits its output to a similar number of sensory neurons. Information from the environment enters the body through one of the sense, and is converted into an electrical signal that begins its journey on the sensory neurons. The signal is then brought to the CNS where it jumps onto the interneurons, which eventually bring the information to the motor neurons in the brain. After the brain processes the information, the resulting information (what response to give, what to say, what muscle to move, etc.) travels from the motor neurons back onto the interneurons, and then to the sensory neurons. It is a big loop, with the interneurons being the middle man in the process.