Switch neurons are cells that are located entirely within a particular structure. For example, a switch neuron in the thalamus has both its axons and its dendrites within the thalamus. Thus, unlike other neurons, this cell does not form a connection with another structure of the nervous system, but with other neurons within the same structure. Thus, they are not sensory neurons, and they are not motor neurons either. In fact, most neurons in the central nervous system are switch neurons, about 99%. You find them, for example, in the cerebral cortex, cerebellum and spinal cord.
Author: Bart Aben (translated by Melanie Smekal)