Interneurons:

Interneurons, also called association neurons, internuncial neurons, relay neurons, connector neurons, intermediate neurons or local circuit neuron: Interneurons carry nerve impulses back and forth between sensory and motor neurons through synapses in the central nervous system (CNS) (brain/spinal cord). They integrate sensory information, regulate motor activity, help with reflexes, and neurogenesis (neuron birth). We have 100 billion interneurons, making up about 99% of all neurons in the body. Also see: Afferent and Efferent Neurons