The sensory information from these organs is processed by the brain.In insects, many neurons have cell bodies that are positioned at the edge of the brain and are electrically passive—the cell bodies serve only to provide metabolic support and do not participate in signalling.
Typically, each body segment has one ganglion on each side, though some ganglia are fused to form the brain and other large ganglia.
The head segment contains the brain, also known as the supraesophageal ganglion.
In vertebrate species it consists of two main parts, the central nervous system (CNS) and the peripheral nervous system (PNS). The PNS consists mainly of nerves, which are enclosed bundles of the long fibers or axons, that connect the CNS to every other part of the body.
Nerves that transmit signals from the brain are called motor or efferent nerves, while those nerves that transmit information from the body to the CNS are called sensory or afferent.
The neurons that give rise to nerves do not lie entirely within the nerves themselves—their cell bodies reside within the brain, spinal cord, or peripheral ganglia Glial cells (named from the Greek for "glue") are non-neuronal cells that provide support and nutrition, maintain homeostasis, form myelin, and participate in signal transmission in the nervous system.