A protoplasmic fiber runs from the cell body and branches profusely, with some parts transmitting signals and other parts receiving signals.Thus, most parts of the insect brain have passive cell bodies arranged around the periphery, while the neural signal processing takes place in a tangle of protoplasmic fibers called neuropil, in the interior.
Grey matter (which is only grey in preserved tissue, and is better described as pink or light brown in living tissue) contains a high proportion of cell bodies of neurons.
White matter is composed mainly of myelinated axons, and takes its color from the myelin.
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.
White matter includes all of the nerves, and much of the interior of the brain and spinal cord.
Grey matter is found in clusters of neurons in the brain and spinal cord, and in cortical layers that line their surfaces.
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.
There is an anatomical convention that a cluster of neurons in the brain or spinal cord is called a nucleus, whereas a cluster of neurons in the periphery is called a ganglion.
There are, however, a few exceptions to this rule, notably including the part of the forebrain called the basal ganglia Arthropods, such as insects and crustaceans, have a nervous system made up of a series of ganglia, connected by a ventral nerve cord made up of two parallel connectives running along the length of the belly.
Both autonomic and enteric nervous systems function involuntarily.