What is "supraesophageal ganglion"

The supraesophageal ganglion ("arthropod brain" or "a. microbrain") is the first part of the arthropod and especially insect central nervous system. It receives and processes information from the first, second, and third metameres. The supraesophageal ganglion lies dorsal to the esophagus and consists of three parts, each a pair of ganglia that may be more or less pronounced, reduced, or fused depending on the genus (biology):

• The protocerebrum, associated with the eyes ( compound eyes and ocelli). Directly associated with the eyes is the optic lobe, as the visual center of the brain.
• The deutocerebrum processes sensory information from the antennae. It consists of two parts, the antennal lobe that receives axons of olfactory receptor neurons from the antenna and the dorsal lobe that receives mechanosensory and gustatory receptor neurons from the antenna. The dorsal lobe also contains motor neurons which controls the antennal muscles. Chelicerata with their missing antennae have a very reduced (or absent) deutocerebrum.
• The tritocerebrum integrates sensory inputs from the previous two pairs of ganglia. The lobes of the tritocerebrum split to circumvent the esophagus and begin the subesophageal ganglion.

The subesophageal ganglion continues the nervous system and lies ventral to the esophagus. Finally, the segmental ganglia of the ventral nerve cord are found in each body segment as a fused ganglion and they provide the segments with some autonomous control.