stomatogastric nerve (sensu Cancer borealis)

The stomatogastric nerve (SGN) in Cancer borealis is the main nerve trunk that connects the paired commissural ganglia to the stomatogastric ganglion. It is composed of four separate nerves: the superior esophageal nerves (SONs) and the inferior esophageal nerves (IONs). The SGN carries modulatory and motor axons between these ganglionic centers.

In Cancer borealis, the stomatogastric nerve runs from the paired commissural ganglia, passing anteriorly along the esophagus, to reach the stomatogastric ganglion on the dorsal surface of the foregut. It serves as the main conduit of information flow between the commissural ganglia and the stomatogastric ganglion.

The stomatogastric nerve is involved in carrying modulatory inputs from the commissural ganglia to the stomatogastric ganglion, which is critical for activating and shaping the motor patterns generated by the gastric mill and pyloric circuits. It also carries sensory and motor axons that contribute to the overall coordination of the crustacean foregut.

Transection of the stomatogastric nerve—a common experimental manipulation—is associated with isolation of the stomatogastric ganglion from descending modulatory input. This de-afferentation is used to study the intrinsic properties of stomatogastric circuits and the role of modulation in circuit activation. Pharmacological application along the nerve can also influence signal transmission.

The stomatogastric nerve is examined using extracellular suction electrode recordings and intracellular recordings in dissected stomatogastric nervous system preparations. Selective transection of the stomatogastric nerve or its component nerves is a standard experimental manipulation. Immunohistochemistry and confocal microscopy characterize the neuromodulatory content of axons within the nerve.