dorsal gastric nerve (sensu Cancer borealis)

The dorsal gastric nerve in Cancer borealis carries the dorsal gastric (DG) neurons, which are motor neurons that control the movements of the medial tooth in the crustacean gastric mill. The DG neuron fires bursts that drive protraction of the medial tooth, coordinating its movements with those of the lateral teeth to grind food particles.

In Cancer borealis, the dorsal gastric nerve projects from the stomatogastric ganglion to the medial tooth musculature of the gastric mill. It exits the ganglion along with other ventricular nerves and runs to the dorsal region of the gastric mill, which houses the medial tooth and its associated muscles.

The dorsal gastric nerve is involved in transmitting motor commands that control the movements of the medial tooth in the gastric mill. The DG neuron is part of the gastric mill central pattern generator circuit and participates in the rhythmic alternation that drives coordinated forward and backward movements of the medial tooth to grind ingested food.

In experimental contexts, manipulation of the gastric mill circuit through pharmacological application of neuromodulators, stomatogastric nerve transection, or activation of projection neurons may be associated with changes in dorsal gastric nerve activity. The gastric mill rhythm, including DG neuron activity, depends on descending modulatory input from commissural neurons.

The dorsal gastric nerve is examined using extracellular suction electrode recordings in dissected stomatogastric nervous system preparations of Cancer borealis. Recording from this nerve provides information about DG neuron activity patterns within the gastric mill rhythm. Intracellular recordings and photoinactivation experiments allow characterization of DG neuron properties and circuit contributions.