junction of superior esophageal nerve and stomatogastric nerve (sensu Cancer borealis)

In Cancer borealis, the junction between the stomatogastric nerve (STN) and the superior esophageal nerve (SON) is a site where synaptic structures have been identified. Neuromodulatory substances such as octopamine may be released at this junction by projection neurons, influencing the activity of modulatory commissural neurons that project to the stomatogastric ganglion.

This junction is located along the course of the stomatogastric nerve as it runs from the esophagus toward the stomatogastric ganglion in Cancer borealis. The superior esophageal nerve meets the stomatogastric nerve at this point before the combined nerve continues to the stomatogastric ganglion, which sits on the dorsal surface of the foregut.

This junction is involved in neuromodulatory signaling within the stomatogastric nervous system. Octopamine released here may be involved in activating projection neurons such as the modulatory commissural neuron 5 (MCN5), which projects from the commissural ganglia to the stomatogastric ganglion. This modulation is thought to influence gastric mill and pyloric circuit activity.

In experimental contexts, application of neuromodulators such as octopamine at this junction may be associated with changes in the firing patterns of commissural projection neurons and, consequently, in gastric mill and pyloric rhythm generation. Physical damage, chemical lesioning, or cooling experiments may also alter signal transmission through this site.

This junction is studied using electrophysiological techniques including extracellular suction electrode recordings and intracellular sharp electrode recordings in semi-intact or dissected nervous system preparations of Cancer borealis. Immunohistochemistry using antibodies against octopamine and synaptic markers, combined with confocal microscopy, can reveal synaptic structures and neuromodulator localization at this site.