The control of foregut movements by the stomatogastric nervous system in the European house cricketAcheta domesticus L.

Abstract

1. The morphology of the stomatogastric nervous system inAcheta domesticus L. is briefly described. 2. Removal of the ventricular ganglia and the hypocerebral ganglion as well as severing the oesophageal nerves and their sidebranches to the gut show that the foregut movements are under nervous control. The neural co-ordinating mechanism is located in the oesophageal nerves, whereas the ganglia seem to play merely a stabilizing role. Foregut movements seem to be under additional myogenic control. 3. Simultaneous recordings of gut movements and the activity in the oesophageal nerves demonstrate a correlation between nervous activity and the contraction waves. This correlation is not very obvious in any single event, however, it becomes clear when the average of activity is taken. 4. The stretch receptors on the gutwall respond phasically to the most part to trapezoid and sinusoidal stretches of the gutwall. 5. There exist interactions between sensory elements within the gutwall and motor elements in the oesophageal nerves. The motor elements react to stretching the gutwall with a decrease of their spike activity; this decrease is greatest during the maximum stretch. However, it is often preceded by a short increase which is dependent on the stretching speed. After removal of the hypocerebral ganglion and the ventricular ganglia these relations show no qualitative change. 6. The co-ordinating mechanism includes stretch receptors on the gutwall and motor neurones in the oesophageal nerves between which interactions do occur. The mechanism can be described functionally as a system of spontaneously active motor elements which are modulated by sensory input from the gutwall.