Temporally patterned activity recorded from mandibular nerves of the isolated subesophageal ganglion of Manduca

We recorded bursts of motor neuron activity from closer and opener mandibular nerves of isolated subesophageal ganglia (SOG) and compared them with the feeding motor pattern of intact Manduca larvae. Closer bursts recorded from isolated SOG lasted from 1 to 4 s, interburst interval durations lasted from 2 to 49 s, and within- and between-animal variability was great. In contrast, motor activity bursts (EMGs) measured from mandibular closer muscles of intact, feeding animals lasted 0.08 to 0.24 s with interburst intervals of 0.26 to 0.57 s. Variability both within and between animals was small. Bath application of 10−4 M octopamine to the isolated SOG tended to increase frequency and reduce the duration of bursts, so that they became more like those recorded during feeding.