Figure 10.

Comparison of buccal motor programs produced by stimulation of the two major esophageal nerve branches. A: Motor programs produced by stimulation (3-msec pulses, 2 Hz) of En₁. Extracellular recordings from buccal nerve 1 (Bn1) were used to monitor the protraction phase of motor programs (Neustadter et al. 2002; duration of protraction indicated by the white bar below recordings). Intracellular recording from the multifunctional neuron B4 provided a monitor of the retraction phase (duration of retraction indicated by gray bar below recordings). Note that retraction phase duration corresponds to the entire period of B/4 depolarization, which typically outlasts its period of firing. Intracellular recording from B8 served as a monitor of radula closure. In A1, the closure phase is coincident with protraction, indicative of a fictive egestive-like program. A2 illustrates an intermediate program in which closure is not preferentially associated with either protraction or retraction (see Materials and Methods for classification algorithm). B: Group data (41 programs from five preparations) showed that the motor programs produced by En₁ stimulation were biased toward the egestive-like classification. C: Motor programs produced by stimulation of En₂. In C1, the closure phase is coincident with protraction, indicative of a fictive egestive-like program. C2 illustrates an intermediate program in which closure is not preferentially associated with either protraction or retraction. In C3, closure was predominantly associated with retraction, indicative of an ingestive-like program. Group data for En₂ stimulation (48 programs from six preparations) are shown in B (right side). No significant bias toward any of the three program classifications was detected.