Fig. 11.

The firing of PAS after relatively strong tactile stimuli appears to be mediated by CC5. In this experiment, both the left and right CC5 cells were impaled. A, The two CC5 cells were slightly hyperpolarized (∼5 mV) in order to decrease spontaneous activity. A relatively strong and prolonged stimulus (indicated by thebar under the trace) applied to the right tentacle produced strong excitatory input to the ipsilateral CC5 and firing of the PAS motor neuron as monitored by its spike recorded extracellularly in the RPAn. The stimulus evoked a weaker input to the contralateral CC5 that failed to fire the hyperpolarized cell and consequently did not alter the activity of the left PA motor neuron recorded in the LPAn. Termination of the stimulus evoked what appeared to be an off response.B, Direct firing of the right CC5 in a pattern similar to that produced by the tactile stimulus also evoked firing of the ipsilateral PAS neuron monitored in RPAn. C, The increased firing of PAS after the tactile stimulus was eliminated completely by hyperpolarizing the CC5s another 15 mV so that their spiking was largely eliminated (n = 6).