Why maintain superfluous neuromodulators?
The data presented in our study raises the question `Is the expression of many well-known neuromodulators in the P. producta STG truly superfluous?’. Clearly, there are many possible answers to this question, the most likely of which is that they are not, in fact, superfluous. We have examined the effects of these neuropeptides on only one target, the neurons of the pyloric central pattern generator, and they undoubtedly have other targets. Although we did not examine the distribution of the modulators in other parts of the nervous system, CabTRP I, proctolin, RPCH and dopamine are widely distributed in the brain and thoracic ganglia in other species, and the similarity of neuromodulator distributions within the tissues we examined suggests that they are likewise present in other parts of the nervous system in P. producta, where they could still be exerting their effects. It is also possible that these modulators do alter the expression of the pyloric pattern, but do so only under cert
