Neuromuscular Systems in Molluscs

Molluscs have become increasingly popular in the study of centralneural mechanisms. More recently, there have been attempts torelate activity in central neurons with behavior in animalsof this phylum. The latter studies necessitate an understandingof the effectors of such behaviors. This requires not only informationabout the neuromuscular junction, but also an awareness of thecapabilities of the muscles themselves. Therefore, we have discussedsome structural and related functional characteristics of molluscanmuscle. We suggest that invertebrate mucles might be comparedon three scales: the amount of myofilament organization, theamount of vesicular specialization and organization, and theamount of paramyosin. We have considered some characteristicsof the widely-studied sustained contraction, known as "catch."Finally, we have discussed the neuromuscular junction—thetypes of junctions, the multiplicity of innervation, and someaspects of pharmacology. The results of such a study indicatedmany areas in which further research is essential before wecan understand behavior in terms of activity in the centralnervous system.