Meeting Abstract

45.6  Tuesday, Jan. 5  Comparative physiology of mechanosensory neurons in three species of leeches. BALTZLEY, MJ; St. Mary’s College of Maryland mjbaltzley@smcm.edu

In the leech Hirudo verbana, each midbody ganglion has four pressure (P) mechanosensory neurons, six touch (T) mechanosensory neurons, and four nociceptive (N) neurons. Putative P cell homologues in the leech Erpobdella obscura were previously identified based on cell location, morphology, and physiology. To determine whether the putative P cell homologues were responding to mechanical stimulation, we recorded from the putative P cells in E. obscura while stimulating the body wall in a semi-intact preparation. Additionally, we used a similar preparation to record from putative T and N cells in E. obscura as well as P, T and N cells in a third leech species, Macrobdella decora. Phylogenetically, M. decora and H. verbana are more closely related to each other than they are to E. obscura. We found that the P cells in M. decora and E. obscura generate more action potentials in response to a given mechanical force applied to the body wall than do the P cells in H. verbana. Similarly, compared to T cells in H. verbana, the T cells in M. decora generate more action potentials in response to a given mechanical force applied to the body wall. However, when standardized to the maximum response, the intensity tuning curves for P and T cells are similar across species. We also examined the action potentials of P, T, and N cells of all three species to identify which characteristics are variable across species.