Model Systems in Neuroethology

Vanderbilt University, Nashville TN

Investigators

Abstract

Investigations of specialized species often lead to important advances in neurobiology and serve as vehicles for communicating basic principles of nervous system function in our classrooms and to the public. This project will continue to investigate the evolutionary origins of the prey control behaviors using a comparative approach focusing on specialized animals, including electric eels, electric catfish, and parasitoid wasps, and the water opossum combining detailed observations of behavior and peripheral sensory structures with exploration of the related brain specializations that allow extreme animals to behave and survive. There are two overarching goals of these studies. The first is to solve general problems of brain function, animal behavior, and evolution that may apply across species and therefore inform us broadly about the animal kingdom, of which humans are a part. The second is to learn about the more specific and often unique abilities of extreme species. The latter goal informs us about the limits of evolution and inspires a sense of wonder and appreciation for the animals that share our planet. The PI will engage in a number of activities to bring the process of discovery to students, inspiring the next generation of scientists. The PI will continue to participate in diverse public outreach, ranging from K-12 presentations, the Vanderbilt Minority Access to Research Careers Program, Vanderbilt’s Brain Blast event for children and parents, the Neuroscience Extravaganza for graduate students, and invited interviews and podcasts. There are three main focuses of this research project: 1) Investigation of the newly discovered stings in the emerald jewel wasp (Ampulex compressa). 2) Further investigation of the extraordinary sensory and predatory aspects of strongly electric fish, including the electric eel (Electrophorus electricus) and new studies of the strongly electric catfish (Malapterurus electricus). 3) Conducting exploratory studies of the water opossum (Chironectes minimus) sensory biology with a focus on its specialized hands. For the first set of studies in jewel wasps—a newly discovered suite of stings into the 2nd thoracic ganglion will be investigated with the goal of further characterizing how the wasp’s venom sequentially controls cockroach behavior to facilitate oviposition and hence reproduction. Data will be collected by recording extracellular action potentials from motor neurons that control femur extension in a restrained roach preparation that is being stung by the wasp. These data will set the stage for investigating venom composition that may include excitatory neurotransmitters (e.g. acetylcholine). In the case of electric eels, we will investigate defensive responses and pursue preliminary data from the last grant period that suggests eels may have a form of “terrestrial” electroreception, during which they assess the resistance of their target during the recently discovered “leaping defense”. We will also investigate and compare the behaviors and abilities of strongly electric catfish with those of the electric eel. The African electric catfish evolved its electrical output independently from the eel, but it may use similar strategies to control the efferents of prey. If so, this would be a remarkable example of convergent evolution. Finally, exploratory studies of the water opossum in fixed museum specimens will explore the sensory specializations of the their unique hands and lay the groundwork for potential future investigation of their brains and behavior. These three aims balance exploratory components with ongoing and less risky investigations, consistent with the spirit of the research line, aimed at diverse model systems in neuroethology. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.