The neural basis of simple rhythmic and reflexive behaviors such as swimming and gill withdrawal have been successfully studied in nudibranchs and other gastropod molluscs because the brains of these animals contain large, individually identifiable neurons. However, it is a painstakingly slow process to identify neurons and determine their functions one neuron at a time, making it impossible to scale up to the whole brain. Furthermore, although nudibranchs are advantageous for electrophysiology, they are generally difficult to obtain because they need to be caught from the ocean. Unlike other nudibranchs, Berghia stephanieae, which was largely unstudied, can be bred in the lab, making it available in large numbers and amenable to developmental studies. In September 2018, we initiated our collaboration to use large scale transcriptomic, connectomic, and live imaging techniques to obtain a whole-brain view of the generation of complex, motivated behaviors. In a short time, our team has delineated behavioral actions in Berghia that are motivated by feeding or reproductive state, and by the presence of food or shelter. A cellular-level atlas of the brain is being constructed that represents the locations and phenotypic properties of all the neurons in the brain. This atlas will be aligned with a synaptic connectivity diagram obtained from reconstructed serial electron micrographic images. Finally, the locations of neuronal activity recorded with voltage-sensitive dyes will be aligned to the brain atlas to test models of how behavioral responses are produced. New mathematical models are being devised to help understand the complexities of such network activity. Plans are underway to use gene-editing technology to express genetically-encoded sensors and actuators in neurons to more precisely observe and control the activity of particular neuron types. The ultimate goal is to move from a small circuit approach to a whole-brain view of the neural control of behavior.
1. Introduce the audience to identified neurons and molluscan neuroscience
2. Explain the approach to introducing a new species for laboratory research
3. Present results from team approach to studying the neural basis of behavior.