This research will illuminate one of the most challenging aspects of the evolution of neuronal circuits: genomic mechanisms underlying cell-specific adaptive modifications and the origin of novel behaviors. The evolutionary approach is less developed in modern neuroscience. However, it is crucial to understand how complex networks and brains are formed or to answer "why" questions (e.g. why different subsets of signal molecules were selected in distinct neuronal circuits). The evolution of centralized complex brains occurs in parallel, where distinct neural patterning might emerge independently in different lineages but use similar molecular building blocks or toolkits.
This project proposes to identify and characterize cellular homologs within defined neural circuitries across opisthobranch species (e.g. Pleurobranchaea and Tritonia) to understand how changes in the genomic organization of homologous neurons lead to adaptive modifications of networks underlying escape and other behaviors. As a result, it will lead to conceptually new approaches when nervous system evolution can be portrayed on an entire genomic scale with single-cell resolution. The hypothesis about whether divergent evolution of neural circuits resulted in the appearance of novel signaling systems and other neuron-specific markers will be tested. Alternatively, novel network properties and connections might emerge as modular rearrangements of preexisting molecular components.
Training opportunities for interdisciplinary students will arise during the development of a nation-wide comparative genomic database that will be searchable for neuronal markers and signal transduction pathways. The extensive collection of transcripts will also allow testing evolutionary relationships across neurobiological models with different levels of centralization of their nervous systems. The proposed approaches and methodologies can be generalized to any system and thus will dramatically increase both the information and education opportunities that can be gained from studying classical electrophysiological preparations. The research will provide a long desired marriage of neuroscience and comparative genomics to understand of how specific neuronal networks are organized and evolved.
