Barry G. Condron

Serotonin is an important modulator in the brain and is associated with a wide range of physiological functions including development. The exact mechanisms whereby serotonin influences brain development are not well understood. Studies in invertebrate and vertebrate model organisms are beginning to unravel a regulatory role for serotonin in neuronal morphology and circuit formation. Growing evidence suggests that alterations in early serotonin signaling contribute to a number of neurodevelopmental and neuropsychiatric disorders such as autism and depression. Thus, understanding how altered serotonin signaling affects neuronal morphology and plasticity, and ultimately animal physiology and pathophysiology, will be of great significance. Our research focuses on the function of serotonin in the regulation of serotonergic neuronal development itself and that of other neurons. We use a range of techniques but especially high-resolution imaging of neuronal structures and quantitative analysis of this data. Using this approach and in conjunction with HHMI/Janelia Farm we have begun to establish an atlas of all neuronal structures in a part of the fly CNS and to develop software to analyze their structures. Serotonin levels in the brain are critical for function and are dependent on both the structure and function of serotonergic neurons. Serotonergic neurons deploy a wide array of varicosities from which serotonin is thought to be released. Our lab is interested in how the underlying branch structures for these neurons form, how varicosities deploy throughout the CNS and how these structures are sensitive to serotonin levels in health and disease. In conjunction with Jill Venton's lab in the Chemistry department, we have begun to examine the physiology of serotonin release. Finally, we have identified a sensory-motor circuit whose morphology is regulated by serotonin and will use this to examine how serotonergic architecture influences the function of this modulator. We have developed spatial information for all or most neurons of the larval abdominal ganglia and are working in conjunction with HHMI/Janelia to have each genetically tagged. We are currently finishing tracing these neurons and plan to integrate them into a 'virtual ganglion' or an electronic version of one fly ganglion that will contain all neurons. This will be very useful in both identifying new morphological targets of serotonin as well as generating a realistic spatial model in which we can simulate serotonin function.