The human brain contains about 1011 neurons, and each makes on average 103 synapses with other neurons. Thus, there are about 1014 synaptic connections in the brain that give rise to our ability to sense, think, remember, and act. How is this vast number of neurons organized into circuits to process information? How are these circuits assembled during development?
We are addressing these questions using model neural circuits in the less numerically complex brains of the fruit fly (~105 neurons) and mouse (~108 neurons). A central focus is on wiring specificity. How precise are the connections between different constituent neurons within a neural circuit? Does the degree of wiring specificity differ for neural circuits serving distinct functions? How does wiring specificity arise during development? What are the respective contributions of molecular determinants and neuronal activity? To tackle these questions, we are combining state-of-the-art molecular genetics and viral techniques—from single cell labeling to trans-synaptic tracing—with physiological and behavioral approaches.
Our studies benefit from attention to multiple aspects of neural circuits—including their development, organization, and function—in two different model organisms that offer distinct advantages. Comparing the similarities and differences between insects and mammals enriches our understanding of evolutionally conserved principles as well as diverse solutions to common problems. Cross-fertilization of mouse and fly studies with the latest tools from each organism facilitates novel approaches to addressing these questions. Studies of neural circuit assembly and function should enlighten each other. Developmental analysis offers a unique angle as well as tools to untangle the complexity of the adult circuit; circuit function provides the ultimate purpose for elaborate developmental programs.
We are pursuing these core interests through four research programs:
1. Organization of the fly and mouse olfactory systems
2. Assembly of the fly olfactory circuit
3. Explorations of mammalian neural development
4. Development of genetic tools to probe neural circuit assembly and organization