Lisha Shao

There are usually multiple layers of neurons between peripheral sensory receptors and reward neurons in the central brain. These interconnected intermediate layers are where multisensory integration takes place. It is common in the natural environment that hungry animals hesitate about pursuing food and mates when a predator suddenly appears. The simultaneous valuation of multimodal sensory stimuli is critical to higher cognitive functions, such as decision making and learning. Therefore, these intertwined and undescribed intermediate layers are key to the proper tuning of reward perception by internal states and external stressors. Resolving this knowledge gap will require delineating the anatomy and functional structure of the neural pathways that mediate the transformation of sensory stimuli to reward perception. We will address this question in Drosophila melanogaster, a tractable system with simple brain circuits and an extensive genetic toolbox for neurogenetic and neurocircuitry studies. Specifically, we will determine how perceived sensory modalities, such as food and sex, are transformed into values by the reward pathways and how this process is tuned by internal states and environmental stresses. Our ultimate goal is to define the neural architecture and principles by which reward information from different sensory modalities is perceived and processed.

2. Identify novel reward neurons and determine their relationships with dopamine neurons

A breakthrough in understanding reward mechanisms was the discovery of dopaminergic molecular pathways and neural circuits. Dopamine neurons (DANs) play versatile roles in reward coding, by responding to reward and punishment directly or responding to a cue associated with these stimuli. With behavioral, imaging, and connectomic approaches, my lab will answer the following questions. How are sensory modalities, such as food, water and sex, transmitted to DANs? How do the animal's internal states regulate DAN's response to reward? Are there reward circuits independent of DANs?

3. Investigate the interaction between stress and reward system

In the natural environment, an animal's fitness and survival are constantly challenged by the imbalance between available resources and situational demands. Environmental stresses are important regulators of the brain reward system. When stress occurs, the stress reaction system is mobilized to maintain homeostasis and causes a series of physical responses that put the animal in fight-or-flight mode. However, if the stress reaction fails to re-achieve homeostasis or if the stressor becomes chronic, there will be adverse physical and mental outcomes, including depression and addiction. Both acute and chronic stress affect the value representation and processing in reward circuits. My lab will work on the genetic and neural mechanisms of how environmental stressors regulate the reward related behaviors.