Neural circuits of valence decisions and innate olfactory behavior
Animals and humans innately like or dislike certain things including particular odors. Some preferences or aversions can be modified, enhanced or suppressed in particular situations, for instance when an animal is hungry or stressed. At the moment, our understanding of how positive and negative cues are processed and modified in higher brain centers is very limited. We aim at identifying the neural circuitry underpinning valence decisions. Using screening and candidate neuron approaches, we have identified several very interesting neural subsets that we are currently analyzing using detailed behavioral analysis.
We study mostly innately attractive or aversive odors and how they are processed in the brain. Drosophila flies show a strong innate aversion to CO2 even at low concentrations. In contrast to flies, CO2 is one of the cues that mosquitoes use to find animal or human hosts. For flies, vinegar represents a mix of odors that is strongly preferred especially when the animals are hungry. We assay these behaviors in standard and custom made behavior assays and use genetic tools to identify the neural networks underpinning them. Additional techniques such as in vivo functional imaging is then employed to characterize the different neurons in a circuit, their function, and how they are influenced by internal and external factors.
In humans, hunger, stress, and other emotions are regulated by hormones, neuropeptides and neurotransmitters. The same is true in the fly, and interestingly, similar molecules as in humans play a role in the insect. Genetic manipulation in flies raised in carefully controlled environments is used in the lab in order to understand which molecules are involved in context dependent valence decisions.
Ultimately, we believe that our research will contribute to the understanding of how hunger, stress or fear are integrated into decision making processes in the human brain.