Study of the aminergic neurons and their roles in controlling fighting behavior

Aminergic neurons have been showed to modulate aggression in a wide range of invertebrates and vertebrates. In our laborartory, we are interested in (i) a detailed characterization of different aminergic neuronal circuits (e.g. octopaminergic, dopaminergic. and GABAergic neurons) that are involved in fighting behavior. (ii) the roles of aminergic neuron in modulating fighting behavior.With the presence of various genetic tools in Drosophila melanogaster, it allows us to manipulate the function of specific types of aminergic neuron and ask their effects on behavior. Using the GAL4/UAS system to express a temperature sensitive dynamin (i.e. shibire), synaptic transmission in specific neurons can be reversibly turned on and off by changing temperature. Loss of function phenotypes are studied using classical mutant approaches or through RNA interference using the newly available RNAi stocks.

Study of the genes and neuronal circuits control the sexually dimorphic fighting pattern

Fighting behavior in fruit flies is sexually dimorphic. Male flies preferentially use lunge and box in fights, while female flies use headbutt and shove instead. This dimorphism is controlled by fruitless and transformer, the same genes that regulate courtship behavior. Fruitless null mutant flies, or males eexpressing female forms of fruitless fight like females, while female flies that express male forms of the gene fight like males. Thus the splicing of a single gene, fruitless, appear to determine both how flies court and how they fight. More detail cellular dissection of the fruitless circuit suggests that diffferent subsets of fruitless neurons are responsible for the dimorphism in fighting pattern and courtship behavior. Combining the information we obtained from the studies of aminergic neurons, we begin to decipher the functions of different subset of fruitless neurons in fighting behavior.

Study of learning and memory associated with hierarchical relatioship in male fruit flies

Fighting contests often lead to the establishment of dominance relationships and hierarchies, especially in males. Similarly, in many species winning or losing an initial fight can change the strategy used in subsequent fighting contests. We recently have demonstrated that at least two behaviors are modified in response to fighting experience in Drosophila melanogaster males. First, losing flies never win their second fights, 30 minutes after an initial contest, when paired with either a socially naïve opponent or a fly with previous winning experience. Second, subordinate males use different fighting strategies depending on if they are paired with a new or previous opponent, suggesting that fruit flies are capable of recognizing and remembering individuals. Currently we are examining how long these behavioral effects persist in flies. While behavioral changes following agonistic experiences have been documented for a number of animals, little is known about the neural substrates that regulate these changes. Using the various tools available for use in Drosophila, we are identifying genes and neural circuits that are responsible for these behaviors.