Neurons that Function within an Integrator to Promote a Persistent Behavioral State in Drosophila.

Innate behaviors involve both reflexive motor programs and enduring internal states, but how these responses are coordinated by the brain is not clear. In Drosophila, male-specific P1 interneurons promote courtship song, as well as a persistent internal state that prolongs courtship and enhances aggressiveness. However, P1 neurons themselves are not persistently active.

P1 interneurons promote a persistent internal state that enhances inter-male aggression in Drosophila.

How brains are hardwired to produce aggressive behavior, and how aggression circuits are related to those that mediate courtship, is not well understood. A large-scale screen for aggression-promoting neurons in Drosophila identified several independent hits that enhanced both inter-male aggression and courtship. Genetic intersections revealed that 8-10 P1 interneurons, previously thought to exclusively control male courtship, were sufficient to promote fighting.

Internal States and Behavioral Decision-Making: Toward an Integration of Emotion and Cognition.

Social interactions, such as an aggressive encounter between two conspecific males or a mating encounter between a male and a female, typically progress from an initial appetitive or motivational phase, to a final consummatory phase. This progression involves both changes in the intensity of the animals' internal state of arousal or motivation and sequential changes in their behavior. How are these internal states, and their escalating intensity, encoded in the brain? Does this escalation drive the progression from the appetitive/motivational to the consummatory phase of a social interaction and, if so, how are appropriate behaviors chosen during this progression? Recent work on social behaviors in flies and mice suggests possible ways in which changes in internal state intensity during a social encounter may be encoded and coupled to appropriate behavioral decisions at appropriate phases of the interaction.

Optogenetic control of Drosophila using a red-shifted channelrhodopsin reveals experience-dependent influences on courtship.

Optogenetics allows the manipulation of neural activity in freely moving animals with millisecond precision, but its application in Drosophila melanogaster has been limited. Here we show that a recently described red activatable channelrhodopsin (ReaChR) permits control of complex behavior in freely moving adult flies, at wavelengths that are not thought to interfere with normal visual function. This tool affords the opportunity to control neural activity over a broad dynamic range of stimulation intensities.

Quantitative fluorescence labeling of aldehyde-tagged proteins for single-molecule imaging.

A major hurdle for molecular mechanistic studies of many proteins is the lack of a general method for fluorescence labeling with high efficiency, specificity and speed. By incorporating an aldehyde motif genetically into a protein and improving the labeling kinetics substantially under mild conditions, we achieved fast, site-specific labeling of a protein with ∼100% efficiency while maintaining the biological function. We show that an aldehyde-tagged protein can be specifically labeled in cell extracts without protein purification and then can be used in single-molecule pull-down analysis.