878A Poster - 14. Neural circuits and behavior
Thursday April 07, 2:00 PM - 4:00 PM

Authors:
Avery Krieger; Ryan York; Luke Brezovec; Thomas Clandinin

Affiliation: Stanford University

Keywords:
b. neuropeptides; l. locomotion/flight

Effectively acting on the demands of internal states is vital for survival. For example, when an animal experiences hunger, signals from nutrient sensors must be transmitted to its brain to orient its behavior towards acquiring sustenance. The internal state of hunger and the sensory inputs relevant to finding food must be integrated and transformed into action.

Neuropeptides signal on a variety of scales and change the dynamics of neural circuits (Bargmann 2012). The majority of neuropeptide functions are unknown, yet their purported mechanisms make them well suited to signal internal state.

Recent advances allow for specific genetic access to around 40 neuropeptide producer and receptor neuron populations (Deng 2019). By placing these flies in a 1x1 meter enclosed environment and tracking their movement, we can precisely track individuals during behavioral bouts. An automated fly dispenser allows for the testing of various genotypes and conditions. Screens completely surrounding the fly allow for both static and dynamic visual stimulus presentation. To test the effects of various neuropeptide neurons on behavior, we activate them via optogenetic stimulation during the trial. This system allows for the first unbiased behavioral screen of the effects of a large variety of neuropeptides in response to stimuli, as well as a comparison between those effects and that of behavioral and physiological states of individual flies.

Through measurements of the fly’s position and heading, we quantify various behavioral metrics of individuals in response to visual stimuli, states, and neuropeptide neuron stimulation. We have found that internal states such as hunger and mated status of flies lead to dramatic changes in the animal’s locomotor behavior and that state changes alter the relationship between behavior and visual stimuli. Optogenetically activating the neuropeptide neuron populations also alters locomotor behavior generally and its relationship to visual stimuli, sometimes with similar effects to changing internal states.

These experiments enable us to probe the effects of many neuropeptides and states on behavior. The goal is to characterize the effect of neuropeptides in interpretable ways as they reflect and manipulate internal states of the animal. The ultimate goal is to build a circuit-level understanding of neuropeptide and state computations that transform sensory inputs into behavior, helping animals reach their goals.