How do the same neural circuits produce different behaviors, different circuits the same behavior, and what is the role of parallel, redundant, or even antagonistic circuits?

Chair: Eva Naumann, Thu. 3-5p EST

3:00-3:10p

Eve Marder (Brandeis University)

Perturbations Reveal that Degenerate Circuits Hide Cryptic Individual Variability

More than 40 years of work on the crustacean stomatogastric nervous system on the cardiac sac, gastric mill, and pyloric rhythms have described numerous instances of circuit reconfiguration by neuromodulation and sensory inputs. These reconfigurations can involve alterations in the frequency and phases relationships of rhythms, and switching of neurons from participating in one circuit to another. Computational works shows clearly that there are multiple, degenerate sets of parameters that can result in similar output patterns. Motivated by this, we have studied the effects of several different perturbations on STG networks. Recent studies on the effects of repeated Hi K⁺ applications reveal long-term adaptations to the high K⁺ that are not evident in the activity patterns after wash in normal saline.

3:20-3:30p

Ben De Bivort (Harvard University)

Connectome-Resolution Model of the Antennal Lobe as a Framework for Understanding Individual Sensory Responses

Behavior varies even among genetically identical animals raised in the same environment. However, little is known about stochasticity gives rise to circuit or anatomical variations underpinning this individuality. Using paired behavior and two-photon imaging measurements, we show that idiosyncratic patterns of neural activity in projection neurons (PNs), but not olfactory receptor neurons (ORNs), predict idiosyncratic odor preferences in flies. The origins of this stochastic variation is a mystery. A challenge of testing hypotheses related to the origins of variability is the lack of experimental tools to manipulate stochastic outcomes. We have developed a spiking model of the entire antennal lobe, with wiring drawn directly from the fly connectome. This circuit model is an in silico sandbox for testing hypotheses about the origins of stochastic variation, and points to developmental variation in all three antennal cell types (ORNs, PNs and local neurons) as contributing to variation in PN odor representations. We believe that these experiments and models constitute an integrative approach to characterizing how functional and structural idiosyncrasy contribute to variable behavior among individuals.

3:40-3:50p

Kenta Asahina (Salk Institute)

Impact of Individual History on Social Behavior

Innate behaviors of animals – including humans – are often associated with the function to maintain the homeostasis. Coined as “survival behaviors”, behaviors like feeding, drinking, and sleeping play an integral role to maintain the vitality of an individual. Although social behaviors are sometimes categorized in a repertoire of such homeostasis behaviors, they are distinct in that the most adaptive behavioral option depends on the individual’s developmental history. Specifically, social experience has a lasting impact on the subsequent action choice of the individual. Behavioral experience must be modulating the nervous system so that it generates a behavior unique to each individual even when a seemingly identical situation is presented. I will discuss a few such examples in the fruit fly Drosophila melanogaster, and how this genetically tractable model organism with surprisingly rich social behavior can advance our understanding on the emergence of experience-dependent individuality of social behaviors.

4:00-4:10p

Steve Flavell (Massachusetts Institute of Technology)

A Neural Circuit for Flexible Control of Persistent Behavioral States

To adapt to their environments, animals must generate behaviors that are closely aligned to a rapidly changing sensory world. However, behavioral states such as foraging or courtship typically persist over long time scales to ensure proper execution. It remains unclear how neural circuits generate persistent behavioral states while maintaining the flexibility to select among alternative states when the sensory context changes. Here, we elucidate the functional architecture of a neural circuit controlling the choice between roaming and dwelling states, which underlie exploration and exploitation during foraging in C. elegans. By imaging ensemble-level neural activity in freely-moving animals, we identify stable, circuit-wide activity patterns corresponding to each behavioral state. Combining circuit-wide imaging with genetic analysis, we find that mutual inhibition between two antagonistic neuromodulatory systems underlies the persistence and mutual exclusivity of the opposing network states. Through machine learning analysis and circuit perturbations, we identify a sensory processing neuron that can transmit information about food odors to both the roaming and dwelling circuits and bias the animal towards different states in different sensory contexts, giving rise to context-appropriate state transitions. Our findings reveal a potentially general circuit architecture that enables flexible, sensory-driven control of persistent behavioral states.

4:20:4:30p

Eva Dyer (Georgia Institute of Technology & Emory University School of Medicine)

4:40-5:00p

General Discussion