Biology subjects

Estrem, C.

Publications and source records attributed to Estrem, C..

4 recordsLinked to original sources

bioRxiv2026

Deconstructing a behavioral state: parallel neural integrators control distinct features of an aversive behavioral state in C. elegans

Transient sensory stimuli can trigger long-lasting changes in behavior and cognition. For example, repeated aversive experiences can lead to persistent changes in arousal and mood. Specialized integrator circuits can store information about recent experiences, but how they are embedded within the architecture of the brain to control internal brain states remains poorly understood. We find that C. elegans accumulates evidence of past aversive experiences over minutes to generate a scalable behavioral state consisting of multiple behavioral changes. Using a brain-wide imaging screen, we identified a set of neurons that integrate aversive sensory stimuli over different timescales, from seconds to minutes. Neuronal perturbations show that these integrator neurons are critical for the aversive behavioral state. They control distinct behavioral features, such as changes in locomotion speed or increased responsiveness to subsequent aversive stimuli. Moreover, the integrator neurons function in parallel to one another, utilize different mechanisms to generate persistent neural activity, and signal through different transmitters. Our result show how a behavioral state can be decomposed into distinct behavioral features that map onto different neural integrators that act in parallel. Combined action of the integrators then generates the full set of behaviors that comprise the global state.

neuroscience↗

bioRxiv2025

Identification of bacterial signals that modulate enteric sensory neurons to influence behavior in C. elegans

The bacterial microbiome influences many aspects of animal health and disease. Some bacteria have beneficial functions, for example providing nutrients, whereas others act as pathogens. These bacteria are sensed by host cells to induce adaptive changes in physiology and behavior. While immune and intestinal cells detect bacterial signals through well-characterized mechanisms, recent studies indicate that neurons can also directly sense bacterial signals. However, the bacterial sensory mechanisms in neurons are less well understood. In the nematode Caenorhabditis elegans, the enteric sensory neuron NSM innervates the pharyngeal lumen and is directly activated by bacterial food ingestion; in turn, NSM releases serotonin to induce feeding-related behaviors. However, the molecular identities of the bacterial signals that activate NSM are unknown. To identify these signals, we systematically probed bacterial macromolecules from nutritive bacteria using biochemical approaches and GC-MS identification. We find that polysaccharides from gram-positive and gram-negative bacteria are sufficient to activate NSM. We further identify peptidoglycan from gram-positive bacteria as a specific component capable of activating NSM. NSM responses to polysaccharides require the acid-sensing ion channels DEL-3 and DEL-7, which localize to its sensory dendrite in the pharyngeal lumen. Ingestion of bacterial polysaccharides enhances feeding rates and reduces locomotion, matching the known effects of NSM on behavior. We also examine bacterial signals from pathogenic bacteria that can infect and kill C. elegans. This approach identifies prodigiosin, a metabolite from pathogenic Serratia marcescens, as a bacterial cue that prevents NSM activation by nutritive bacterial signals. This study identifies molecular signals that underlie neuronal recognition of nutritive bacteria in the alimentary canal and competing signals from a pathogenic bacterial strain that mask this form of recognition.

neuroscience↗

bioRxiv2023

Dissecting the Functional Organization of the C. elegans Serotonergic System at Whole-Brain Scale

Serotonin controls many aspects of animal behavior and cognition. But how serotonin acts on its diverse receptor types in neurons across the brain to modulate global activity and behavior is unknown. Here, we examine how serotonin release from a feeding-responsive neuron in C. elegans alters brain-wide activity to induce foraging behaviors, like slow locomotion and increased feeding. A comprehensive genetic analysis identifies three core serotonin receptors that collectively induce slow locomotion upon serotonin release and three others that interact with them to further modulate this behavior. The core receptors have different functional roles: some induce behavioral responses to sudden increases in serotonin release, whereas others induce responses to persistent release. Whole-brain calcium imaging reveals widespread serotonin-associated brain dynamics, impacting different behavioral networks in different ways. We map out all sites of serotonin receptor expression in the connectome, which, together with synaptic connectivity, helps predict serotonin-associated brain-wide activity changes. These results provide a global view of how serotonin acts at defined sites across a connectome to modulate brain-wide activity and behavior.

neuroscience↗

bioRxiv2022

Brain-wide representations of behavior spanning multiple timescales and states in C. elegans

Changes in an animals behavior and internal state are accompanied by widespread changes in activity across its brain. However, how neurons across the brain encode behavior and how this is impacted by state is poorly understood. We recorded brain-wide activity and the diverse motor programs of freely-moving C. elegans and built probabilistic models that explain how each neuron encodes quantitative features of the animals behavior. By determining the identities of the recorded neurons, we created, for the first time, an atlas of how the defined neuron classes in the C. elegans connectome encode behavior. Many neuron classes have conjunctive representations of multiple behaviors. Moreover, while many neurons encode current motor actions, others encode recent actions. Changes in behavioral state are accompanied by widespread changes in how neurons encode behavior, and we identify these flexible nodes in the connectome. Our results provide a global map of how the cell types across an animals brain encode its behavior.

neuroscience↗