Biology subjects

Aimon, S.

Publications and source records attributed to Aimon, S..

5 recordsLinked to original sources

bioRxiv2026

An atlas of functional ensembles in the zebrafish hindbrain links structural and molecular features to behavior

The vertebrate hindbrain sustains functions essential for survival and behavioral control, yet how it operates as a whole remains poorly understood. Here we map its functional organization in larval zebrafish, whose transparency permits imaging of the entire hindbrain. We first curate established functional populations from the literature into an atlas annotated with putative mammalian counterparts. We then complement this library with ensembles of co-active neurons extracted without prior labels from whole-hindbrain light-field recordings in behaving larvae. We identify 70 ensembles that recur across individuals and recover most of them in independent light-sheet datasets. Ensembles also align with spatial gene-expression patterns and share their bilateral symmetry. Behavioral characterization identifies known eye- and tail-movement-related populations and reveals new associations with fin and mouth movements. Combining co-activity, molecular signatures, and neuronal projections suggests a candidate recurrent inter-regional circuit. Our atlas thus provides a common spatial reference for linking functional, molecular, and anatomical data to guide circuit discovery.

neuroscience↗

bioRxiv2025

Parallel and convergent pathways for multifeature visual processing in larval zebrafish sensorimotor decision-making

Animals continuously extract and evaluate diverse sensory information from the environment to guide behavior. Yet, how neural circuits integrate multiple, potentially conflicting, inputs during decision-making remains poorly understood. Here, we use larval zebrafish to address this question, leveraging their robust optomotor response to coherent random dot motion and phototaxis towards light. We demonstrate that animals employ an additive behavioral algorithm of three visual features: motion coherence, luminance level, and changes in luminance. Using brain-wide two-photon imaging, we identify the loci of these computations, with the anterior hindbrain emerging as a multifeature sensory integration hub. Through single-cell neurotransmitter and morphological analyses of functionally identified neurons, we characterize potential connections within and across computational nodes. These experiments reveal three parallel and converging pathways, matching our behavioral results. Our study provides a mechanistic brain-wide account of how a vertebrate brain integrates multiple features to drive sensorimotor decisions, bridging the algorithmic bases of behavior and its neural implementation.

neuroscience↗

bioRxiv2023

Neural and behavioral organization of rapid eye movement sleep in zebrafish

Sleep is ubiquitous across the animal kingdom. However, the definition for sleep varies significantly across species. In organisms such as C. elegans, Drosophila, and zebrafish, sleep is classically defined as periods of locomotor quiescence with an increased arousal threshold1-6. In mammals, sleep is further subdivided into rapid eye movement (REM) and non-rapid eye movement (NREM) sleep, but the evolutionary origin of these two sleep states remains unclear7-12. Using longitudinal, high-resolution imaging of naturalistic sleep-wake behavior, we find that the classical definition of larval zebrafish sleep encompasses two clearly distinct quiescent states, one with rapid eye movements (qREM) and one without rapid eye movements (qNREM). Remarkably, qREM states are maintained in congenitally blind larval zebrafish, suggesting that qREM emerged during vertebrate evolution not as a response to internally generated visual imagery (i.e., the "scanning hypothesis")13, but potentially as a strategy to maintain oculomotor stimulation during rest14. Lastly, using brain-wide imaging in freely swimming animals, we find that, in contrast to fixed point attractor models of sleep developed in invertebrates15, population-level activity during zebrafish qREM unfolds along smooth committed trajectories through state-space. This work suggests a significant rethinking of the behavioral and neural organization of sleep in early vertebrates and the emergence of REM during vertebrate evolution.

neuroscience↗

bioRxiv2022

Walking elicits global brain activity in Drosophila

Movement-correlated brain activity has been found across species and brain regions. Here, we used fast whole-brain lightfield imaging in adult Drosophila to investigate the relationship between walk and neuronal activity. We observed brainwide activity that tightly correlated with spontaneous bouts of walk. While imaging specific sets of excitatory, inhibitory, and neuromodulatory neurons highlighted their joint contribution, spatial heterogeneity in forward walk- and turning-induced activity allowed parsing unique responses from subregions and sometimes individual neurons. For example, previously uncharacterized serotonergic neurons were inhibited during walk. While activity onset in some areas preceded walk onset exclusively in spontaneously walking animals, spontaneous and forced walk elicited highly similar activity in most brain regions. These data suggest a major contribution of walk and walk-related sensory or proprioceptive information to brain state. We conclude that walk-related signals induce global but heterogeneous patterns of activity, allowing for local and brain-wide integration of behavioral state into other processes in the brain.

neuroscience↗

bioRxiv2019

Valence and state-dependent population coding in dopaminergic neurons in the fly mushroom body

Neuromodulation permits flexibility of synapses, neural circuits and ultimately behavior. One neuromodulator, dopamine, has been studied extensively in its role as reward signal during learning and memory across animal species. Newer evidence suggests that dopaminergic neurons (DANs) can modulate sensory perception acutely, thereby allowing an animal to adapt its behavior and decision-making to its internal and behavioral state. In addition, some data indicate that DANs are heterogeneous and convey different types of information as a population. We have investigated DAN population activity and how it could encode relevant information about sensory stimuli and state by taking advantage of the confined anatomy of DANs innervating the mushroom body (MB) of the fly Drosophila melanogaster. Using in vivo calcium imaging and a custom 3D image registration method, we find that the activity of the population of MB DANs is predictive of the innate valence of an odor as well as the metabolic and mating state of the animal. Furthermore, DAN population activity is strongly correlated with walking or running, consistent with a role of dopamine in conveying behavioral state to the MB. Together our data and analysis suggest that distinct DAN population activities encode innate odor valence, movement and physiological state in a MB-compartment specific manner. We propose that dopamine shapes innate odor perception through combinatorial population coding of sensory valence, physiological and behavioral context.

neuroscience↗