Biology subjects

Serneels, B.

Publications and source records attributed to Serneels, B..

4 recordsLinked to original sources

bioRxiv2025

Hierarchical processing of sensory information across topographically organized thalamocortical-like circuits in the zebrafish brain

Thalamocortical projections contribute to the spatial organization and functional hierarchies of the mammalian cortex. Primary sensory cortices receive topographically segregated information from first-order thalamic nuclei, which process distinct sensory modalities. In contrast, higher-order cortical regions integrate information from multiple information channels. While such hierarchical processing and integration of information is the foundation for neural computations in the mammalian cortex, the fundamental principles of thalamocortical computations in non-mammalian vertebrates remains unexplored. The zebrafish pallium, located in the dorsal telencephalon, is regarded as the homolog of the mammalian cortex. However, it remains unclear how the zebrafish pallium receives and processes sensory information, and how the architecture and function of these processes compare to the thalamocortical circuits in other vertebrates. Using anatomical tracing, electrophysiological circuit mapping, and in vivo Ca2+ imaging, we revealed a thalamocortical-like pathway in the zebrafish brain. We found that the preglomerular nucleus (PG) is the primary source of visual and mechano-vibrational information to the zebrafish pallium. We demonstrated that PG neurons and their pallial projections exhibit sensory-specific and topographically organized responses. In contrast, the sensory responses of pallial neurons display multiple layers of topographically organized hierarchies, ranging from simple sensory-specific responses to multimodal and coincidence-detecting nonlinear responses. Notably, we observed a progressive increase in the complexity of sensory computations, which is organized topographically along the posterior-anterior axis of the zebrafish pallium. Collectively, our results suggest that hierarchical sensory processing across topographically organized pallial regions is a conserved functional feature of the vertebrate pallium.

neuroscience↗

bioRxiv2025

Topographically organized dorsal raphe activity modulates forebrain sensory-motor computations and adaptive behaviors.

The dorsal raphe nucleus (DRN) plays an important role in shaping a wide range of behaviors, including mood, motivation, appetite, sleep, and social interactions. Reflecting these diverse roles, the DRN is composed of molecularly distinct and topographically organized groups of neurons that target specific regions of the forebrain. Despite these insights, fundamental questions remain regarding how DRN neurons process sensory information, what do DRN communicate to forebrain, and the role of DRN inputs in forebrain computations and animal behavior. To address these questions, we investigated the spatiotemporal activity patterns of DRN neurons, along with DRN axons and their targets in the juvenile zebrafish forebrain. Our findings revealed a remarkable topographic organization of ongoing activity and sensory-motor responses within the DRN. We discovered that a large fraction of DRN neurons are primarily driven by animals locomotor activity. We also observed that an anterior group of DRN neurons, marked by Gad1, exhibited distinct activity patterns during rest, locomotor activity and sensory stimulation. DRN axons broadly innervating the forebrain exhibit topographically organized excitation and inhibition in response to sensory stimulation and motor activity. Notably, we observed significant and rapid covariation between the activity of DRN axons and nearby forebrain neurons. Chemogenetic ablation of the DRN led to a marked reduction in the synchrony and sensory-motor responses across forebrain neurons, accompanied by significant deficits in adaptive behaviors. Collectively, our findings revealed the functional diversity of DRN neurons and their role in transmitting sensory and locomotor signals via topographically organized projections, which can regulate forebrain activity and play a crucial role in modulating animal behavior.

neuroscience↗

bioRxiv2024

Inhibition mediated by group III mGluRs regulates habenula activity and defensive behaviors

Inhibition contributes to various brain computations from sensory motor transformations to cognitive operations. While most studies on inhibition focus on GABA, the main excitatory neurotransmitter of the brain, glutamate, can also elicit inhibition via metabotropic glutamate receptors (mGluRs). The function of mGluR-mediated inhibition remains largely elusive. Here, we investigated the role of group III mGluR-dependent inhibition in the habenula. This primarily glutamatergic and conserved forebrain region acts as a hub between multiple forebrain inputs and neuromodulatory mid- and hindbrain targets that regulate adaptive behaviors. We showed that both zebrafish and mice habenula express group III mGluRs. We identified that group III mGluRs regulate the membrane potential and calcium activity of zebrafish dorsal habenula. Pharmacological and genetic perturbation of group III mGluRs increased sensory-evoked excitation and reduced selectivity of habenular neurons to different sensory modalities. We also observed that inhibition is the main channel of communication between primarily glutamatergic habenula neurons. Blocking group III mGluRs reduced inhibition within habenula and increased correlations during spontaneous activity. In line with such inhibition within habenula, we identified that multi-sensory information is integrated mainly through competition and suppression across habenular neurons, which in part relies on group III mGluRs. Finally, genetic perturbation of a habenula-specific group III mGluR, mGluR6a, amplified neural responses and defensive behaviors evoked by sensory stimulation and environmental changes. Altogether, our results revealed that mGluR driven inhibition is essential in encoding, integration, and communication of information between Hb neurons, ultimately playing a critical role in regulating defensive and adaptive behaviors.

neuroscience↗

bioRxiv2019

Zebrafish dorsal habenula is required for updating learned behaviors

Operant conditioning requires multiple cognitive processes, such as learning, prediction of potential outcomes and decision making. It is less clear how interactions of these processes lead to the behavioral adaptations that allow animals to cope with a changing environment. We showed that juvenile zebrafish can perform conditioned place avoidance learning, with an improving performance across development. Ablation of the dorsolateral habenula (dlHb), a brain region involved in associative learning and prediction of outcomes, led to an unexpected improvement in performance and delayed memory extinction. Interestingly, while the control animals exhibited rapid adaptation to a changing learning rule, dlHb ablated animals failed to adapt. Altogether, our results show that the dlHb plays a central role in switching animals strategies while integrating new evidence with prior experience.

neuroscience↗