Biology subjects

Severi, K. E.

Publications and source records attributed to Severi, K. E..

3 recordsLinked to original sources

bioRxiv2026

Establishing an assay for visual desensitization in larval zebrafish for understanding synaptic plasticity

Synaptic plasticity, the ability of neurons to modify the strength of their connections, is essential for learning. Desensitization is a type of synaptic plasticity during which a behavioral response to a stimulus is reduced after repeated presentations of a weakened version of the stimulus which does not produce the behavioral response and thus is deemed a subthreshold stimulus. Here we explore whether the larval zebrafish escape response from visual threats, such as an expanding dark spot, can act as a potential model to study desensitization. We developed a novel experimental setup to investigate visual desensitization, exposing larvae to looming visual threats of varying contrast, and used high-speed cameras to verify rapid escape movements. First, we established stimuli which reliably acted as subthreshold and suprathreshold stimuli. Next, we quantified the response rate before and after desensitization and compared those data to control larvae who were not desensitized. We observed desensitized larvae reduced their response rate to threatening looming stimuli. By providing an opportunity to explore the plasticity mechanisms governing sensory-motor transformations and behavioral adaptation, this research contributes to our understanding of fundamental principles of learning and neural plasticity across vertebrates.

neuroscience↗

bioRxiv2026

The Effects of Environmental Enrichment on the Behavior of Laboratory Zebrafish (Danio rerio).

Enclosures for laboratory animals are often simple for economic and practical reasons. Enrichment items, such as plants, toys, and refuges, have been shown to improve measures of welfare in commonly used species such as mice and dogs. The numbers of laboratory zebrafish have been increasing in recent years, and most are housed in systems devoid of enrichment. The aim of this study is to assess the impact of environmental enrichment on adult laboratory zebrafish behavior. Experimental fish were raised in the presence of three different enrichment regimes: plastic plants, toys, and photos of gravel. These were compared to a control group raised under standard housing conditions. Once the fish reached sexual maturity, we measured aggression, reproduction, and growth. We found that each enrichment treatment led to significant reductions in aggression in a mirror test compared to control. Reproduction was largely unaffected by the three enrichment treatments. However, we found egg production was decreased following the gravel treatment, and egg survival was increased following the plant treatment. There were no significant impacts of enrichment on measures of growth. In a parallel experiment, breeding fish were exposed to plastic plant enrichment during overnight breeding. Surprisingly, there was no significant impact on egg production or egg survival.

animal behavior and cognition↗

bioRxiv2021

Larval zebrafish exhibit collective motion behaviors in constrained spaces

Collective behavior may be elicited or can spontaneously emerge by a combination of interactions with the physical environment and conspecifics moving within that environment. To investigate the relative contributions of these factors in a small millimeter-scale swimming organism, we observed larval zebrafish, interacting at varying densities under circular confinement. Our aim was to understand the biological and physical mechanisms acting on these larvae as they swim together inside circular confinements. If left undisturbed, larval zebrafish swim intermittently in a burst and coast manner and are socially independent at this developmental stage, before shoaling behavioral onset. We report here our analysis of a new observation for this well-studied species: in circular confinement and at sufficiently high densities, the larvae collectively circle rapidly alongside the boundary. This is a new physical example of self-organization of mesoscale living active matter driven by boundaries and environment geometry. We believe this is a step forward toward using a prominent biological model system in a new interdisciplinary context to advance knowledge of the physics of social interactions.

animal behavior and cognition↗