Biology subjects

Darnet, L.

Publications and source records attributed to Darnet, L..

3 recordsLinked to original sources

bioRxiv2026

Lateralized Tenm4 expression biases visual performance and modulates axonal growth and pre-synapse size in retinal ganglion cells

The precise wiring of neuronal connections is a striking feature of the central nervous system and is critical for correct brain function. During vertebrate visual development, retinal ganglion cells (RGCs) establish synaptic connections with postsynaptic cells in the optic tectum, a process that is in part conferred by cell adhesion molecules. However, a complete understanding of the retinotectal wiring mechanism is lacking. Here, we show that the synaptic adhesion molecule Teneurin-4 (Tenm4) is expressed by RGCs and their postsynaptic tectal cell targets in a left-right side-specific manner in zebrafish. Loss of tenm4 leads to defects in presynaptic structures in RGCs and further affects their axonal growth and arbor complexity. Functional assessment of RGC responses to visual stimuli showed a general increase in response amplitude in mutant animals. Visual behavioral analysis revealed a deficit with a strong left-right asymmetrical component in mutant larvae. Our findings demonstrate that tenm4 plays an important role in sensorimotor circuit assembly, extending to neural activities and visual acuity.

neuroscience↗

bioRxiv2019

Investigating olfactory behaviors in adult zebrafish

Odor-driven behaviors such as feeding, mating and predator avoidance are crucial for animal survival. While the zebrafish olfactory circuitry is well understood, a comprehensive description of odor-driven behaviors is needed to better relate olfactory computations to animal responses. Here, we used a medium-throughput setup to measure the swimming trajectories of 10 zebrafish in response to 17 ecologically relevant odors. By selecting appropriate locomotor metrics, we constructed ethograms systematically describing odor-induced changes in the swimming trajectory. We found that fish reacted to most odorants, using different behavioral programs and that combination of few relevant behavioral metrics enabled to capture most of the variance in these innate odor responses. We observed that monomolecular odors in similar chemical categories were weakly clustered based on the behavioral responses, likely because natural odors elicited stronger reactions than the monomolecular odors. Finally, we uncovered a previously undescribed intra and inter-individual variability of olfactory behaviors and suggest a small set of odors that elicit robust responses. In conclusion, our setup and results will be useful resources for future studies interested in characterizing olfactory responses in aquatic animals.

animal behavior and cognition↗

bioRxiv2018

An amplitude code increases the efficiency of information transmission across a visual synapse

Most neurons in the brain transmit information digitally using sequences of spikes that trigger release of synaptic vesicles of fixed size. The first stages of vision and hearing are distinct in operating with analogue signals, but it is unclear how these are recoded for synaptic transmission. By imaging the release of glutamate in live zebrafish, we demonstrate how ribbon synapses of retinal bipolar cells transmit analogue visual signals by changes in both the rate and amplitude of synaptic events. Higher contrasts released glutamate packets composed of more vesicles and coding by amplitude often continued after rate coding had saturated. Glutamate packets equivalent to five vesicles transmitted four times as many bits of information per vesicle compared to independent release events. By discretizing analogue signals into sequences of numbers ranging up to eleven, ribbon synapses increase the dynamic range, temporal precision and efficiency with which visual information is transmitted.

neuroscience↗