Biology subjects

Medan, V.

Publications and source records attributed to Medan, V..

5 recordsLinked to original sources

bioRxiv2025

Integration of Audiovisual Danger Stimuli in the Zebrafish Tectum is Linked with Premotor and Behavioral Enhancements

Multisensory integration enables animals to combine sensory cues, enhancing threat detection and escape behaviors. Although the Tectum is traditionally considered a visual center, its role in integrating auditory and visual danger signals is not fully understood. Using in vivo calcium imaging in larval zebrafish, we demonstrate that auditory stimuli recruit a significant population of tectal neurons, mainly in deep layers. Visual looms elicit strong tectal responses, but combined auditory-visual stimuli robustly increase neural activity and the likelihood of rapid escape, especially for less salient cues engaging more tectal neurons than unisensory stimuli. These results establish the zebrafish Tectum as a multisensory processing area. Notably, the heightened tectal response during multisensory stimulation is strongly correlated with increased activity in hindbrain neurons implicated in escape-like motion events, connecting tectal integration to premotor circuits that drive behavioral output. Our findings provide a mechanistic basis for tectal multisensory processing in enhancing behavioral escape responses.

neuroscience↗

bioRxiv2023

Multisensory integration enhances audiovisual responses in the Mauthner cell

Multisensory integration combines information from multiple sensory modalities to create a coherent perception of the world. In contexts where sensory information is limited or equivocal, it also allows animals to integrate individually ambiguous stimuli into a clearer or more accurate percept and, thus, react with a more adaptive behavioral response. Although responses to multisensory stimuli have been described at the neuronal and behavioral levels, a causal or direct link between these two is still missing. In this study, we studied the integration of audiovisual inputs in the Mauthner cell, a command neuron necessary and sufficient to trigger a stereotypical escape response in fish. We performed intracellular recordings in adult goldfish while presenting a diverse range of stimuli to determine which stimulus properties affect their integration. Our results show that stimulus modality, intensity, temporal structure, and interstimulus delay affect input summation. Mechanistically, we found that the distinct decay dynamics of feedforward inhibition triggered by auditory and visual stimuli can account for certain aspects of input integration. Altogether, this is a rare example of the characterization of multisensory integration in a cell with clear behavioral relevance, providing both phenomenological and mechanistic insights into how multisensory integration depends on stimulus properties.

neuroscience↗

bioRxiv2021

Audiovisual integration in the Mauthner cell enhances escape probability and reduces response latency

Fast and accurate threat detection is critically important for animal survival. Reducing perceptual ambiguity by integrating multiple sources of sensory information can enhance threat detection and reduce response latency. However, studies showing a direct link between behavioral correlates of multisensory integration and its underlying neural basis are rare. In fish, an explosive escape behavior known as C-start is driven by an identified neural circuit centered on the Mauthner cell. The Mauthner cell can trigger C-starts in response to visual and auditory stimuli allowing to investigate how multisensory integration in a single neuron affects behavioral outcome after threat detection. Here we demonstrate that in goldfish visual looms and brief auditory stimuli can be integrated to increase C-start probability and that this enhancement is inversely correlated to the saliency of the cues with weaker auditory cues producing a proportionally stronger multisensory effect. We also show that multisensory stimuli reduce response latency locked to the presentation of the auditory cue. Finally, we make a direct link between behavioral data and its underlying neural mechanism by reproducing empirical data with an integrate-and-fire computational model of the Mauthner cell.

neuroscience↗

bioRxiv2019

Stimulus contrast information modulates sensorimotor decision making in goldfish

Animal survival relays on environmental information gathered by their sensory systems. We found that contrast information of a looming stimulus biases the type of defensive behavior goldfish (Carassius auratus) perform. Low contrast looms only evoke subtle alarm reactions whose probability is independent of contrast. As looming contrast increases, the probability of eliciting a fast escape maneuver, the C-start response, increases dramatically. Contrast information also modulates the decision of when to escape. Although looming retinal size is determinant of response latency, we found that contrast acts as an additional parameter influencing this decision. When presented progressively higher contrast stimuli, animals need shorter periods of stimulus integration to initiate the response. Our results comply the notion that the decision to escape is a flexible process initiated with stimulus detection and followed by assessment of the perceived risk posed by the stimulus. Highly disruptive behaviors as the C-start are only observed when a multifactorial threshold that includes stimulus contrast is surpassed. Summary statementThis study highlights that in fish, the decision of what to do after threat detection is a multifactorial non-binary process that includes assessing the relative contrast of the potential threat. Increasingly higher contrast stimuli produce a progressive increase in C-start escape probability and a decrease in response latency. More subtle alarm reactions are, on the contrary, mostly insensitive to changes in contrast. This might reflect that while subtle reactions have lower thresholds to be executed, disruptive behaviors as the C-start must surpass higher saliency thresholds that integrate multiple aspects including contrast.

neuroscience↗

bioRxiv2018

Polarized light information modulates sensorimotor decision making in goldfish

Animal survival relays on environmental information gathered by their sensory systems. In invertebrates the polarization angle of light is known to provide vital information for a wide range of visual tasks. However, the role of polarization sensitivity in vertebrates remains poorly understood. Here we study if polarization vision enhances threat detection in goldfish. We found that adding a polarization cue to a low intensity contrast looming stimulus biases the type of evasive behavior the animals perform. While low contrast looms mostly evoke subtle alarm reactions, the addition of a polarized cue dramatically increases the probability of eliciting a fast escape maneuver, the C-start response. Goldfish can be startled by polarized light stimuli coming not only from above but also from the sides indicating that polarization sensitivity spans large areas of the retina. In addition, we observed that while low intensity contrast looms preferentially elicit alarm behaviours, high intensity contrast looms rarely induced them, but elicited C-start responses with a high probability. Together, our results show that the addition of a polarized light cue to a low intensity contrast stimulus shifts animals decision making from low threshold alarm responses to the higher threshold C-start escape behaviour. This additional visual cue, thus, might aid underwater threat detection and predator avoidance in the animals natural environment. Summary statementThis study gives the first compelling evidence that fish can use polarized light information to improve their decision making in the context of visual threat detection.

neuroscience↗