Otero Coronel, S. | Search bioRxiv

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↗

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↗