Within visual neuroscience, depth perception is a fundamental question and has been studied extensively. However, the identity and circuitry of the responsible neurons remain unclear. Due to their transparency and ease of genetic manipulation, we propose to use zebrafish larvae as a model organism to study depth perception. To investigate whether larvae could perceive depth, we used the innate visual behaviour of prey capture as an indicator of successful perception of nearby objects. We expected that the strike, the final stage of prey capture, would be distance dependent, as it usually occurs when the prey is physically close enough to be consumed. We conducted behavioural assays with head-fixed larvae exposed to live paramecia in order to ask whether we could observe the distance dep...[ Read more ]

Within visual neuroscience, depth perception is a fundamental question and has been studied extensively. However, the identity and circuitry of the responsible neurons remain unclear. Due to their transparency and ease of genetic manipulation, we propose to use zebrafish larvae as a model organism to study depth perception. To investigate whether larvae could perceive depth, we used the innate visual behaviour of prey capture as an indicator of successful perception of nearby objects. We expected that the strike, the final stage of prey capture, would be distance dependent, as it usually occurs when the prey is physically close enough to be consumed. We conducted behavioural assays with head-fixed larvae exposed to live paramecia in order to ask whether we could observe the distance dependence of the strike behaviour in this paradigm. We track the position of the eyes and tail, then identify the strike and non-strike prey capture based on the kinematics. Since vision in the UV range has been implicated in natural prey capture behaviour, we also incorporated ultra-violet (UV) radiation into the behaviour paradigm. In our preliminary results, the strike distance dependence was not clearly observed. We suspected that larval vision was greatly improved in the presence of UV, leading to the extension of the strike distance beyond the recording frame. Thus, we made several improvements to the set-up and analysis programme to obtain recordings with a larger area, aiming to obtain behaviours triggered by more distant prey. With future functional imaging, depth perception related neurons and their associated circuitry might be found, providing a simpler model system for depth perception studies.