Zebrafish vision: Shedding light on the structural and functional properties of the area centralis and its role in prey capture

The successful student will spend 2 years at the University of Sussex supervised by Dr Baden and 2 years at the Hong Kong University of Science and Technology (HKUST) supervised by Professor Semmelhack. Zebrafish are a key vertebrate model for vision research. Their transparent early life stages, powerful genetic access and large array of well-studied visual behaviours means that circuits underlying specific functions can be studied at depth and at several levels, from the retina to the brain leading to behaviour. One particularly interesting behaviour is prey capture. Both larval and adult zebrafish rely on their sense of vision to capture their live food, which initially includes single celled organisms (paramecia) and later extends to insects and other small animals that fall into the water from overhanging shrubbery. Building on early anatomical studies, we have recently identified an area of the ventral retina that appears to harbour a high density of cone photoreceptors, much akin to the more well-known “area centralis” of carnivorous mammals such as cats or dogs. In the live fish, the identified retinal domain appears to project to a point in probably binocular visual space just above and in front of the animal. In agreement, preliminary data indicates that larval zebrafish tend to position themselves just beneath and behind prospective prey immediately before they strike – as such, the position of this presumptive area centralis would be appropriate to support prey capture.

Project description
The project will combine 2-photon population imaging of visual neurons genetic manipulation, computational modelling and behavioural analysis to shed light on the structural and functional properties of the area centralis and its role in prey capture. Building on previous work from both labs, we will survey visual circuits underlying prey capture with particular reference to this presumed retinal specialisation. By taking advantage of the optical tractability and numerical simplicity of the larval zebrafish nervous system, we will be able to understand the circuitry underlying high-resolution vision, and how specialised visual information is transformed at each stage of processing to give rise to behaviour.

Distribution between HKUST and Sussex:

Retinal imaging and computational modelling will be mainly performed in the lab of Tom Baden at Sussex www.badenlab.org, while behavioural experiments as well as brain imaging and ablation studies will be mainly performed in the lab of Julie Semmelhack at HKUST http://life-sci.ust.hk/faculty/Dr.J.Semmelhack/

Example timeline:
Year 1: Sussex. Map retinal extent of area centralis in zebrafish using confocal and 2-photon imaging. Probe functional properties of key retinal neurons of this retinal domain including retinal ganglion cells and bipolar cells.
Year 2: Sussex. Continue functional survey and develop simple computational framework to explore the consequences any found specialisations for visual coding.
Year 3: HKUST. Record prey capture behaviour, analyse eye and body angles to asses positioning of prey on retina.
Year 4: HKUST. Functional imaging to identify and manipulate neurons in visual brain areas that respond to area centralis stimulation.

Tuesday 2nd May - deadline to apply
Friday 26th May - all applicants will be notified regarding the outcome of their application