All visual systems are specialised to best serve an animal’s sensory niche1–3, yet how such specialisations are achieved through phylogenetic and developmental adaptations are poorly understood. This project will study these adaptations in the visual system of zebrafish. Specifically, we will use two-photon functional imaging to survey how the visual systems of both larval and adult zebrafish sample and process behaviourally meaningful natural stimuli to ultimately drive behaviour. We will also build a robotic camera system capable of realistically documenting the zebrafish natural world to guide stimulus design.
The retina breaks high-dimensional patterns of light modulated in space, time and wavelength into parallel, feature selective pathways for transmission to the brain4. Retinal ganglion cells (RGCs), the only retinal neurons that send information to the brain, inherit much of their visual response selectivity in the retina’s ‘switchboard’, the inner plexiform layer5 (IPL). Here, the presynaptic terminals of bipolar cells (BCs)5, the only neurons that relay the photoreceptor (PR) signal into the inner retina, form complex synapses with amacrine cells (ACs) and RGC dendrites. This BC/AC/RGC synapse is probably the most important yet least understood computational locus of the circuit6. At the same time, BCs inherit their excitatory drive directly from photoreceptors (PRs) at the so-called cone/rod-pedicle, a computationally powerful feedback synapse. Both BC and PR presynaptic terminals, which as populations represent the two most fundamental processing layers of the retina, are optically accessible in vivo (zebrafish larva) and retinal explants7,8. By monitoring light-driven activity in large populations of synaptic terminals of PRs and BCs it is possible to systematically follow how the visual input is sequentially broken down and distributed into parallel processing channels by the retinal network before it is forwarded to the brain9. Presentation of stimuli designed to specifically probe prominent and behaviourally essential aspects of the zebrafish natural world will allow linking identified principles to their ecological purpose. Taken together, the approach will address how retinal computations acknowledge the visual world of the larval and adult zebrafish.
To be considered complete online application http://www.sussex.ac.uk/study/pg/applying/
Apply for PhD in Neuroscience, September 2016 entry. Mention name of supervisor in “suggested supervisor” section. In funding mention sponsored or seeking funding. In Award details mention School of Life Sciences funded studentship. Include brief statement of interest (upto 2 pages), CV, two academic references, UG/PG transcripts, IELTS/TOEFL results if residing in EU. The studentship is for 3.5 years (full fee waiver, stipend Research Council equivalent rate). Only full time Home/EU students will be accepted.
For further queries contact Tom Baden ([email protected])
1. Land, M. & Nilson, D.-E. Animal Eyes. (Oxford University Press, 2012).
2. Cronin, T. W., Johnsen, S., Marshall, N. J. & Warrant, E. J. Visual Ecology. (Princeton University Press, 2014).
3. Baden, T. et al. A tale of two retinal domains: near-optimal sampling of achromatic contrasts in natural scenes through asymmetric photoreceptor distribution. Neuron 80, 1206–17 (2013).
4. Masland, R. H. The fundamental plan of the retina. Nat. Neurosci. 4, 877–86 (2001).
5. Euler, T., Haverkamp, S., Schubert, T. & Baden, T. Retinal Bipolar Cells: Elementary Building Blocks of Vision. Nat. Rev. Neurosci. 15, 507–519 (2014).
6. Baden, T., Euler, T., Weckström, M. & Lagnado, L. Spikes and ribbon synapses in early vision. Trends Neurosci. 36, 480–8 (2013).
7. Dreosti, E., Esposti, F., Baden, T. & Lagnado, L. In vivo evidence that retinal bipolar cells generate spikes modulated by light. Nat Neurosci 14, 951–952 (2011).
8. Baden, T., Esposti, F., Nikolaev, A. & Lagnado, L. Spikes in Retinal Bipolar Cells Phase-Lock to Visual Stimuli with Millisecond Precision. Curr. Biol. 21, 1859–1869 (2011).
9. Wässle, H. Parallel processing in the mammalian retina. Nat. Rev. Neurosci. 5, 747–57 (2004).