Visuomotor systems in larval zebrafish
Dr. Isaac Bianco
Sir Henry Dale Fellow
|Tel: +44-(0)20-3549-5509 (UCL int. 65509)|
Pedro Henriques, PhD Student
Mingxu Shan, MSc student
Samuel Jackson, iBSc student
The goal of our research is to understand how neural circuits control behaviour. How does the brain process sensory information, decide what actions to take and orchestrate the motor programmes that mediate a behavioural response? How are sensorimotor circuits organised at structural and functional levels and what do individual cells and neural populations contribute to information processing?
Image caption: Tectal neuron in the midbrain of a larval zebrafish labeled by focal electroporation
To address these questions, we are using larval zebrafish as a powerful systems model to examine the structure and function of neural circuits controlling specific behaviours. A key advantage of this animal is that it has a tiny, optically transparent brain, which enables us to use optical techniques to both monitor and manipulate neural activity at single-cell resolution throughout the nervous system. Moreover, by larval stages zebrafish have a rich behavioural repertoire and a well developed visual system. One of their most complex visually guided behaviours is hunting, which begins from only 5 days post-fertilisation. How does the larval brain categorise visual inputs as prey? What visual features are extracted and how does prey identification lead to the initiation of a hunting routine? During prey tracking, how are goal-directed swims and turns selected in response to a changing sensory input to close in on the target? How do factors such as motivational state and recent experience modulate the core sensorimotor pathway controlling this behaviour?
To investigate the circuit basis of this complex natural behaviour, we combine quantitative behavioural assays, functional calcium imaging, optogenetics and anatomical circuit tracing techniques. We have developed a virtual hunting assay for tethered larvae that can be combined with functional imaging allowing us to monitor network activity and behaviour simultaneously: larvae are partially restrained using gel and presented with prey-like visual cues on a miniature computer screen which they respond to with characteristic hunting behaviours. At the same time, we use two-photon laser scanning microscopy or light-sheet microscopy with transgenic fish expressing genetically encoded fluorescent calcium indicators to monitor neural activity throughout the brain. In this way we can monitor population activity across thousands of neurons, at sub-cellular resolution, whilst the animal performs a complex visuomotor task. In addition we are developing optogenetic methods to control the activity of neurons using light and thereby test the requirement for specific cells and activity patterns for the generation of downstream activity and motor outputs. These approaches, combined with mathematical modelling, are allowing us to understand the sensorimotor transformations that convert visual input into action. Our aim is to build models of complete sensorimotor circuits, from primary sensory tissues, such as the retina, through to the motor neurons that innervate muscles to effect a behavioural response.
We warmly welcome applications from prospective PhD students and postdocs.
Please contact Isaac well in advance and include a CV as well as contact details for at least two referees.
Our lab participates in two excellent PhD programmes at UCL:
Hüsken U, Stickney HL, Roussigne M, Beretta CA, Brinkmann I, Young RM, Bianco IH, Tsalavouta M, Zigman M, Hawkins TA, Wen L, Zhang B, Blader P, Lin S, Wilson SW, Carl M.* Tcf7l2-dependent asymmetries in Wnt signalling mediate the left-right asymmetric differentiation of habenular neurons. Under review.
Concha MC, Bianco IH, Wilson SW. Encoding asymmetry within neural circuits. Nature Reviews Neuroscience. (2012). 13:832-43.
Bianco IH, Ma L-H, Schoppik D, Robson DN, Orger MB, Beck JC, Li JM, Schier AF, Engert F, Baker R. The tangential nucleus controls a gravito-inertial vestibulo-ocular reflex. Current Biology (2012). 22:1285-95.
Bianco IH, Kampff AR, Engert F. Prey capture behavior evoked by simple visual stimuli in larval zebrafish. Front. Syst. Neurosci. (2011). 5:101.
Tawk M, Bianco IH, Clarke JD. Focal electroporation in zebrafish embryos and larvae. Methods Mol Biol. (2009). 546:145-51.
Roussigné M, Bianco IH, Wilson SW, Blader P. Nodal signalling imposes left-right asymmetry upon neurogenesis in the habenular nuclei. Development. (2009). 136:1549-57.
Bianco IH, Wilson SW. The habenular nuclei: a conserved asymmetric relay station in the vertebrate brain. Philos Trans R Soc Lond B Biol Sci. (2009). 364:1005-20.
Bianco IH, Carl M, Russell C, Clarke JD, Wilson SW. Brain asymmetry is encoded at the level of axon terminal morphology. Neural Dev. (2008). 3:9.
Carl M, Bianco IH, Bajoghli B, Aghaallaei N, Czerny T, Wilson SW. Wnt/Axin1/beta-catenin signaling regulates asymmetric nodal activation, elaboration, and concordance of CNS asymmetries. Neuron. (2007). 55:393-405.
Barth KA, Miklosi A, Watkins J, Bianco IH, Wilson SW, Andrew RJ. fsi zebrafish show concordant reversal of laterality of viscera, neuroanatomy, and a subset of behavioral responses. Curr Biol. (2005). 15:844-50.
Aizawa H, Bianco IH, Hamaoka T, Miyashita T, Uemura O, Concha ML, Russell C, Wilson SW, Okamoto H. Laterotopic representation of left-right information onto the dorso-ventral axis of a zebrafish midbrain target nucleus. Curr Biol. (2005). 15:238-43.
Mo E, Amin H, Bianco IH, Garthwaite J. Kinetics of a cellular nitric oxide/cGMP/phosphodiesterase-5 pathway. J Biol Chem. (2004). 279:26149-58.