Plasticity of visual circuits

How does a circuit of neurons process sensory information? And how is processing adjusted in relation to changes in the sensory environment or internal state of the animal? These questions will be investigated in larval zebrafish, where visual circuits and the behaviours they drive are altered in the context of i) changes in the visual environment, such as luminance or contrast, ii) information arriving through chemical and mechanical senses, iii) the internal state, such as arousal or satiety, and iv) circadian mechanisms. To investigate how visual processing is adjusted under these different conditions we will use larval zebrafish to image neural activity through the retina and brain of the behaving animal. Zebrafish generate distinct motor responses to stimuli of different contrasts, size and speed, allowing us to investigate the plasticity of computations directly linked to behaviour. Our guiding hypothesis is that the plasticity of visual circuits reflects use-dependent changes in synaptic strength and the actions of neuromodulators that reconfigure signal flow. A comparison of computations carried out in different circuits will be key to identifying general mechanisms by which the brain adjusts sensory processing to the sensory environment and/or internal state of the animal.