Our focus is on two neural circuits that are involved in the processing of visual information – the retina and the visual cortex. The question that guides our research is “how do synapses in the visual system contribute to the processing and transfer the information in a visual stimulus?”. More recently, we have also been investigating how mechanical information is encoded in the lateral line system of zebrafish.
All these projects have a focus on the synaptic machinery that transfers signals within circuits. We use fluorescent reporter proteins by which the electrical activation of synapses and the resulting output – vesicle fusion – can be monitored across hundreds of neurons simultaneously. By applying multiphoton microcopy to transgenic zebrafish and mice expressing these reporters we can observe synaptic activity in vivo as the visual system or neurons in the lateral line respond to stimuli.
Much of our past work has investigated the retina of zebrafish, but we are now also working on visual processing beyond the retina, including the visual cortex of mice. One of our aims is to understand how the short-term platicity of synapses contributes to the control of tuning and responsitivity within these circuits. We are particularly interested in “network adaptation” – changes in the way that visual stimuli are processed by the neural circuit according to the recent history of activity.
Our experimental approaches involve a combination of techniques, including electrophysiology, molecular biology, multiphoton imaging, optogenetics, single-plane illumination microscopy (SPIM) and computational modelling.
Left: Mosaic labelling of excitatory neurons (photoreceptors, bipolar cells and ganglion cells) in the retina of a larval zebrafish imaged in vivo. The neurons are expressing a calcium-sensitive protein (GCamP6f) and a movie shows a stack through the retina. Right: Spontaneous activity in mouse visual cortex (layer 2/3) showing synapses (green; SyGCaMP6f) and blood vessels (magenta).