Completed Brain & Nervous System Cells, Biochemistry & Physiology

The functional organisation of synaptic connectivity in visual cortex.

Funder Wellcome Charity-funded
Recipient organisation University College London
Funding £1.7M
Period Jun 2011 — May 2016

In plain English

AI plain-English summary

A new technique lets scientists watch how individual neurons in the brain’s visual cortex respond to images, then slice into the same tissue to map exactly which cells are wired together. This matters because neuroscientists have long known which brain regions process vision, but not the precise rules that govern how individual neurons connect to form functional circuits. Without that wiring diagram, it is impossible to understand how sensory information—like the edges, colours, and motion in a scene—gets transformed into a coherent perception. The team will test whether connections depend on where a neuron’s receptive field lies, whether simple and complex cells link up in specific ways, and how feedforward versus recurrent signals shape those fields. If successful, this work will produce a biophysically realistic computer model of a cortical circuit, showing how different cell types and connections contribute to network function. This is fundamental science—it will not directly change medical treatment or technology tomorrow. But the method itself is generalisable to any optically accessible brain region, meaning it could eventually help uncover the wiring of memory, decision-making, or sensory systems beyond vision. Similar circuit-mapping approaches have already transformed our understanding of neural computation.

View original technical description
I propose to determine the relationship between synaptic connectivity and neuronal function in primary visual cortex (V1) with the aim of revealing circuit-level mechanisms of sensory processing. To this end, my laboratory has developed a new method, by which visual response properties of neurons are first characterised with two-photon calcium imaging in vivo, and then synaptic connections between a subset of these neurons are assayed with multiple whole-cell recordings in slices of the same tis sue. We will use this method to determine how connectivity, synaptic and intrinsic properties of different excitatory and inhibitory cell types relate to the emergence of their visual receptive fields (RFs). Specifically, we will test the dependence of connections on RF position and structure, the specificity of connections between simple and complex cells, and the relative contribution of feedforward and recurrent excitation and inhibition towards shaping RFs. Morphological, physiological, conn ectional and functional data will be used to develop a biophysically realistic network model of this V1 circuit to examine the contribution of different circuit components to single-neuron and network function. Our new method can be used to uncover the functional wiring of any optically-accessible brain region, and thus provide fundamental knowledge of brain function in general.

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Researchers

Tom Mrsic-Flogel (EPMC Awardee)

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Original classification

Residual Award

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