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Cortical Development and Amblyopia

Colour coded image of the cortex
Colour coded image of the cortex obtained while viewing gratings of specific orientations. Orientation is coded with a strict spatial cortical organization.

While we have a good handle on the basic physiology and anatomy of the primary visual cortex, V1, we are only now starting to understand how V1 wires itself up: no mean feat when one considers the millions of connections that are required. Perhaps it is not surprising that those connections go wrong quite frequently.

One very prominent example of this is amblyopia, which occurs in 2-5% of the population, depending on the country reporting the figures. To put these figures in context, it means that there are likely to be more than six children in every primary school in Australia that have amblyopia. In the US, it is estimated that amblyopia costs around $10Billion USD per year in treatment and lost productivity – no minor problem. In amblyopia, V1 fails to appropriately connect the neural wiring that normally leads to good binocular vision.

In extreme cases, the input from one eye dominates so much that one eye is effectively blind. It is important to note that this is not a problem with the eyes. Rather, it is a problem with the mechanisms of cortical development in the brain.

The NVRI is investigating how the normal brain wires itself together and, alongside that work, is investigating how alterations to visual input can modify V1 structure. In the near future it is hoped that pharmacological treatments might encourage the brain to re-wire itself but we need to understand the basic developmental mechanisms before this exciting possibility becomes a reality.

To investigate brain structure it is necessary to use imaging techniques and we are fortunate to have Dr Shaun Cloherty, one of Australia’s leading scientists in the art of intrinsic optical imaging. The team works in collaboration with Professor Geoff Goodhill, who is located at the Queensland Brain Institute in Brisbane.