Our eyes once developed thousands of nerve cells (neurons) ready to be bombarded with light and colour for the very first time. The grey-coloured retinal ganglion cell pictured on the left (from a developing mouse eye) takes visual signals from the eye to the brain. Coloured dots highlight where connections (synapses) have formed with neurons near the retina’s surface – visual signals flow in from ‘excitatory’ neurons (red), and are ‘fine-tuned’ by ‘inhibitory’ neurons (connected at the green spots) before being sent brain-wards. Excitatory and inhibitory neurons arrange in specific patterns early in development (pictured on the right, in a computer reconstruction) – a bit like machinery along a production line, ready to shape and balance the huge amount of information from the eye’s first glimpse of the world.
Written by John Ankers
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