Scientists try to measure the rapid and tiny electrical pulses that pass along nerve cells with microscopic electrodes. It is hard enough to probe just one cell, let alone a whole network, but now there is a way to ‘see’ pulses move from cell to cell. These images show human cells genetically-engineered to make a light-sensitive protein called rhodopsin. The protein is here detected with fluorescence under laser light (left). Located within the cell membrane, the brightness readings are a measure of the voltage across the membrane. As the voltage increases rhodopsin ‘glows’ more brightly. When a nerve pulse passes by, the protein effectively flashes on and off again. A computer program analyses the flashes (right; red is high voltage, blue is low) allowing scientists to trace impulses passing between cells. Understanding how these biological networks operate is fundamental to developing successful strategies for therapeutic intervention.
Written by Edwin Colyer
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