Chemicals control our thoughts. Calcium, for example, regulates the signals that zip along miles of nerve cells – neurons – to and from the brain. ‘Waves’ of calcium signalling are tell-tale signs of healthy brain activity, but they’re often difficult to detect inside living tissues. Pictured here, neurons in a mouse brain are lit up with a fluorescent calcium sensor (green) – the result of a type of genetic modification, inserting manmade DNA into the mouse's genome without harming the rest of its genes. As the healthy mouse develops, the fluorescent sensor (together with a red marker) can be used to map activity in important brain regions like the hippocampus (pictured). Calcium measurements in different parts of the brain also reveal details about how mammalian senses work – such as inside the olfactory bulb, where neurons fizzle into life in response to smells from the outside world.
Written by John Ankers
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