I recently asked myself if I’ll still have a healthy brain as I get older. I hold a professorship at a neurology department. Nevertheless, it is difficult for me to judge if a particular brain, including my own, suffers from early neurodegeneration.

My new study, however, shows that part of your brain increases in size with age rather than degenerating.

The reason it’s so hard to measure neurodegeneration is because of how complicated it is to measure small structures in our brain.

Modern neuroimaging technology allows us to detect a brain tumour or to identify an epileptic lesion. These abnormalities are several millimetres in size and can be depicted by a magnetic resonance imaging (MRI) scanner, which operates at around 30,000-60,000 times stronger than the natural magnetic field of the Earth. The problem is that human thinking and perception operate at an even smaller scale.

Our thinking and perception happens in the neocortex. This outer part of our brain consists of six layers. When you feel touch to your body, layer four of your sensory cortex gets activated. This layer is the width of a grain of sand – much smaller than what MRI scanners at hospitals can usually depict. When you modulate your body sensation, for example by trying to........

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