The brain dedicates more space to skin with tactile acuity

Since adolescence in the brain stem there is a mechanism that could help explain why some areas of the body, such as the hands or lips, are more sensitive than others, indicates a study published yesterday in the journal “Cell”.

Those parts with especially sensitive skin are essential tools in our ability to discern the most intricate details of the world around us and are key to our survival.

Due to its importance, the brain dedicates considerable space to the sensitive surfaces of the skin that are specialized in fine and selective touch, which continuously collect detailed information through the sensory neurons that innervate them.

A team from Harvard University investigated the way in which the connection between sensory neurons and the brain occurs to give rise to very sensitive skin and revealed the mechanism that could underlie this sensitivity.

“The study provides a mechanical understanding of why more brain space is devoted to skin surfaces with high tactile acuity,” leading to greater sensory acuity in the parts of the body that need it, said lead author David Ginty. .

With mice

The research was conducted in mice, but the team noted that overrepresentation in the brain of sensitive regions is seen in all mammals, suggesting that the mechanism may be generalized to other species.

According to the new work, overrepresentation in the brain develops in early adolescence and can be pinpointed in the brainstem.

The sensory neurons that populate the most sensitive parts of the skin and transmit information to the brain stem form more and stronger connections than the less sensitive parts.

Understanding

The team believes that this discovery would one day help to better understand certain neurodevelopmental disorders that affect the connection between touch receptors and the brain.

Scientists have long known that certain parts of the body are overrepresented in the brain, as shown by the sensory map of this organ.

The so-called somatosensory homunculus is a scheme in which it is seen that some parts of the body – such as the hands, lips or tongue – have considerably more space in the sensory cortex than other areas such as the legs.

It was thought that the overrepresentation could be attributed to a higher density of neurons that innervated these areas of the skin.

However, Ginty saw that although sensitive skin contains more neurons, the number of neurons is not enough to explain the extra brain space.

The team conducted experiments in mice to image the brain and neurons as they were stimulated in different ways.

At the beginning of development, the sensitive and hairless skin of the mouse leg was represented in proportion to the density of sensory neurons, but between adolescence and adulthood it became increasingly overrepresented, although the density of neurons remained stable.

“This immediately indicated to us that there is something more than the density of innervation of nerve cells in the skin to explain this overrepresentation in the brain,” Ginty said. – EFE

Take a look

Sensitivity representation

The team of scientists at Harvard University determined that the brain stem – the region at the base of the brain that transmits information from sensory neurons to more sophisticated brain regions – is where the magnified representation of the sensitive surfaces of the brain occurs. the skin.

Its origin

This finding led the researchers to conclude that the overrepresentation of sensitive skin must arise from the connections between sensory and brain stem neurons.