Extensive use of smartphone touch screens is changing the sensory relationship between our brains and our thumbs, a study published in Current Biology has revealed.

The plasticity of the human brain and how it adapts to repetitive gestures has been tested in multiple contexts previously, including in musicians and gamers, but neuroscientists from the University of Zurich and ETH Zurich believe smartphones provide a unique opportunity to understand how everyday life can shape the human brain on a huge scale.

Smartphone growth has seen people using their fingers—and in particular their thumbs—in a completely new way multiple times a day, every day. The very nature of the devices means there is usually a record kept of all the things we are doing with our thumbs on our phones, providing the neuroscientists extensive data to work with.

"What this means for us neuroscientists is that the digital history we carry in our pockets has an enormous amount of information on how we use our fingertips (and more)," explains one of the study's authors, Arko Ghosh.

Linking this "digital history" to brain activity was a case of using electroencephalography (EEG) to examine how regular smartphone users responded in tests compared to those who use older-style feature phones. Each set of phone users had their brain response to various mechanical touches recorded, with a focus on the thumb, forefinger, and middle finger.

The results showed that in smartphone users, electrical brain activity was enhanced when each of the three fingers were being touched. The level of activity in the cortex was also found to be directly proportional to the intensity of phone use, which was qualified by the battery logs.

The very tip of the thumb was even found to be sensitive to day-to-day fluctuations in phone use. The shorter the period of time that had elapsed after the last episode of intense touchscreen use, the more activity was observed in the brain.

What this means is that the repetitive movements made by our thumbs as they glide over touch screens is reshaping the sensory processing from our hands, and this can be adjusted on demand when we are using our phones. The researchers believe this is evidence that "the contemporary brain is continuously shaped by the use of personal digital technology."

While the study does not take into account the mechanical abilities of our thumbs or the long-term physical toll that smartphone use may take on them, it does suggest that touchscreen use is causing our brains to reorganize and to host an enhanced sensory representation of our thumbs.

This story originally appeared on Wired UK.