Using smartphones affects more than people’s behavior, it appears. While some research has shown that access to a smartphone can change social interactions, a new scientific study posits that changes are evident in the brain, too.

“Our results suggest that repetitive movements on the smooth touchscreen reshaped sensory processing from the hand and that the thumb representation was updated daily depending on its use,” noted the study authors cited in Current Biology. “We propose that cortical sensory processing in the contemporary brain is continuously shaped by the use of personal digital technology.”

In other words, smartphone users are truly changed by the experience — and not just when they post a selfie on Facebook. The mere activity of using the thumb and fingers on a touchscreen changes sensory processing sectors in the brain.

In sum, “brain activity is proportional to use accumulated over the previous 10 days, an episode of intense use is transiently imprinted on the sensory representation, and sensory processing in the brain is adjusted on demand by touchscreen phone use.”

Amazing, but true: our technology is changing us not just on the outside, but the inside as well.

“Smartphones offer us an opportunity to understand how normal life shapes the brains of ordinary people,” said study co-author Arko Ghosh, a neuroscientist at University of Zurich in Switzerland.

Sensations experienced by the entire body are wired to an area in the brain known as the somatosensory cortex — and they become more sensitive when a specific body part is used with regularity. Just as violinists show greater response in the cortex by use of the critical smallest fingertip, avid smartphone users show intense response because of their activity, especially when it comes to the thumb.

In the new study, the research team employed electroencephalography (EEG) to measure electrical activity in the brain in response to touch on the thumb, index fingertip, and middle fingertips. Of the 37 subjects in the study, 26 used touch screen smartphones and 11 used older style cellphones.

The participants who used touch screens had greater activity in brain areas associated with the thumb and fingertips.

“Remarkably, the thumb tip was sensitive to the day-to-day fluctuations in phone use: the shorter the time elapsed from an episode of intense phone use, the larger the cortical potential associated with it,” the researchers explained.