Opposable thumbs gave ancient humans a huge evolutionary advantage by allowing for use of tools. More recently, these thumbs also allow for people to quickly type on screens of smartphones and other touchscreen devices. A new study has found that this recent widespread mode of communication is actually changing the way thumbs and the brain talk to one another, demonstrating the plasticity of the human brain. Arko Ghosh of the University of Zurich is lead author of the paper, which has been published in Current Biology.

"I was really surprised by the scale of the changes introduced by the use of smartphones," Ghosh said in a press release. "I was also struck by how much of the inter-individual variations in the fingertip-associated brain signals could be simply explained by evaluating the smartphone logs."

Ghosh and his team were inspired to embark on this research after noticing that a large number of people are now using their thumbs and fingertips in a way that has not been seen before in human history. In addition to merely performing these tasks, they are done for several hours a day, every single day. This is a tremendous amount of time spent on a repetitive movement.

"I think first we must appreciate how common personal digital devices are and how densely people use them," Ghosh explains. "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)."

While there has been extensive research performed on how playing video games can alter the plasticity of the brain, or how music can influence the brains of those who play professionally, there has not been similar study into the tactile influence of touch screens of the average person. The research was aided by the fact that the phones of the study participants provide a complete history of the activities performed over the course of each day, keeping a record of the amount of use the phone received.

The researchers monitored the study participants through the use of electroencephalography (EEG), which recorded the brain activity associated with the use of smartphones. The participants used their thumbs along with the middle and index fingers.

The researchers found that the brain was very responsive to the digits engaging in smartphone use. When compared to those who don't use smartphones, those that did had higher spikes of activity in the regions of the brain associated with the thumb and fingertips. The more frequently the subject used the phone, the higher the level of activity was.

"We propose that cortical sensory processing in the contemporary brain is continuously shaped by personal digital technology," the authors wrote in the paper.

Of course, there are overuse injuries such as carpal tunnel syndrome that go along with excessive use of smartphones, so not everything associated with this technology is a good thing. Weighing the full influence of this mode of communication will be the subject of future injuries. Additionally, other study is needed to determine if the type of activity performed on the phone influences brain activity levels.

