Teaming up with colleagues from the University of Fribourg, he studied the activation in the sensorimotor cortex, which is triggered by finger movements. The scientists used electroencephalography (EEG) to measure the cortical brain activity in 37 right-handed people, of whom 26 were touchscreen Smartphone users and 11 users of old cellphones. 62 electrodes placed on the test subject's heads recorded this potential based on movements of the thumb, forefinger and middle finger. The results revealed that the cortical representation in touchscreen Smartphone users differed compared to people with conventional cellphones.
Ghosh was also able to demonstrate that the frequency of Smartphone usage influences cortical activity. The more the Smartphone had been used in the previous ten days, the greater the signal in the brain. This correlation was the strongest, i.e. proportional, in the area that represented the thumb.
"At first glance, this discovery seems comparable to what happens in violinists," explains Ghosh. However, the researchers were able to draw two distinctions: Firstly, how long Smartphone users have owned and used a device does not play a role. In the case of violinists, however, the activity in the brain depended on the age at which they started playing. Secondly, there is a linear connection between the activation in the brain and the most recent use of a Smartphone, while there was no evidence of this for violinists in earlier studies.
"The digital technology we use on a daily basis shapes the sensory processing in our brains -- and on a scale that surprised us," says the neuroscientist in summary.
Anne-Dominique Gindrat, Magali Chytiris, Myriam Balerna, Eric Rouiller, Arko Ghosh. Use-dependent cortical processing from fingertips in touchscreen phone users. Current Biology.