Smartphone deprivation alters cortical sensorimotor processing of the hand

Abstract

Brain areas representing the body can change in response to behavioral alterations. This idea is firmly established for the adult cortex in response to extraordinary alterations such as traumatic amputation or casting of the limb. Here we address how adult cortical sensorimotor processing alters in response to a subtle perturbation in the form of smartphone deprivation lasting for ~7 days. We quantified the sensorimotor processes associated with the fingertips before and after the deprivation in right-handed smartphone users. The measurements were contrasted with those of a control group with unperturbed smartphone behavior. First, smartphone tapping speed in daily life became slower after the deprivation. Second, according to reaction time tests conducted in the laboratory the asymmetrically superior performance of the right vs. left thumb was eroded by the deprivation. Third, according to EEG measurements at physical rest, tactile stimulation at the right thumb tip resulted in smaller signal amplitudes after the deprivation. Moreover, the EEG measurements during smartphone use revealed larger signal amplitudes for tactile stimulation at the right little fingertip after the deprivation. We show that cortical plasticity can occur by merely disengaging from a common day-to-day behavior. We suggest that in daily life the adult brain continuously and selectively updates its sensorimotor processing according to recent experience.