Kwon MS, Huotilainen M, Shestakova A, Kujala T, Näätänen R, Hämäläinen H. No effects of mobile phone use on cortical auditory change-detection in children: An ERP study. Bioelectromagnetics Ahead of print. Sep 21, 2009.
Studies on the effects of mobile phone electromagnetic fields (EMF) on children’s auditory sensory memory are important because this type of memory is involved in speech, learning, and attention. Auditory sensory memory refers to the ability to temporarily retain auditory information for a few seconds after the stimulus has ceased. This is measured by electroencephalography (EEG), which measures electrical activity in the brain with electrodes placed on the scalp, and by the event-related potential (ERP), a type of electrical signal in the brain. A specific component of the ERP called mismatch negativity (MMN) measures the auditory sensory memory.
The objective of this study was to investigate whether there were any short term effects of EMF on the auditory sensory memory of children by comparing the mismatch negativity responses in different EMF conditions.
Subjects were 17 healthy children (13 female) 11-12 years of age that were recruited from local public schools. Most (15) had their own mobile phone. During the experiment, participants sat in an armchair watching a movie without sound and were instructed not to pay attention to the auditory stimuli. A GSM mobile phone was attached to a headset worn by the subjects and subjects wore earphones through which auditory stimuli were delivered. For most of the experiment, a standard sound was emitted. Four deviant sounds, which differed from the standard sound in one of: duration, intensity, frequency, and gap, were also emitted during the experiment. The total sound stimuli lasted 6 minutes. The EEG was recorded in three 6-minute blocks, two in which the EMF was on and one in which the EMF was off, in each ear. Subjects were blind to the exposure conditions.
The brain’s response to the standard sound was not affected by the exposure condition. The duration, frequency, and gap deviant sounds elicited significant MMN responses while the intensity deviant sound did not. However these effects did not differ by EMF exposure.
Interpretation and Limitations
The authors found no statistically significant differences in the brain’s response to either standard sound or deviant sounds under different EMF exposure conditions. They interpret this as sensory memory and attention functions not being susceptible to concurrent exposure to EMF emitted by a typical GSM mobile phone. This is in accordance with their previous work in adults using the same study design. Because the intensity deviant sound did not illicit a significant response, the authors suggest that the stimulus be increased in future studies. This study is limited by the small sample size which may have limited the researchers’ ability to detect a significant difference.
The EMF emitted by a typical GSM mobile phone did not affect the perceptive accuracy, sensory memory, and attention-allocation functions in children.