Vecchio F, Babiloni C, Ferreri F, Curcio G, Fini R, Del Percio C, Rossini PM. (2007). Mobile phone emission modulates interhemispheric functional coupling of EEG alpha rhythms. Eur J Neurosci. 25(6):1908-13.
Some evidence suggests that electromagnetic fields from mobile phones (EMFs) affect resting electroencephalographic (EEG) activity, which is a sign of interference with neural activity caused by the physiological effects of EMFs. This finding has been observed in some, but not all studies. If EMFs influence brain EEG rhythms, this may in turn affect coupling between brain regions and information transfer. This is best reflected by brain EEG alpha rhythms. Higher levels of alpha activity lead to better cognitive performance, and the study of the coupling of alpha rhythms as a sign of information exchange between different brain areas could reveal the efficiency of the brain after EMF stimulation.
The authors tested the hypothesis that EMF is able to modulate interhemispheric coupling of cerebral rhythms, a sign of interference with neural activity and information transfer and processing.
Study participants were 10 healthy male volunteers, ranging from 20 to 36 years of age, none of whom had ever suffered from epilepsy or had a family history of seizures. Women were excluded from the study because of ovarian hormonal effects on brain excitability and rhythmicity. A standard and commercially available mobile phone was mounted on a helmet and was positioned 1.5 cm from the ear with the microphone oriented towards the corner of the mouth. To mimic normal conditions of mobile phone use, subjects were allowed to move around the room during the exposure session and to chat with the experimenters. Each subject participated in two 45-minute sessions separated by one week. One session consisted of real GSM-EMF exposure and the other consisted of sham-exposure, with the order decided randomly and subjects and experimenters blind to the test condition. EEG recordings in an eyes-closed, resting position lasted 5 minutes before and after exposure.
The authors found that mobile phone emissions enhanced interhemispheric coupling of alpha rhythms between the temporal areas, which are closest to the site of stimulation and receive its maximum energy. Furthermore, the mobile phone emission reduced interhemispheric coupling of alpha rhythms between the frontal areas.
Interpretation and Limitations
These results build on previous studies that found effects of mobile phone emissions on EEG activity recorded over the scalp midline, and evidence showing that mobile phone emission does affect alpha rhythms, not only during mental performance but also during the resting state of waking. Previous EEG studies have shown that on the one hand, resting alpha rhythms reflect readiness for information processing, and on the other hand, reduction in power of alpha rhythms has been related to speed of information processing, the subject’s global attention, and cognitive performance. The increased coupling of temporal alpha rhythms found in this study could reflect a readiness of the brain areas devoted to language and auditory processing, hence requiring lower interhemispheric synchronization of frontal areas.
The authors concluded that acute and prolonged mobile phone emission modulated the interhemispheic coupling of frontal and temporal alpha rhythms in healthy subjects in awake resting conditions. This suggests that mobile phone emission influences brain physiology.