Due to the widespread use of wireless communication technologies and the proximity of mobile phones to the head, it is important to consider the potential impact of radiofrequency electromagnetic fields (RF-EMFs) on brain physiology. Previous studies have shown that alpha brain waves (8–12 Hz) are particularly sensitive to mobile phone radiation. (Alpha waves typically occur in healthy, awake adults with their eyes closed during periods of rest. The alpha rhythm is associated with cognitive and visual relaxation; editor's note). However, previous studies of brain activity have been limited to electroencephalography (EEG) analyses, which primarily examine the strength of brain activity in different frequency ranges. To determine whether mobile phone radiation influences the interaction between different brain regions, magnetoencephalography (MEG) is necessary. This study is the first to investigate the effects of mobile phone radiation on connectivity between different brain regions using MEG. Connectivity refers to the interaction and coordination between different groups of neurons when the brain processes information. MEG can determine how well the electrical oscillations of different brain regions synchronize over time and if they operate in synchrony.
Thirty-two healthy subjects (15 men and 17 women with an average age of 25 years) participated in a randomized, double-blind, counterbalanced crossover procedure consisting of two sessions one week apart. Each test session included a baseline phase, an exposure phase, and a post-exposure phase. The exposure phase lasted 25 minutes and 30 seconds. Two Nokia 6650 mobile phones (GSM at 900 MHz with 217 Hz modulation) served as the RF radiation source. One phone was a "dummy device" that did not emit RF radiation. The measured SAR value, averaged over 10 g of tissue, was 0.7 W/kg. The mobile phone was placed on the left ear of the test subjects. MEG measurements were performed before and after the exposure phase. Functional connectivity was calculated using cIPLV, which quantifies phase synchronization. The brain was divided into 68 regions, resulting in a total of 2,278 compared connections (each region compared with every other region). A two-way ANOVA test with Bonferroni correction was performed for statistical analysis.
The results show that mobile phones modulate connectivity in a statistically significant manner. After applying the Bonferroni correction, three connections within the right hemisphere showed a statistically significant decrease when comparing the sham-exposed group to the exposed group: 1) connectivity between the right transverse temporal cortex (rTTC) and the right entorhinal cortex (rEC), 2) connectivity between the rTTC and the right insular cortex (rIC), and 3) conncectivity between the rTTC and the right posterior cingulate cortex (rPCC). These modulations predominantly occurred in the alpha frequency range.
The scientists' data revealed significant changes in connectivity values between cortical areas in the right hemisphere of the brain, particularly in and around the temporal lobe. This region contains the TTC, also known as Heschl's gyrus, which processes auditory information. The EC plays a central role in memory, the IC is involved in consciousness and emotions, and the PCC is a central hub in the brain. The authors speculate that mobile phone radiation may influence neural activity in the ear because auditory processing largely occurs contralaterally (on the opposite side of the mobile phone, which is located on the left ear).
Editor’s note:
This study's strengths lie primarily in its rigorous methodology, which minimizes confounding factors and artifacts. Of particular significance is the use of magnetoencephalography (MEG) to address the lack of knowledge about how mobile phone radiation affects brain activity. However, the study has limitations, including its small sample size and focus on acute effects. A long-term study on chronic effects would also be highly relevant. (RH)