Autores

Kwon MS, Kujala T, Huotilainen M, Shestakova A, Näätänen R, Hämäläinen H. Preattentive auditory information processing under exposure to the 902 MHz GSM mobile phone electromagnetic field: A mismatch negativity (MMN) study. Bioelectromagnetics Jan 12, 2009 Ahead of print.

Background
Some studies assessed the effects of short-term exposure to mobile phone electromagnetic fields (EMFs) on brain functions by using the event-related potential (ERP) method based on the assumption that facilitated or inhibited brain activity can be indicated by the altered amplitude and/or latency of EPR components. The results of these studies are inconsistent and even contradictory. The mismatch negativity (MMN) is an auditory ERP component elicited by infrequent (deviant) stimuli differing in some physical features from the repetitive frequent (standard) stimuli in a sound sequence. The MMN provides a sensitive measure for cortical auditory stimulus feature discrimination, regardless of attention and other factors.

Objective
The present study examined the short-term effects of the GSM mobile phone EMF on the MMN and associated brain processing within the multifeature paradigm including duration, intensity, frequency and gap deviants.

Methods
MMN responses to duration, intensity, frequency and gap changes were recorded in 17 healthy young adult volunteers (12 females; mean age 23.1±4.5 years). An ordinary GSM mobile phone, which was attached to a headset, was placed on either ear in the position of normal phone use with 902 MHz EMF pulsed at 217 Hz; SAR1g =1.14 W/kg, SAR10g = 0.82 W/kg, peak value 1.21 W/kg. Auditory stimuli were generated apart from the mobile phone and then conducted to the ear through thin flexible silicon tubes and foam ear tips. The EEG was recorded in three successive blocks, once with the EMF off and twice on, and then the 3-block recording was continued with the mobile phone on the other ear.

Results and interpretation
MMNs were elicited by all the deviants (duration, intensity, frequency and gap) in the multifeature paradigm under the 3 different EMF conditions (off, on-left, on-right). The duration deviant elicited the largest MMN response, which is consistent with observations of other researchers. Regardless of the deviant type, the MMN latency and amplitude showed no significant differences due to EMF exposure on either side. The results of this study provide no systematic evidence that acute exposure to GSM mobile phone EMF affects the MMN and underlying auditory information processing. However, the authors note that, although the sample size of 17 subjects was not small compared with other EEG/ERP studies, it might not be large enough to ensure sufficient statistical power and effect size.

Conclusion
This study provides no conclusive evidence for the short-term effects of mobile phone EMF on the cortical auditory change detection processing reflected by the MMN. However, considering the lack of consistency in the literature and the obvious requirement for replication, the present results should be replicated with a larger number of subjects in order to firmly conclude that mobile phone EMF does not affect the auditory information processing reflected by the MMN.



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