Study type: Medical/biological study (experimental study)

Principal component analysis of the P600 waveform: RF and gender effects. med./bio.

Published in: Neurosci Lett 2010; 478 (1): 19-23

Aim of study (acc. to author)

To study the patterns of activation of the P600 waveform of the event-related potentials (EEG) during a working memory task (digit span test) and whether these patterns are radiofrequency exposure and gender dependent.

Background/further details

The P600 component is related to linguistic processes and working memory.
Two different groups took part in two separate experiments. The first group consisted of 19 healthy subjects (9 men and 10 women). In the second experiment 20 individuals participated (10 men, 10 women). One group was exposed to 900 MHz signal and the other group to 1800 MHz. The subjects performed the memory test (digit span test) 52 times and the duration of one recording was about 45 minutes. Each subject performed the test twice (with and without exposure). Each task started with a warning stimulus signal tone of either low (500 Hz) or high frequency (3000 Hz). At the end of the number sequence presentation, the same tone was repeated and the subjects had to recall the numbers in the same (500 Hz) or in the opposite order (3000 Hz tone).

Endpoint

Exposure

Exposure Parameters
Exposure 1: 900 MHz
Exposure duration: about 45 min.
Exposure 2: 1,800 MHz
Exposure duration: about 45 min.

Exposure 1

Main characteristics
Frequency 900 MHz
Type
Exposure duration about 45 min.
Exposure setup
Exposure source
Distance between exposed object and exposure source 20 cm
Chamber tests performed in a Faraday room
Setup dipole antenna fixed near the volunteer's right ear; warning signal and auditory tasks were presented via a non-metallic earphone
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
power 64 mW mean - - -

Exposure 2

Main characteristics
Frequency 1,800 MHz
Type
Exposure duration about 45 min.
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
power 128 mW mean - - -

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated material:
Investigated organ system:
Time of investigation:
  • during exposure

Main outcome of study (acc. to author)

Both principal component analysis and analysis of variance produced congruent results, showing that activation of the P600 component occurs early and more intensely in the region of the posterior EEG electrodes and in a less intense manner in the central electrodes. Conversely, the activation at the anterior electrodes arises later with a considerably reduced intensity.
In the absence of the radiofrequency electromagnetic field female subjects exhibited significantly lower amplitudes at anterior electrodes and earlier latencies at central electrodes than male subjects. These differences disappear under radiofrequency exposure. Thus, the P600 component follows distinct patterns of activation in the anterior, central and posterior brain areas and gender differences are observed simultaneously at several electrodes within these areas.

Study character:

Study funded by

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