Effects of pulsed and continuous wave 902 MHz EMF exposure on human cognitive function as measured by behavioural- and EEG-methodology Christian Haarala
Christina Krause
Effects of pulsed and continuous wave 902 MHz EMF exposure on human cognitive function as measured by behavioural- and EEG-methodology Christian Haarala
Christina Krause
Introduction
Thus far somewhat conflicting results from human provocation studies.
Differences in design and exposure between studies.
Modulation and exposed hemisphere not in specific focus previously (?).
Present studies
1 behavioural (reaction time, RT) and 2 EEG studies (event-related desynchronisation/synchronisation)
Methodology of all three studies based on our previous reports with added focus on signal modulation and exposed hemisphere.
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Subjects were healthy adult males (n = 36 per study).
Within-subjects design, however, in the behavioural study a control subject group (n = 16) also used.
Double-blind.
Exposure from a signal generator.
Sham, continuous wave (CW), and pulse modulated (PM) signals (902 MHz).
Left and right hemisphere exposures.
Both hemispheres exposed within one session, modulations (n = 3) in separate sessions separated by one week.
All factors (EMF, hemisphere, test order) counter-balanced according to a balanced Latin square design.
Subjects
Separate subject group for each study
All right-handed healthy males
n = 36 + a control group in the behavioural study (n = 16) AGE
Study Mean SD
Behavioural 23.8 2.4
EEG, auditory 23.6 2.4
EEG, visual 22.9 2.4
Control group 23.9 3.4
Testing procedure
2. session, EMF 2
first testing (one hemisphere exposed)
second testing (the other hemisphere exposed) 3. session, EMF 3
first testing (one hemisphere exposed)
second testing (the other hemisphere exposed) One week One week EMF and hempishere conditions, and test order counter balanced 1. session, EMF 1
first testing (one hemisphere exposed)
second testing (the other hemisphere exposed)
Exposure
Milmega
AS 0822-7
linear power amplifier Nokia
6110
shell
902 MHz
CW 0.25W
PM mean 0.25 W
pulsed @ 217 Hz
pulse width 0.557 ms Rohde & Schwarz
SMIQ 06B
signal generator
SAR
measured with DASY4,
generic twin phantom,
900 MHz head tissue
simulating liquid
σ = 0.97 ohm/m
εr = 41.5
Peak: 1.18 W/Kg
Average1g: 1.1 W/Kg
Average10g: 0.74 W/Kg
Background radiation in the 10 Hz – 20 kHz frequency range: < 400 nT
Results, Auditory memory task EEG study
Results, Auditory memory task EEG study
Sham -CW Sham -PM CW - PM Differences in the ERD/ERS responses were observed mainly between the CW and PM exposure conditions.
During encoding, greater ~8 Hz ERS during PM whereas during retrieval less ~8 Hz ERD during PM exposure. Sham CW PM
Results, Auditory memory task EEG study
During left hemisphere exposure, differences were mainly observed between the sham vs CW and CW vs PM
exposure conditions in the ~10 Hz frequencies. This was due to smaller magnitude ERD/ERS responses during the CW
exposure as compared to sham and PM, especially during encoding. Sham CW PM
Results, Auditory memory task EEG study
During the right hemisphere exposure, differences were mainly observed between the sham vs CW and sham vs PM exposure
conditions during memory encoding. This was due to that both during CW and PM exposure the ~8-10 Hz ERS responses
were of greater magnitude than during sham exposure. Sham CW PM
Results, Auditory memory task EEG study
Differences in the ERD/ERS responses between the exposed hemispheres were witnessed during sham
(encoding: greater ~8-10 Hz ERS during left hemisphere exposure) and CW (encoding: greater ~10-15 Hz ERS during right
hemisphere exposure - and retrieval: greater ~10 Hz ERD during left hemisphere exposure). Sham CW PM
Results, Auditory memory task EEG study
Conclusions of the auditory memory task EEG study
During left hemisphere exposure, differences were mainly observed between the sham vs CW and CW vs PM exposure conditions in the ~10 Hz frequencies. This was due to the least magnitude ERD/ERS responses during the CW exposure as compared to sham and PM, especially during encoding.
2) During right hemisphere exposure, differences were mainly observed between the sham vs CW and sham vs PM exposure conditions during encoding. This was due to that both during CW and PM exposure the ~8-10 Hz ERS responses were of greater magnitude than during sham exposure.
3) The differences in the ERD/ERS responses between the exposed hemispheres were witnessed during sham and CW.
4) Differences between CW and PM were observed but not when exposure was on the right hemisphere.
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