Study type: Medical/biological study (experimental study)

Interaction of microwaves and a temporally incoherent magnetic field on spatial learning in the rat. med./bio.

Published in: Physiol Behav 2004; 82 (5): 785-789

Aim of study (acc. to author)

To study the effect of a temporally incoherent magnetic field ('noise') on microwave-induced spatial learning deficit in the rat.

Background/further details

Rats were trained in six sessions to locate a submerged platform in a circular water maze. Four treatment groups were investigated: microwave-exposure, 'noise' exposure (60 mG), 'microwave + noise' exposure, and sham exposure.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 2.45 GHz
Modulation type: CW
Exposure duration: continuous for 1 h
Exposure 2: 30–100 Hz
Exposure duration: intermittent for 1 h
Exposure 3: 2.45 GHz
Modulation type: CW
Exposure duration: continuous for 1 h

General information

Rats were arranged into four treatrment groups, 8 rats/group, which were arranged according the following treatment conditions: microwave exposure, microwave and noise exposure, noise exposure and sham exposure.

Exposure 1

Main characteristics
Frequency 2.45 GHz
Charakteristic
  • guided field
Polarization
  • circular
Exposure duration continuous for 1 h
Modulation
Modulation type CW
Exposure setup
Exposure source
Setup A rat was placed in a cylindrical plastic chamber (19.6 cm long x 17.6 cm in diameter x 14.5 cm wide) situated inside the waveguides where it was able to move freely.
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
SAR 1.2 mW/g mean unspecified whole body -
power density 20 W/m² mean unspecified - -

Exposure 2

Main characteristics
Frequency 30–100 Hz
Type
Exposure duration intermittent for 1 h
Modulation
Modulation type cf. additional info
Additional info

The magnetic field was switched on and off during the exposure. The on/off pattern consisted of a repeating set of 660 alternating on and off intervals that cycled in approx. 11 mins. The duration of these intervals was chosen at random from a set of 11 time values which included 0.56 s, 1.67 s and values between separated by approx. 0.11 s.

Exposure setup
Exposure source
Setup A waveguide containing a rat was placed between the coils but it was not activated.
Additional info The temporally incoherent magnetic field referred to as noise was generated using a signal recorded in an audio cassette tape. The tape was placed back in a continuous play cassette player connected to a power amplifier whose output was in turn connected to the coil.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 6 µT mean measured - -

Exposure 3

Main characteristics
Frequency 2.45 GHz
Charakteristic
  • guided field
Exposure duration continuous for 1 h
Additional info Simultaneous exposure to microwave and noise.
Modulation
Modulation type CW
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 6 µT mean measured - -
power density 20 W/m² mean unspecified - -
SAR 1.2 mW/g mean unspecified whole body -

Reference articles

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

Data show that exposed rats had significant deficit in learning to locate the submerged platform when compared with the sham-exposed rats. Exposure to 'noise' alone did not significantly affect the performance of the rats: it was similar to that of the sham-exposed rats.
However, simultaneous exposure to 'noise' significantly attenuated the microwave-induced spatial learning deficit: 'microwave + noise'-exposed animals learned significantly better than the microwave-exposed rats.
During the probe trial, microwave-exposed rats spent significantly less time in the quadrant where the platform was located. However, response of the 'microwave + noise'-exposed rats was similar to that of the sham-exposed animals during the probe trial.
Thus, simultaneous irradiation to a temporally incoherent magnetic field blocks microwave-induced spatial learning and memory deficits in the rat.

Study character:

Study funded by

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