To study the effect of a temporally incoherent magnetic field ('noise') on microwave-induced spatial learning deficit in the rat.
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.
| 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
|
|
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.
| Frequency | 2.45 GHz |
|---|---|
| Charakteristic |
|
| Polarization |
|
| Exposure duration | continuous for 1 h |
| Modulation type | CW |
|---|
| 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. |
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| SAR | 1.2 mW/g | mean | unspecified | whole body | - |
| power density | 20 W/m² | mean | unspecified | - | - |
| Frequency | 30–100 Hz |
|---|---|
| Type | |
| Exposure duration | intermittent for 1 h |
| 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 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. |
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| magnetic flux density | 6 µT | mean | measured | - | - |
| Modulation type | CW |
|---|
| Exposure source |
|
|---|
| 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 | - |
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.
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