Study type: Medical/biological study (experimental study)

Modification of acoustic startle by microwave pulses in the rat: a preliminary report med./bio.

By: Seaman RL, Beblo DA
Published in: Bioelectromagnetics 1992; 13 (4): 323-328
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Aim of study (acc. to author)

Single, 1.25-GHz microwave pulses of 0.8- to 1.0 µs duration were presented to rats 100 ms before presentation of a startle-inducing acoustic stimulus. This sequential pairing of microwave pulse and acoustic stimulus was found to change the startle response. The purpose of the study was to validate methodology for future investigations.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 1.25 GHz
Modulation type: single pulse
  • power: 5.2 kW peak value (1.1-5.2 kW)
  • SAR: 48 kW/kg peak value (brain) (23-48 kW/kg)
  • SA: 43 mWs/kg peak value (brain) (22-43 mWs/kg)
  • SAR: 111 kW/kg peak value (brain) (63-111 kW/kg)
  • SA: 107 mWs/kg peak value (brain) (59-107 mWs/kg)

Exposure 1

Main characteristics
Frequency 1.25 GHz
Type
Charakteristic
  • guided field
Modulation
Modulation type single pulse
Pulse width 1 µs
Additional info

Pulse durations were between 0.8 and 1.0 µs.
Exposure setup
Exposure source
Chamber sound attenuating chamber
Setup The exposure device was a downward-pointing WR-650 waveguide with a shorted end plane and a hole in one of the wider walls. The rat was placed in a ventilated plastic cylinder one end of which was moved through the hole to position the animal's head inside the waveguide.
Additional info A single pulse was delivered 100 ms before the onset of the startle-inducing acoustic stimulus.
Parameters
Measurand Value Type Method Mass Remarks
power 5.2 kW peak value measured - 1.1-5.2 kW
SAR 48 kW/kg peak value measured brain 23-48 kW/kg
SA 43 mWs/kg peak value measured brain 22-43 mWs/kg
SAR 111 kW/kg peak value measured brain 63-111 kW/kg
SA 107 mWs/kg peak value measured brain 59-107 mWs/kg
Measurement and calculation details

Directional couplers were used for monitoring forward and reflected powers. Head SARs depending on body mass were determined by thermometric measurements during CW irradiation of cadavers.

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

At an energy dose to the head of 22-43 mWs/kg per pulse (peak SAR, 23-48 kW/kg), the mean latency to the startle response was longer and the mean amplitude of the response was smaller with respect to control responses that occured to acoustic stimuli alone. However, at a higher energy dose per microwave pulse (59-107 mWs/kg; peak SAR, 63-111 kW/kg), the mean latency and amplitude of the startle response were not statistically different from the respective mean of control responses.

Study character:

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