Study type: Medical/biological study (experimental study)

Modification of acoustic and tactile startle by single microwave pulses med./bio.

By: Seaman RL, Beblo DA, Raslear TG
Published in: Physiol Behav 1994; 55 (3): 587-595
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Aim of study (acc. to author)

Single microwave pulses at 1.25 GHz were delivered to the head and neck of rats as a prestimulus to acoustic and tactile startle. The effectiveness of single microwave pulses as prestimuli were tested.

Background/further details

For acoustic startle, pulses averaging 0.96 microseconds in duration were tested with two specific absorption rate ranges, 15.0-30.0 kW/kg and 35.5-86.0 kW/kg, delivered 201, 101, 51, 3, and 1 ms before and 1 ms after onset of a startling noise. For tactile startle, either microwave pulses averaging 7.82 microseconds in duration and 55.9-113.3 kW/kg or 94 dB SPL clicks were delivered 157, 107, 57, and 7 ms before and 43 ms after onset of a startling air burst.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 1.25 GHz
Modulation type: single pulse
Exposure duration: 15 min
  • SAR: 64.28 W/g mean (partial body) (35.5-86.0 kW/kg; at pulse durations of 0.73-1.20 µs)
  • SAR: 21.24 W/g mean (partial body) (15.0-30.0 kW/kg; at pulse durations of 0.7-1.26 µs)
Exposure 2: 1.25 GHz
Modulation type: pulsed
Exposure duration: 15 min
  • SAR: 76.95 W/g mean (partial body) (55.9-113.3 kW/kg; at pulse durations of 6.80-8.36 µs)

Exposure 1

Main characteristics
Frequency 1.25 GHz
Type
Charakteristic
  • guided field
Exposure duration 15 min
Modulation
Modulation type single pulse
Exposure setup
Exposure source
Chamber Plexiglas holder: 18.9 long, internal and outer diameter of 7 and 7.6 cm respectively
Setup Animals were tested in cylindrical holders that positioned the head within the exposure device and restricted extraneous motion.
Additional info The waveguide terminated with a shorting screen inside a sound-attenuating chamber. The terminal section of the waveguide accepted the animal holder through a round hole in one broad wall to position the head of the animal inside the waveguide.
Parameters
Measurand Value Type Method Mass Remarks
SAR 64.28 W/g mean calculated partial body 35.5-86.0 kW/kg; at pulse durations of 0.73-1.20 µs
SAR 21.24 W/g mean calculated partial body 15.0-30.0 kW/kg; at pulse durations of 0.7-1.26 µs

Exposure 2

Main characteristics
Frequency 1.25 GHz
Type
Charakteristic
  • guided field
Exposure duration 15 min
Modulation
Modulation type pulsed
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
SAR 76.95 W/g mean calculated partial body 55.9-113.3 kW/kg; at pulse durations of 6.80-8.36 µs

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

The data show that a single microwave pulse of sufficient intensity can modify the amplitude and/or latency of whole-body acoustic or tactile startle of the rat depending on the timing between it and startling stimulus. The low-intensity pulse did not affect peak amplitude, integral, or latency of the acoustic startle response. The high-intensity pulse at 101 and 51 ms inhibited the acoustic startle response (by decreasing peak amplitude and integral); at 201 and 51 ms latency was increased. The high-intensity pulse at 1 ms enhanced the acoustic startle response by increasing peak amplitude and at 3 ms by increasing integral. The microwave pulse at 57 ms inhibited the tactile startle response by decreasing peak amplitude; at 157, 107, 57, and 7 ms it increased latency. The microwave pulse at 43 ms enhanced the tactile startle response by increasing peak amplitude.

Study character:

Study funded by