Effect of therapeutic level ultrasound on visual evoked potentials in the hypoxic cat
George V. Forester, Eric A. Peterson, Orest Z. Roy
Ultrasound in Medicine & Biology 1987 · 10.1016/0301-5629(87)90098-6
Abstract
The effect of 1.0 MHz ultrasound at an intensity of 1.0 W/cm2 SATA on brain function of anaesthetized cats was assessed using Visual Evoked Potentials (VEPs). Ultrasound alone did not significantly modify the averaged VEP signals. However, acute hypoxia depressed the VEP response. When the brain was exposed to ultrasound during the hypoxic episode, the VEP response remained normal. Raising brain temperature by whole body heating could not mimic the beneficial effect of ultrasound on the VEP response during hypoxia. This suggests that therapeutic ultrasound may have a protective effect on hypoxic tissues and may have clinical applications.
Abstract via europepmc.
Exposures
Exposure 1: 1 W/cm2 SATA, 1036 kHz, applied to exposed cat brain
Target: cerebral cortex — “brain exposed by removing a 3.9 cm diameter portion of the calvareum”
Device: not reported
| Waveform | not reported | |
|---|---|---|
| Fundamental frequency (kHz) | 1,036 | ✓✓✓ |
| Pulse duration (ms) | not reported | |
| Pulse repetition frequency (Hz) | not reported | |
| Duty cycle (%) | not reported | |
| Sonication duration (s) | not reported |
| Free-field pressure (kPa) | not reported | |
|---|---|---|
| Free-field Isppa (W/cm²) | not reported | |
| Free-field Ispta (W/cm²) | 1 | ✓✓✓⚑ |
| In-situ estimate | not reported | |
| In-situ pressure (kPa) | not reported | |
| In-situ Isppa (W/cm²) | not reported | |
| In-situ Ispta (W/cm²) | not reported |
For Phase 3 the ultrasound generator was turned on one minute prior to the commencement of the two-minute hypoxic phase and turned off after the hypoxic episode; continuous versus pulsed mode and exposure duration are not stated for the VEP experiments (temperature measurements used five minutes of exposure).
Flags from extraction
exposures[0].free_field.ispta_w_cm2— Reported as spatial-average temporal-average (SATA) intensity, measured in a water tank at the position of the proximal brain surface; recorded in the ispta field.exposures[0].target.terms— Ultrasound applied through water over the exposed dura of both hemispheres (unfocused applicator, 2.5 cm element); recording electrode over primary visual cortex. Target term is a judgement.exposures[0].timing.waveform— Continuous or pulsed mode not stated for this study.exposures[0].device.family— Transducer maker not named; described as a piezoelectric ceramic element in an acrylic applicator, system described in an earlier paper.