Physiological effects of focused ultrasound pulses on mammalian CNS tissue in an in-vitro preparation

We have investigated the effects of pulsed and highly focused ultrasound on the physiology of 500 micron thick hippocampal slices obtained from 50 male, 120 gram Sprague-Dawley rats. During the study the slices were kept alive in a special in-vitro preparation. We compared the magnitude and latency of the control evoked responses to those of the responses recorded during ultrasound irradiation. Comparisons were made for both the orthodromic and antidromic population responses. For all studies, a highly focused pulsed ultrasonic beam was used with a center frequency of 5 MHz and an intensity (SPTA) of 52 W/cm ². Significant changes in both the magnitude and the stimulus-response delay were observed. Full recovery was observed when the ultrasound was removed. In addition, temperature effects could be rejected as the sole mechanism producing such changes