A method for measuring acoustic startle response latency and magnitude in rats: Detection of a single stimulus effect using latency measurements

Abstract

A method is described for measuring startle response magnitude in terms of acceleration using an accelerometer transducer with suitable frequency characteristics to enable accurate measurements of latency to be made. Cine photography synchronised with the accelerometer trace was used to investigate the body movements accompanying the startle response. Histograms show a normal distribution for startle response magnitude and a skew distribution for startle response latency. Significant reductions in startle response latency occur without change in startle response magnitude when a single large stimulus is followed by a second stimulus 24 hr later. This effect is dependent upon stimulus strength, a weak stimulus resulting in a significant reduction in startle response magnitude without change in startle response latency, indicating habituation.