Figure 2.

The custom-built whole-body acoustic startle device is depicted in this drawing. The upper chamber is removed from the base and the animal transferred from below, after which a false floor is inserted. The chamber is then slowly righted and set onto the base. As the false floor is removed the animal steps down onto the instrumented platform. The platform, itself, is cantilevered from a low-friction hinge. An adjustable flat steel spring provides preload; a pair of small shock-absorbers (not shown) damp post-movement oscillations; the accelerometer transduces platform movements. Wide-band headphones (not shown) supply acoustic stimuli through large holes cut into the sidewalls of the upper chamber and guarded by acoustically transparent metal screens. Safety features include tape strips indicating the otherwise transparent enclosure walls and a padded ceiling. Further details are supplied in the text.