Figure 1. SR-LAB startle apparatus.

A. Each experimental apparatus consists of an outer, lighted and ventilated, chamber that serves to prevent external noise or vibrations interfering with experiment. B. Inside the chamber a stabilimeter consisting of a Plexiglas cylinder is secured to a platform. C. A piezoelectric accelerometer-indicated by the red arrow-mounted under the cylinder transduces animal movements that are then digitized, rectified, and recorded by a computer and interface assembly. A loudspeaker-indicated by the blue arrow-generates the startling acoustic stimuli, according to the desired settings.