The tolerometer: a fast, automated method for the measurement of righting reflex latency in chronic drug studies.

We describe a fast, automated system for the measurement of righting reflex latencies in drug studies. This system, which we call a 'tolerometer', is especially useful for studies of drug tolerance which require a simple measurement of motor behaviour on a daily basis, for long periods of time. The tolerometer consists of a semi-cylindrical platform positioned on a 2 kg load cell, connected to a strain gauge amplifier (Radio Spares Ltd). The output from the amplifier is connected to a MacLab data acquisition system (Analog Digital Instruments), controlled by a Macintosh Classic computer. The MacLab Chart program is used to display, on the Macintosh screen, the load changes which occur during a righting reflex; sampling frequencies up to 40 kHz can be used, but we find 20-100 Hz adequate. Using measurement cursors provided by the Chart program, the latency from the point at which an animal is placed on the tolerometer platform in the supine position, until the completion of a righting reflex, can be measured accurately and easily.

Simple device for quantifying drug effects on the righting reflex.

A simple, inexpensive device is described that allows quantification of the effects of drugs on the righting reflex. This device consists of a modified set of kitchen scales connected to a digital timer. Two moveable Hall effect switches are positioned around the pointer, which registers the weight of the animal on the scales; when the animal is placed on the scales in the supine position, the initiation of a righting reflex causes the pointer to cross one of the switches, stopping the digital timer and providing a measure of righting reflex latency (RRL). We describe an efficient protocol for using this device that provides quantification of drug effects on the RRL, which can then be subjected to analysis using parametric statistics such as analysis of variance.