A force-plate actometer for quantitating rodent behaviors: illustrative data on locomotion, rotation, spatial patterning, stereotypies, and tremor

This report describes a new kind of actometer for recording the behavior of rodents or other small animals. The instrument, a force-plate actometer, u ses a stiff, low-mass horizontal plate coupled to four supporting force tra nsducers positioned at the corners of the plate. When an animal moves on th e plate, its movements are sensed by the transducers whose signals are proc essed by computer to yield measurements of a wide range of behaviors or beh avioral attributes, such as locomotor activity, rotation around the center, whole-body tremor, and amphetamine-induced stereotypies. Spatial resolutio n is less than 1 mm, and temporal resolution is 0.02 s. Sample data were pr esented comparing the locomotor activity of CD-1, BALB/c, and C57BL/6 mice before and after treatment with D-amphetamine sulfate. Rotational behavior was recorded in an amphetamine-treated rat that had sustained a unilateral 6-hydroxydopamine-induced lesion of the nigrostriatal system. In the C57BL/ 6 mouse, harmaline-induced tremor was quantified. With rats as subjects, th e force-plate actometer was used to quantify amphetamine-induced stereotypi es, to demonstrate the development of sensitization to amphetamine's effect s, and to quantitate the consistent 11-12 Hz rhythmicities that underlie th e sterotypies. The performance of the force-plate actometer was compared wi th that of a variety of instruments reported in the literature on behaviora l instrumentation. Finally, potential applications in neuroscience research other than those illustrated in this report were discussed. (C) 2001 Elsev ier Science B.V. All rights reserved.