Pharmacology Biochemistry and Behavior, Vol. 54, No. 2, pp. 479-483, 1996 Copyright Q 1996 Elsevier Science Inc. Printed in the USA. All rights reserved 0091-3057196 $15.00 + .OO zyxwvutsr SSDI 0091-3057(95)02277-S Development of an Affordable Hi-Resolution Activity Monitor System for Laboratory Animals MARTIN H. TEICHER,’ SUSAN L. ANDERSEN, PAUL WALLACE, DIANE A. KLEIN AND JACK HOSTETTER Laboratory of Developmental Psychopharmacology, Mailman Laboratories for Psychiatric Research, McLean Hospital, 115 Mill St., Belmont, MA 02178 USA Received 2 June 1995; Revised 2 November 1995; Accepted 15 November 1995 TEICHER, M. H., S. L. ANDERSEN, P. WALLACE, D. A. KLEIN AND J. HOSTETTER. Development of an uf- fordable hi-resolution activity monitor system for laboratory animals. PHARMACOL BIOCHEM BEHAV 54(2) 479-483, 1996. -We describe a hardware and software system for recording and analyzing the spatial and temporal pattern of locomo- tor activity of laboratory animals. The system offers maximal spatial resolution SOO-fold greater than existing light beam monitors. An infrared motion analysis systems (MacReflex, Qualysis) simultaneously tracks the location of up to 20 subjects (identified by reflective markers) to within 0.04 mm at a rate of up to 50 Hz. Macintosh software provides measures of distance traveled, amount of area traversed, number of position changes (microevents), average time between movements, number of left and right turns, number of forward movements and reversals, as well as temporal and spatial scaling exponents. This system was validated by comparing these parameters to direct observer scoring of video tapes and other commercially available activity monitors. Our findings show that applying reflective markers to the subjects does not significantly alter activity levels. The effect of pharmacological manipulation with d-amphetamine is provided to show the value of the different activity parameters. The main advantages of this system are very high spatial resolution, capacity to monitoring up to 20 animals simultaneously at reasonable cost, and lack of sensitivity of the system to ambient lighting. The main limitation is the need to apply reflective markers. Activity Amphetamine Behavior Infrared Monitor Spatial scaling Temporal scaling EARLY activity monitors included tambor cages, stabilimet- ers, and running wheels in which the animal jiggled, tilted, or rotated the cage to activate mechanical counters (6). Advances in technology produced more sensitive monitors that could detect subtle vibrations (14), perturbations in radiofrequency fields, or disruption of visible or infrared photobeams (8). In general, these devices have produced a single overall index of activity. Microprocessor technology has made it possible to develop activity monitors using photobeam arrays or video cameras that could effectively trace and record the animal’s path of movement and have substantially enhanced the quan- tity and quality of experimental data. To date, the best activity monitors have had a spatial resolution of about 2.5 cm [e.g., (2,5,13)], which, while impressive, ignores a whole range of subtle movements discernable by human observers. Cost has also been a prohibitive factor, especially when it is important to simultaneously monitor many animals. In the present report we describe the development of an infrared motion analysis system than can simultaneously mon- itor up to 20 animals (in separate cages) at a sampling rate of up to 50 Hz with a spatial resolution of 0.04 mm. The video camera and computer interface are commercially available (Qualysis, Glasbury, CT), and provide the basis for an ex- tremely precise, economical, high resolution activity monitor. Software to use this instrument, and to simultaneously moni- tor 12 individually housed rats, has been written by Dr. Teicher for Macintosh computers, and includes an array of interesting measures of locomotor activity. ’ To whom requests for reprints should be addressed. 479