Pharmacology Biochemistry & Behavior, Vol. 30, pp. 199-203. © PergamonPress plc, 1988. Printedin the U.S.A. 0091-3057/88$3.00 + .00 BRIEF COMMUNICATION A New Device for Monitoring Early Motor Development: Prenatal Nicotine-Induced Changes M. SCHLUMPF,1 M. G)i, HWILER, U. RIBARY AND W. LICHTENSTEIGER Institute of Pharmacology, University of Ziirich, CH-8006 Ziirich, Switzerland Received 13 July 1987 SCHLUMPF, M., M. GAHWILER, U. RIBARY AND W. LICHTENSTEIGER. A new device for monitoring early motor development: Prenatal nicotine-induced changes. PHARMACOL BIOCHEM BEHAV 30(1) 199-203, 1988.--A new type of activity meter has been designed especially for young rats. It consists of a warmed platform for the animal, a TV camera with monitor and a microprocessor. The TV camera detects the animal as a black figure on a light background. This picture is digitalized and stored in a Z80 microprocessor. Every 200 msec a new image is compared to the foregoing one. The total number of black points that are changing from black to white and vice versa provides a measure for motor activity of the animal. Prenatally nicotine-treated rat pups were tested on the activity meter. The developmental pattern of motor activity was different for male and female pups. Motor activity of nicotine-treated male pups differed significantly from controls at postnatal days 7 and 15 while this drug effect was not seen in females. Activity meter Motor activity Nicotine Prenatal drug treatment MOTOR activity is one of the prominent manifestations of a normally functioning nervous system. It is known to be very sensitive to many kinds of environmental influences espe- ciaUy during pre- and postnatal development of the brain, Testing motor activity has become a useful diagnostic tool in order to evaluate adverse developmental impacts. Disturbed motor patterns in pups have been reported after prenatal exposure to several drugs: benzodiazepines [2], opiates [8], alcohol [9], nicotine [6,7] and environmental pollutants such as lead [5]. Some of these studies clearly show that developmental profiles of motor activity provide better information on behavioral deficiencies in the offspring than single activity measurements at individual postnatal stages. Yet, currently available activity meters still lack suf- ficient resolution for evaluating motor activity patterns in single neonate pups. In the following, we describe a newly designed activity meter with a high resolution capacity suit- able also for detection of minute motor activity in the neo- nate and very young rat pup. METHOD The activity meter consists of an activity platform, a TV camera with monitor and a microprocessor. TV camera and platform are shielded against scattering light by a dark screen with an open slit on the operating side (ca. 1/2 platform width, Figs. 1 and 2). The Plexiglas platform is built as an illumi- nated table with light bulbs (Philips 220 V PF 712 E) emitting red light of 760 nm wave length. The surface temperature of the platform is set at 30°C (-+2°C). The TV camera (Bosch TYK 9A) equipped with a Heimann (Siemens) multidiodic tube is fixed in a vertical position above the platform. It detects the animal as a black figure on a light background. This picture is digitalized to 64 lines with 64 points =4096 points by a comparator and stored in a Z80 processor. During measurements, the monitor shows the digitalized image. For focussing of the image, the camera can be switched to the monitor. Movements are detected as follows: Two video signals are digitalized and stored at an interval of 200 msec (equal to 4 complete pictures of the camera). The computer then scores for differences (changed bits) between the second and the first picture by comparing the total number of black points at the two time points. Every 200 msec a new image is compared with the preceding one. The system provides 3 types of data: (1) The total number of black points is deter- mined before measurements start. It is a measure of the pro- jection surface and hence, of the size of the animal. (2) Ac- tivity is expressed as the mean number of points exhibiting a change. This value is newly calculated every 200 msec for the period starting with the onset of measurements. (3) Ac- tRequest for reprints should be addressed to Dr. Margret Schlumpf, Pharmakologisches Institut, Universitiit Ziirich, Gloriastrasse 32, CH-8006 Ztirich, Switzerland. 199