Analysis of chemically-induced alterations of the motor activity in rats

A computerized method for the evaluation of behavioral responses induced by neurotoxicants in rats is described. A dynamic image analysis system was adapted for the measurement of the duration, vigor and averaged velocity of motor activity (locomotor or not) of behavioral responses induced chemically in rats. Three known animal models of epilepsy: systemic administration of kainic acid, pentylenetetrazole and 4-aminopyridine were used for reference. The method, based on the concurrent measurement of the quantity and quality of the movements, allowed the systematic evaluation of the behavior patterns induced. Three different levels of analysis were used. Firstly, we measured the time spent by the animal performing physical movements during long successive intervals (30 min) of the test, a motor activity analysis similar to that obtained with other motor activity recording devices. Secondly, the system was designed to distinguish movements energetically or forcefully performed by the animal according to a previously defined vigor level and then we determined the presence of vigorous and non-vigorous activity throughout the test at 2 min interval. Finally, we applied the method to perform a more detailed analysis of the motor characteristic of behavioral components exhibited by the animals determining the velocity and vigor of movements over short intervals of time (5 sec). Thus, motor activity profiles, the vigor of the motor responses and the description of behavioral components were used for the comparative analysis of behavior induced by the aforementioned convulsant agents.