VAMP: a video activity monitoring processor for the registration of animal locomotor activity.

In many bioenergetic investigations, the discrimination of resting and activity metabolism represents an important problem. Personal observation, a possible solution to this problem, becomes very impractical in highly automated long-term experiments. An adequate method of measuring activity should meet the following demands: it should be able to quantify the movement of several objects simultaneously, it should be usable with animals of different shapes and sizes, and it should cause minimal disturbance to the animals. Very simple methods, such as registration of electric potentials of aquatic animals (Cairns & Thompson, 1980), become difficult with more than a single animal, and photocell arrays lack flexibility. A video-based apparatus, however, can be adapted to a variety of problems by using different lenses on the camera. Expensive and sophisticated digital image-analysis techniques are not necessary. Inexpensive methods for tracing single objects (Lubinski, Dickson & Cairns, 1977) or light sources (Atkinson & Faulkner, 1981), as well as detecting objects crossing certain lines (van Lenterten, van der Linden & Gluvers, 1976), have been described in the literature, but these methods cannot be adapted to handle several objects or shapes like worms without losing their simplicity. This paper presents a quite different approach: the area displacement of the objects is estimated instead of their position and velocity.