Applications of video mixing and digital overlay to neuroethology

Neuroethological experiments often require video images of animal behavior and recordings of physiological data to be acquired simultaneously, synchro nized with each other, stored, and analyzed together. The use of inexpensiv e multimedia computers offers new possibilities for mixing video images, an alog voltages, and computer data, storing these combined signals to videota pe, and extracting quantitative data for analysis. In this paper, we summar ize methods for mixing images from multiple video cameras and a Macintosh c omputer display to facilitate manipulation of data generated during our neu rophysiological and behavioral research. These technologies enhance accurac y, speed, and flexibility during experiments, and facilitate selecting and extracting quantitative data from the videotape for further analysis. Three applications are presented: (A) we used an analog video mixer to synchroni ze neurophysiological recordings with ongoing behaviors of freely moving ra ts; (B) we used a chroma keyed digital overlay to generate positional data for the rat's face during drinking behavior; and (C) we combined a computer model of a rat's head and whiskers with videos of exploratory behaviors to better track and quantify movements in three dimensions. Although the appl ications described here are specific to our neuroethological work, these me thods will be useful to anyone wishing to combine the signals from multiple video sources into a single image or to extract series of positional or mo vement data from video frames without frame grabbing. (C) 2000 Academic Pre ss.