Novel approach to automatically classify rat social behavior using a video tracking system.

BACKGROUND: In the past, studies in behavioral neuroscience and drug development have relied on simple and quick readout parameters of animal behavior to assess treatment efficacy or to understand underlying brain mechanisms. The predominant use of classical behavioral tests has been repeatedly criticized during the last decades because of their poor reproducibility, poor translational value and the limited explanatory power in functional terms. NEW METHOD: We present a new method to monitor social behavior of rats using automated video tracking. The velocity of moving and the distance between two rats were plotted in frequency distributions. In addition, behavior was manually annotated and related to the automatically obtained parameters for a validated interpretation. RESULTS: Inter-individual distance in combination with velocity of movement provided specific behavioral classes, such as moving with high velocity when "in contact" or "in proximity". Human observations showed that these classes coincide with following (chasing) behavior. In addition, when animals are "in contact", but at low velocity, behaviors such as allogrooming and social investigation were observed. Also, low dose treatment with morphine and short isolation increased the time animals spent in contact or in proximity at high velocity. COMPARISON WITH EXISTING METHODS: Current methods that involve the investigation of social rat behavior are mostly limited to short and relatively simple manual observations. CONCLUSION: A new and automated method for analyzing social behavior in a social interaction test is presented here and shows to be sensitive to drug treatment and housing conditions known to influence social behavior in rats.

Automated quantitative analysis to assess motor function in different rat models of impaired coordination and ataxia.

BACKGROUND: An objective and automated method for assessing alterations in gait and motor coordination in different animal models is important for proper gait analysis. The CatWalk system has been used in pain research, ischemia, arthritis, spinal cord injury and some animal models for neurodegenerative diseases. NEW METHOD: Our goals were to obtain a comprehensive gait analysis of three different rat models and to identify which motor coordination parameters are affected and are the most suitable and sensitive to describe and detect ataxia with a secondary focus on possible training effects. RESULTS: Both static and dynamic parameters showed significant differences in all three models: enriched housed rats show higher walking and swing speed and longer stride length, ethanol-induced ataxia affects mainly the hind part of the body, and the SCA17 rats show coordination disturbances. Coordination changes were revealed only in the case of the ethanol-induced ataxia and the SCA17 rat model. Although training affected some gait parameters, it did not obscure group differences when those were present. COMPARISON WITH EXISTING METHODS: To our knowledge, a comparative gait assessment in rats with enriched housing conditions, ethanol-induced ataxia and SCA17 has not been presented before. CONCLUSIONS: There is no gold standard for the use of CatWalk. Dependent on the specific effects expected, the protocol can be adjusted. By including all sessions in the analysis, any training effect should be detectable and the development of the performance over the sessions can provide insight in effects attributed to intervention, treatment or injury.

Reproducibility and relevance of future behavioral sciences should benefit from a cross fertilization of past recommendations and today's technology: "Back to the future".

Thanks to the discovery of novel technologies and sophisticated analysis tools we can now 'see' molecules, genes and even patterns of gene expression, which have resulted in major advances in many areas of biology. Recently, similar technologies have been developed for behavioral studies. However, the wide implementation of such technological progress in behavioral research remains behind, as if there are inhibiting factors for accepting and adopting available innovations. The methods of the majority of studies measuring and interpreting behavior of laboratory animals seem to have frozen in time somewhere in the last century. As an example of the so-called classical tests, we will present the history and shortcomings of one of the most frequently used tests, the open field. Similar objections and critical remarks, however, can be made with regard to the elevated plus maze, light-dark box, various other mazes, object recognition tests, etc. Possible solutions and recommendations on how progress in behavioral neuroscience can be achieved and accelerated will be discussed in the second part of this review.