A 3D-video-based computerized analysis of social and sexual interactions in rats

PLoS One. 2013 Oct 30;8(10):e78460. doi: 10.1371/journal.pone.0078460. eCollection 2013.


A large number of studies have analyzed social and sexual interactions between rodents in relation to neural activity. Computerized video analysis has been successfully used to detect numerous behaviors quickly and objectively; however, to date only 2D video recording has been used, which cannot determine the 3D locations of animals and encounters difficulties in tracking animals when they are overlapping, e.g., when mounting. To overcome these limitations, we developed a novel 3D video analysis system for examining social and sexual interactions in rats. A 3D image was reconstructed by integrating images captured by multiple depth cameras at different viewpoints. The 3D positions of body parts of the rats were then estimated by fitting skeleton models of the rats to the 3D images using a physics-based fitting algorithm, and various behaviors were recognized based on the spatio-temporal patterns of the 3D movements of the body parts. Comparisons between the data collected by the 3D system and those by visual inspection indicated that this system could precisely estimate the 3D positions of body parts for 2 rats during social and sexual interactions with few manual interventions, and could compute the traces of the 2 animals even during mounting. We then analyzed the effects of AM-251 (a cannabinoid CB1 receptor antagonist) on male rat sexual behavior, and found that AM-251 decreased movements and trunk height before sexual behavior, but increased the duration of head-head contact during sexual behavior. These results demonstrate that the use of this 3D system in behavioral studies could open the door to new approaches for investigating the neuroscience of social and sexual behavior.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Behavior, Animal / drug effects
  • Behavior, Animal / physiology*
  • Imaging, Three-Dimensional / methods
  • Male
  • Motor Activity / drug effects
  • Motor Activity / physiology
  • Movement / drug effects
  • Movement / physiology
  • Piperidines / pharmacology
  • Pyrazoles / pharmacology
  • Rats
  • Receptor, Cannabinoid, CB1 / antagonists & inhibitors
  • Receptor, Cannabinoid, CB1 / metabolism
  • Sexual Behavior / drug effects
  • Sexual Behavior / physiology*
  • Social Behavior
  • Video Recording / methods


  • Piperidines
  • Pyrazoles
  • Receptor, Cannabinoid, CB1
  • AM 251

Grants and funding

This work was supported partly by the Japan Society for the Promotion of Science Asian Core Program and the Ministry of Education, Science, Sports and Culture, Grant-in-Aid for Scientific Research (A) (22240051), (B) (25290005) and a Grant-in-Aid for Young Scientists (B) (25830006). No additional external funding received for this study. The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.