Abstract
Animals often learn through observing their conspecifics. However, the mechanisms of them obtaining useful knowledge during observation are beginning to be understood. This protocol describes a novel social observation task to test the ‘local enhancement theory’, which proposes that presence of social subjects in an environment facilitates one’s understanding of the environments. By combining behavior test and in vivo electrophysiological recording, we found that social observation can facilitate the observer’s spatial representation of an unexplored environment. The task protocol was published in Mou and Ji, 2016.
Keywords: Hippocampus, Place cell, Social observation, Local enhancement
Background
Social learning is defined as acquiring new knowledge through observing or interacting with others (Heyes and Galef, 1996; Bandura, 1997; Meltzoff et al., 2009). One form of social learning utilized by many species is the so-called ‘local enhancement’ (Heyes and Galef, 1996): an animal’s understanding of an environment is facilitated by the presence of other social subjects in the same environment. Animals achieve local enhancement possibly by heightened attention, acquiring environmental attributes such as safety or food availability, or other unspecified means (Zajonc, 1965; Heyes and Galef, 1996; Zentall, 2006). The hypothesis predicts that the presence of social subjects in an environment impacts other animals’ neural processing of information related to the environment, therefore facilitate their understanding of the environment. It has been shown that spatial information of an environment is represented by hippocampal place cells (O’Keefe and Dostrovsky, 1971; Wilson and McNaughton, 1993; Burgess and O’Keefe, 2003) in rodents and humans. Place cells become active at specific locations of a given environment, called place fields. We asked how an observer’s place cell sequence representing an environment can be influenced by another rat navigating in the environment, even if the observer is located in a physically different environment. This protocol is designed to explore the neural basis of such local enhancement effect of social observation. Specifically, we monitored the hippocampus place cells in observer rats as they stayed in a small box while a demonstrator rat was running on a separate, nearby linear track, and then later when observer rats were running the same track themselves. Our results show that observer’s place cell sequences during track running also appeared in the box during observation, but only when a demonstrator was present on the track. Observer’s running speed, number of run laps and place cells’ specificity are significantly higher than those in control animals.
Materials and Reagents
Equipment
Software
Procedure
Note: All experimental procedures followed the guidelines by the National Institute of Health and were approved by the Institutional Animal Care and Use Committee at Baylor College of Medicine.
Note: The recorded rats have never been exposed to the track before the first recording day. In each of the following days, the Pre-box and Post-box session is set up in various ways as the following, while the Track session remains the same. Each condition is recorded for 1-3 days.
For the other group of rats that have seen only the empty track in the pre-recording training, the Pre-box and Post-box sessions on the first day are under Empty-track condition. In the following days, the Pre-box and Post-box sessions are replaced by Trained-demo and other conditions as described above.
Data analysis
Acknowledgments
The authors would like to thank the entire Ji lab for help on constructing and configuring the apparatus, and for suggestions on preparation of the manuscript. This work was supported by grants NIMH R01MH106552, Simons Foundation 273886 to D.J.
References
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