Fig. 1

The experimental setup and analysis system. a The experimental arena, pictured from above with a mouse exploring two social stimuli located in grooved chambers. Inset—schematic representation of the experimental setup with grooved chambers. b Computer screenshot during analysis, showing the arena viewed from above. The front walls of the triangular chambers are marked as “stimulus 1” and “stimulus 2,” and the arena floor is divided into “compartment 1” and “compartment 2.” Also, shown are the tracked mouse and the tracked path. c Plot of investigation bouts during 35 s of the experiment shown in b, labeled according to the number of investigated stimulus (red for stimulus 1, blue for stimulus 2). d Four frames from the video file of the experiments shown in b, demonstrating distinct behavioral events and the location of the center of the animal body (cross) identified by the analysis system for each one. The cross is white during non-investigative behavior, red during investigation of stimulus 1, and blue during investigation of stimulus 2. Dashed lines mark the borders of the chambers. e Analysis of the correlation between investigation times of both object and social stimuli measured by a trained observer during SP experiments (n = 20 male mice) and those measured for the same experiments by the computerized analysis system. f Representative image of a mouse with an electrical wire connecting head-implanted probe to electrophysiological recording system in the experimental arena. g Analysis of mean (±SEM) investigation time of wired animals (n = 4) towards two chambers located in opposite corners of the arena while both were empty (before the time marked by dashed line) and after insertion of a social stimulus to one of them (after the time marked by dashed line)