Figure 1.

Identification of empathy-related behaviors in the observational distress test

(A) Diagram of the observational distress test. As a control experiment, a group of rats experienced the task with a solid, opaque divider (opaque control group) instead of a perforated, transparent divider (transparent group).

(B) Recording sites of ACC and InC electrodes from the transparent group (red dots) and opaque control group (black dots). Numbers at the bottom right corner of each brain coronal section, distance to bregma in mm along the anterior-posterior axis (Paxinos and Watson, 2007); scale bar, 2 mm

(C) Averaged percentages of freezing (red), sniffing (black), and social approach (blue) behaviors in observer rats through trials of “air”, “demo”, and “self” blocks from the transparent and opaque control groups.

(D) Percentages of freezing, sniffing and social approach are significantly higher during the “demo” block (oblique bars) than the percentages during the “air” block (open bars) in the transparent group, but not the opaque control group (mean ± SEM from the 10 trials in a block). ∗p< 0.016, compare to values in the “air” block. ^#p< 0.016, compare to values in the “demo” block in the same group. ^✝p< 0.016, compare to values in the opaque control group (one sided Mann-Whitney U test at a significance level of α = 0.05, with Bonferroni correction). f, freezing; n, sniffing; a, social approach; w, walking; h, heading; r, resting; l, licking.

See also Figure S1.