Table 1.

Correlation matrix of analyzed variables.

	Tot. Hip	CA1	CA2/3	CA4	DG	Subic	Tot. PSB	PSB1	PSB3	P	C	TT	Carry	Age	Weight
Hippocampus
Tot. Hip	–
CA1	0.73*	–
CA2/3	0.68*	0.32	–
CA4	0.76*	0.37	0.88*	-
DG	0.41	− 0.02	− 0.09	0.05	–
Subic	0.68*	0.43	0.85*	0.93*	− 0.15	–
Presubiculum
Tot. PSB	0.54	0.46	0.34	0.22	0.30	0.16	–
PSB1	0.42	0.34	0.39	0.18	0.17	0.15	0.96*	–
PSB3	0.69*	0.55†	0.48	0.36	0.33	0.31	0.96*	0.90*	–
Affiliation states
Proximity	− 0.49	− 0.41	− 0.31	− 0.25	− 0.21	− 0.08	− 0.88*	− 0.80*	− 0.88*	–
Contact	− 0.53	− 0.35	− 0.40	− 0.36	− 0.28	− 0.17	− 0.91*	− 0.84*	− 0.91*	0.98*	–
Tail twine	− 0.58	− 0.62	− 0.54	− 0.63†	0.14	− 0.58	− 0.54	− 0.46	− 0.60	0.67†	0.69†	–
Infant carrying
Carrying	− 0.32	− 0.01	0.03	− 0.34	− 0.49	− 0.47	− 0.13	− 0.07	− 0.10	0.01	0.11	− 0.11	–
Covariates
Age	0.12	0.29	0.53	0.16	− 0.54	0.29	0.01	0.18	0.11	0.05	0.07	− 0.13	0.62	–
Weight	− 0.02	− 0.08	0.38	0.18	− 0.27	0.06	− 0.28	− 0.15	− 0.23	0.23	0.18	0.07	0.89*	0.61†	-
Pair tenure	− 0.02	− 0.31	− 0.17	− 0.33	0.62†	− 0.33	− 0.01	0.02	0.03	0.33	0.29	0.79*	− 0.33	− 0.07	− 0.08

The correlation table shows the Pearson correlations between average OXTR binding density (in each subregion), average pair mate affiliation states, and average infant carrying. There were 10 subjects used in correlations between OXTR binding in different brain regions, eight subjects used in correlations between OXTR binding and pair mate affiliation, and six subjects used in correlations between OXTR binding and infant carrying. * indicates p < 0.05; † indicates p < 0.10.

CA1, CA2/3, CA4 CA fields of the hippocampus, DG dentate gyrus, Subic subiculum, Tot. Hip. total hippocampus area (including CA1, CA2/3, CA4, DG, and Subic) , PSB1 presubiculum layer 1, PSB3 presubiculum layer 3, Tot. PSB total presubiculum area (including PSB1 and PSB3), P proximity, C contact, TT tail twine, Carry infant carrying.