Allocation of littermates to experimental tests

Each dam provided four male mice to the study. Littermates were tested according to the schedule reported in the table. E.g. mouse 2 performed the novelty-seeking test between PND 37-41 and was then assessed for immune response between PND 90-104. This schedule was adopted in order to maximize the information obtained by each mouse and to minimize the potential carry-over effects due to previous testing. In one case we could not use naïve mice; therefore we first exposed mice to the least stressful procedure (novelty seeking) and then waited a long time before the second test (immune resistance).