Social reward-fibre photometry (SR-FP) protocol
Each SR-FP test comprised 3 consecutive phases of 20 min: no stimulus-FP to allow the mouse to adjust to the test environment including the patch cord and to check the optical signal, distal SR-FP and proximal SR-FP (Table S1). The mouse was transferred in its home cage to the attenuation chamber and connected to the patch cord for no stimulus-FP. It was then disconnected from the patch cord and transferred to the home cage of a (pro-)estrous female, which was separated longitudinally into two equal compartments by a transparent and perforated Plexiglas divider. The male and female were in separate compartments, the male was reconnected to the patch cord, and distal SR-FP was conducted during which the mice could have distal social contact i.e. approach and contact (Table S2). For proximal SR-FP, the divider was removed and the mice could have proximal socio-sexual contact (Table S2). The patch cord was then disconnected, and the mouse returned to its home cage. Two such tests were conducted on 2 consecutive days.