Experimental design
Fos-TRAP2 mice (n=46) were infused bilaterally in NAc with 300 nL
of 1 mg/mL CTB-647 (Invitrogen). At 8-10 days post-surgery, mice were
single-caged and, after a further 3-4 days, assigned at random to the
following stimulus groups: social reward-social aversion (SR-SA, n=9),
SA-SR (n=8) (experimental social mice), SR-SR (n=8), SA-SA (n=8)
(control social mice), and no stimulus-no stimulus (No S-No S, n=11). To
adjust mice to the procedures of restraint and intraperitoneal (i.p.)
injection required for 4-hydroxytamoxifen (4-OHT) administration, on
post-surgery days 15-17 they received 2 daily i.p. injections of sterile
0.9% NaCl and 1 i.p. injection of castor oil:sunflower seed oil (1:4, 5
mL/kg). On day 18, mice underwent the first stimulus test, SR or SA (or
No S), during t0-90. Directly afterwards they received
an i.p. injection of 4-OHT. A period of 7 days was allowed for reporter
recombination and expression; this was assumed to be sufficient based on
in-house pilot tests and relevant literature . Mice then underwent the
second stimulus exposure, SA or SR (or No S), during
t0-90. Directly afterwards, mice were deeply
anaesthetized by injection of pentobarbital and transcardially
perfused-fixed. The brains were further processed for c-Fos
immunohistochemistry and quantification of CTB+,
tdTomato+, c-Fos+ neurons, and
combinations thereof, in the BA.