A, Sagittal brain sections of Adora2a-Cre mouse in bright field (left) and fluorescence (right) showing ChR2 expression in NAc core (NAc C) and projections to the ventral pallidum (VP). NAc Sh: nucleus accumbens shell, ac: anterior commissure, Tu: olfactory tubercle. B, Schematic of experimental configuration. C,
Top, Depolarizing current steps were applied to dMSNs before or during optogenetic stimulation of iMSNs axon collaterals at baseline and in gabazine. Bottom, Representative AP traces recorded in dMSNs under each condition. D, Number of APs during laser OFF and ON at baseline (black) and after gabazine (5 μM, orange) (n = 6). E, Percent inhibition of APs by opto-stimulation of iMSNs collaterals at baseline and gabazine. **p < 0.01. All data expressed as mean ± s.e.m.