To verify if selective stimulation of CINs is sufficient to evoke accumbal DA release, optical stimulation was delivered by a 125 μm optical fiber placed on the surface of the slice, while real-time changes in DA release were measured with fast-scan cyclic voltammetry (FSCV) using a glass-encased carbon fiber placed 100 μm away from the optical fiber (Fig. 1C). Single pulse optical stimulation (4 ms duration square, 10 mW) in coronal slices of NAc from ChR2-expressing ChAT-Cre mice elicited an immediate and robust increase in DA levels, which was comparable to single pulse electrical stimulation (400 mA; 4 ms duration square; 23 paired measurements made in 12 animals) (Figure 1D-G). This result confirms that endogenous ACh actions on DA terminals are sufficient to elicit DA release in the NAc.
