Furthermore, from the uptake rate of dopamine by the DAT, we can estimate the distance it can diffuse from the release sites to the electrode. Dopamine has a half life of ~0.05 s in the NAc, therefore, its concentration will halve in ~5 μm (Garris et al., 1994). In the NAc shell, with fewer uptake sites (Jones et al., 1996) dopamine can diffuse twice as far before its concentration is halved (i.e., ~ 10 μm). Thus, to detect released dopamine in our experiments, its release site must be in very close proximity to the detecting electrode. Similarly, the release sites must be a similar distance from receptor sites on the dendrites. To measure both DA release and NAc cell firing, the electrode must also be positioned close to the cell body.
