FSCV Technique for Dopamine Release Measurement

FSCV was performed using carbon fiber microelectrodes encased in fused-silica capillary tubing (Polymicro Technologies) (Clark et al., 2010 (link)). The carbon fiber microelectrode was positioned in the dorsomedial striatum at stereotaxic coordinates: A-P = 1.2 mm, M-L = 1.2 mm, D-V = 3.5 below the dura and a waveform was applied at a frequency of 60 Hz. After 40 min, the waveform frequency was reduced to 10 Hz for 10 min or until baseline recordings stabilized. Next, the carbon fiber microelectrode was lowered into the nucleus accumbens in 0.05 mm increments until maximum dopamine release was observed (D-V coordinates ranged from 3.60–3.98 below bregma, average 3.80). An Ag/AgCl reference electrode was placed in the contralateral hemisphere. The stimulation electrode (Plastics One) was placed above the PPTg at stereotaxic coordinates: A-P: −4.6 mm, M-L: 0.8 mm and lowered in 0.1 mm increments from 2.5 mm below the dura until optimal dopamine release was observed after 1 s stimulations of 60 Hz (average D-V coordinate: 2.7 mm below the dura). For the MFB stimulations, the stereotaxic coordinates were A-P: 2.4 mm, M-L: 1.1 mm, DV: 0.1 increments from 4 mm.