Principal component regression was used to extract the dopamine component from the voltammetric data (Heien et al., 2004). For each experiment a calibration set of cyclic voltammograms of dopamine and pH changes was obtained in vivo during different stimulations employing 6, 12 or 24 stimulus pulses as well as 2 different frequencies (30 or 60 Hz). Principal component regression analysis yielded dopamine and pH contributions as well as a residual from the measured data. Data was retained only if a low residual was found (Heien et al., 2005). The scaling factor to relate current to concentration was obtained by calibration of the carbon-fiber electrodes after the in vivo experiment (Logman et al., 2000).
