Fig. 4: CCM self-regeneration and in vivo validation.

a Schematic for dynamic DA sensing in a flow cell. b Color plot (bottom) and current-time trace at 0.6 V (indicated by the white dashed line in the color plot, top) measured over nine consecutive injections of DA. 100 μL PBS containing 5 μM DA was injected into the flow cell approximately every 30 s. The color plot is generated from continuous background-subtracted voltammograms. c Background-subtracted voltammograms extracted from 100 DA sensing events using the same CCM in a flow cell. The waveforms were taken at the peak current times identified in the current-time traces at 0.6 V. d Schematic of DA sensing in the NAc by a CCM while electrically stimulating the MFB in rats. Representative trace of phasic DA release and corresponding background-subtracted color plot from electrical stimulation (60 Hz, 60 pulses at 300 µA; indicated by the red bar) of the MFB. NAc, nucleus accumbens; MFB, medial forebrain bundle. e Schematic for measurements of DA release in the NAc induced by 10% sucrose feeding in head-fixed mice (left) and representative voltammetric signal in response to reward delivery (right). The red triangle marker indicates the time point when the mouse started eating. Representative (f) current-time traces of, and (g) half-peak response time (t_50%) calculated from spontaneous phasic DA transients in freely behaving rats (n = 10, 8, 6, 6 DA transients). Data are presented as mean ± SEM. The mean value (center line), lower and upper quartile (box edges) are indicated in the box plot.