Figure 4.

Changes in [DA] in response to the fear-evoking CS are attributable to changes in the probability and amplitude of DA release events. a, d, Representative transient traces. White inverted triangles indicate transients. The panel underneath each color plot shows the converted [DA] traces. b, e, Transient probability calculated during 2 s bins for block 1 within the NAc core (i.e. averaged over first five tones for n = 5; 25 traces all together) and shell (i.e. averaged over first five tones for n = 6; 30 traces). Tone onset caused a significant decrease in transient probability that lasted the duration of the tone presentation, but returned to pretone levels following tone offset in the NAc core. Transient probability did not change with tone presentation in the NAc shell. c, f, Average transient amplitude before and following cue onset in the NAc core and shell. Cue onset did not alter transient amplitude in the NAc core, but increased transient amplitude in the NAc shell. *p < 0.05.