Modulation of DA neuron burst firing by the vSub, the NAc, and the mPFC. A, As with firing rate, activation of the vSub did not cause a significant change in DA cell burst firing, although inactivation of the vSub did attenuate bursting. The mean % SIB of DA neurons (+SEM) recorded from rats receiving vehicle infusions (white bar), 0.25 or 0.75 μg of NMDA (black bars), or TTX (gray bar) into the vSub is shown. B, Similarly, glutamate transmission in the NAc also controls basal levels of burst firing of VTA DA neurons. The mean % SIB of DA neurons (+SEM) recorded from rats receiving vehicle infusions (same as A;white bar), infusions of kynurenic acid into the NAc in combination with vehicle infusions into the vSub (hatched bar), infusions of kynurenic acid into the NAc in combination with 0.75 μg of NMDA into the vSub (cross-hatched bar), or infusions of TTX into the mPFC in combination with 0.75 μg of NMDA into the vSub (gray bar) is shown. *p < 0.05 and **p < 0.01, versus control.C, Distribution of % SIB of all DA neurons recorded from rats receiving vehicle injection (C1) or infusions of TTX into the mPFC in combination with 0.75 μg of NMDA into the vSub (C2) is shown.