Fig. 7.

DA overflow recorded with amperometry in response to stimulation trains of five pulses with intervals of 0.2, 0.5, and 1 sec. a, Examples of amperometric recordings of DA overflow in response to stimulation trains of five pulses at 2 Hz in a slice from a WT and a D₂−/− mouse (arrowsindicate peak of evoked DA overflow; vertical lines are stimulation artifacts). b, Average response (mean ± SEM) to pulse numbers 2–5 expressed as a fraction of the maximal response to the first pulse for stimulation trains with intervals of 1, 0.5, and 0.2 sec for WT mice (n = 5 for 1 and 0.5 sec intervals; n = 3 for 0.2 sec interval) and D₂−/− mice (n = 8 for 1 and 0.5 sec intervals; n = 5 for 0.2 sec interval). Responses to all three stimulation trains were significantly different from WT (p < 0.01).