In the simulations, ramping neuronal activity in the CD leads to a gradual decrease of GPe activity and a corresponding increase of STN activity, which cancels out the direct impact of CD output on SNr activity. This balancing effect weakens, however, when GPe activity becomes sufficiently low and disappears entirely when the GPe activity reaches zero and STN activity correspondingly plateaus. The continued rise in CD output then sharply suppresses SNr activity. The abrupt decline of SNr activity releases the downstream suppression of the SC, which combined with direct excitation of decision neurons in the cortex results in a burst of activity in the SC. The feedback from the SC to the cortex in turn recruits the inhibitory cortical population, Cxi, which terminates the evidence accumulation process there. Thus, the extension of a previous model to include the indirect pathway allows appropriate evidence accumulation thresholding and decision responses in the presence of more realistic neuronal activity at the striatum.