Recent physiological studies suggest that in motion discrimination tasks, neurons in the lateral intraparietal (LIP) area integrate sensory evidence during decision making process by carrying persistent response selective to the saccadic response. LIP neurons also discharge at high frequency shortly before the saccade onset. We propose that the later response is due to the activity form the bursting neurons in the Superior Colliculus (SC). To test the hypothesis we developed a decision making model with populations of neurons in LIP, Basal Ganglia (BG) and SC where BG and SC process the threshold detection and action generation. The model successfully describes the LIP activity from the experiment, and is also consistent with the behavioral measurements.