Abstract
Precision defines successful behavior, yet the brain mechanisms promoting precision are unclear. Here, we dissect dopaminergic circuits controlling precision along a single behavioral dimension - the timing of action. We use an interval timing paradigm that requires participants to indicate their estimate of an interval of several seconds with a motor response. We find that humans with Parkinson's disease (PD) had increased timing variability that predicted PD-related cognitive deficits and executive dysfunction. Surprisingly, lesioning ventral tegmental area (VTA) dopamine neurons increased temporal variability. Further, GCaMP6s fiber photometry demonstrated that VTA dopamine neuron activity is strongly modulated at the start of temporal intervals, and that this trial start-related activity predicted temporal variability. Finally, we found that stimulation of VTA dopamine neurons improved timing by decreasing temporal variability in both intact and dopamine-depleted animals. Our data establish a model of cognitive symptoms of human PD and provide insight into the neuronal control of temporal variability, which impacts a wide range of executive functions.