||Recent investigations into the neural structures and mechanisms that underlie interval timing have revealed that the striatum is essential to interval timing processes (Harrington & Haaland, 1999). Although electrophysiological recording studies have shown that striatal neurons can encode specific durations of time (Matell, Meck, & Nicolelis, 2003), it remained unclear whether striatal neurons can abstractly encode specific durations, or whether the temporal information was embedded within striatal motor coding. This study evaluated these two hypotheses by recording from striatal neurons while rats performed a variant of the peak-interval procedure. In this experiment, rats were trained to respond on different nosepokes for food reward under two simultaneously active reinforcement schedules: a variable-interval (VI-15s) schedule and a fixed-interval (FI-15s) schedule of reinforcement. A subset of striatal neurons (23/88 single units) were modulated as a function of time during FI and VI responding, and were also activated by motor activity that occurred during transitions between responding. Another group of striatal neurons (52/88 single units), were differentially activated during the start and/or stop of FI responding as compared to VI responding. The results indicate that neurons in the striatum that encode motor activity are modulated by the processing of temporal information, and are also involved in the decision processes associated with the initiation and termination of a temporal estimate.