We report that in rats running a spatial decision task, gamma-50 (45–55 Hz) and gamma-80 (70–85 Hz) oscillations in ventral striatal LFPs exhibited distinct relationships to behavior, task events, and spiking activity. Gamma-50 power was increased following reward delivery and before movement initiation; in contrast, gamma-80 power ramped up gradually to reward locations. Gamma-50 power was low and contained little structure early during sessions, but developed a stable pattern within 10 laps, while gamma-80 power was high during early laps, particularly at the final choice point, and returned to a relatively stable level within a similar timeframe. These patterns were consistent across subjects. Putative FSIs exhibited a variety of spiking relationships with both gamma-50 and gamma-80, including phase preference, independent firing rate tuning to gamma-50 and gamma-80 power, and independent coherence at gamma-50 and gamma-80. Implications of these results are discussed below.
