In rats, gamma-50 oscillations in striatum have been previously linked to movement initiation (Masimore et al., 2005) and reward processing (Kalenscher et al., 2008), while gamma-80 oscillations have been linked to reward delivery (Berke and Kunec, 2004). We thus compared the distributions of gamma-50 and gamma-80 power over spatial location on the track, as well as over laps. An example distribution from a single recording session is shown in Figures 5A,B; gamma-50 was increased at the reward sites, extending beyond departure before returning to baseline. Over laps, there was a tendency for power to increase overall (Figure 5A). In contrast, gamma-80 power appeared to “ramp up” to the reward sites (Figure 5B). To examine this impression over all sessions, positions were first converted to a standard, linearized metric, so that different maze configurations could be compared (Schmitzer-Torbert and Redish, 2004a). Average power (for correct, rewarded laps only) was then plotted as a function of both position on the linearized track, and lap number (Figures 5C,D). Averages over laps and position are shown to the top and to the right respectively.
