this gamma-50 pattern. Rewarded and non-rewarded trials have at least movement cessation (stop running) and movement initiation (start running) in common, thus those factors cannot account for the observed difference. A possibility is that gamma-50 is associated with appetitive approach movements specifically, such as the rat actually placing its snout in the reward delivery tube in order to catch expected food pellets. However, we observed the rats engaging in such behavior on both rewarded and non-rewarded trials, with if anything more vigorous food-searching behavior on non-rewarded trials. Hence, differences in approach or food-seeking behaviors are unlikely to account for the observed gamma-50 differences on rewarded vs. non-rewarded trials. A further potential explanation is that gamma-50 is simply associated with pausing or non-activity. While this could in theory be consistent with both the gamma-50 increase before turnarounds and the slow, sustained increase following reward delivery, it cannot explain the sharp early peak that follows reward delivery, or the persistence of gamma-50 beyond movement initiation. Furthermore, modulations in gamma-50 power developed over the first 10 laps or so (Figures 5 and 9). Taken together, these results strongly suggest that overt behaviors such as movement cessation or initiation, pausing, or approach cannot account
