as biomarker in drug discovery (McNaughton et al. 2007). PFC 2 Hz rhythm was not studied in this experimental paradigm and thus the first goal of this study was to test whether RPO stimulation can modify the slow PFC rhythm as well as HC theta, and whether there is any meaningful relationship between the two signals. As we expected, RPO stimulation shifted the frequency of PFC oscillations in a stimulus intensity-dependent manner within the entire “awake” range of 2–5 Hz. The amplitude of this signal however decreased with increasing stimulus intensity, i.e. changed in the direction opposite to HC theta.
