Effects of GABAergic inhibition on neocortical long-term potentiation in the chronically prepared rat

In this study we investigated the hypothesis whether P2-related differences tested in a visual priming paradigm are associated with theta phase-locking. We recorded the EEG from 31 electrodes and calculated phase-locking index and total power differences for frequencies between 2 and 20 Hz. ERPs (event-related potentials) were analyzed for P1, N1 and P2 components. P2 showed strongest task-related amplitude differences between congruent and incongruent targets. A source analyses was performed for the P2 component using sLoreta that revealed local generators of the P2 in parieto-occipital regions. Phase-locking analyses showed specific effects in the theta range (4-6 Hz) appearing in time windows at around the P2 component. We draw the conclusion that phase-locked theta reflect top-down regulation processes mediating information between memory systems and is in part involved in the modulation of the P2 component.