The intracranial studies we have discussed so far feature prominent theta power decreases, which are at odds with theta increases reported in many scalp EEG studies. There are however, several intracranial studies that show increases in theta power associated with successful encoding [13] or retrieval [14,54]. These intracranial studies found increases in theta by correlating power with a measure of the degree of associative memory rather than by comparing successful to unsuccessful trials. Below we discuss findings from three of these studies.
