Figure 2.

Subsequent memory effect. Comparison of spectral power for successful and unsuccessful memory encoding events (remembered/forgotten) based on hippocampal depth electrode recordings from 300 to 1300 ms following item presentation. Values represent fixed-effect coefficients for the effect of successful recall on spectral power. A red asterisk indicates that the effect size is significant after correcting for multiple comparisons (p < 0.05). A, Power computed using traditional Morlet wavelets. B, The mixed power spectrum (before separating broadband and narrowband effects) shows the expected theta and alpha decreases, analogous to the results using wavelets. C, The fractal power spectrum (broadband only) likewise shows broad decreases in low frequency. D, The oscillatory power spectrum, which is computed as the difference of the mixed and fractal power spectra, exhibits an increase in theta power while retaining the same decrease in alpha power.