Recently, elevated ongoing pre-stimulus beta power (13-17 Hz) at encoding has been
associated with subsequent memory formation for visual stimulus material. It is unclear
whether this activity is merely specific to visual processing or whether it reflects a state
facilitating general memory formation, independent of stimulus modality. To answer
that question, the present study investigated the relationship between neural
pre-stimulus oscillations and verbal memory formation in different sensory modalities.
For that purpose, a within-subject design was employed to explore differences between
successful and failed memory formation in the visual and auditory modality.
Furthermore, associative memory was addressed by presenting the stimuli in
combination with background images. Results revealed that similar EEG activity in the
low beta frequency range (13-17 Hz) is associated with subsequent memory success,
independent of stimulus modality. Elevated power prior to stimulus onset differentiated
successful from failed memory formation. In contrast, differential effects between
modalities were found in the theta band (3-7 Hz), with an increased oscillatory
activity before the onset of later remembered visually presented words. In addition,
pre-stimulus theta power dissociated between successful and failed encoding of
associated context, independent of the stimulus modality of the item itself. We therefore
suggest that increased ongoing low beta activity reflects a memory-promoting state,
which is likely to be moderated by modality-independent attentional or inhibitory
processes, whereas high ongoing theta power is suggested as an indicator of the
enhanced binding of incoming interlinked information.