title: Induced electroencephalogram oscillations during source memory: familiarity is reflected in the gamma band, recollection in the theta band.
abstract: Modulations of oscillatory electroencephalogram (EEG) activity in the induced gamma and theta frequency ranges (induced gamma and theta band responses; iGBRs: >30 Hz; iTBRs: approximately 6 Hz) have been associated with retrieval of information from long-term memory. However, the specific functional role of these two forms of oscillatory activity remains unclear. The present study examines theta- and gamma-oscillations within a dual-process framework, which defines "familiarity" and "recollection" as the two component processes of recognition memory. During encoding, participants were instructed to make "bigger/smaller than a shoebox" or "living/nonliving" decisions for different object pictures. During retrieval "old/new" recognition was followed (for items judged old) by a source discrimination task regarding the decision made for each item at encoding. iGBRs (35-80 Hz; 210-330 msec) were higher for correctly identified "old" relative to "new" objects. Importantly, they did not distinguish between successful and unsuccessful source judgments. In contrast, iTBRs (4-7.5 Hz; 600-1200 msec) were sensitive to source discrimination. We propose that iGBRs mirror early associative processes linked to familiarity-related retrieval processes, whereas iTBRs reflect later onsetting, episodic, recollection-related mechanisms.
authors.affiliation: Institute of Psychology, University of Leipzig, Leipzig, Germany. gruber@rz.uni-leipzig.de
authors.forename: Thomas
authors.initials: T
authors.lastname: Gruber
authors.forename: Dimitris
authors.initials: D
authors.lastname: Tsivilis
authors.forename: Claire-Marie
authors.initials: CM
authors.lastname: Giabbiconi
authors.forename: Matthias M
authors.initials: MM
authors.lastname: Müller
mesh_terms: D000293:Adolescent; D000328:Adult; D003627:Data Interpretation, Statistical; D004569:Electroencephalography; D004585:Electrooculography; D005260:Female; D006801:Humans; D008297:Male; D008568:Memory / Q000502:physiology*; D011939:Mental Recall / Q000502:physiology; D010775:Photic Stimulation; D013826:Theta Rhythm; D014796:Visual Perception / Q000502:physiology