title: Blocking of irrelevant memories by posterior alpha activity boosts memory encoding.
abstract: In our daily lives, we are confronted with a large amount of information. Because only a small fraction can be encoded in long-term memory, the brain must rely on powerful mechanisms to filter out irrelevant information. To understand the neuronal mechanisms underlying the gating of information into long-term memory, we employed a paradigm where the encoding was directed by a "Remember" or a "No-Remember" cue. We found that posterior alpha activity increased prior to the "No-Remember" stimuli, whereas it decreased prior to the "Remember" stimuli. The sources were localized in the parietal cortex included in the dorsal attention network. Subjects with a larger cue-modulation of the alpha activity had better memory for the to-be-remembered items. Interestingly, alpha activity reflecting successful inhibition following the "No-Remember" cue was observed in the frontal midline structures suggesting preparatory inhibition was mediated by anterior parts of the dorsal attention network. During the presentation of the memory items, there was more gamma activity for the "Remember" compared to the "No-Remember" items in the same regions. Importantly, the anticipatory alpha power during cue predicted the gamma power during item. Our findings suggest that top-down controlled alpha activity reflects attentional inhibition of sensory processing in the dorsal attention network, which then finally gates information to long-term memory. This gating is achieved by inhibiting the processing of visual information reflected by neuronal synchronization in the gamma band. In conclusion, the functional architecture revealed by region-specific changes in the alpha activity reflects attentional modulation which has consequences for long-term memory encoding.
authors: Department of Nuclear Medicine, Seoul National University College of Medicine, Seoul, 110-744, Korea; Institute of Radiation Medicine, Medical Research Center, Seoul National University, Seoul, 110-744, Korea; Interdisciplinary Program in Cognitive Science, Seoul National University, Seoul, 151-742, Korea.
authors: Hyojin
authors: H
authors: Park
authors: Dong Soo
authors: DS
authors: Lee
authors: Eunjoo
authors: E
authors: Kang
authors: Hyejin
authors: H
authors: Kang
authors: Jarang
authors: J
authors: Hahm
authors: June Sic
authors: JS
authors: Kim
authors: Chun Kee
authors: CK
authors: Chung
authors: Ole
authors: O
authors: Jensen
mesh_terms: D000328:Adult; D000513:Alpha Rhythm; D001288:Attention / Q000502:physiology; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D003463:Cues; D056344:Executive Function / Q000502:physiology; D005260:Female; D065818:Gamma Rhythm; D006801:Humans; D008279:Magnetic Resonance Imaging; D015225:Magnetoencephalography; D008297:Male; D008568:Memory / Q000502:physiology*; D009483:Neuropsychological Tests; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010775:Photic Stimulation; D012815:Signal Processing, Computer-Assisted; D055815:Young Adult
keywords: electroencephalography (EEG); episodic memory; gamma; magnetoencephalography (MEG); oscillations; synchronization