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Falling neonatal autopsy rates

2002; BMJ; Volume: 324; Issue: 7340 Linguagem: Inglês

10.1136/bmj.324.7340.749

0959-8138

T. Yee Khong,

Autopsy Techniques and Outcomes

Abstract Reading literature (e.g., an entire book) is an enriching experience that qualitatively differs from reading a single sentence; however, the brain dynamics of such context-dependent memory remains unclear. This study aimed to elucidate mnemonic neural dynamics during natural reading of literature by performing electroencephalogram (EEG) and functional magnetic resonance imaging (fMRI). Brain activities of human participants recruited on campus were correlated with their subsequent memory, which was quantified by semantic correlation between the read text and reports subsequently written by them based on state of the art natural language processing procedures. The results of the EEG data analysis showed a significant positive relationship between subsequent memory and fixation-related EEG. Sentence-length and paragraph-length mnemonic processes were associated with N1-P2 and P3 fixation-related potential (FRP) components and fixation-related theta-band (4-8 Hz) EEG power, respectively. In contrast, the results of fMRI analysis showed a significant negative relationship between subsequent memory and blood-oxygenation-level dependent (BOLD) activation. Sentence-length and paragraph-length mnemonic processes were associated with networks of regions forming part of the salience network and the default mode network (DMN), respectively. Taken together with the EEG results, these memory-related deactivations in the salience network and the DMN were thought to reflect the reading of sentences characterized by low mnemonic load and the suppression of task-irreverent thoughts, respectively. It was suggested that the context-dependent mnemonic process during literature reading requires large-scale network deactivation, which might reflect coordination of a range of voluntary processes during reading. Significance statement Context-dependent memory encoding during natural reading of literature was evaluated using electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) based on a subsequent memory paradigm. Subsequent memory was quantified by semantic correlation between the read text and reports subsequently written by the participants, based on a recent natural language processing procedure. Our results demonstrated a positive correlation between subsequent memory and fixation-related EEG and a negative correlation with fMRI activity. Sentence-length and paragraph-length processes were associated with regions belonging to the salience network and the default mode network, respectively. This is the first demonstration that memory encoding during literature reading is associated with large-scale network deactivations, which might reflect the coordination of a range of voluntary processes during reading.