Abstract
Although activation/deactivation of specific brain regions has been shown to be predictive of successful memory encoding, the relationship between time-varying large-scale brain networks and fluctuations of memory encoding performance remains unclear. Here, we investigated time-varying functional connectivity patterns across the human brain in periods of 30-40 s, which have recently been implicated in various cognitive functions. During functional magnetic resonance imaging, participants performed a memory encoding task, and their performance was assessed with a subsequent surprise memory test. A graph analysis of functional connectivity patterns revealed that increased integration of the subcortical, default-mode, salience, and visual subnetworks with other subnetworks is a hallmark of successful memory encoding. Moreover, multivariate analysis using the graph metrics of integration reliably classified the brain network states into the period of high (vs. low) memory encoding performance. Our findings suggest that a diverse set of brain systems dynamically interact to support successful memory encoding.
Highlights
In everyday life, new memories of events and episodes are constantly formed, sometimes incidentally
To investigate dynamic fluctuations in functional connectivity (FC) patterns associated with memory encoding performance, we examined time-varying FC within a period of 36 s
Based on the individual participants’ responses in the surprise memory test, the picture trials of the incidental encoding task were categorized into high-confidence hit (HH, the pictures later remembered with high confidence; 48.9 ± 15.4%), low-confidence hit (LH, the pictures later remembered with low confidence; 18.8 ± 8.9%), or Miss trials
Summary
New memories of events and episodes are constantly formed, sometimes incidentally. Evidence from neuroimaging studies has shown that activation/deactivation of specific sets of brain regions is predictive of successful memory encoding (Buckner and Wheeler, 2001; Fernandez and Tendolkar, 2001; Morcom et al, 2003; Simons and Spiers, 2003; Kao et al, 2005; Sommer et al, 2005; Uncapher and Rugg, 2009). Studies using functional magnetic resonance imaging (fMRI) have demonstrated that regions such as the medial temporal lobes (MTL) and the prefrontal cortex show greater activation in response to stimuli successfully recalled later (vs forgotten), a phenomenon referred to as the subsequent memory effect (SME) (Wagner et al, 1998; Brewer et al, 1998; Paller and Wagner, 2002; Reber et al, 2002; Uncapher and Rugg, 2005; Kim, 2011).
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