Subjective Sense of Memory Strength and the Objective Amount of Information Accurately Remembered Are Related to Distinct Neural Correlates at Encoding

Abstract

Although commonly used, the term memory strength is not well defined in humans. Besides durability, it has been conceptualized by retrieval characteristics, such as subjective confidence associated with retrieval, or objectively, by the amount of information accurately retrieved. Behaviorally, these measures are not necessarily correlated, indicating that distinct neural processes may underlie them. Thus, we aimed at disentangling neural activity at encoding associated with either a subsequent subjective sense of memory strength or with a subsequent objective amount of information remembered. Using functional magnetic resonance imaging (fMRI), participants were scanned while incidentally encoding a series of photographs of complex scenes. The next day, they underwent two memory tests, quantifying memory strength either subjectively (confidence on remembering the gist of a scene) or objectively (the number of details accurately remembered within a scene). Correlations between these measurements were mutually partialed out in subsequent memory analyses of fMRI data. Results revealed that activation in left ventral-lateral prefrontal cortex and temporoparietal junction predicted subsequent confidence ratings. In contrast, parahippocampal and hippocampal activity predicted the number of details remembered. Our findings suggest that memory strength may reflect a functionally heterogeneous set of (at least two) phenomena. One phenomenon appears related to prefrontal and temporoparietal top-down modulations, resulting in the subjective sense of memory strength that is potentially based on gist memory. The other phenomenon is likely related to medial-temporal binding processes, determining the amount of information accurately encoded into memory. Thus, our study dissociated two distinct phenomena that are usually described as memory strength.

Understanding Low Reliability of Memories for Neutral Information Encoded under Stress: Alterations in Memory-Related Activation in the Hippocampus and Midbrain

“…First, this paradigm has been shown to assess memory for the gist of an episode (Adolphs et al, 2001(Adolphs et al, , 2005Qin et al, 2011). Thus, it allowed us to more closely examine the hypothesis of how acute stress leads to a shift of mnemonic processing toward extracting central thematic information, or gist.…”

Dissociable Neural Networks Supporting Metacognition for Memory and Perception

“…However, whereas the mnemonic metacognitive network found in the Baird et al (2013) study included right parietal clusters, indications of parietal involvement in episodic retrieval success are more generally associated with left hemispheric activations (Wagner et al, 2005). Similarly, an investigation into the subjective sense of memory strength found that confidence in relating the gist of a scene correlated with left rather than right hemisphere lateral parietal activations (Qin et al, 2011). The significance of this discrepancy regarding laterality is unclear.…”

Factors Influencing Polychronous Group Sustainability as a Model of Working Memory

“…in the hippocampus as opposed to smaller percentage in cortical areas [17]. This could also relate to the fMRI data results revealing that activation in left ventral lateral prefrontal cortex and temporoparietal junction predicted subsequent confidence ratings and in contrast, parahippocampal and hippocampal activity predicted the number of details remembered [13].…”

“…Unfortunately, literature is not very clear on how to measure aspects of working memory [13] such as sustainability, item retention, delay interval and the decay of memory traces etc. Here we therefore measure PNG quality in two ways: 1. by their strength, and by 2. their duration.…”