Differential Medial Temporal Lobe and Parietal Cortical Contributions to Real-world Autobiographical Episodic and Autobiographical Semantic Memory

Thackery I Brown,Jesse Rissman,Anthony D Wagner,Melina R Uncapher,Tiffany E Chow

doi:10.1038/s41598-018-24549-y

Abstract

Autobiographical remembering can depend on two forms of memory: episodic (event) memory and autobiographical semantic memory (remembering personally relevant semantic knowledge, independent of recalling a specific experience). There is debate about the degree to which the neural signals that support episodic recollection relate to or build upon autobiographical semantic remembering. Pooling data from two fMRI studies of memory for real-world personal events, we investigated whether medial temporal lobe (MTL) and parietal subregions contribute to autobiographical episodic and semantic remembering. During scanning, participants made memory judgments about photograph sequences depicting past events from their life or from others’ lives, and indicated whether memory was based on episodic or semantic knowledge. Results revealed several distinct functional patterns: activity in most MTL subregions was selectively associated with autobiographical episodic memory; the hippocampal tail, superior parietal lobule, and intraparietal sulcus were similarly engaged when memory was based on retrieval of an autobiographical episode or autobiographical semantic knowledge; and angular gyrus demonstrated a graded pattern, with activity declining from autobiographical recollection to autobiographical semantic remembering to correct rejections of novel events. Collectively, our data offer insights into MTL and parietal cortex functional organization, and elucidate circuitry that supports different forms of real-world autobiographical memory.

Highlights

Cognitive science has traditionally divided declarative memory into systems underlying episodic memory and general semantic memory, and drawing a contrast between episodic and semantic memory has proven useful for understanding the neural systems that underlie these qualitatively distinct forms of remembering
Autobiographical remembering can depend on two forms of memory: episodic memory and autobiographical semantic memory
Our experiment utilized wearable camera technology[64] to enable us to catalog a broad set of potentially memorable events from participants’ daily lives, and to subsequently examine the neural correlates of different forms of real-world autobiographical memory for stimuli drawn from these events

Summary

Introduction

Cognitive science has traditionally divided declarative memory into systems underlying episodic memory (autobiographical events) and general semantic memory, and drawing a contrast between episodic and semantic memory has proven useful for understanding the neural systems that underlie these qualitatively distinct forms of remembering. While autobiographical semantics can be experienced independent of recalling a specific experience, there is debate about whether the neural substrates of episodic recollection, including the medial temporal lobe (MTL) and subregions of parietal cortex, contribute to autobiographical semantic remembering. A third line of evidence, using network-level analyses targeting autobiographical memory, laboratory-based episodic memory, and (non-autobiographical) semantic memory, suggests that a common neural network may underlie the retrieval of declarative memories regardless of memory content[5]. Perirhinal cortex, by contrast, has been posited to play a role in semantic coding, including during episodic memory paradigms[29,30,31,32,33,34], raising the possibility that content representations in anterior MTL cortex contribute to autobiographical semantic remembering. A fundamental question is whether the PPC regions that show parietal Old/New, decision uncertainty, and episodic recollection effects contribute to autobiographical semantic remembering

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Results

Conclusion