Context Memory Encoding and Retrieval Temporal Dynamics are Modulated by Attention across the Adult Lifespan.

Soroush Mirjalili,Taylor James,Audrey Duarte,Jonathan Strunk,Patrick Powell

doi:10.1523/eneuro.0387-20.2020

Abstract

Episodic memories are multidimensional, including simple and complex features. How we successful encode and recover these features in time, whether these temporal dynamics are preserved across age, even under conditions of reduced memory performance, and the role of attention on these temporal dynamics is unknown. In the current study, we applied time-resolved multivariate decoding to oscillatory electroencephalography (EEG) in an adult lifespan sample to investigate the temporal order of successful encoding and recognition of simple and complex perceptual context features. At encoding, participants studied pictures of black and white objects presented with both color (low-level/simple) and scene (high-level/complex) context features and subsequently made context memory decisions for both features. Attentional demands were manipulated by having participants attend to the relationship between the object and either the color or scene while ignoring the other context feature. Consistent with hierarchical visual perception models, simple visual features (color) were successfully encoded earlier than were complex features (scenes). These features were successfully recognized in the reverse temporal order. Importantly, these temporal dynamics were both dependent on whether these context features were in the focus of one’s attention, and preserved across age, despite age-related context memory impairments. These novel results support the idea that episodic memories are encoded and retrieved successively, likely dependent on the input and output pathways of the medial temporal lobe (MTL), and attentional influences that bias activity within these pathways across age.

Highlights

Numerous episodic memory studies have investigated the neural underpinnings of successful encoding and retrieval of different kinds of context features including color, spatial, and various semantic attributes (Uncapher et al, 2006; Awipi and Davachi, 2008; Duarte et al, 2011; Staresina et al, 2011; Park et al, 2014; Liang and Preston, 2017)
Why would the temporal dynamics of successful context encoding and/or retrieval be impacted by context feature type? Numerous perception studies have established that simple features like color are discriminated earlier in time and by earlier visual cortical regions than more complex features like scenes (Carlson et al, 2013; Kravitz et al, 2014; Clarke et al, 2015)
To assess the effect of age on context memory performance, we computed d9 for color and scene features when they were the target, and distractor, separately, using the following formula: d9 = Z – Z

Summary

Introduction

Numerous episodic memory studies have investigated the neural underpinnings of successful encoding and retrieval of different kinds of context features including color, spatial, and various semantic attributes (Uncapher et al, 2006; Awipi and Davachi, 2008; Duarte et al, 2011; Staresina et al, 2011; Park et al, 2014; Liang and Preston, 2017). Little is known about the time course with which different context features are successfully encoded and retrieved. Some regions supporting feature perception support successful encoding of the features to which they are sensitive (Hayes et al, 2007; Awipi and Davachi, 2008; Preston et al, 2010; Dulas and Duarte, 2011). It is possible that simple context features may be successfully encoded into memory before complex ones

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