Distinct Neural Substrates Support Phonological and Orthographic Working Memory: Implications for Theories of Working Memory.

Jeremy Purcell,Brenda Rapp,Randi C Martin

doi:10.3389/fneur.2021.681141

Jeremy Purcell, Brenda Rapp + Show 1 more

Open Access

https://doi.org/10.3389/fneur.2021.681141

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Abstract

Prior behavioral and neuroimaging evidence supports a separation between working memory capacities in the phonological and orthographic domains. Although these data indicate distinct buffers for orthographic and phonological information, prior neural evidence does indicate that nearby left inferior parietal regions support both of these working memory capacities. Given that no study has directly compared their neural substrates based on data from the same individuals, it is possible that there is a common left inferior parietal region shared by both working memory capacities. In fact, those endorsing an embedded processes account of working memory might suggest that parietal involvement reflects a domain-general attentional system that directs attention to long-term memory representations in the two domains, implying that the same neural region supports the two capacities. Thus, in this work, a multivariate lesion-symptom mapping approach was used to assess the neural basis of phonological and orthographic working memory using behavioral and lesion data from the same set of 37 individuals. The results showed a separation of the neural substrates, with regions in the angular gyrus supporting orthographic working memory and with regions primarily in the supramarginal gyrus supporting phonological working memory. The results thus argue against the parietal involvement as supporting a domain-general attentional mechanism and support a domain-specific buffer account of working memory.

Highlights

IntroductionStudies of verbal working memory (WM) have often focused on phonological WM - the capacity for maintaining phonological codes for words or non-words as assessed by memory span (e.g., recall of a list of digits in order) or recognition/probe tasks (e.g., judging whether a probe word or non-word matches any item in a preceding list) [1,2,3]
Studies of verbal working memory (WM) have often focused on phonological WM - the capacity for maintaining phonological codes for words or non-words as assessed by memory span or recognition/probe tasks [1,2,3]
In the current study, we evaluated whether the neural substrates for phonological and orthographic WM differ, as revealed through multivariate lesion symptom mapping of individuals with brain damage who were assessed on phonological WM and orthographic WM capacity

Summary

Introduction

Studies of verbal working memory (WM) have often focused on phonological WM - the capacity for maintaining phonological codes for words or non-words as assessed by memory span (e.g., recall of a list of digits in order) or recognition/probe tasks (e.g., judging whether a probe word or non-word matches any item in a preceding list) [1,2,3]. Neuropsychological evidence has supported the existence of other verbal WM capacities, those involved in maintaining semantic [4, 5] and orthographic information [for an overview see [6, 7]]. With regard to the latter, orthographic WM ( referred to as the graphemic buffer) is argued to be involved in retaining the identity and order of letters during the spelling of individual. The aim of the current study is to use lesion-symptom mapping on the same set of brain-damaged individuals to determine whether there is neural evidence for distinct phonological and orthographic WM capacities

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