Neuroimaging studies of working memory:

Abstract

Working memory (WM), a system for actively maintaining and manipulating information, has been one of the most studied topics in cognitive psychology and cognitive neuroscience. It is fundamental to the performance of many cognitive tasks and day-to-day activities: imagining how an object might look from a different perspective, remembering a phone number while taking something out of the oven, solving a math problem "in your head," or planning the next move in a chess game, to give just a few examples. WM is sometimes conceptualized as an active workspace because it is closely linked with the voluntary allocation of attention. The study of WM is central to understanding how memory and thought work. Models of Working MemoryBaddeley (1992) and colleagues have given one of the clearest conceptualizations of WM. They proposed two basic subsystems for maintaining information-the phonological loop and the visuospatial sketch pad, for remembering verbal and visual information, respectively. These subsystems are further subdivided into passive storage and active rehearsal mechanisms. Manipulation of information held in WM is accomplished by a third, central executive system. Most broad architectures of human cognition incorporate some version of this framework. In this meta-analysis, we are concerned with the neural basis of WM. Controversies on the Organization of the Frontal LobesSome of the earliest neuroimaging studies of WM addressed questions raised in part by Baddeley's (1992) framework-particularly, how the putative components of WM map onto brain systems and whether patterns of brain activation respect the distinctions between types of WM apparent in behavioral studies.Organization by material type. One of the major dimensions along which WM systems may be subdivided is the type of material stored in WM. Three types of material have been most commonly studied: verbal, spatial, and object information. Verbal information includes words, letters, or other material that is primarily coded linguisticallyand is likely to be maintained by a rehearsal process involving a subvocal sequential generation of memory items. Spatial information includes information about the spatial positions of stimuli. Object information includes storage of nonspatial visual features or object identity.We tested three hypotheses about the organization of WM by material type. One organizationalprinciple, based on monkey and human studies (e.g., Funahashi, Chafee, & Goldman- Wilson, 255 Copyright 2003 Psychonomic Society, Inc. Neuroimaging studies of working memory:A meta-analysis TOR D. WAGER and EDWARD E. SMITH University of Michigan, Ann Arbor, MichiganWe performed meta-analyses on 60 neuroimaging (PET and fMRI) studies of working memory (WM), considering three types of storage material (spatial, verbal, and object), three types of executive function (continuous updating of WM, memory for temporal order, and manipulation of information in WM), and interactions between material and executive function. Analyses of material type showed ...

Abstinent adolescent marijuana users show altered fMRI response during spatial working memory

“…MJ teens displayed reduced SWM BOLD response relative to control teens in the right dorsolateral prefrontal cortex, which is consistently implicated in spatial working memory (Wager and Smith, 2003). In contrast, our previous work revealed increased SWM response in this region among heavy alcohol-and marijuana-using teens who had been abstinent an average of just 8 days (Schweinsburg et al, 2005b).…”

“…MJ teens in the current study displayed increased response in parietal cortex, yet diminished activation in prefrontal cortex, both of which play important roles in SWM (Wager and Smith, 2003). Frontal cortex may be primarily involved in general executive functioning components of working memory tasks, while superior parietal cortex may more specifically subserve attentional allocation and visuospatial rehearsal demands of SWM (Diwadkar et al, 2000;Wager and Smith, 2003;Wager et al, 2004). Thus, abstinent MJ teens may rely more on spatial rehearsal and attention rather than general executive abilities to perform the task, resulting in increased recruitment of posterior parietal cortex, but decreased right dorsolateral prefrontal activity.…”

“…Compared with controls, MJ teens demonstrated increased SWM activation in right posterior parietal cortex, a region involved in SWM and attentional processes (Wager and Smith, 2003;Wager et al, 2004). Research on parietal functioning during working memory among individuals with substance use disorders has been somewhat inconsistent.…”

Lost in localization: The need for a universal coordinate database

“…It should also be possible to conduct searches for sets of coordinates, so that it is possible to search for networks (i.e., find papers that report activations within a set of locations). In addition, we consider it important that quantitative meta-analyses (Chein et al, 2002;Laird et al, 2005a;Turkeltaub et al, 2002;Wager & Smith, 2003) be included in the database and it be possible to restrict searches to these types of papers. This would allow for the identification of relevant papers on a meta-level.…”

Neural activity patterns between different executive tasks are more similar in adulthood than in adolescence

“…It is commonly held that a “frontoparietal control network” is crucial to all executive processes (Badre & D'Esposito, 2007; Fedorenko et al., 2013; Vincent et al., 2008). In addition to this shared brain circuitry, brain imaging studies have repeatedly observed a differential functional organization or unique response patterns within shared brain regions between different executive control components (Marklund et al., 2007; Miyake et al., 2000; Stiers, Mennes, & Sunaert, 2010; Wager & Smith, 2003). It is therefore likely that the neural networks recruited by executive functions demonstrate both unity and diversity (Friedman & Miyake, 2017).…”