Abstract
Working memory (WM) is assumed to consist of a process that sustains memory representations in an active state (maintenance) and a process that operates on these activated representations (manipulation). We examined evidence for two distinct, concurrent cognitive functions supporting maintenance and manipulation abilities by testing brain activity as participants performed a WM alphabetization task. Maintenance was investigated by varying the number of letters held in WM and manipulation by varying the number of moves required to sort the list alphabetically. We found that both maintenance and manipulation demand had significant effects on behavior that were associated with different cortical regions: maintenance was associated with bilateral prefrontal and left parietal cortex, and manipulation with right parietal activity, a link that is consistent with the role of parietal cortex in symbolic computations. Both structural and functional architecture of these systems suggested that these cognitive functions are supported by two dissociable brain networks. Critically, maintenance and manipulation functional networks became increasingly segregated with increasing demand, an effect that was positively associated with individual WM ability. These results provide evidence that network segregation may act as a protective mechanism to enable successful performance under increasing WM demand.
Highlights
Working memory (WM) is a fundamental ability that allows humans to process information not currently available to the senses
A comparison between the two types of WM processes was first examined behaviorally using behavioral responses to a Delayed Recognition Alphabetization Task (DRAT) during fMRI scanning (Fig. 1A). In this task Set Size is defined by the number of letters present within a stimulus array, while Sorting Steps are the minimum number of discrete changes required to transform the initial random letter array into the alphabetized array
The current paradigm quantifies the number of items to be held in working memory, and the complexity of the manipulation operation to be performed during the delay
Summary
Working memory (WM) is a fundamental ability that allows humans to process information not currently available to the senses. WM is typically assumed to consist of dissociable maintenance processes, which sustain information in an activated state, and manipulation processes, which operate on the maintained information[1] This distinction is fundamental for WM theory and it has been the focus of multiple fMRI studies[2,3,4,5]. In the typical manipulation task in which participants are asked to put letters in alphabetical order[4], the critical operation is mentally shifting the position of each letter into a new order The difficulty of this process depends on the number of “sorting steps” needed to achieve the reordering, which is a factor that has not been investigated in behavioral or fMRI studies of WM. It was expected that this segregation of processing would increase with task difficulty, insulating local processing regions from competing information from a separate subnetwork
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
