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Lee H, Choi W, Park Y, Paik SB. Distinct role of flexible and stable encodings in sequential working memory. Neural Netw 2019; 121:419-429. [PMID: 31606611 DOI: 10.1016/j.neunet.2019.09.034] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 08/03/2019] [Accepted: 09/20/2019] [Indexed: 11/29/2022]
Abstract
The serial-position effect in working memory is considered important for studying how a sequence of sensory information can be retained and manipulated simultaneously in neural memory circuits. Here, via a precise analysis of the primacy and recency effects in human psychophysical experiments, we propose that stable and flexible codings take distinct roles of retaining and updating information in working memory, and that their combination induces serial-position effects spontaneously. We found that stable encoding retains memory to induce the primacy effect, while flexible encoding used for learning new inputs induces the recency effect. A model simulation based on human data, confirmed that a neural network with both flexible and stable synapses could reproduce the major characteristics of serial-position effects. Our new prediction, that the control of resource allocation by flexible-stable coding balance can modulate memory performance in sequence-specific manner, was supported by pre-cued memory performance data in humans.
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Affiliation(s)
- Hyeonsu Lee
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea.
| | - Woochul Choi
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea; Program of Brain and Cognitive Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea.
| | - Youngjin Park
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea.
| | - Se-Bum Paik
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea; Program of Brain and Cognitive Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea.
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Ahmad J, Swan G, Bowman H, Wyble B, Nobre AC, Shapiro KL, McNab F. Competitive interactions affect working memory performance for both simultaneous and sequential stimulus presentation. Sci Rep 2017; 7:4785. [PMID: 28684800 PMCID: PMC5500476 DOI: 10.1038/s41598-017-05011-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 06/05/2017] [Indexed: 11/13/2022] Open
Abstract
Competition between simultaneously presented visual stimuli lengthens reaction time and reduces both the BOLD response and neural firing. In contrast, conditions of sequential presentation have been assumed to be free from competition. Here we manipulated the spatial proximity of stimuli (Near versus Far conditions) to examine the effects of simultaneous and sequential competition on different measures of working memory (WM) for colour. With simultaneous presentation, the measure of WM precision was significantly lower for Near items, and participants reported the colour of the wrong item more often. These effects were preserved when the second stimulus immediately followed the first, disappeared when they were separated by 500 ms, and were partly recovered (evident for our measure of mis-binding but not WM precision) when the task was altered to encourage participants to maintain the sequentially presented items together in WM. Our results show, for the first time, that competition affects the measure of WM precision, and challenge the assumption that sequential presentation removes competition.
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Affiliation(s)
- Jumana Ahmad
- School of Psychology, University of Birmingham, Birmingham, UK.,Department of Forensic and Neurodevelopmental Science, Kings College London, London, UK
| | - Garrett Swan
- Department of Psychology, The Pennsylvania State University, Pennsylvania, USA
| | - Howard Bowman
- School of Psychology, University of Birmingham, Birmingham, UK.,Centre for Cognitive Neuroscience and Cognitive Systems (CCNCS), School of Computing, University of Kent, Canterbury, UK
| | - Brad Wyble
- Department of Psychology, The Pennsylvania State University, Pennsylvania, USA
| | - Anna C Nobre
- Department of Experimental Psychology and Oxford Centre for Human Brain Activity, University of Oxford, Oxford, UK
| | | | - Fiona McNab
- School of Psychology, University of Birmingham, Birmingham, UK. .,Department of Psychology, University of York, York, UK.
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