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Parietal contributions to visual working memory depend on task difficulty.
Front Psychiatry 2012; 3:81FP

Abstract

The nature of parietal contributions to working memory (WM) remain poorly understood but of considerable interest. We previously reported that posterior parietal damage selectively impaired WM probed by recognition (Berryhill and Olson, 2008a). Recent studies provided support using a neuromodulatory technique, transcranial direct current stimulation (tDCS) applied to the right parietal cortex (P4). These studies confirmed parietal involvement in WM because parietal tDCS altered WM performance: anodal current tDCS improved performance in a change detection task, and cathodal current tDCS impaired performance on a sequential presentation task. Here, we tested whether these complementary results were due to different degrees of parietal involvement as a function of WM task demands, WM task difficulty, and/or participants' WM capacity. In Experiment 1, we applied cathodal and anodal tDCS to the right parietal cortex and tested participants on both previously used WM tasks. We observed an interaction between tDCS (anodal, cathodal), WM task difficulty, and participants' WM capacity. When the WM task was difficult, parietal stimulation (anodal or cathodal) improved WM performance selectively in participants with high WM capacity. In the low WM capacity group, parietal stimulation (anodal or cathodal) impaired WM performance. These nearly equal and opposite effects were only observed when the WM task was challenging, as in the change detection task. Experiment 2 probed the interplay of WM task difficulty and WM capacity in a parametric manner by varying set size in the WM change detection task. Here, the effect of parietal stimulation (anodal or cathodal) on the high WM capacity group followed a linear function as WM task difficulty increased with set size. The low WM capacity participants were largely unaffected by tDCS. These findings provide evidence that parietal involvement in WM performance depends on both WM capacity and WM task demands. We discuss these findings in terms of alternative WM strategies employed by low and high WM capacity individuals. We speculate that low WM capacity individuals do not recruit the posterior parietal lobe for WM tasks as efficiently as high WM capacity individuals. Consequently, tDCS provides greater benefit to individuals with high WM capacity.

Authors+Show Affiliations

Memory and Brain Laboratory, Department of Psychology, University of Nevada Reno, NV, USA.No affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

22973241

Citation

Jones, Kevin T., and Marian E. Berryhill. "Parietal Contributions to Visual Working Memory Depend On Task Difficulty." Frontiers in Psychiatry, vol. 3, 2012, p. 81.
Jones KT, Berryhill ME. Parietal contributions to visual working memory depend on task difficulty. Front Psychiatry. 2012;3:81.
Jones, K. T., & Berryhill, M. E. (2012). Parietal contributions to visual working memory depend on task difficulty. Frontiers in Psychiatry, 3, p. 81. doi:10.3389/fpsyt.2012.00081.
Jones KT, Berryhill ME. Parietal Contributions to Visual Working Memory Depend On Task Difficulty. Front Psychiatry. 2012;3:81. PubMed PMID: 22973241.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Parietal contributions to visual working memory depend on task difficulty. AU - Jones,Kevin T, AU - Berryhill,Marian E, Y1 - 2012/09/10/ PY - 2012/05/07/received PY - 2012/08/21/accepted PY - 2012/9/14/entrez PY - 2012/9/14/pubmed PY - 2012/9/14/medline KW - PPC KW - individual differences KW - tDCS KW - task difficulty KW - working memory SP - 81 EP - 81 JF - Frontiers in psychiatry JO - Front Psychiatry VL - 3 N2 - The nature of parietal contributions to working memory (WM) remain poorly understood but of considerable interest. We previously reported that posterior parietal damage selectively impaired WM probed by recognition (Berryhill and Olson, 2008a). Recent studies provided support using a neuromodulatory technique, transcranial direct current stimulation (tDCS) applied to the right parietal cortex (P4). These studies confirmed parietal involvement in WM because parietal tDCS altered WM performance: anodal current tDCS improved performance in a change detection task, and cathodal current tDCS impaired performance on a sequential presentation task. Here, we tested whether these complementary results were due to different degrees of parietal involvement as a function of WM task demands, WM task difficulty, and/or participants' WM capacity. In Experiment 1, we applied cathodal and anodal tDCS to the right parietal cortex and tested participants on both previously used WM tasks. We observed an interaction between tDCS (anodal, cathodal), WM task difficulty, and participants' WM capacity. When the WM task was difficult, parietal stimulation (anodal or cathodal) improved WM performance selectively in participants with high WM capacity. In the low WM capacity group, parietal stimulation (anodal or cathodal) impaired WM performance. These nearly equal and opposite effects were only observed when the WM task was challenging, as in the change detection task. Experiment 2 probed the interplay of WM task difficulty and WM capacity in a parametric manner by varying set size in the WM change detection task. Here, the effect of parietal stimulation (anodal or cathodal) on the high WM capacity group followed a linear function as WM task difficulty increased with set size. The low WM capacity participants were largely unaffected by tDCS. These findings provide evidence that parietal involvement in WM performance depends on both WM capacity and WM task demands. We discuss these findings in terms of alternative WM strategies employed by low and high WM capacity individuals. We speculate that low WM capacity individuals do not recruit the posterior parietal lobe for WM tasks as efficiently as high WM capacity individuals. Consequently, tDCS provides greater benefit to individuals with high WM capacity. SN - 1664-0640 UR - https://www.unboundmedicine.com/medline/citation/22973241/Parietal_contributions_to_visual_working_memory_depend_on_task_difficulty_ L2 - https://doi.org/10.3389/fpsyt.2012.00081 DB - PRIME DP - Unbound Medicine ER -