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Marian Berryhill, Ingrid Olson; Determining parietal involvement in visual working memory: Causal or Incidental?. Journal of Vision 2007;7(9):350. doi: 10.1167/7.9.350.
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© ARVO (1962-2015); The Authors (2016-present)
Recent neuroimaging studies (Todd & Marois, 2004; Xu & Chun, 2006) report bilateral posterior parietal activity during visual working memory (VWM) tasks that is associated with capacity limitations. These findings are surprising when viewed through the lens of neuropsychology: damage to the parietal lobe is not usually associated with VWM deficits. The goal of the present study was to determine whether parietal activations reflect a functional role in VWM or whether observed fMRI activity reflects non-mnemonic aspects of the task. We tested patients with right parietal damage (as assessed through neuroimaging) and matched controls in several VWM tasks. Patients were tested at least 1-year post-insult and did not have neglect. Subjects were required to remember either four novel shapes, colors, tools, or locations over a 1 s delay. Two tasks were used: a sequential VWM task in which each item was presented centrally, and a simultaneous VWM task in which all items were presented at the same time and both item and spatial processing were critical. The patients demonstrate preserved VWM for the sequential task, and modest deficits in the simultaneous task that required some spatial memory. However, when asked to remember locations alone, the patients showed considerable impairment. The present data do not find strong support for the hypothesis that the parietal lobe is critical for VWM in general. We speculate that the association between the BOLD response and VWM capacity limitations in the parietal lobe reflects limitations in spatial attention and enumeration.
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