ORCID Profile
0000-0002-5607-6376
Current Organisations
Veterans Affairs San Diego Healthcare System
,
University of California San Diego Health Sciences
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Publisher: Oxford University Press (OUP)
Date: 18-01-2018
DOI: 10.1093/SLEEP/ZSX213
Abstract: Working memory (WM) has been described as a multicomponent process, comprised of the following: attention-driven encoding, maintenance and rehearsal of information, and encoding to and retrieval from episodic memory. Impairments can affect higher-order cognitive processes and many everyday functions. The impact of sleep changes on these cognitive processes across the life span needs to be investigated. The aim of the current study is to examine the effects of sleep deprivation on component processes of WM, comparing younger and older adults across verbal and visuospatial modalities. Thirty-one younger adults (19-38 years) and 33 older adults (59-82 years) attended two counterbalanced sleep protocols: a regular night of sleep followed by testing the next day (normally rested condition), and 36 hr of total sleep deprivation (TSD), followed by testing (TSD condition). Participants completed matched versions of verbal and visuospatial WM tasks across conditions. Younger adults significantly outperformed older adults on encoding and displacement component processes, for both verbal and visuospatial WM. Following TSD, younger adults showed a significantly larger drop compared with older adults in verbal encoding and in visuospatial displacement. A main effect of condition was observed for verbal displacement. Differences were observed in the performance of younger and older adults on component processes of WM following TSD. This suggests that TSD can have differential effects on each component process when younger and older adults are compared, in both verbal and visuospatial tasks. Understanding this profile of changes is important for the development of possible compensatory strategies or interventions and the differentiation of clinical and healthy populations.
Publisher: Elsevier BV
Date: 08-2014
Publisher: Frontiers Media SA
Date: 2012
Publisher: American Psychological Association (APA)
Date: 2013
DOI: 10.1037/A0031515
Abstract: A fundamental dissociation for most working memory (WM) theories involves the separation of sensory-perceptual encoding of stimulus information from the maintenance of this information. The present paper reports tests of this separability hypothesis for visually presented pseudowords at both mathematical and neuroimaging levels of analysis. Levels of analysis were linked by two experimental manipulations-visual degradation and pseudoword length variation-that coupled findings from a mathematical modeling study of WM performed in a separate s le to findings from an event-related functional MRI (fMRI) study reported in the present paper. Results from the mathematical modeling study generated parametric signatures of stimulus encoding and WM rehearsal and displacement. These signatures led to specific predictions about neurophysiological responses to study manipulations in a priori regions of interest (ROI). Results demonstrated predicted dissociations of activation signatures in several ROIs. Significant patterns of brain response mirroring the encode signature were observed only during the task encode interval and only in the visual cortex and posterior fusiform gyrus. In contrast, significant brain response mirroring the rehearsal/displacement signature was observed only in the dorsolateral prefrontal cortex, inferior frontal gyrus, and supramarginal gyrus. Present findings support the separability hypothesis insofar as brain regions that underlie sensory-perceptual processes demonstrated encode signatures whereas brain regions that support WM maintenance demonstrated the rehearsal/displacement signature. These results also provide evidence for the utility of combining mathematical modeling with fMRI to integrate information across cognitive and neural levels of analysis.
Publisher: Wiley
Date: 17-08-2007
DOI: 10.1111/J.1365-2869.2007.00591.X
Abstract: Sleep deprivation has been shown to alter decision-making abilities. The majority of research has utilized fairly complex tasks with the goal of emulating 'real-life' scenarios. Here, we use a Lottery Choice Task (LCT) which assesses risk and ambiguity preference for both decisions involving potential gains and those involving potential losses. We hypothesized that one night of sleep deprivation would make subjects more risk seeking in both gains and losses. Both a control group and an experimental group took the LCT on two consecutive days, with an intervening night of either sleep or sleep deprivation. The control group demonstrated that there was no effect of repeated administration of the LCT. For the experimental group, results showed significant interactions of night (normal sleep versus total sleep deprivation, TSD) by frame (gains versus losses), which demonstrate that following as little as 23 h of TSD, the prototypical response to decisions involving risk is altered. Following TSD, subjects were willing to take more risk than they ordinarily would when they were considering a gain, but less risk than they ordinarily would when they were considering a loss. For ambiguity preferences, there seems to be no direct effect of TSD. These findings suggest that, overall, risk preference is moderated by TSD, but whether an in idual is willing to take more or less risk than when well-rested depends on whether the decision is framed in terms of gains or losses.
Publisher: Oxford University Press (OUP)
Date: 03-2009
Location: United States of America
Location: United States of America
Location: No location found
No related grants have been discovered for Benjamin mcKenna.