Working memory (WM) serves as the 'mental workspace'permitting us to maintain and manipulate on-line mental representations of everything from a phone number to the objects around us. Given its critical importance for healthy cognition, it is not surprising that WM impairments can lead to a significant decrease in the quality of life. As such, understanding the behavioral and neuronal mechanisms that underlie healthy WM function is critical to one day developing treatments and interventions to stave off declines in WM performance. In spite of its importance for performing cognitive tasks, a surprising feature of WM is that it is severely capacity limited to ~4 items. One of the mysterie surrounding WM is how and why this capacity limitation arises. One potential source of capacity limitation may arise from how items from the environment are encoded into WM from the numerous possible items around us at any given time. Previous work has relied on behavioral and physiological measures to study factors influencing WM encoding, e.g. manipulations of encoding depth, stimulus number, or stimulus set size. However, all of these previous approaches used indirect measurements of the aggregate processing associated with performing the WM task, and none have focused directly on the processes associated with the encoding of a specific individual stimulus. Here, we propose to apply a powerful event related potential (ERP) technique: Frequency-Tagging, to directly measure the processing of individual items at encoding. This technique has been widely used in the study of visual perception, and here we propose to apply it to perform a comprehensive investigation of WM encoding. The approach entails the presentation of stimuli each flickering on and off at unique flicker rate. Intriguingly, this periodic stimulation leads to corresponding neural oscillations that can be recorded in the electroencephalogram (EEG) and analyzed in the frequency domain by looking at the frequencies at which a stimulus was flickered. The amplitudes of these 'frequency-tags'can be correlated with the behavioral outcomes of whether or not the stimulus is successfully retrieved from WM to obtain a neuronal correlate of WM encoding that is specific to an individual-stimulus. This R15/AREA grant proposal combines the theoretical and technical expertise of two researchers with years of experience studying visual perception and memory. The PIs will work closely with undergraduate and graduate students to advance our understanding of the WM encoding process. Through the proposed experiments, students will receive training in a number of areas (critical to establishing a solid foundation upon which to build future research careers in psychology and neuroscience. This innovative proposal will significantly contribute to the research and educational training goals of the University of Nevada, Reno

Public Health Relevance

Working memory (WM) is a fundamental aspect of cognition that is highly limited in capacity. The fundamental goal of this proposal is to further our understanding of the behavioral and neural mechanisms that underlie healthy WM function. In the long-term, this research may contribute to the development of effective interventions and treatments designed to prevent or alleviate WM impairments. This R15/AREA grant proposal investigates the WM encoding process using a powerful ERP approach called frequency-tagging. We propose the collaboration between two laboratories (Caplovitz Vision Lab and the Berryhill Memory and Brain Lab) to provide student training in multiple experimental techniques to answer longstanding questions in the WM field.

National Institute of Health (NIH)
National Eye Institute (NEI)
Academic Research Enhancement Awards (AREA) (R15)
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Special Emphasis Panel (ZRG1-MDCN-E (96))
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Wiggs, Cheri
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University of Nevada Reno
Schools of Arts and Sciences
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Killebrew, Kyle W; Gurariy, Gennadiy; Peacock, Candace E et al. (2018) Electrophysiological correlates of encoding processes in a full-report visual working memory paradigm. Cogn Affect Behav Neurosci 18:353-365
Stephens, Jaclyn A; Jones, Kevin T; Berryhill, Marian E (2017) Task demands, tDCS intensity, and the COMT val158met polymorphism impact tDCS-linked working memory training gains. Sci Rep 7:13463
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Jones, Kevin T; Stephens, Jaclyn A; Alam, Mahtab et al. (2015) Longitudinal neurostimulation in older adults improves working memory. PLoS One 10:e0121904

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