Working memory refers to the ability to hold information in mind, to manipulate it, and to use it to guide behavior. It is an elemental cognitiv function that supports such high-level abilities as planning, problem solving, and language comprehension and production; it is an important factor underlying individual differences across a broad spectrum of experimental and real world measures of human performance; and its dysfunction is characteristic of many psychiatric and neurological diseases. The overarching goal of the present proposal is to address the question how does working memory work? by focusing on the role of attention. Building on findings from the previous funding cycle of this project, we propose to investigate the contributions, and boundary conditions, of attentional mechanisms to working memory performance, by pursuing the following Specific Aims:
Specific Aim 1 : To test the hypothesis that common attention-related factors underlie the selection of an object, or a feature, in both attention and working memory tasks. In vision, top-down attentional priority is implemented via the mechanism of biased competition among neural representations of stimuli in the scene. In Experiments 1-4, we will use multivariate analysis methods to first characterize the temporal dynamics of biased competition in visual search, then perform head-to-head comparisons of the effects of attentional prioritization in visual search vs. in visual working memory.
Specific Aim 2 : To test the hypothesis that the state of neural activation of `attended memory items' and of `unattended memory items' varies with strategic factors. Is it possible to definitively dissociate the neural bases of focusing attention on information held in working memory vs. the retention of this information when it is momentarily outside of the focus of attention? To address this question we will systematically vary two factors to which visual search is sensitive: the validity of retrocues; and the trial-to-trial predictability of the search target.
Specific Aim 3 : To test the hypothesis that activity in the intraparietal sulcus implements the context- appropriate control of attention in working memory. Although elevated delay-period activity is frequently observed in the dorsal frontoparietal control network during working memory tasks, research published during the previous funding period has challenged the notion that this activity corresponds to the storage, per se, of stimulus information. The experiments pursing this Aim will assess the idea that IPS functions as an amodal priority map that tracks and manages the priority status of items that are relevant for the current trial.
Working memory, the ability to hold information in mind in support of complex behavior (e.g., planning, problem solving, language comprehension), is a limiting factor of mental performance in healthy individuals, and its impairment is debilitating ina wide array of psychiatric and neurological disorders (including, but not limited to, depression, PTSD, schizophrenia, Alzheimer's disease, and Parkinson's disease). The experiments proposed here will assess in detail the idea that elemental cognitive functions - the ability to sustain attention on one or a few pieces of information, and the ability to efficiently shift attenion - are key contributors to working memory. The outcomes of these experiments will help identify specific mechanisms and brain systems that may be effective targets for interventions to improve working memory function.
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