The ability to maintain and manipulate information in working memory (WM) underlies critical high-level behaviors from directing attention to making complex decisions. The neural correlates of WM have been the focus of various research and studies have produced fruitful insights into the nature of this maintained information. One traditional view of WM is that it is a specialized system within the fronto-parietal network. Alternatively, the sensory recruitment model suggests that WM recruits the posterior sensory regions to maintain the actual content, supported by recent neuroimaging evidence that temporarily maintained information is decodable from the corresponding sensory areas. However, it remains unclear how behaviorally meaningful this sensory representation of WM is. The goals of this thesis were to 1) directly test the behavioral consequences of maintaining WM information in sensory regions, 2) to provide a cohesive framework for WM function, and 3) to provide an explanation for the contradictory findings in the field.
The current work consisted of four sets of experiments that demonstrated an overlapping neural resource between visual WM and perception in the visual cortex. The first finding was that the interaction between visual WM and selective attention was bidirectional, originating from their representational overlap in the visual cortex, and the interference was not modulated by the level of engagement fronto-parietal network. Secondly, visual WM directly affected ongoing perceptual processing and can distort the perception of basic visual features, as resulted from and predicted by the overlap in neuronal populations recruited by visual WM maintenance and perceptual processing. The third important finding was that visual WM and perceptual priming produced qualitatively similar influence on perception but with different temporal dynamics, indicating that bottom-up and top-down visual effects can be directly compared in the same context. These findings altogether demonstrated that as a consequence of sharing the early visual cortices, what you are seeing and what you are holding in mind are intertwined at even the most fundamental stages of processing. WM as a distributed and dynamic system can flexibly recruit sensory regions to represent the maintained information and this sensory representation has a direct impact on behavior.
|Advisor:||Kravitz, Dwight J.|
|Commitee:||Dopkins, Stephen, Mitroff, Stephen, Shomstein, Sarah, Zawidzki, Tadeusz|
|School:||The George Washington University|
|School Location:||United States -- District of Columbia|
|Source:||DAI-B 80/09(E), Dissertation Abstracts International|
|Subjects:||Experimental psychology, Cognitive psychology|
|Keywords:||Attention, Perception, Short-term memory, Working memory|
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