Adam Gazzaley
Gazzaley Lab
University of California, San Francisco
Networks Underlying Top-down Enhancement and Suppression of Visual Processing
Top-down modulation is a bi-directional process in that it underlies our ability to both focus our attention on task-relevant stimuli and ignore irrelevant distractions by differentially enhancing or suppressing neural activity in sensory cortical regions depending on the relevance of the information to our goals. I will first present evidence that enhancement and suppression are dissociable processes, as revealed by their differential influence on working memory performance in younger and older adults. It is also believed that top-down modulation during visual processing is not an intrinsic property of visual cortices, but is achieved via functional connectivity between sensory regions and a distributed network of frontal and parietal regions. New data will be presented that reveals differential entrainment of stimulus-selective, visual association cortical areas with regions of the “task-positive” attention network or the “task-negative” default-mode network depending on the participant’s goals. Lastly, there is sparse evidence in humans that a direct causal connection exists between prefrontal control regions and visual cortical activity modulation. Using an approach that couples fMRI-guided rTMS and high-density EEG, I will present new evidence of a direct role of the inferior frontal junction (IJF) in top-down modulation of color and motion feature processing. All of the data presented will explore the role of top-down control networks in mediating the interaction between attention and memory systems.
Video
References
Gazzaley A, D’Esposito M (2007) Top-down modulation and normal aging. Ann NY Acad Sci 1097:67-83
Gazzaley A, Cooney JW, Rissman J, D’Esposito M (2005) Top-down suppression deficit underlies working memory impairment in normal aging. Nature Neuroscience 8(10):1298-1300
Zanto T, Gazzaley A (2009) Neural suppression of irrelevant information underlies optimal working memory performance. Journal of Neuroscience 29 (10):3059-3066