Poster E43, Monday, March 27, 2:30 – 4:30 pm, Pacific Concourse
The role of the frontoparietal cortex in attentional guidance by working memory: a TMS study
min wang1,2,3,4, Ling Li1,2,3,4; 1Key Laboratory for NeuroInformation of Ministry of Education, 2High-Field Magnetic Resonance Brain Imaging Key Laboratory of Sichuan Province, 3Center for Information in Medicine, 4University of Electronic Science and Technology of China
Previous studies have demonstrated that working memory (WM) plays a crucial role in the control of visual selection. There is much evidence showing that frontoparietal regions are involved in visual search tasks, but the specific neural mechanisms involved in memory and search processes remain unclear. Here, we examined the role of the dorsal prefrontal cortex (DLPFC) and the posterior parietal cortex (PPC) in determining the interaction between WM and attention, using transcranial magnetic stimulation (TMS). Subjects maintained a color in WM while performing a visual search. The color cue indicated the target location (valid), the distractor location (invalid), or did not reappear (neutral). Repetitive TMS was applied to the right DLPFC, the right PPC, or the vertex site immediately after the onset of the search display. Search reaction times (RTs) and accuracy were recorded when subjects correctly memorized the color. Search performance was facilitated in the valid relative to the invalid and neutral conditions. The application of DLPFC-TMS and PPC-TMS showed stronger benefit of validity (valid-neutral) on search RTs, relative to the vertex-TMS. Specifically, PPC-TMS disengaged the interference of irrelevant memory color (invalid-neutral). These results suggest that the DLPFC and PPC are responsible for dividing relevant (search template) from irrelevant (memory template) information concurrently held in WM. When this process was interfered by TMS, activation of both templates accumulated and showed greater guidance on search in valid trials. Moreover, our findings reveal that PPC-TMS promotes the visual reorienting to sensory events which helped subjects disengage attention from the memory distractor.
Topic Area: EXECUTIVE PROCESSES: Working memory