Abstract Details

Title A Game of Networks: Examining Effective Connectivity during Task-Switching

Topic Behavioral Neurology

Presentation(s) P01 - (-)

Poster/Presentation
Number 005

Objective

Background Task-switching studies using fMRI have shown specific areas of the dorso-lateral prefrontal cortex (DLPFC), supplementary motor cortex (SMA), inferior frontal cortex (IFC), anterior cingulate cortex (ACC), insula (IN) and inferior parietal lobe (IPL) show increased activity on switch trials relative to repeat trials. This study used eu-SEM to explore the interaction between these brain areas, as opposed to the magnitude of the response in these areas (as observed in traditional topographical activation studies).

Design/Methods 13 healthy, right-handed subjects (8 female; mean age 34.8 ± 12.4 yrs, mean education 16.3 ±1.1 yrs) were scanned in a 3T MRI while performing a cued task switching paradigm (subjects switched between two tasks: a color judgment task and a speed judgment task). Effective connectivity between twelve nodes of the brain network underlying task-switching [bilateral DLPFC, SMA, IFC, ACC, IN and IPL] was determined by using eu-SEM.

Results During task-switches (from color to speed or vice-versa) subjects showed more effective connectivity compared to task-repeats (color to color or speed to speed). The connectivity between (L) IFC, (L) SMA and (L) IN was found to be common between the two trial types (switch vs repeat). There was more bilateral connectivity during switching (e.g., right to left DLPFC) and nodes in (R) DLPFC, (R) ACC and (R)IN showed effective connectivity only during switching.

Conclusions While the existing fMRI literature shows the brain areas that are more active on switch trials than repeat trials, this study shows how the information is transmitted between these areas. Switching appears to depend on increased involvement of the homologue of the left-sided areas that are used for repeating a given task (within the context of a task-switching experiment).

Authors/Disclosures
Abhijit Das, MD, MBBS, DM (AMRI Institute of Neurosciences) PRESENTER	No disclosure on file
Horacio Capote, MD (Dent Neurologic Group, LLP)	No disclosure on file
	No disclosure on file
Dale C. Hesdorffer (Columbia University)	No disclosure on file

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