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Task-related functional connectivity study of attentional control in monkeys

Puiu F. Balan1*, Annelies Gerits1 and Wim Vanduffel1, 2, 3
  • 1 KU Leuven, Neuroscience, Belgium
  • 2 Massachusetts General Hospital, A.A. Martinos Center for Biomedical Imaging, United States
  • 3 Harvard Medical School, Department of Radiology, United States

We aimed to determine differences in top-down and bottom-up control of attention using monkey fMRI, MVPA and psychophysiological interaction (PPI) analyses. Three macaque monkeys were trained to covertly detect a random dimming occurring with equal probability at one out of four locations in each quadrant. The target-dimming was cued either in a bottom-up or top-down manner, using a change in color of the target itself or the fixation point (symbolic cue for each quadrant), respectively. Target but not distractor-dimmings (appearing at the 3 other quadrants) had to be indicated with a manual response. The monkeys were scanned using an event-related paradigm on a 3 T Siemens Trio scanner and an 8-channel receive coil (contrast-agent-enhanced (Vanduffel et al., 2001), 1.25 mm isotropic voxels). We measured cue related fMRI activations using standard GLM, MVPA and task-specific network interactions using PPI. Conjunctions of the GLM and MVPA maps (activation maps and percent accuracy of the correct classifications, respectively) of the whole brain allowed us to detect subtle differences and similarities between the bottom-up and top-down attention control networks. In addition, based on the beta-strength of the PPI interactions, we assessed network metrics (node betweenness centrality; node strength) (Rubinov and Sporns, 2010) to characterize the topology of functional connectivity networks. The behavioral performance of all monkeys was better for bottom-up compared to the randomly-interleaved top-down cued trials (higher percent correct; shorter reaction times). While the GLM-defined activation patterns revealed some functional differences between key nodes within the parieto-frontal attentional network, task-based functional connectivity analyses showed a stronger contribution of LIP during bottom-up and FEF during top-down trials. In conclusion, it is not necessarily the degree of fMRI activation in the individual nodes but rather the interaction across nodes within a functional network which determines their functionality in attentional control. Furthermore, subtle functional differences across brain areas participating in the bottom-up and/or top-down control of attention show that the recruited networks have both overlapping and disjoint nodes.

References

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Keywords: attention control, Bottom-up, Top-Down, Task-based functional connectivity, PPI, MVPA, fMRI

Conference: Second Belgian Neuroinformatics Congress, Leuven, Belgium, 4 Dec - 4 Dec, 2015.

Presentation Type: Poster Presentation

Topic: Brain Imaging

Citation: Balan PF, Gerits A and Vanduffel W (2015). Task-related functional connectivity study of attentional control in monkeys. Front. Neuroinform. Conference Abstract: Second Belgian Neuroinformatics Congress. doi: 10.3389/conf.fninf.2015.19.00029

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Received: 13 Nov 2015; Published Online: 17 Nov 2015.

* Correspondence: Dr. Puiu F Balan, KU Leuven, Neuroscience, Leuven, 3000, Belgium, puiubalan@gmail.com