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Neural mechanisms of top-down control during spatial and feature attention

Neural mechanisms of top-down control during spatial and feature attention. Giesbrecht , B., Woldorff M. G., Song, A. W. & Mangun , G. R. (2003). NeuroImage , 19 , 496-512. Introduction.

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Neural mechanisms of top-down control during spatial and feature attention

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  1. Neural mechanisms of top-down control during spatial and feature attention Giesbrecht, B., Woldorff M. G., Song, A. W. & Mangun, G. R. (2003). NeuroImage, 19, 496-512.

  2. Introduction • Theories of visual selective attention posit that this enhanced cortical activity reflects the influence of top-down control mechanisms on bottom-up sensory processing structure. • Previous fMRI studies have shown that the frontoparietal network is involved in the top-down control of spatial attention.

  3. Previous study • By using cuing paradigm, past research identified a fast and dynamic pattern of frontal and parietal activity in response to spatial cues.(Harter et al.,1989; Hopf and Mangun, 2000; Yanaguchi et al., 1994) (Posner, 1980)

  4. Frontoparietal network

  5. Question • Is this frontoparietal network specific to the top-down control of covert orienting to spatial locations or is it more general and is also involved in the control of nonspatial orienting?

  6. Previous research • Measure the cortical response to cues that direct attention to nonspatial stimulus features. • The frontoparietal network is involved as well. • The frontoparietal network represents a generalized control system for attention orienting.

  7. However, … • No direct comparisons of spatial and nonspatialattentional control systems have been undertaken. • None of the event-related fMRI studies that have investigated top-down control activity independently from bottom-up sensory activity have include both spatial and nonspatial control systems.

  8. Purpose • Investigate the generality of frontal and parietal cortex in the top-down control of visual selective attention to spatial location and to nonspatial stimulus features using direct statistical comparisons between conditions.

  9. Present approach Image aquisition

  10. Configuration concern • There is the possibility that any observed differences between the spatial and nonspatial conditions would be due to differences in attending for peripheral and foveal events. • Aside from “foveal configuration”, the “peripheral configuration” is included.

  11. Peripheral configuration Image aquisition

  12. Prediction • There would be significant overlap in the frontoparietal network across two types of attentional cuing. • If completely generalized, no areas should show selective activation. • Ifsubregions of the network are specialized for different types of top-down attentional control, then these area should show selective activation during orienting to either spatial or feature cues.

  13. Method

  14. Control task Press anyway “Attend P, T, K or X” Press anyway “Attend P, T, K or X”

  15. Experiment design • Two configuration conditions and the order is randomized. • The cuing types were intermixed randomly within runs. • 9 runs of 24 trials • fMRI and EOG were included.

  16. Statistical analyses • For experiment task: • compare the two kind of cue types directly. • For control task: • divided the cues into those that preceded color targets and those that preceded location targets.

  17. Results

  18. Results

  19. Results

  20. Results

  21. Results

  22. Results

  23. Results

  24. Discussion • Both location and color cuing led to increased activity in superior frontal and posterior parietal cortex. • Spatial attention induced greater activity in circumscribed subregions within superior frontal and superior parietal cortex than did feature attention.

  25. Discussion – the overlap • The overlap in frontoparietal network reflects the common operations. • Left lateral frontal cortex (inferior frontal gyrusespecially), are often activated in verbal encoding tasks. • Parietal cortex observed here may reflect the coding and maintenance of task relevant dimension. • The PreCG likely reflects the preparation for a motor response.

  26. Discussion – the overlap • This generalization within the frontoparietal network not only holds across different nonspatial features, such as motion and color, but also holds across spatial and nonspatial feature dimensions.

  27. Discussion – the specificity • Dorsal areas of the frontoparietal network were clearly more active when orienting attention to locations than colors.

  28. Thank you for the listening

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