Dear Friends:
I designed a visual search task with 3 different task load (block design) to
test sustained attention. The stimuli composed of two objects A and B.
Assume A is target and B is distracter.
Assume V1A and V4A are activated areas by target A in V1 and V4,
respectively. V1B and V4B are activated areas by distracter B in V1 and V4,
respectively. I predict that while attention load increased from low to
high, the activation level at V1A and V4A should increase, and the effective
connectivity between V1A and V4A also increase. The connectivity can be
analyzed by using DCM.
I also predict that while attention load increased from low to high, the
activation level at V1B and V4B should decrease, and the effective
connectivity between V1B and V4B should decrease. Any one has different
predictions?
I also assume there are 4 clusters in the frontoparietal cortex showed load
sensitive increase in BOLD signal. Because the frontoparietal cortex is the
attention source, it exerts top down attention control on the activation of
attention sites such as the V1 and V4. Therefore, the activation level in V1
and V4, and the effective connectivity between V1 and V4 is under the
control of the activity in the frontoparietal cortex.
My question is: how can I test which cluster or clusters in the
frontoparietal cortex responsible for the increase and/or decrease of
effective connectivity between V1 and V4, and increase and/or decrease in
activation level in V1 and V4?
Best Regards
Jiansong
|