We predicted that the recruitment of sensory/motor regions would vary according to the feature, with more activity within visual areas for visual decisions (e.g., lateral occipital cortex, occipital pole), and within motor/praxis areas for action decisions (e.g., precentral gyrus; IPL; pMTG).
Within each visual area, "mexican-hat" distributions of local signal intensity changes, which describe a particular combination of facilitatory and suppressive effects, were found.
A precise evaluation of localizer techniques in regard to efficient scanning time, optimal BOLD (blood oxygenic level dependent) response, as well as quantification of the resulting ROIs within each visual area (size, overlap, surround effects) has not been studied to date.
Within each visual area, we selected separate ROIs of significant positive and negative BOLD and performed the linear regression analysis (as in Fig. 7).
Within each visual area (V1 through V4), we defined separate regions-of-interest (ROIs) for the negative and positive BOLD response for each subject.
For Experiment 1, the resulting average time series from each position ROI within a visual area were combined, producing a single time series consisting of 3560 data points per visual area (890 data points per run × 4 ROIs).
Within each visual area, we additionally defined an ROI corresponding to the maximal response to our persistence stimulus-area localizer (∼125 voxels per ROI; P<10−4); all fMRI data from early visual areas was obtained using both retinotopy and the stimulus-area localizer.
Within cortical visual area V5/MT of two macaque monkeys, we applied electrical stimulation at sites with consistent multiunit tuning to combinations of binocular depth and direction of motion, while the monkey made perceptual decisions about the rotation of SFM stimuli.
Note that both viewing conditions yielded loci of power decreases within the same visual area, close to V3a, and no significant activity was evident within area V1.
Unity and variety are derived from the number of elements, or kinds of material, within a given visual area and from the way they are combined.
