Fig 1.
Example of UAV visual search task.
A) Image of red truck target and five possible distractors. All distractors were set to share a similar feature with the target (red color) in order to increase difficulty and could be present multiple times or not at all within each trial. A total of five vehicles were present per trial, including the target for target-present trials. B) Snapshot of a visual search trial used for both test and training sessions. C) Snapshot of target feedback from the training session. Following participant response, the sphere would appear over the area where the target was present in target-present trials.
Fig 2.
Example of UAV visual search task.
Timing of the different types of trials in the A. Training session (simultaneous tDCS stim or sham) and B. Pre- and post-training sessions.
Table 1.
Behavioral results for the training session.
Table 2.
Behavioral results for the pre- and post- training sessions between tDCS stim and sham groups.
Fig 3.
Behavioral improvement related activity post- relative to pre-training (Visual search—Baseline control) greater for the active stim group over the sham group.
A. Clusters of differential activity included: right pre- and post-central gyrus, left superior and middle temporal gyrus, as well as right Heshyl’s gyrus and superior temporal gyrus. The results are corrected for multiple comparisons at the cluster level (p < 0.05) using Monte-Carlo simulation (corrected cluster extent threshold greater than 781 contiguous voxels over uncorrected significance threshold of p < 0.005). The white arrow indicates the location of the peak-voxel for the corresponding contrast. B. The linear relationship between behavioral improvement in performance (percent correct change) on the visual search task and the corresponding change in brain activity (contrast estimate: post-pre brain activity) post- relative to pre-training. PreCG = Precentral Gyrus.
Fig 4.
Behavioral improvement related activity post- relative to pre-training (Visual search—Baseline control) greater for the sham group over the active stim group.
A. One cluster of significant differential activity encompassing the left and right calcarine sulcus, and the right the middle and inferior occipital gyrus including human occipital cortex visual processing areas V3 and V4. The results are corrected for multiple comparisons at the cluster level (p < 0.05) using Monte-Carlo simulation (corrected cluster extent threshold greater than 781 contiguous voxels over uncorrected significance threshold of p < 0.005). The white arrow indicates the location of the peak-voxel for the corresponding contrast. B. The linear relationship between behavioral improvement in performance (percent correct change) on the visual search task and the corresponding change in brain activity (contrast estimate: post-pre brain activity) post- relative to pre-training.
Fig 5.
Brain activity unique to the active stim group over the sham group for target feedback of incorrect trials relative to correct trials during the training session.
A) Differential activity rendered on the surface of the cortex. A single cluster of activity is present in the pre- and post-central gyrus and the premotor cortex. The results are corrected for multiple comparisons at the cluster level (p < 0.05) using Monte-Carlo simulation (corrected cluster extent threshold greater than 757 contiguous voxels over uncorrected significance threshold of p < 0.005). Differential activity determined by region of interest analysis in the left (B) and Right (C) basal ganglia rendered on MRI anatomical slices. Significant at p < 0.05 using Monte-Carlo simulation (corrected cluster extent threshold = 38 contiguous voxels for left basal ganglia and 35 contiguous voxles for the right basal ganglia, over uncorrected significance threshold of p < 0.005 within the region of interest). To ensure that activity wasn’t related to differences in hit rate between the stim and sham group but rather processing differences between incorrect and correct trials we employed an exclusive mask of activity present for the hit rate weighted F contrast of incorrect—correct for stim over sham at a lenient threshold of p < 0.05 uncorrected.
Fig 6.
Overlap in behavioral improvement related activity with target feedback activity that is greater for the active stim group over the sham group.
Overlap in significant voxels for the two analyses (Improvement Related Activity and Target Feedback Activity) are rendered on the surface of the cortex and are present in the pre- and post-central gyrus.
Table 3.
Behavioral improvement related activity post-training relative to preTraining (Stim—Sham).
Table 4.
Behavioral improvement related activity post-training relative to pre-training (Sham—Stim).
Table 5.
Target feedback incorrect trials relative to target feedback correct trials (Stim—Sham).
Table 6.
Overlap in behavioral improvement related activity to target feedback activity and connectivity during training that is unique to tDCS (Stim—Sham).