Fig. 2: Contact localization and trajectory clustering. | Nature Communications

Fig. 2: Contact localization and trajectory clustering.

From: Intracortical recordings reveal vision-to-action cortical gradients driving human exogenous attention

Fig. 2

A Left: Illustration of the localization in normalized space (MNI152) of the contacts included in the analysis (black circles; n = 1403) in the left hemisphere (LH; n = 671) and in the right hemisphere (RH, n = 732), pooled across patients. Each localization is the mean coordinates of the two contacts composing the contact’s bipolar montage. To reveal prototypical temporal patterns simultaneously across all conditions, the trajectories across the 8 condition dimensions of the mean high-frequency broadband (HFBB) target-locked activity of 664 significantly responsive contacts (significant time-point-by-time-point t-test for at least 100 ms in one of the experimental conditions compared to baseline), were clustered using a custom-made trajectory K-means approach. Right: Example of target-locked mean normalized HFBB responses of one contact in the right angular gyrus in Congruent (full lines) and Incongruent (dashed lines) trials, at short-SOA (blue) and long-SOA (red), with targets contralateral or ipsilateral to the contact. Dashed vertical lines represent onsets of the target (black), short-SOA (blue), and long-SOA (red) cues. Shaded areas represent SEM across trials. Brain visualization was done using BrainNet Viewer Matlab toolbox (Xia M, Wang J, He Y (2013) BrainNet Viewer: A Network Visualization Tool for Human Brain Connectomics. PLoS ONE 8(7): e68910. doi:10.1371/journal.pone.0068910). B Prototypical temporal profiles of contact clusters across conditions: Trimmed-mean target-locked activity profiles of three contact clusters across the 8 conditions (Congruent/Incongruent Trial ×  short-SOA/long-SOA × Ipsilateral target (Ipsi)/contralateral target (Contra)). Cluster 1 (yellow) shows contralateral fast responses, with cue-target activity segregation at both SOAs; Cluster 2 (red) shows bilateral slower responses with spatial sensitivity, with cue-target activity segregation at long-SOA but response integration in short-SOA; and Cluster 3 (green) shows bilateral slowest responses with stimulus-type sensitivity, with cue-target activity segregation at long-SOA but response integration at short-SOA. Dashed vertical lines represent target onset (black) and cue onset at short-SOA (blue) and long-SOA (red). C Temporal gradient of target-locked activity (trimmed-mean) of the three clusters. The Black dashed line depicts the target onset. D Scatter plot of peak times of mean target-locked activity of contacts of Cluster 1 (yellow circles), Cluster 2 (red circles), and Cluster 3 (green circles), in Congruent (x-axis) and Incongruent (y-axis) conditions, showing a significant temporal gradient (Mixed 2-way ANOVA, Cluster main effect p < 0.001, η2 = 0.378; linear polynomial contrast: p ≤ 0.001). Squares represent mean peak time; the Dotted gray line denotes the equity line; Shaded areas represent peak time distributions.

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