Media 2: Real-time high resolution laser speckle imaging of cerebral vascular changes in a rodent photothrombosis model

Originally published in Biomedical Optics Express on 01 May 2014 (boe-5-5-1483

Graphic patterns of cortical functional connectivity of depressed patients on the basis of EEG measurements

Considerable evidences have shown a decrease of neu-ronal activity in the left frontal lobe of depressed patients, but the underlying cortical network is still unclear. The present study intends to investigate the conscious-state brain network patterns in depressed patients compared with control individuals. Cortical functional connectivity is quantified by the partial directed coherence (PDC) analysis of multichannel EEG signals from 12 depressed patients and 12 healthy volunteers. The corresponding PDC matrices are first converted into unweighted graphs by applying a threshold to obtain the topographic property in-degree (K in). A significantly larger K in in the left hemisphere is identified in depressed patients, while a symmetric pattern is found in the control group. Another two topographic measures, i.e., clustering coefficients (C) and characteristic path length (L), are obtained from the original weighted PDC digraphs. Compared with control individuals, significantly smaller C and L are revealed in the depression group, indicating a random network-like architecture due to affective disorder. This study thereby provides further support for the presence of a hemispheric asymmetry syndrome in the depressed patients. More importantly, we present evidence that depression is characterized by a loss of optimal small-world network characteristics in conscious state

Brain mappings of beta-ERD.

<p><b>A–D:</b> Beta-ERD mapping results for control subjects were shown in four sub-stages. <b>E–H:</b> Beta-ERD mapping results for stroke patients were illustrated which were corresponding to four sub-stages respectively. All other three sub-stages had lower ERD than Baseline, and deeper blue color represented higher phase-unlocked activation (i.e., more negative compared with Baseline).</p

Schematic diagram of experimental procedure and topological cortical regions.

<p><b>A:</b> Experimental procedure with red wafer indicated the correct response button was illustrated. ISI denoted interstimulus interval (i.e., 800 ms with black crosshair “+” in this study). <b>B:</b> Grouped thirteen cortical regions with their abbreviations, (i.e., PF (prefrontal area, Fp1 and Fp2), LF (left frontal area, F3 and F7), MF (middle frontal area, Fz), RF (right frontal area, F4 and F8), LT (left temporal area, T7), LC (left central area, FC1, FC5, CP1, CP5 and C3), MC (middle central area, Cz), RC (right central area, FC2, FC6, CP2, CP6 and C4), RT (right temporal area, T8), LP (left parietal area, P3 and P7), MP (middle parietal area, Pz), RP (right parietal area, P4 and P8), O (occipital area, O1, Oz and O2)) were shown.</p

Demography of stroke patients.

<p>M =  Male.</p><p>F =  Female.</p><p>NIHSS  =  National Institute of Health Stroke Scale.</p

Brain mappings of beta-ERD for control group at different angles in response sub-stage.

<p>Higher ERD in larger brain areas particularly in right hemisphere was found with larger angles in control subjects (i.e., more brain areas with deeper blue color represented higher phase-unlocked cortical activation).</p

Behavior performance.

<p><b>A</b> and <b>C:</b> Response time was illustrated in aspects of HAND and ANGLE factors respectively. <b>B</b> and <b>D:</b> Accuracy rate was shown also with respect to HAND and ANGLE factors respectively. White bar represented control subjects and gray bar represented stroke patients. Significance was indicated with*.</p

Brain mappings of ERP.

<p><b>A</b> and <b>C:</b> Brain mappings of P200 and P300 for control subjects were shown respectively. <b>B</b> and <b>D:</b> Brain mappings of P200 and P300 for stroke patients were illustrated. In the brain mappings of ERP, more red color represented higher phase-locked activation.</p

Nodal betweenness in three sub-stages.

<p>Nodal betweenness of two groups with respect to angle in Beginning (<b>A</b>), Middle (<b>B</b>), and End sub-stages (<b>C</b>) were illustrated respectively. Gray wafers indicated the channels where stroke patients have larger betweenness than control subjects, while black wafers indicated the channels where patients have lower betweenness than control subjects by t-test (p<0.05). However, the t-test p-values of these channels are larger than the significance threshold estimated by FDR (q<0.05) for multiple comparisons correction.</p

Global network properties in Middle sub-stage.

<p>Clustering coefficient (<b>A</b>) and characteristic path length (<b>B</b>) with respect to ANGLE were shown. GROUP effect on clustering coefficient (<b>C</b>) and characteristic path length (<b>D</b>) were illustrated. Clustering coefficient in aspect to HAND factor was in (<b>E</b>). Significant difference was indicated by *(p<0.05).</p