Journal: Brain

Article Title: Stable functional networks exhibit consistent timing in the human brain

doi: 10.1093/brain/aww337

Figure Lengend Snippet: Contributions to stability. (A) The spatial distribution of homogeneity for all nodes in a single participant is not uniform. The connections for a single node during all data blocks can be represented by a connectivity matrix (inset). Every row represents a possible connection with another node, and every column represents a data block. Every black bar represents a functional connection. (B) The correlation between node homogeneity and its degree for all nodes in a single participant. (C) The correlation between node homogeneity and its clustering coefficient for all nodes in the same participant. (D) Correlations of latency (τmax, top) and coupling strength [W(τmax), bottom] to distance between electrodes for all participants. Error bars represent 95% confidence intervals across all data blocks. (E) Scatter plots of scaled coupling pooled across participants versus distance. (F) The black bars represent the mean and standard error in scaled coupling within 15 mm bins. The red curve is the fit of a power law model to the data (adjusted R2 = 0.97).

Article Snippet: Statistical analysis To assess the extent to which two functional networks are similar, we calculated the phi similarity coefficient, φ , between unweighted undirected versions of the adjacency matrices describing those networks ( Cramer, 1945 ; Guilford, 1954 ).

Techniques: Blocking Assay, Functional Assay

Journal: Brain

Article Title: Stable functional networks exhibit consistent timing in the human brain

doi: 10.1093/brain/aww337

Figure Lengend Snippet: Stability of network connectivity and topology. (A) Functional networks calculated for a single participant on different days exhibit similar profiles (inset, CT scan showing electrode locations). Nodes are placed according to 3D coordinates of the electrodes they represent, and each edge represents an effective connection. The colour of each node represents its degree. (B) The average similarity, ϕ- ?>, between networks from 10 blocks recorded in the same day, as well as between networks from different days, is significantly larger than zero for all participants (mean ± SD). (C) The probability densities of surrogate similarities and of Day 1 versus Day 2 similarities are shown in blue and red, respectively for Participant 1. The average similarity between networks from different days is significantly larger than the similarity between degree-matched surrogate networks. ϕ* represents P = 0.05. (D) The distributions of degree, characteristic clustering coefficient, characteristic path length, and global efficiency are not significantly different for each participant from day to day, but show differences between participants. Each pair of Tukey boxplots represents the distributions of network metrics for Day 1 (black) and Day 2 (red) for one participant. The whiskers cover points within 1.5 IQR of the first and third quartile (where IQR is the inter-quartile range); values outside of this range are considered outliers and are represented by individual points. The notches (triangles) are placed at the median ± 1.57 IQR/√n, where n is the number of networks from each day (n = 10).

Article Snippet: Statistical analysis To assess the extent to which two functional networks are similar, we calculated the phi similarity coefficient, φ , between unweighted undirected versions of the adjacency matrices describing those networks ( Cramer, 1945 ; Guilford, 1954 ).

Techniques: Functional Assay, Computed Tomography