The distribution characteristics of affected white matter pathways.

<p>WM fiber pathways intersected by the rod were pooled across all N = 110 subjects and examined for a) the relative lengths (w_ij) of affected pathways and b) the relative percentages of lost fiber density (g_ij); c) the bivariate distribution of g_ij versus w_ij indicating that local fiber pathways were affected, <i>e.g.</i> relatively short pathways proximal to the injury site, as well as damaging dense, longer-range fiber pathways, <i>e.g.</i> innervating regions some distance from the tamping iron injury (see “<i>Calculation of Pathology Effects upon GM/WM Volumetrics</i>” for further details).</p

The circular representation of cortical anatomy and WM connectivity from N = 110 normal right-handed males (age 25–36).

<p>The outermost ring shows the various brain regions arranged by lobe (fr – frontal; ins – insula; lim – limbic; tem – temporal; par – parietal; occ- occipital; nc – non-cortical; bs – brain stem; CeB - cerebellum) and further ordered anterior-to-posterior based upon the centers-of-mass of these regions in the published Destrieux atlas <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0037454#pone.0037454-Destrieux1" target="_blank">[72]</a> (see also <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0037454#pone-0037454-t006" target="_blank">Table 6</a> for complete region names, abbreviations, and FreeSurfer IDs, and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0037454#pone-0037454-t007" target="_blank">Table 7</a> for the abbreviation construction scheme). The left half of the connectogram figure represents the left-hemisphere of the brain, whereas the right half represents the right hemisphere with the exception of the brain stem, which occurs at the bottom, 6 o'clock position of the graph. The lobar abbreviation scheme is given in the text. The color map of each region is lobe-specific and maps to the color of each regional parcellation as shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0037454#pone.0037454.s002" target="_blank">Fig. S2</a>. The set of five rings (from the outside inward) reflect average i) regional volume, ii) cortical thickness, iii) surface area, and iv) cortical curvature of each parcellated cortical region. For non-cortical regions, only average regional volume is shown. Finally, the inner-most ring displays the relative degree of connectivity of that region with respect to WM fibers found to emanate from this region, providing a measure of how connected that region is with all other regions in the parcellation scheme. The links represent the computed degrees of connectivity between segmented brain regions. Links shaded in blue represent DTI tractography pathways in the lower third of the distribution of fractional anisotropy, green lines the middle third, and red lines the top third. Circular “color bars” at the bottom of the figure describe the numeric scale for each regional geometric measurement and its associated color on that anatomical metric ring of the connectogram.</p

Comparison of Intact, Tamping Iron, and Simulated Network Attributes.

<p>Comparison of Intact, Tamping Iron, and Simulated Network Attributes.</p

Regional Parcellation Coding Scheme.

<p>Regional Parcellation Coding Scheme.</p

Mean connectivity affected by the presence of the tamping iron combined across subjects.

<p>The lines in this connectogram graphic represent the connections between brain regions that were lost or damaged by the passage of the tamping iron. Fiber pathway damage extended beyond the left frontal cortex to regions of the left temporal, partial, and occipital cortices as well as to basal ganglia, brain stem, and cerebellum. Inter-hemispheric connections of the frontal and limbic lobes as well as basal ganglia were also affected. Connections in grayscale indicate those pathways that were completely lost in the presence of the tamping iron, while those in shades of tan indicate those partially severed. Pathway transparency indicates the relative density of the affected pathway. In contrast to the morphometric measurements depicted in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0037454#pone-0037454-g002" target="_blank">Fig. 2</a>, the inner four rings of the connectogram here indicate (from the outside inward) the regional network metrics of betweenness centrality, regional eccentricity, local efficiency, clustering coefficient, and the percent of GM loss, respectively, in the presence of the tamping iron, in each instance averaged over the N = 110 subjects.</p

Healthy region-specific graph theoretical metrics, the effects of systematic lesions, and the difference between the observed and simulated tamping iron lesions.

<p>A) Cortical maps of regional graph theoretical properties. Regions affected by the passage of the tamping iron include those having relatively high betweenness centrality and clustering coefficients but relatively low mean local efficiency and eccentricity. B) A cortical surface schematic of the relative effects of systematic lesions of similar WM/GM attributes over the cortex for both network integration (i) and segregation (ii). For each mapping, colors represent the Z-score difference between systematic lesions of that area relative the average change in integration taken across all simulated lesions. C) Cortical maps of the differences/similarity between the effects on integration and segregation observed from the tamping iron lesion with that of each simulated lesion. Here black is most similar (e.g. the observed lesion is most similar to itself) whereas white is least similar to (e.g. most different from) the tamping iron's effects on these measures of network architecture.</p

Descriptions of Damage to Gages' Skull Serving as Constraints for Determining the Trajectory of the Tamping Iron.

<p>Descriptions of Damage to Gages' Skull Serving as Constraints for Determining the Trajectory of the Tamping Iron.</p

Regional Parcellation Coding Scheme.

<p>Regional Parcellation Coding Scheme.</p

Estimates of the Damage to Gage's Brain.

<p>Estimates of the Damage to Gage's Brain.</p

Gage Skull Measurements.

<p>Gage Skull Measurements.</p