Summary of the variables and definitions used in this text.

<p>Summary of the variables and definitions used in this text.</p

Model 1: Atrophy distribution via exitotoxicity.

<p>(a) Eigen-mode <b>u</b>₅ captures the essentials of estimating network diffusion from the Laplacian’s eigen-modes for TLE-MTS when the ipsilateral hippocampus is seeded. (b) Eigen-mode <b>u</b>₂ recovers features of the TLE-no when the temporal lobe is bilaterally seeded. (c) Plot of <i>R</i> vs the eigen-mode index for TLE-MTS when each eigen-mode <b>u</b>_<i>i</i> is correlated with the group atrophy. (d) Plot of <i>R</i> vs. the eigen-mode index for the TLE-no when eigen-modes <b>u</b>_<i>i</i> are each correlated with the group atrophy.</p

Subcortical Pearson correlation <i>R</i> of the estimated atrophy and the <i>t</i>-statistics for both epilepsy types.

<p>“Max” refers to the overall highest <i>R</i> and the corresponding region, all located in the ipsilateral hemisphere.</p

Relating Cortical Atrophy in Temporal Lobe Epilepsy with Graph Diffusion-Based Network Models

<div><p>Mesial temporal lobe epilepsy (TLE) is characterized by stereotyped origination and spread pattern of epileptogenic activity, which is reflected in stereotyped topographic distribution of neuronal atrophy on magnetic resonance imaging (MRI). Both epileptogenic activity and atrophy spread appear to follow white matter connections. We model the networked spread of activity and atrophy in TLE from first principles via two simple first order network diffusion models. Atrophy distribution is modeled as a simple consequence of the propagation of epileptogenic activity in one model, and as a progressive degenerative process in the other. We show that the network models closely reproduce the regional volumetric gray matter atrophy distribution of two epilepsy cohorts: 29 TLE subjects with medial temporal sclerosis (TLE-MTS), and 50 TLE subjects with normal appearance on MRI (TLE-no). Statistical validation at the group level suggests high correlation with measured atrophy (<i>R</i> = 0.586 for TLE-MTS, <i>R</i> = 0.283 for TLE-no). We conclude that atrophy spread model out-performs the hyperactivity spread model. These results pave the way for future clinical application of the proposed model on individual patients, including estimating future spread of atrophy, identification of seizure onset zones and surgical planning.</p></div

Eigen-modes ∣<b>u</b>₅∣ and ∣<b>u</b>₂∣ (Fig 2(a) and 2(b)), and their dominant regions (Model 1).

<p>Eigen-modes ∣<b>u</b>₅∣ and ∣<b>u</b>₂∣ (<a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1004564#pcbi.1004564.g002" target="_blank">Fig 2(a) and 2(b)</a>), and their dominant regions (Model 1).</p

Systematic comparison and reconstruction of sea urchin (Echinoidea) internal anatomy: a novel approach using magnetic resonance imaging-6

Igestive tract. Resolution: (81 μm), no contrast agent added. The two specimens show a high degree of similarity in their overall internal architecture. Arrows indicate paramagnetic gut content. (C), (D) Effects of a contrast agent on image quality. MRI sections at the height of perignathic girdle and lower stomach. Resolution: (81 μm). This freshly fixed specimen was scanned (C) before and (D) after the application of a contrast agent, Magnevist. Arrows indicate susceptibility artefacts. (E), (F) Comparison of a freshly fixed and a museum specimen. MRI sections at the height of gonads and upper oesophagus. Resolution: (81 μm). The 135-year-old museum specimen (F) gives imaging results comparable to the freshly fixed specimen (E). Both specimens were scanned with contrast agent added. Orientation: ambulacrum II facing upwards. Scale bar: 0.5 cm. ac, axial complex; al, Aristotle's lantern; am, ampulla; es, oesophagus; go, gonad; im, interpyramidal muscle; in, intestine; is, inner marginal sinus; l m, lantern muscle; os, outer marginal sinus; pg, perignathic girdle; re, rectum; si, siphon; st, stomach; to, tooth.<p><b>Copyright information:</b></p><p>Taken from "Systematic comparison and reconstruction of sea urchin (Echinoidea) internal anatomy: a novel approach using magnetic resonance imaging"</p><p>http://www.biomedcentral.com/1741-7007/6/33</p><p>BMC Biology 2008;6():33-33.</p><p>Published online 23 Jul 2008</p><p>PMCID:PMC2500006.</p><p></p

Systematic comparison and reconstruction of sea urchin (Echinoidea) internal anatomy: a novel approach using magnetic resonance imaging-4

Grams show an aboral view, the lower diagrams a lateral view with the anterior side (ambulacrum III) oriented towards the right-hand side. Arrows indicate the position of the junction of the gastric caecum with the stomach. (A) , Echinoneoida. (B) , Cassiduloida. Species of this sea urchin taxon presumably all possess a highly reduced gastric caecum consisting of numerous small blindly ending sacs. (C) , Holasteroida. (D) , Spatangoida. Scale bar: 0.5 cm.<p><b>Copyright information:</b></p><p>Taken from "Systematic comparison and reconstruction of sea urchin (Echinoidea) internal anatomy: a novel approach using magnetic resonance imaging"</p><p>http://www.biomedcentral.com/1741-7007/6/33</p><p>BMC Biology 2008;6():33-33.</p><p>Published online 23 Jul 2008</p><p>PMCID:PMC2500006.</p><p></p

Systematic comparison and reconstruction of sea urchin (Echinoidea) internal anatomy: a novel approach using magnetic resonance imaging-2

Odels of reconstructed selected internal organs, stepwise turned by 90°: (C) aboral view (interambulacrum 5 facing upwards); (D) lateral view (interambulacrum 5 at back); (E) oral view (interambulacrum 5 facing downwards). The buccal sacs of as well as the siphon of could not be seen on the magnetic resonance imaging sections. Scale bar: 1 cm. The colour legend specifies organ designation.<p><b>Copyright information:</b></p><p>Taken from "Systematic comparison and reconstruction of sea urchin (Echinoidea) internal anatomy: a novel approach using magnetic resonance imaging"</p><p>http://www.biomedcentral.com/1741-7007/6/33</p><p>BMC Biology 2008;6():33-33.</p><p>Published online 23 Jul 2008</p><p>PMCID:PMC2500006.</p><p></p

Systematic comparison and reconstruction of sea urchin (Echinoidea) internal anatomy: a novel approach using magnetic resonance imaging-0

Igestive tract. Resolution: (81 μm), no contrast agent added. The two specimens show a high degree of similarity in their overall internal architecture. Arrows indicate paramagnetic gut content. (C), (D) Effects of a contrast agent on image quality. MRI sections at the height of perignathic girdle and lower stomach. Resolution: (81 μm). This freshly fixed specimen was scanned (C) before and (D) after the application of a contrast agent, Magnevist. Arrows indicate susceptibility artefacts. (E), (F) Comparison of a freshly fixed and a museum specimen. MRI sections at the height of gonads and upper oesophagus. Resolution: (81 μm). The 135-year-old museum specimen (F) gives imaging results comparable to the freshly fixed specimen (E). Both specimens were scanned with contrast agent added. Orientation: ambulacrum II facing upwards. Scale bar: 0.5 cm. ac, axial complex; al, Aristotle's lantern; am, ampulla; es, oesophagus; go, gonad; im, interpyramidal muscle; in, intestine; is, inner marginal sinus; l m, lantern muscle; os, outer marginal sinus; pg, perignathic girdle; re, rectum; si, siphon; st, stomach; to, tooth.<p><b>Copyright information:</b></p><p>Taken from "Systematic comparison and reconstruction of sea urchin (Echinoidea) internal anatomy: a novel approach using magnetic resonance imaging"</p><p>http://www.biomedcentral.com/1741-7007/6/33</p><p>BMC Biology 2008;6():33-33.</p><p>Published online 23 Jul 2008</p><p>PMCID:PMC2500006.</p><p></p

Enhanced Adult Neurogenesis Increases Brain Stiffness: <i>In Vivo</i> Magnetic Resonance Elastography in a Mouse Model of Dopamine Depletion

<div><p>The mechanical network of the brain is a major contributor to neural health and has been recognized by in vivo magnetic resonance elastography (MRE) to be highly responsive to diseases. However, until now only brain softening was observed and no mechanism was known that reverses the common decrement of neural elasticity during aging or disease. We used MRE in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine hydrochloride (MPTP) mouse model for dopaminergic neurodegeneration as observed in Parkinson’s disease (PD) to study the mechanical response of the brain on adult hippocampal neurogenesis as a robust correlate of neuronal plasticity in healthy and injured brain. We observed a steep transient rise in elasticity within the hippocampal region of up to over 50% six days after MPTP treatment correlating with increased neuronal density in the dentate gyrus, which could not be detected in healthy controls. Our results provide the first indication that new neurons reactively generated following neurodegeneration substantially contribute to the mechanical scaffold of the brain. Diagnostic neuroimaging may thus target on regions of the brain displaying symptomatically elevated elasticity values for the detection of neuronal plasticity following neurodegeneration.</p></div