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OBJECTIVES: Fatigue in multiple sclerosis (MS) is a frequent and invalidating symptom, which can be relieved by non-invasive neuromodulation, which presents only negligible side effects. A 5-day transcranial direct-current stimulation, 15 min per day, anodically targeting the somatosensory representation of the whole body against a larger occipital cathode was efficacious against MS fatigue (fatigue relief in multiple sclerosis, Faremus treatment). The present proof-of-concept study tested the working hypothesis that Faremus S1 neuromodulation modifies the homology of the dominant and non-dominant corticospinal (CST) circuit recruitment. METHODS: CST homology was assessed via the Fréchet distance between the morphologies of motor potentials (MEPs) evoked by transcranial magnetic stimulation in the homologous left- and right-hand muscles of 10 fatigued MS patients before and after Faremus. RESULTS: In the absence of any change in MEP features either as differences between the two body sides or as an effect of the treatment, Faremus changed in physiological direction the CST's homology. Faremus effects on homology were more evident than recruitment changes within the dominant and non-dominant sides. CONCLUSIONS: The Faremus-related CST changes extend the relevance of the balance between hemispheric homologs to the homology between body sides. With this work, we contribute to the development of new network-sensitive measures that can provide new insights into the mechanisms of neuronal functional patterning underlying relevant symptoms.

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Patient mobility is considered one of the main concerns for policy-makers as it impacts financial sustainability of regional health systems due to the high percentage of patients accessing care services in other regions. For a better understanding of this phenomenon, it is necessary to define a behavioral model able to represent the patient-system interaction. In this paper we adopted the Agent-Based Modelling (ABM) approach with the aim of simulating patient flow across regions and determining which are the main factors influencing it. This may provide a new insight for policy makers to capture which are the main factors influencing mobility and actions that may contribute to contain this phenomenon.

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OBJECTIVES: The homology of hemispheric cortical areas plays a crucial role in brain functionality. Here, we extend this concept to the homology of the dominant and non-dominant hemi-bodies, investigating the relationship of the two corticospinal tracts (CSTs). The evoked responses provide an estimate of the number of in-phase recruitments via their amplitude as a suitable indicator of the neuronal projections' integrity. An innovative concept derived from experience in the somatosensory system is that their morphology reflects the recruitment pattern of the whole circuit. METHODS: CST homology was assessed via the Fréchet distance between the morphologies of motor-evoked potentials (MEPs) using a transcranial magnetic stimulation (TMS) in the homologous left- and right-hand first dorsal interosseous muscles of 40 healthy volunteers (HVs). We tested the working hypothesis that the inter-side Fréchet distance was higher than the two intra-side distances. RESULTS: In addition to a clear confirmation of the working hypothesis (p < 0.0001 for both hemi-bodies) verified in all single subjects, we observed that the intra-side Fréchet distance was higher for the dominant than the non-dominant one. Interhemispheric morphology similarity increased with right-handedness prevalence (p = 0.004). CONCLUSIONS: The newly introduced measure of circuit recruitment patterning represents a potential benchmark for the evaluation of inter-lateral mechanisms expressing the relationship between homologous hemilateral structures subtending learning and suggests that variability in recruitment patterning physiologically increases in circuits expressing greater functionality.

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Introduction: The formation and functioning of neural networks hinge critically on the balance between structurally homologous areas in the hemispheres. This balance, reflecting their physiological relationship, is fundamental for learning processes. In our study, we explore this functional homology in the resting state, employing a complexity measure that accounts for the temporal patterns in neurodynamics. Methods: We used Normalized Compression Distance (NCD) to assess the similarity over time, neurodynamics, of the somatosensory areas associated with hand perception (S1). This assessment was conducted using magnetoencephalography (MEG) in conjunction with Functional Source Separation (FSS). Our primary hypothesis posited that neurodynamic similarity would be more pronounced within individual subjects than across different individuals. Additionally, we investigated whether this similarity is influenced by hemisphere or age at a population level. Results: Our findings validate the hypothesis, indicating that NCD is a robust tool for capturing balanced functional homology between hemispheric regions. Notably, we observed a higher degree of neurodynamic similarity in the population within the left hemisphere compared to the right. Also, we found that intra-subject functional homology displayed greater variability in older individuals than in younger ones. Discussion: Our approach could be instrumental in investigating chronic neurological conditions marked by imbalances in brain activity, such as depression, addiction, fatigue, and epilepsy. It holds potential for aiding in the development of new therapeutic strategies tailored to these complex conditions, though further research is needed to fully realize this potential.

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Somatosensory evoked potential (SEP) monitoring is a standard tool during clipping of aneurysms of the middle cerebral artery (MCA), and the parameter used to detect a state of cortical ischemia is amplitude. We think that the sensitivity of SEP can however be improved by using other parameters. Our study moves in this direction via SEP morphology. In this pilot preliminary study, involving a small sample without postoperative neurological deficit, we aimed at investigating the value of SEP morphology (in the 15- to 35-ms time frame), in comparison with SEP amplitude (N20 peak-to-peak), as a measure of sensitivity to blood flow reduction. The changes in the SEP morphology of 16 patients undergoing clipping of an unruptured MCA aneurysm was studied. We applied the Morph-Fréchet index for each recorded SEP (at 30-second intervals), quantifying the pattern shape change with regard to the average SEP recorded after dura opening (baseline). We also compared 3 measurements of the SEP morphology, without and with GARCH-derived filter. Filtered Morph-Fréchet never exceeded the individual's "normality" range in baseline but did so in 81% of the risk phase on average across the 16 subjects, which is more than that for amplitude (36%, P = .002). This pilot study indicates that a measurement derived from the networking nature of the brain was sensitive to blood flow reduction. The SEP morphology approach promises to improve SEP monitoring sensitivity during clipping of unruptured MCA aneurysms. New and Noteworthy. The higher sensitivity to blood flow reduction of SEP morphology than amplitude promises to improve the effectiveness of intraoperative monitoring during MCA aneurysm clipping procedures.

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We study numerically the ordering process of two very simple dynamical models for a two-state variable on several topologies with increasing levels of heterogeneity in the degree distribution. We find that the zero-temperature Glauber dynamics for the Ising model may get trapped in sets of partially ordered metastable states even for finite system size, and this becomes more probable as the size increases. Voter dynamics instead always converges to full order on finite networks, even if this does not occur via coherent growth of domains. The time needed for order to be reached diverges with the system size. In both cases the ordering process is rather insensitive to the variation of the degree distribution from sharply peaked to scale free.

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The investigation of community structures in networks is an important issue in many domains and disciplines. This problem is relevant for social tasks (objective analysis of relationships on the web), biological inquiries (functional studies in metabolic and protein networks), or technological problems (optimization of large infrastructures). Several types of algorithms exist for revealing the community structure in networks, but a general and quantitative definition of community is not implemented in the algorithms, leading to an intrinsic difficulty in the interpretation of the results without any additional nontopological information. In this article we deal with this problem by showing how quantitative definitions of community are implemented in practice in the existing algorithms. In this way the algorithms for the identification of the community structure become fully self-contained. Furthermore, we propose a local algorithm to detect communities which outperforms the existing algorithms with respect to computational cost, keeping the same level of reliability. The algorithm is tested on artificial and real-world graphs. In particular, we show how the algorithm applies to a network of scientific collaborations, which, for its size, cannot be attacked with the usual methods. This type of local algorithm could open the way to applications to large-scale technological and biological systems.

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Analysis of the acid content of coffee extracts has been performed by adaptation of a procedure, recently introduced by our laboratory, to the task of evaluating both the "volatile" and "non volatile" fractions. Besides useful changes in the preparation of the acid pool, diazobutane was used to obtain esters of volatile acids suitable for GC-MS analysis, to minimize losses of material by evaporation. The new procedures have been used to evaluate changes in the acid content of some Italian-style roasted coffee extracts after accelerated ageing (65 degrees C, 72 h) and in coffee beans after different amounts of roasting. The origin of formation of volatile acidity was also investigated. Electronic supplementary material is available if you access this article at http://dx.doi.org/10.1007/s00216-002-1561-y On that page (frame on the left side) a link takes you directly to the supplementary material.