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Avena-Koenigsberger A.,Indiana University Bloomington | Goni J.,Indiana University Bloomington | Betzel R.F.,Indiana University Bloomington | van den Heuvel M.P.,Rudolf Magnus Institute | And 4 more authors.
Philosophical transactions of the Royal Society of London. Series B, Biological sciences | Year: 2014

Graph theory has provided a key mathematical framework to analyse the architecture of human brain networks. This architecture embodies an inherently complex relationship between connection topology, the spatial arrangement of network elements, and the resulting network cost and functional performance. An exploration of these interacting factors and driving forces may reveal salient network features that are critically important for shaping and constraining the brain's topological organization and its evolvability. Several studies have pointed to an economic balance between network cost and network efficiency with networks organized in an 'economical' small-world favouring high communication efficiency at a low wiring cost. In this study, we define and explore a network morphospace in order to characterize different aspects of communication efficiency in human brain networks. Using a multi-objective evolutionary approach that approximates a Pareto-optimal set within the morphospace, we investigate the capacity of anatomical brain networks to evolve towards topologies that exhibit optimal information processing features while preserving network cost. This approach allows us to investigate network topologies that emerge under specific selection pressures, thus providing some insight into the selectional forces that may have shaped the network architecture of existing human brains. Source


Dyck P.J.,Mayo Medical School | Albers J.W.,University of Michigan | Andersen H.,Aarhus University Hospital | Arezzo J.C.,Yeshiva University | And 6 more authors.
Diabetes/Metabolism Research and Reviews | Year: 2011

Prior to a joint meeting of the Neurodiab Association and International Symposium on Diabetic Neuropathy held in Toronto, Ofntario, Canada, 13-18 October 2009, Solomon Tesfaye, Sheffield, UK, convened a panel of neuromuscular experts to provide an update on polyneuropathies associated with diabetes (Toronto Consensus Panels on DPNs, 2009). Herein, we provide definitions of typical and atypical diabetic polyneuropathies (DPNs), diagnostic criteria, and approaches to diagnose sensorimotor polyneuropathy as well as to estimate severity. Diabetic sensorimotor polyneuropathy (DSPN), or typical DPN, usually develops on long-standing hyperglycaemia, consequent metabolic derangements and microvessel alterations. It is frequently associated with microvessel retinal and kidney disease-but other causes must be excluded. By contrast, atypical DPNs are intercurrent painful and autonomic small-fibre polyneuropathies. Recognizing that there is a need to detect and estimate severity of DSPN validly and reproducibly, we define subclinical DSPN using nerve conduction criteria and define possible, probable, and confirmed clinical levels of DSPN. For conduct of epidemiologic surveys and randomized controlled trials, it is necessary to pre-specify which attributes of nerve conduction are to be used, the criterion for diagnosis, reference values, correction for applicable variables, and the specific criterion for DSPN. Herein, we provide the performance characteristics of several criteria for the diagnosis of sensorimotor polyneuropathy in healthy subject- and diabetic subject cohorts. Also outlined here are staged and continuous approaches to estimate severity of DSPN. © 2011 John Wiley & Sons, Ltd. Source


Avena-Koenigsberger A.,Indiana University Bloomington | Goni J.,Indiana University Bloomington | Betzel R.F.,Indiana University Bloomington | van den Heuvel M.P.,Rudolf Magnus Institute | And 7 more authors.
Philosophical Transactions of the Royal Society B: Biological Sciences | Year: 2014

Graph theory has provided a key mathematical framework to analyse the architecture of human brain networks. This architecture embodies an inherently complex relationship between connection topology, the spatial arrangement of network elements, and the resulting network cost and functional performance. An exploration of these interacting factors and driving forces may reveal salient network features that are critically important for shaping and constraining the brain's topological organization and its evolvability. Several studies have pointed to an economic balance between network cost and network efficiency with networks organized in an 'economical' small-world favouring high communication efficiency at a low wiring cost. In this study, we define and explore a network morphospace in order to characterize different aspects of communication efficiency in human brain networks. Using a multi-objective evolutionary approach that approximates a Paretooptimal set within the morphospace, we investigate the capacity of anatomical brain networks to evolve towards topologies that exhibit optimal information processing features while preserving network cost. This approach allows us to investigate network topologies that emerge under specific selection pressures, thus providing some insight into the selectional forces that may have shaped the network architecture of existing human brains. © 2014 The Authors. Source


Smeets T.,Maastricht University | Cornelisse S.,Rudolf Magnus Institute | Quaedflieg C.W.E.M.,Maastricht University | Meyer T.,Maastricht University | And 2 more authors.
Psychoneuroendocrinology | Year: 2012

Stress-related research has employed several procedures to activate the human stress system. Two of the most commonly used laboratory paradigms are the Trier Social Stress Test (TSST) and the Cold Pressor Test (CPT). We combined their most stressful features to create a simple laboratory stress test capable of eliciting strong autonomic and glucocorticoid stress responses. In comparison with the CPT and its variations, our stress tool (labeled the Maastricht Acute Stress Test; MAST) was found to yield superior salivary cortisol responses, while being equally effective in eliciting subjective stress reactions and (systolic and diastolic) blood pressure increases (study 1; N= 80). In study 2 (N= 20), we directly compared the effectiveness of the MAST and TSST and found that both methods elicited similar subjective, salivary alpha-amylase, and salivary cortisol stress responses. Finally, we developed and evaluated an appropriate no-stress control version of the MAST that was similar to the stress version, although it did not comprise stressful components (study 3; N= 40). Collectively, our results confirm the effectiveness of the MAST in terms of subjective, autonomic, and - most importantly - glucocorticoid stress responses. Thus, as a brief and simple stress protocol, the MAST holds considerable promise for future research. © 2012 Elsevier Ltd. Source


Tesfaye S.,Diabetes Research Unit | Boulton A.J.M.,University of Manchester | Dyck P.J.,Mayo Medical School | Freeman R.,Beth Israel Deaconess Medical Center | And 38 more authors.
Diabetes Care | Year: 2010

Preceding the joint meeting of the 19th annual Diabetic Neuropathy Study Group of the European Association for the Study of Diabetes (NEURODIAB) and the 8th International Symposium on Diabetic Neuropathy in Toronto, Canada, 13-18 October 2009, expert panels were convened to provide updates on classification, definitions, diagnostic criteria, and treatments of diabetic peripheral neuropathies (DPNs), autonomic neuropathy, painful DPNs, and structural alterations in DPNs. © 2010 by the American Diabetes Association. Source

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