OBJECTIVE: Differences between people with and without migraine on various measures of visual perception have been attributed to abnormal cortical processing due to the disease. The aim of the present study was to explore the dynamics of the basic interictal state with regard to the extrastriate, motion-responsive middle temporal area (MT-complex) with functional magnetic resonance imaging (fMRI) at 3 tesla using coherent/incoherent moving dot stimuli.
METHOD: Twenty-four migraine patients (12 with aura [MwA], 12 without aura [MwoA]) and 12 healthy subjects participated in the study. The individual cortical folding pattern was accounted for by using a cortical matching approach.
RESULTS: In the inferior-posterior portion of the MT-complex, most likely representing MT, control subjects showed stronger bilateral activation compared to MwA and MwoA patients. Compared with healthy controls MwoA and MwA patients showed significantly stronger activation mainly at the left side in response to visual stimulation in the superior-anterior portion of the MT-complex, representing the medial-superior temporal area (MST).
CONCLUSION: Our findings strengthen the hypothesis that hyperresponsiveness of the visual cortex in migraine goes beyond early visual areas, even in the interictal period.
Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that alters cortical excitability and activity in a polarity-dependent way. Stimulation for a few minutes has been shown to induce plastic alterations of cortical excitability and to improve cognitive performance. These effects might be related to stimulation-induced alterations of functional cortical network connectivity. We aimed to investigate the impact of tDCS on cortical network function by functional connectivity and graph theoretical analysis of the BOLD fMRI spontaneous activity. fMRI resting-state datasets were acquired immediately before and after 10-min bipolar tDCS during rest, with the anode placed over the left primary motor cortex (M1) and the cathode over the contralateral frontopolar cortex. For each dataset, grey matter voxel-based synchronization matrices were calculated and thresholded to construct undirected graphs. Nodal connectivity degree and minimum path length maps were calculated and compared before and after tDCS. Nodal minimum path lengths significantly increased in the left somatomotor (SM1) cortex after anodal tDCS, which means that the number of direct functional connections from the left SM1 to topologically distant grey matter voxels significantly decreased. In contrast, functional coupling between premotor and superior parietal areas with the left SM1 significantly increased. Additionally, the nodal connectivity degree in the left posterior cingulate cortex (PCC) area as well as in the right dorsolateral prefrontal cortex (right DLPFC) significantly increased. In summary, we provide initial support that tDCS-induced neuroplastic alterations might be related to functional connectivity changes in the human brain. Additionally, we propose our approach as a powerful method to track for neuroplastic changes in the human brain.
Measurements of motor evoked potentials (MEPs) have shown that anodal and cathodal transcranial direct current stimulations (tDCS) have facilitatory or inhibitory effects on corticospinal excitability in the stimulated area of the primary motor cortex (M1). Here, we investigated the online effects of short periods of anodal and cathodal tDCS on human brain activity of healthy subjects and associated hemodynamics by concurrent blood-oxygenation-level-dependent (BOLD) functional magnetic resonance imaging (fMRI) at 3T. Using a block design, 20s periods of tDCS at 1 mA intensity over the left M1 altered with 20s periods without tDCS. In different fMRI runs, the effect of anodal or cathodal tDCS was assessed at rest or during finger tapping. A control experiment was also performed, in which the electrodes were placed over the left and right occipito-temporo-parietal junction. Neither anodal nor cathodal tDCS over the M1 for 20s stimulation duration induced a detectable BOLD signal change. However, in comparison to a voluntary finger tapping task without stimulation, anodal tDCS during finger tapping resulted in a decrease in the BOLD response in the supplementary motor area (SMA). Cathodal stimulation did not result in significant change in BOLD response in the SMA, however, a tendency toward decreased activity could be seen. In the control experiment neither cathodal nor anodal stimulation resulted in a significant change of BOLD signal during finger tapping in any brain area including SMA, PM, and M1. These findings demonstrate that the well-known polarity-dependent shifts in corticospinal excitability that have previously been demonstrated using measurements of MEPs after M1 stimulation are not paralleled by analogous changes in regional BOLD signal. This difference implies that the BOLD signal and measurements of MEPs probe diverse physiological mechanisms. The MEP amplitude reflects changes in transsynaptic excitability of large pyramidal neurons while the BOLD signal is a measure of net synaptic activity of all cortical neurons.
BACKGROUND: Several computational methods exist to suggest rational genetic interventions that improve the productivity of industrial strains. Nonetheless, these methods are less effective to predict possible genetic responses of the strain after the intervention. This problem requires a better understanding of potential alternative metabolic and regulatory pathways able to counteract the targeted intervention.
RESULTS: Here we present SPABBATS, an algorithm based on Boolean satisfiability (SAT) that computes alternative metabolic pathways between input and output species in a reconstructed network. The pathways can be constructed iteratively in order of increasing complexity. SPABBATS allows the accumulation of intermediates in the pathways, which permits discovering pathways missed by most traditional pathway analysis methods. In addition, we provide a proof of concept experiment for the validity of the algorithm. We deleted the genes for the glutamate dehydrogenases of the Gram-positive bacterium Bacillus subtilis and isolated suppressor mutant strains able to grow on glutamate as single carbon source. Our SAT approach proposed candidate alternative pathways which were decisive to pinpoint the exact mutation of the suppressor strain.
CONCLUSIONS: SPABBATS is the first application of SAT techniques to metabolic problems. It is particularly useful for the characterization of metabolic suppressor mutants and can be used in a synthetic biology setting to design new pathways with specific input-output requirements.
Am Zentrum für Evolutionäre Medizin (Anatomisches Institut) und am Institut für Volkswirtschaftslehre der Universität Zürich werden seit einigen Jahren die historischen und modernen medizinischen Daten der Aushebungen in der Schweiz und in Deutschland untersucht. Anthropometrische Daten der Rekrutierung bieten die Möglichkeit, in repräsentativer Betrachtung Jahr für Jahr das kumulative Längen- und Breitenwachstum junger Männer und somit deren gesundheitliche Situation nachzuzeichnen. In der Schweiz und in Deutschland nahm die mittlere Körperhöhe seit den 1950-er Jahren um zirka sechs Zentimeter zu auf rund 178 Zentimeter, bzw. 180 Zentimeter. Die neusten Daten zeigen allerdings für beide Länder keine Grössenzunahme mehr. Gemeinhin wird angenommen, dass ein genetisches Maximum des menschlichen Wachstums nun erreicht scheint. Dafür aber legen die jungen Männer weiterhin stetig an Gewicht zu, was einen Aufschwung in der Prävalenz des Übergewichts und der Adipositas bedeutet. 2010 hatten über 25 Prozent der Deutschen und Schweizer Stellungspflichtigen einen BMI über 25 kg/m2! Weitere Forschungsprojekte mit den anthropometrischen und medizinischen Daten der Deutschen und Schweizer Stellungspflichtigen sind zurzeit in Bearbeitung.
This study is the first to analyze economic time series of one of the world’s most preeminent traditional events, the most popular beer festival, and the largest regular fair in the world: Munich Oktoberfest. Since people from around the world attend this cultural festival as of the first decades of the 20th century, it represents a unique opportunity to analyze elasticities of consumption both in the short and medium run (i.e. at business cycle frequencies) and in the
long-run. Against the backdrop of two secularly increasing demand factors –a rise in real disposable incomes and an increased amount of leisure– we use a novel data set to study elasticities of the consumption of beer and food and the revenues of breweries. To account for asymmetries we apply partial sum decompositions in an autoregressive distributed lag (ARDL) model to estimate elasticities for state, national, European and world GDP.
We analyze the impact of bank internationalization on domestic market power (Lerner index) and risk for German banks. Risk is measured by the official declaration of regulatory authorities that a bank is distressed. We distinguish the volume of foreign assets, the number of foreign countries, and different modes of foreign entry. Our analysis has three main results. First, higher market power is associated with lower risk. Second, holding assets in many countries reduce market power at home, but banks with a higher share of foreign assets exhibit higher market power. Third, bank internationalization is only weakly related to bank risk.
Die gesetzliche Unfallversicherung wurde im Rahmen des Unfallversicherungsmodernisierungsgesetzes (UVMG) zum 1.1.2009 grundlegend reformiert. Ein wesentliches Ziel der Reformen war es, durch Fusionen der Versiche-rungsträger die Verwaltungs- und Verfahrenskosten je Versicherten zu reduzieren, also Skaleneffekte zu realisieren. Allerdings gab es zum Zeitpunkt der Reform keinerlei empirische Evidenz, dass bedeutsame Skaleneffekte zu erwar-ten wären. Basierend auf Daten der Jahre 1998-2007 wird die Frage untersucht, ob große Unfallkassen geringere Verwaltungs- und Verfahrenskosten je Versicherten aufwenden müssen als kleine. Mittels Paneldatenanalyse kann über mehrere Spezifikationen hinweg robust gezeigt werden, dass die Höhe der Verwaltungs- und Verfahrenskos-ten je Versicherten negativ von der Größe des Trägers (gemessen durch die Anzahl der Versicherten) abhängt. Im statistischen Mittel sinken die Verwaltungs- und Verfahrenskosten je Versicherten um ca. 33 Cent, wenn die Anzahl der Versicherten um 100.000 zunimmt. Bei mittleren Kosten von ca. 6,54 € je Versicherten über den betrachteten Zeitraum und durchschnittlich 960.000 Versicherten je Unfallkasse ist dieses Einsparpotential erheblich. Bei einer Steigerung der Kassengröße um ca. 600.000 Versicherte (um eine Standardabweichung) besteht damit ein Einspar-potenzial von ca. 30%.
We construct and estimate a unified model combining three of the main sources of cross-country income disparities: differences in factor endowments, barriers to technology adoption and the inappropriateness of frontier technologies to local conditions. The key components are different types of workers, distortions to capital accumulation, directed technical change, costly adoption and spillovers from the world technology frontier. Despite its parsimonious parametrization, our empirical model provides a good fit of GDP data for up to 86 countries in 1970 and 122 countries in 2000. Removing barriers to technology adoption would increase the output per worker of the average non-OECD country relative to the US from 0.19 to 0.61, while increasing skill premia in all countries. Removing barriers to trade in goods amplifies income disparities, induces skill-biased technology adoption and increases skill premia in the majority of countries. These results are reverted if trade liberalization is coupled with international IPR protection.
