Audiovisual temporal correspondence modulates human multisensory superior temporal sulcus plus primary sensory cortices

The brain should integrate related but not unrelated information from different senses. Temporal patterning of inputs to different modalities may provide critical information about whether those inputs are related or not. We studied effects of temporal correspondence between auditory and visual streams on human brain activity with functional magnetic resonance imaging ( fMRI). Streams of visual flashes with irregularly jittered, arrhythmic timing could appear on right or left, with or without a stream of auditory tones that coincided perfectly when present ( highly unlikely by chance), were noncoincident with vision ( different erratic, arrhythmic pattern with same temporal statistics), or an auditory stream appeared alone. fMRI revealed blood oxygenation level-dependent ( BOLD) increases in multisensory superior temporal sulcus (mSTS), contralateral to a visual stream when coincident with an auditory stream, and BOLD decreases for noncoincidence relative to unisensory baselines. Contralateral primary visual cortex and auditory cortex were also affected by audiovisual temporal correspondence or noncorrespondence, as confirmed in individuals. Connectivity analyses indicated enhanced influence from mSTS on primary sensory areas, rather than vice versa, during audiovisual correspondence. Temporal correspondence between auditory and visual streams affects a network of both multisensory ( mSTS) and sensory-specific areas in humans, including even primary visual and auditory cortex, with stronger responses for corresponding and thus related audiovisual inputs

Relationship between hippocampal structure and memory function in elderly humans

With progressing age, the ability to recollect personal events declines, whereas familiarity-based memory remains relatively intact. It has been hypothesized that age-related hippocampal atrophy may contribute to this pattern because of its critical role for recollection in younger humans and after acute injury. Here, we show that hippocampal volume loss in healthy older persons correlates with gray matter loss (estimated with voxel-based morphometry) of the entire limbic system and shows no correlation with an electrophysiological (event-related potential [ERP]) index of recollection. Instead, it covaries with more substantial and less specific electrophysiological changes of stimulus processing. Age-related changes in another complementary structural measure, hippocampal diffusion, on the other hand, seemed to be more regionally selective and showed the expected correlation with the ERP index of recollection. Thus, hippocampal atrophy in older persons accompanies limbic atrophy, and its functional impact on memory is more fundamental than merely affecting recollection

A Variational Principle Based Study of KPP Minimal Front Speeds in Random Shears

Variational principle for Kolmogorov-Petrovsky-Piskunov (KPP) minimal front speeds provides an efficient tool for statistical speed analysis, as well as a fast and accurate method for speed computation. A variational principle based analysis is carried out on the ensemble of KPP speeds through spatially stationary random shear flows inside infinite channel domains. In the regime of small root mean square (rms) shear amplitude, the enhancement of the ensemble averaged KPP front speeds is proved to obey the quadratic law under certain shear moment conditions. Similarly, in the large rms amplitude regime, the enhancement follows the linear law. In particular, both laws hold for the Ornstein-Uhlenbeck process in case of two dimensional channels. An asymptotic ensemble averaged speed formula is derived in the small rms regime and is explicit in case of the Ornstein-Uhlenbeck process of the shear. Variational principle based computation agrees with these analytical findings, and allows further study on the speed enhancement distributions as well as the dependence of enhancement on the shear covariance. Direct simulations in the small rms regime suggest quadratic speed enhancement law for non-KPP nonlinearities.Comment: 28 pages, 14 figures update: fixed typos, refined estimates in section

High-field fMRI reveals brain activation patterns underlying saccade execution in the human superior colliculus

Background The superior colliculus (SC) has been shown to play a crucial role in the initiation and coordination of eye- and head-movements. The knowledge about the function of this structure is mainly based on single-unit recordings in animals with relatively few neuroimaging studies investigating eye-movement related brain activity in humans. Methodology/Principal Findings The present study employed high-field (7 Tesla) functional magnetic resonance imaging (fMRI) to investigate SC responses during endogenously cued saccades in humans. In response to centrally presented instructional cues, subjects either performed saccades away from (centrifugal) or towards (centripetal) the center of straight gaze or maintained fixation at the center position. Compared to central fixation, the execution of saccades elicited hemodynamic activity within a network of cortical and subcortical areas that included the SC, lateral geniculate nucleus (LGN), occipital cortex, striatum, and the pulvinar. Conclusions/Significance Activity in the SC was enhanced contralateral to the direction of the saccade (i.e., greater activity in the right as compared to left SC during leftward saccades and vice versa) during both centrifugal and centripetal saccades, thereby demonstrating that the contralateral predominance for saccade execution that has been shown to exist in animals is also present in the human SC. In addition, centrifugal saccades elicited greater activity in the SC than did centripetal saccades, while also being accompanied by an enhanced deactivation within the prefrontal default-mode network. This pattern of brain activity might reflect the reduced processing effort required to move the eyes toward as compared to away from the center of straight gaze, a position that might serve as a spatial baseline in which the retinotopic and craniotopic reference frames are aligned

Evolution of spectral properties along the O(6)-U(5) transition in the interacting boson model. II. Classical trajectories

This article continues our previous study of level dynamics in the [O(6)-U(5)]$\supset$O(5) transition of the interacting boson model [nucl-th/0504016] using the semiclassical theory of spectral fluctuations. We find classical monodromy, related to a singular bundle of orbits with infinite period at energy E=0, and bifurcations of numerous periodic orbits for E>0. The spectrum of allowed ratios of periods associated with beta- and gamma-vibrations exhibits an abrupt change around zero energy. These findings explain anomalous bunching of quantum states in the E$\approx$0 region, which is responsible for the redistribution of levels between O(6) and U(5) multiplets.Comment: 11 pages, 7 figures; continuation of nucl-th/050401

Der berufundfamilie-Index – ein Instrument zur Messung des betrieblichen Familienbewusstseins

Angestoßen durch die demografische Entwicklung und deren absehbaren volkswirtschaftlichen und gesellschaftlichen Folgen ist die Vereinbarkeit von Beruf und Familie in den vergangenen Jahren in Deutschland von einer eher randständigen Position ins Zentrum der deutschen Reformdiskussion gerückt. Unternehmen nehmen sich hierbei zunehmend als eigenständige Akteure wahr, die durch betriebsinterne Vereinbarkeitsmodelle dazu beitragen, die Elternschaft respektive die Pflege Familienangehöriger mit dem Berufsleben ihrer Mitarbeiter zu harmonisieren – unabhängig von staatlichen Reglementierungen und Steuerungsmodellen. Die in diesem Zusammenhang vertrauten Schlüsselbegriffe wie Familienbewusstsein, Familienorientierung oder Familienfreundlichkeit werden zwar häufig – und scheinbar synonym – verwendet, eine semantische Abgrenzung sowie eine detaillierte Betrachtung bleiben jedoch aus. Darüber hinaus fehlen valide Messinstrumente, die Aussagen darüber ermöglichen, ob und inwiefern Unternehmen familienbewusst sind. Vor diesem Hintergrund erscheint es von zentraler Bedeutung, Familienbewusstsein grundlegend zu konzeptualisieren und zu operationalisieren. Der vorliegende Beitrag soll zur Schließung dieser Forschungslücke beitragen.Due to the demographic development in Germany, the importance of reconciling work and family is constantly increasing. Companies progressively more perceive themselves as independent players, who contribute to the reconcilability of work and family by the use of family-friendly policies, independent from governmental regimentations and steering models. The keywords which are familiar in this context – Familienbewusstsein, Familienorientierung, Familienfreundlichkeit – are often and seemingly synonymously used but neither differentiated from each other nor in detail filled with meaning and content. Furthermore, attempts to state whether or not and in how far companies are family-friendly – in other words attempts to measure family consciousness – are missing. Taking this deficiency into account, it is of vital importance to conceptualise and operationalise family consciousness. This article aims at closing this gap

Contribution of riverine nutrients to the silicon biogeochemistry of the global ocean – a model study

Continental shelf seas are known to support a large fraction of the global primary production. Yet, they are mostly ignored or neglected in global biogeochemical models. A number of processes that control the transfer of dissolved nutrients from rivers to the open ocean remain poorly understood. This applies in particular to dissolved silica which drives the growth of diatoms that form a large part of the phytoplankton biomass and are thus an important contributor to export production of carbon. <br><br> Here, the representation of the biogeochemical cycling along continents is improved by coupling a high resolution database of riverine fluxes of nutrients to the global biogeochemical ocean general circulation model HAMOCC5-OM. Focusing on silicon (Si), but including the whole suite of nutrients – carbon (C), nitrogen (N) and phosphorus (P) in various forms – inputs are implemented in the model at coastal coupling points using the COSCAT global database of 156 mega-river-ensemble catchments from Meybeck et al. (2006). The catchments connect to the ocean through coastal segments according to three sets of criteria: natural limits, continental shelf topography, and geophysical dynamics. <br><br> According to the model the largest effects on nutrient concentrations occur in hot spots such as the Amazon plume, the Arctic – with high nutrient inputs in relation to its total volume, and areas that encounter the largest increase in human activity, e.g., Southern Asia