Oscillatory brain activity during multisensory attention reflects activation, disinhibition, and cognitive control.

In this study, we used a novel multisensory attention paradigm to investigate attention-modulated cortical oscillations over a wide range of frequencies using magnetencephalography in healthy human participants. By employing a task that required the evaluation of the congruence of audio-visual stimuli, we promoted the formation of widespread cortical networks including early sensory cortices as well as regions associated with cognitive control. We found that attention led to increased high-frequency gamma-band activity and decreased lower frequency theta-, alpha-, and beta-band activity in early sensory cortex areas. Moreover, alpha-band coherence decreased in visual cortex. Frontal cortex was found to exert attentional control through increased low-frequency phase synchronisation. Crossmodal congruence modulated beta-band coherence in mid-cingulate and superior temporal cortex. Together, these results offer an integrative view on the concurrence of oscillations at different frequencies during multisensory attention.

Oscillatory activity in auditory cortex reflects the perceptual level of audio-tactile integration.

Cross-modal interactions between sensory channels have been shown to depend on both the spatial disparity and the perceptual similarity between the presented stimuli. Here we investigate the behavioral and neural integration of auditory and tactile stimulus pairs at different levels of spatial disparity. Additionally, we modulated the amplitudes of both stimuli in either a coherent or non-coherent manner. We found that both auditory and tactile localization performance was biased towards the stimulus in the respective other modality. This bias linearly increases with stimulus disparity and is more pronounced for coherently modulated stimulus pairs. Analyses of electroencephalographic (EEG) activity at temporal-cortical sources revealed enhanced event-related potentials (ERPs) as well as decreased alpha and beta power during bimodal as compared to unimodal stimulation. However, while the observed ERP differences are similar for all stimulus combinations, the extent of oscillatory desynchronization varies with stimulus disparity. Moreover, when both stimuli were subjectively perceived as originating from the same direction, the reduction in alpha and beta power was significantly stronger. These observations suggest that in the EEG the level of perceptual integration is mainly reflected by changes in ongoing oscillatory activity.

[Iron deficiency, Fatigue and Restless-Legs-Syndrome]. / Eisenmangel, Müdigkeit und Restless-Legs-Syndrom.

Iron deficiency without anaemia is a widespread health problem that often remains undetected. In this context, neurological and psychopathological problems like fatigue and poor concentration are a major issue, but also in Restless-Legs-Syndrome (RLS) iron deficiency is a key element.The exact pathogenesis is often unknown, however, it is known that iron is involved in several very important metabolic processes in the human body. In particular when it comes to fatigue and RLS, it's assumed that reduced activity of tyrosine hydroxylase - a central iron-dependent element of dopamine synthesis - can lead to deficiencies.As part of the therapy, oral iron supplementation is considered to be treatment of choice since it's most cost-effective and well tolerated. Intravenous iron treatment is indicated if primary attempts were not sufficient or not tolerated. To successfully replenish iron storages, about 500-1000 mg are needed. Doses of 200 mg can be administered (iron sucrose) or 1-2 single doses as for ferric carboxymaltose. A check of ferritin-levels not earlier than 8 weeks after last administration is recommended.

Voltammetric analysis of Pinus needles with physiological, phylogenetic, and forensic applications.

Polyphenolic compounds are electrochemically active components of vegetal matter which were targeted under simple experimental conditions to produce voltammetric profiles characterizing the metabolite composition. Application to bivariate and multivariate chemometric techniques permits to discriminate the species and age of plant leaves, illustrated here for the case of six Pinus species from two different subgenera. Such responses, associated with the electrochemical oxidation of polyphenolic compounds (quercetin, gallic acid, ellagic acid, among others), define a voltammetric profile which varies systematically with the age of the leaves for the different species. The application of this methodology for phylogenetic studies, plant physiology, forensic science, and chemoecology is discussed. Graphical Abstract Image of Pinus in a typical Mediterranean forest; Courtesy of the Botanic Garden of the University of Valencia.

Visual stimulus locking of EEG is modulated by temporal congruency of auditory stimuli.

Disparate sensory streams originating from a common underlying event share similar dynamics, and this plays an important part in multisensory integration. Here we investigate audiovisual binding by presenting continuously changing, temporally congruent and incongruent stimuli. Recorded EEG signals are used to quantify spectrotemporal and waveform locking of neural activity to stimulus dynamics. Spectrotemporal analysis reveals locking to visual stimulus dynamics in both a broad alpha and the beta band. The properties of these effects suggest they are a correlate of bottom-up processing in the visual system. Waveform locking reveals two cortically distinct processes that lock to visual stimulus dynamics with differing topographies and time lags relative to the stimuli. Most importantly, these are modulated in strength by the congruency of an accompanying auditory stream. In addition, the waveform locking found at occipital electrodes shows an increase over stimulus duration for visual and congruent audiovisual stimuli. Hence we argue that these effects reflect audiovisual interaction. We thus propose that spectrotemporal and waveform locking reflect different mechanisms involved in the processing of dynamic audiovisual stimuli.

Effect of chronic repetitive transcranial magnetic stimulation on regional cerebral blood flow and regional cerebral glucose uptake in drug treatment-resistant depressives. A brief report.

Brain imaging studies have shown that repetitive transcranial magnetic stimulation (rTMS) is biologically active. The aim of the present study was to investigate the patterns of the regional cerebral glucose uptake rate (rCMRGlu) and regional (99m)Tc HMPAO uptake rate (regional cerebral blood flow; rCBF) during a series of therapeutic rTMS sessions at low frequency. Four drug-resistant depressed patients underwent 10 rTMS sessions as an add-on measure over 14 days. One day before and 1 day after the TMS series, 511-keV SPECT with simultaneous (18)F-fluorodeoxyglucose and (99m)Tc HMPAO measurements were carried out. All patients showed a good clinical outcome. Statistically significant common changes in rCBF and rCMRGlu patterns were found in the upper frontal regions bilaterally in terms of increased uptake rates and in the left orbitofrontal cortex in terms of decreased uptake rates of both isotopes compared to controls. However, the lateralization patterns of rCBF and rCMRGlu after rTMS treatment revealed marked differences. Thus, although no relevant changes in lateralization of the glucose uptake were observed, a clear right-sided preponderance of rCBF also in areas remote from the stimulation site was described. Therapeutic rTMS seems to influence distinct cortical regions, affecting rCBF and rCMRGlu in a homogeneous manner as well as in different ways, which are probably region dependent and illness related. The role of the stimulation coil placement site should be taken into account.