The spinal cord is not only the first part of the central nervous system where somatosensory information is processed, but also plays a substantial role in both acute and chronic forms of pain. Imaging this structure with fMRI faces several unique challenges, but has recently become feasible. Here, I will present several studies that investigate the spinal cord’s resting-state organization, its evoked responses to noxious stimulation and a modulation thereof due to cognitive manipulations. Having laid this ground-work, I will present current and planned studies that are based on the theory of predictive coding and aim to deconstruct the spinal cord pain response into prediction and prediction error signals. My hope is that this will allow for a more mechanistically informed understanding of pain in both its healthy and pathological form. [mehr]

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Deep brain stimulation treatment allows for the recording of local field potentials in the subthalamic nucleus of patients with Parkinson’s disease. This has revealed that beta band oscillations (13-30Hz) are a hallmark of the disease. In this presentation, I will first show how beta band oscillations relate to Parkinsonian symptoms. Their coupling with high-frequency oscillations (HFO, 150-400Hz) might be an important clue in order to understand how they lead to movement impairment. However, little is known about the neuronal origin of these HFO. We investigated whether they are likely to arise from the same cell populations as beta oscillations using intra-operative recordings. This involved localization of electrode contacts on post-operative MRI scans and warping to MNI space for group-level results. Finally, in the last part of the talk I will present our efforts to study the effect of dopaminergic medication on synaptic coupling strengths within the cortico-basal ganglia circuit using dynamic causal modelling. [mehr]

Over the last couple of years, the public fascination about colorful brain images seems to have a little waned and also expectations that social neuroscience will soon replace psychology. In this situation, the availability of in-vivo histology – in itself certainly a highly valuable method to validate imaging data and to search for objective pathological criteria – may have a problematic sociopolitical effect: Offering in-vivo anatomical information of new quality may foster unjustified trust in more problematic applications of neuroimaging. The talk will discuss this issue in light of shifting trends over the last decades: The availability of new technologies for visualizing brain activity generated some 25 years ago expectations to identify the centers responsible for all psychic states and to “reduce” mental processes to neuronal states – a project spurring harsh critiques from philosophy and cultural studies. With the visualization of more sophisticated phenomena, social and cultural neuroscience emerged, replacing overstated reductionist claims by integrating sociocultural aspects into neuroimaging but kindling “critical neuroscience” to question implicit essentialist assumptions. The new realism of in-vivo histology poses the question whether it will undermine concerns about the societal applications of neuroimaging. [mehr]

There is an increasing number of research studies that are based on quantitative MR imaging (qMRI) techniques for the direct mapping of brain tissue properties. The parameters most frequently mapped are the water content or proton density (PD) and the relaxation times (T1, T2, T2*). An important application of qMRI is the construction of synthetic anatomical data sets with novel contrasts. In clinical studies, the careful evaluation of qMRI data allows for the detection of diffuse pathologies in normal appearing brain tissue. However, the design of reliable mapping methods is technically challenging as various secondary effects have to be compensated for to avoid a residual bias in the data. In the presentation, some of the most prominent qMRI techniques will be shortly described. There will be a special focus on the application of qMRI in clinical research, in particular for Tumour Imaging, in Multiple Sclerosis (MS) and in Epilepsy. [mehr]

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The observation of the living body by the magnetic resonance imaging (MRI) depends on the spatial resolution and signal noise ratio (SNR), as well as relaxation time and contrast which is a tissue parameter. The advent of 7 tesla (T) ultra high field MR technology provides unprecedented capabilities for non-invasive imaging of human and animal model brain. This technical ability encompasses a range of functional and structural domains, as well as new opportunities for quantifying neurochemicals using spectroscopic techniques. In addition, increasing the static magnetic field strength promotes signal phase dispersion and shift. Predicted benefits included a stronger Blood Oxygenation Level Dependent (BOLD) effect which is used for detecting brain activity, improved signal and contrast-to-noise (CNR) ratio. By using optimal measurement techniques, improved CNR provides the delineation of the brain microstructure including laminar structure in cortex in vivo. In this talk, I'd like to present our experiences of 7T human brain imaging, especially in high resolution susceptibility imaging and somatotopic fMRI studies. [mehr]

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In this talk I will introduce epilepsy treatment using surgery in children, which can be highly effective when drug therapy fails. Many of these patients have cortical abnormalities that are termed focal cortical dysplasia's. In this context, the identification and classification of abnormal tissue that is performed using MRI has important implications for treatment. However, there is also a unique scientific opportunity to validate MRI measures by comparison to tissue samples obtained during surgery. In this talk I show some of our results using diffusion-based MRI maps and some preliminary analysis of MPM maps. Sara Lorio will then describe our work using quantitative susceptibility maps to characterise abnormalities in cortical structure in focal cortical dysplasia. [mehr]

The first part of the presentation deals with an improvement of the central SNR of human head array at ultra-high magnetic fields (UHF, > 7T). Increasing the number of surface loops in a human head receive (Rx) array improves the peripheral signal-to-noise ratio (SNR), while SNR near the brain center doesn’t substantially change. Recent theoretical works demonstrated that an optimal central SNR at UHF requires contribution of two current patterns associated with a combination of surface loops and dipole antennas. Use of various dipole antennas as MRI RF detectors has been recently introduced and successfully implemented mostly for imaging human body sized objects. In this work, we evaluated and compared several Rx dipole-like elements for use within human head UHF Rx-array. We constructed and characterized novel single-row and double-row phased arrays, which consisted of transceiver (TxRx) surface loops and Rx-dipoles. We demonstrated that combining surface loops and dipole-like elements substantially (> 30%) improve SNR near the brain center as compare to arrays consisted of surface loops only. The second part of the presentation discusses an improvement of the transmit (Tx) coverage of the human head array coils. Due to a substantial shortening of the RF wave length (below 15 cm at 7 T), RF magnetic field at UHF has a specific Tx excitation pattern with strongly decreased (more than 2 times) values at the periphery of a human head. This effect is seen not only in the transversal slice but also in the coronal and sagittal slices, which considerably limits the longitudinal Tx-coverage (along the magnet’s axis) of conventional surface loop head arrays. In this work, we developed a novel human head UHF array consisted of 8 TxRx folded dipole antennas circumscribing a head. Due to an asymmetrical shape of dipole elements, the array couples to the intrinsic “dielectric resonance” mode of the head. Due to this interaction, firstly, the new array provides for a simple way of minimizing the maximum local SAR. Secondly, it provides for a longitudinal coverage better than that achieved by a similar array consisted of unfolded dipoles as well as by an 8-element single-row and 16-element double-row surface loop arrays. [mehr]

Multisensory integration does not only recruit higher-level association cortex, but also primary sensory cortices like A1 (auditory), S1 (somatosensory), and V1 (visual). The underlying anatomical pathways, which might preferentially serve short-latency integration processes, include direct thalamocortical and corticocortical connections across the senses. We investigated how these multisensory connections develop over the individual’s lifespan and how early sensory deprivation alters them. Using tracer injections into A1, S1, and V1 of a rodent model (Mongolian gerbil) we could show that multisensory thalamocortical connections emerge before corticocortical connections but mostly disappear towards the end of the critical sensory period. Early auditory, somatosensory, or visual deprivation increases multisensory connections via axonal reorganization processes mediated by non-lemniscal thalamic nuclei and the primary areas themselves. Functional imaging reveals a mostly reduced stimulus-induced activity but a higher functional connectivity specifically between primary areas in deprived animals. In adult animals, primary sensory cortices receive substantial inputs from thalamic nuclei and cortical areas of non-matched sensory modalities. In very old animals, these multisensory connections strongly decrease in number or vanish entirely. This is likely due to a retraction of the projection neuron axonal branches and is accompanied by changes in anatomical correlates of inhibition and excitation in the sensory thalamus and cortex. Together, we show that during early development, intracortical multisensory connections are formed as a consequence of sensory driven multisensory thalamocortical activity and that during aging, multisensory processing is probably shifted from primary cortices towards other sensory brain areas. [mehr]

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Magnetic Resonance Fingerprinting (MRF) was introduced in 2013 as an approach for mapping multiple tissue properties simultaneously using MRI. This presentation will provide an overview of the MRF technique, with an emphasis on practical aspects of implementation, and describe how tissue property maps derived from MRF may be leveraged to provide additional information about structure and function in the brain and beyond. [mehr]

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