711 research outputs found
Comparison of Resting-State Brain Activation Detected by BOLD, Blood Volume and Blood Flow
Resting-state brain activity has been widely investigated using blood oxygenation level dependent (BOLD) contrast techniques. However, BOLD signal changes reflect a combination of the effects of cerebral blood flow (CBF), cerebral blood volume (CBV), as well as the cerebral metabolic rate of oxygen (CMRO2). In this study, resting-state brain activation was detected and compared using the following techniques: (a) BOLD, using a gradient-echo echo planar imaging (GE-EPI) sequence; (b) CBV-weighted signal, acquired using gradient and spin echo (GRASE) based vascular space occupancy (VASO); and (c) CBF, using pseudo-continuous arterial spin labeling (pCASL). Reliable brain networks were detected using VASO and ASL, including sensorimotor, auditory, primary visual, higher visual, default mode, salience and left/right executive control networks. Differences between the resting-state activation detected with ASL, VASO and BOLD could potentially be due to the different temporal signal-to-noise ratio (tSNR) and the short post-labeling delay (PLD) in ASL, along with differences in the spin-echo readout of VASO. It is also possible that the dynamics of spontaneous fluctuations in BOLD, CBV and CBF could differ due to biological reasons, according to their location within the brain
Neural fingerprinting on MEG time series using MiniRocket
Neural fingerprinting is the identification of individuals in a cohort based on neuroimaging recordings of brain activity. In magneto- and electroencephalography (M/EEG), it is common practice to use second-order statistical measures, such as correlation or connectivity matrices, when neural fingerprinting is performed. These measures or features typically require coupling between signal channels and often ignore the individual temporal dynamics. In this study, we show that, following recent advances in multivariate time series classification, such as the development of the RandOm Convolutional KErnel Transformation (ROCKET) classifier, it is possible to perform classification directly on short time segments from MEG resting-state recordings with remarkably high classification accuracies. In a cohort of 124 subjects, it was possible to assign windows of time series of 1 s in duration to the correct subject with above 99% accuracy. The achieved accuracies are vastly superior to those of previous methods while simultaneously requiring considerably shorter time segments
Recording visual evoked potentials and auditory evoked P300 at 9.4T static magnetic field.
peer reviewedSimultaneous recording of electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) has shown a number of advantages that make this multimodal technique superior to fMRI alone. The feasibility of recording EEG at ultra-high static magnetic field up to 9.4 T was recently demonstrated and promises to be implemented soon in fMRI studies at ultra high magnetic fields. Recording visual evoked potentials are expected to be amongst the most simple for simultaneous EEG/fMRI at ultra-high magnetic field due to the easy assessment of the visual cortex. Auditory evoked P300 measurements are of interest since it is believed that they represent the earliest stage of cognitive processing. In this study, we investigate the feasibility of recording visual evoked potentials and auditory evoked P300 in a 9.4 T static magnetic field. For this purpose, EEG data were recorded from 26 healthy volunteers inside a 9.4 T MR scanner using a 32-channel MR compatible EEG system. Visual stimulation and auditory oddball paradigm were presented in order to elicit evoked related potentials (ERP). Recordings made outside the scanner were performed using the same stimuli and EEG system for comparison purposes. We were able to retrieve visual P100 and auditory P300 evoked potentials at 9.4 T static magnetic field after correction of the ballistocardiogram artefact using independent component analysis. The latencies of the ERPs recorded at 9.4 T were not different from those recorded at 0 T. The amplitudes of ERPs were higher at 9.4 T when compared to recordings at 0 T. Nevertheless, it seems that the increased amplitudes of the ERPs are due to the effect of the ultra-high field on the EEG recording system rather than alteration in the intrinsic processes that generate the electrophysiological responses
Prefrontal involvement in imitation learning of hand actions : effects of practice and expertise.
In this event-related fMRI study, we demonstrate the effects of a single session of practising configural hand actions (guitar chords) on cortical activations during observation, motor preparation, and imitative execution. During the observation of non-practised actions, the mirror neuron system (MNS), consisting of inferior parietal and ventral premotor areas, was more strongly activated than for the practised actions. This finding indicates a strong role of the MNS in the early stages of imitation learning. In addition, the dorsolateral prefrontal cortex (DLPFC) was selectively involved during observation and motor preparation of the non-practised chords. This finding confirms Buccino et al.’s (2004a) model of imitation learning: for actions that are not yet part of the observer’s motor repertoire, DLPFC engages in operations of selection and combination of existing, elementary representations in the MNS. The pattern of prefrontal activations further supports Shallice’s (2004) proposal of a dominant role of the left DLPFC in modulating lower-level systems, and of a dominant role of the right DLPFC in monitoring operations
The Feasibility of Societal Cost Equivalence between Robotic Hysterectomy and Alternate Hysterectomy Methods for Endometrial Cancer
Objectives. We assess whether it is feasible for robotic hysterectomy for endometrial cancer to be less expensive to society than traditional laparoscopic hysterectomy or abdominal hysterectomy. Methods. We performed a retrospective cohort analysis of patient characteristics, operative times, complications, and hospital charges from all (n = 234) endometrial cancer patients who underwent hysterectomy in 2009 at our hospital. Per patient costs of each hysterectomy method were examined from the societal perspective. Sensitivity analysis and Monte Carlo simulation were performed using a cost-minimization model. Results. 40 (17.1%) of hysterectomies for endometrial cancer were robotic, 91 (38.9%), were abdominal, and 103 (44.0%) were laparoscopic. 96.3% of the variation in operative cost between patients was predicted by operative time (R = 0.963, P < 0.01). Mean operative time for robotic hysterectomy was significantly longer than other methods (P < 0.01). Abdominal hysterectomy was consistently the most expensive while the traditional laparoscopic approach was consistently least expensive. The threshold in operative time that makes robotic hysterectomy cost equivalent to the abdominal approach is within the range of our experience. Conclusion. It is feasible for robotic hysterectomy to be less expensive than abdominal hysterectomy, but unlikely for robotic hysterectomy to be less expensive than traditional laparoscopy
The effects of a DTNBP1 gene variant on attention networks: an fMRI study
<p>Abstract</p> <p>Background</p> <p>Attention deficits belong to the main cognitive symptoms of schizophrenia and come along with altered neural activity in previously described cerebral networks. Given the high heritability of schizophrenia the question arises if impaired function of these networks is modulated by susceptibility genes and detectable in healthy risk allele carriers.</p> <p>Methods</p> <p>The present event-related fMRI study investigated the effect of the single nucleotide polymorphism (SNP) rs1018381 of the <it>DTNBP1 </it>(dystrobrevin-binding protein 1) gene on brain activity in 80 subjects while performing the attention network test (ANT). In this reaction time task three domains of attention are probed simultaneously: alerting, orienting and executive control of attention.</p> <p>Results</p> <p>Risk allele carriers showed impaired performance in the executive control condition associated with reduced neural activity in the left superior frontal gyrus [Brodmann area (BA) 9]. Risk allele carriers did not show alterations in the alerting and orienting networks.</p> <p>Conclusions</p> <p>BA 9 is a key region of schizophrenia pathology and belongs to a network that has been shown previously to be involved in impaired executive control mechanisms in schizophrenia. Our results identified the impact of <it>DTNBP1 </it>on the development of a specific attention deficit via modulation of a left prefrontal network.</p
The Feasibility of Societal Cost Equivalence between Robotic Hysterectomy and Alternate Hysterectomy Methods for Endometrial Cancer
Objectives. We assess whether it is feasible for robotic hysterectomy for endometrial cancer to be less expensive to society than traditional laparoscopic hysterectomy or abdominal hysterectomy.Methods. We performed a retrospective cohort analysis of patient characteristics, operative times, complications, and hospital charges from all (n = 234) endometrial cancer patients who underwent hysterectomy in 2009 at our hospital. Per patient costs of each hysterectomy method were examined from the societal perspective. Sensitivity analysis and Monte Carlo simulation were performed using a cost-minimization model. Results. 40 (17.1%) of hysterectomies for endometrial cancer were robotic, 91 (38.9%), were abdominal, and 103 (44.0%) were laparoscopic. 96.3% of the variation in operative cost between patients was predicted by operative time (R = 0.963, P < 0.01). Mean operative time for robotic hysterectomy was significantly longer than other methods (P < 0.01). Abdominal hysterectomy was consistently the most expensive while the traditional laparoscopic approach was consistently least expensive. The threshold in operative time that makes robotic hysterectomy cost equivalent to the abdominal approach is within the range of our experience. Conclusion. It is feasible for robotic hysterectomy to be less expensive than abdominal hysterectomy, but unlikely for robotic hysterectomy to be less expensive than traditional laparoscopy
Excitatory-inhibitory balance within EEG microstates and resting-state fMRI networks: assessed via simultaneous trimodal PET-MR-EEG imaging
The symbiosis of neuronal activities and glucose energy metabolism is reflected in the generation of functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) signals. However, their association with the balance between neuronal excitation and inhibition (E/I-B), which is closely related to the activities of glutamate and γ-aminobutyric acid (GABA) and the receptor availability (RA) of GABAA and mGluR5, remains unexplored. This research investigates these associations during the resting state (RS) condition using simultaneously recorded PET/MR/EEG (trimodal) data. The trimodal data were acquired from three studies using different radio-tracers such as, [11C]ABP688 (ABP) (N = 9), [11C]Flumazenil (FMZ) (N = 10) and 2-[18F]fluoro-2-deoxy-D-glucose (FDG) (N = 10) targeted to study the mGluR5, GABAA receptors and glucose metabolism respectively. Glucose metabolism and neuroreceptor binding availability (non-displaceable binding potential (BPND)) of GABAA and mGluR5 were found to be significantly higher and closely linked within core resting-state networks (RSNs). The neuronal generators of EEG microstates and the fMRI measures were most tightly associated with the BPND of GABAA relative to mGluR5 BPND and the glucose metabolism, emphasising a predominance of inhibitory processes within in the core RSNs at rest. Changes in the neuroreceptors leading to an altered coupling with glucose metabolism may render the RSNs vulnerable to psychiatric conditions. The paradigm employed here will likely help identify the precise neurobiological mechanisms behind these alterations in fMRI functional connectivity and EEG oscillations, potentially benefitting individualised healthcare treatment measures
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