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Bayesian Brain

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https://www.readbyqxmd.com/read/28522346/seeing-in-the-dark-phosphene-thresholds-with-eyes-open-versus-closed-in-the-absence-of-visual-inputs
#1
T A de Graaf, F Duecker, Y Stankevich, S Ten Oever, A T Sack
BACKGROUND: Voluntarily opening or closing our eyes results in fundamentally different input patterns and expectancies. Yet it remains unclear how our brains and visual systems adapt to these ocular states. OBJECTIVE/HYPOTHESIS: We here used transcranial magnetic stimulation (TMS) to probe the excitability of the human visual system with eyes open or closed, in the complete absence of visual inputs. METHODS: Combining Bayesian staircase procedures with computer control of TMS pulse intensity allowed interleaved determination of phosphene thresholds (PT) in both conditions...
May 3, 2017: Brain Stimulation
https://www.readbyqxmd.com/read/28504643/exploiting-neurovascular-coupling-a-bayesian-sequential-monte-carlo-approach-applied-to-simulated-eeg-fnirs-data
#2
Pierpaolo Croce, Filippo Zappasodi, Arcangelo Merla, Antonio Chiarelli
OBJECTIVE: Electrical and hemodynamic brain activity are linked through the neurovascular coupling process and they can be simultaneously measured through integration of Electroencephalography (EEG) and functional Near-Infrared Spectroscopy (fNIRS). Thanks to the lack of electro-optical interference, the two procedures can be easily combined and, whereas EEG provides electrophysiological information, fNIRS can provide measurements of two hemodynamic variables, such as oxygenated and deoxygenated hemoglobin...
May 15, 2017: Journal of Neural Engineering
https://www.readbyqxmd.com/read/28503664/fixing-the-stimulus-as-fixed-effect-fallacy-in-task-fmri
#3
Jacob Westfall, Thomas E Nichols, Tal Yarkoni
Most functional magnetic resonance imaging (fMRI) experiments record the brain's responses to samples of stimulus materials (e.g., faces or words). Yet the statistical modeling approaches used in fMRI research universally fail to model stimulus variability in a manner that affords population generalization, meaning that researchers' conclusions technically apply only to the precise stimuli used in each study, and cannot be generalized to new stimuli. A direct consequence of this stimulus-as-fixed-effect fallacy is that the majority of published fMRI studies have likely overstated the strength of the statistical evidence they report...
December 9, 2016: Wellcome Open Research
https://www.readbyqxmd.com/read/28498501/ppar-gamma-agonist-pioglitazone-modifies-craving-intensity-and-brain-white-matter-integrity-in-patients-with-primary-cocaine-use-disorder-a-double-blind-randomized-controlled-pilot-trial
#4
Joy M Schmitz, Charles E Green, Khader M Hasan, Jessica Vincent, Robert Suchting, Michael F Weaver, F Gerard Moeller, Ponnada A Narayana, Kathryn A Cunningham, Kelly T Dineley, Scott D Lane
BACKGROUND AND AIMS: Pioglitazone (PIO), a potent agonist of PPAR-gamma, is a promising candidate treatment for cocaine use disorder (CUD). We tested the effects of PIO on targeted mechanisms relevant to CUD: cocaine craving and brain white matter (WM) integrity. Feasibility, medication compliance, and tolerability were evaluated. DESIGN: Two-arm double-blind randomized controlled proof-of-concept pilot trial of PIO or placebo (PLC). SETTING: Single-site outpatient treatment research clinic in Houston, Texas, USA...
May 12, 2017: Addiction
https://www.readbyqxmd.com/read/28495368/the-dynamic-programming-high-order-dynamic-bayesian-networks-learning-for-identifying-effective-connectivity-in-human-brain-from-fmri
#5
Shilpa Dang, Santanu Chaudhury, Brejesh Lall, Prasun Kumar Roy
BACKGROUND: Determination of effective connectivity (EC) among brain regions using fMRI is helpful in understanding the underlying neural mechanisms. Dynamic Bayesian Networks (DBNs) are an appropriate class of probabilistic graphical temporal-models that have been used in past to model EC from fMRI, specifically order-one. NEW-METHOD: High-order DBNs (HO-DBNs) have still not been explored for fMRI data. A fundamental problem faced in the structure-learning of HO-DBN is high computational-burden and low accuracy by the existing heuristic search techniques used for EC detection from fMRI...
May 8, 2017: Journal of Neuroscience Methods
https://www.readbyqxmd.com/read/28487642/resting-state-neurophysiological-abnormalities-in-posttraumatic-stress-disorder-a-magnetoencephalography-study
#6
Amy S Badura-Brack, Elizabeth Heinrichs-Graham, Timothy J McDermott, Katherine M Becker, Tara J Ryan, Maya M Khanna, Tony W Wilson
Posttraumatic stress disorder (PTSD) is a debilitating psychiatric condition that is common in veterans returning from combat operations. While the symptoms of PTSD have been extensively characterized, the neural mechanisms that underlie PTSD are only vaguely understood. In this study, we examined the neurophysiology of PTSD using magnetoencephalography (MEG) in a sample of veterans with and without PTSD. Our primary hypothesis was that veterans with PTSD would exhibit aberrant activity across multiple brain networks, especially those involving medial temporal and frontal regions...
2017: Frontiers in Human Neuroscience
https://www.readbyqxmd.com/read/28486504/sequential-inference-as-a-mode-of-cognition-and-its-correlates-in-fronto-parietal-and-hippocampal-brain-regions
#7
Thomas H B FitzGerald, Dorothea Hämmerer, Karl J Friston, Shu-Chen Li, Raymond J Dolan
Normative models of human cognition often appeal to Bayesian filtering, which provides optimal online estimates of unknown or hidden states of the world, based on previous observations. However, in many cases it is necessary to optimise beliefs about sequences of states rather than just the current state. Importantly, Bayesian filtering and sequential inference strategies make different predictions about beliefs and subsequent choices, rendering them behaviourally dissociable. Taking data from a probabilistic reversal task we show that subjects' choices provide strong evidence that they are representing short sequences of states...
May 9, 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/28479476/high-resolution-magnetic-resonance-imaging-reveals-nuclei-of-the-human-amygdala-manual-segmentation-to-automatic-atlas
#8
Z M Saygin, D Kliemann, J E Iglesias, A J W van der Kouwe, E Boyd, M Reuter, A Stevens, K Van Leemput, A McKee, M P Frosch, B Fischl, J C Augustinack
The amygdala is composed of multiple nuclei with unique functions and connections in the limbic system and to the rest of the brain. However, standard in vivo neuroimaging tools to automatically delineate the amygdala into its multiple nuclei are still rare. By scanning postmortem specimens at high resolution (100-150µm) at 7T field strength (n = 10), we were able to visualize and label nine amygdala nuclei (anterior amygdaloid, cortico-amygdaloid transition area; basal, lateral, accessory basal, central, cortical medial, paralaminar nuclei)...
May 4, 2017: NeuroImage
https://www.readbyqxmd.com/read/28473287/a-bayesian-heteroscedastic-glm-with-application-to-fmri-data-with-motion-spikes
#9
Anders Eklund, Martin A Lindquist, Mattias Villani
We propose a voxel-wise general linear model with autoregressive noise and heteroscedastic noise innovations (GLMH) for analyzing functional magnetic resonance imaging (fMRI) data. The model is analyzed from a Bayesian perspective and has the benefit of automatically down-weighting time points close to motion spikes in a data-driven manner. We develop a highly efficient Markov Chain Monte Carlo (MCMC) algorithm that allows for Bayesian variable selection among the regressors to model both the mean (i.e., the design matrix) and variance...
May 1, 2017: NeuroImage
https://www.readbyqxmd.com/read/28471701/the-brain-derived-neurotrophic-factor-val66met-polymorphism-delivery-method-birth-weight-and-night-sleep-duration-as-determinants-of-obesity-in-vietnamese-children-of-primary-school-age
#10
Le Thi Tuyet, Bui Thi Nhung, Duong Thi Anh Dao, Nguyen Thi Hong Hanh, Le Danh Tuyen, Tran Quang Binh, Vu Thi Minh Thuc
BACKGROUND: Obesity is a complex disease that involves both environmental and genetic factors in its pathogenesis. Several studies have identified multiple obesity-associated loci in many populations. However, their contribution to obesity in the Vietnamese population is not fully described, especially in children. The study aimed to investigate the association of obesity with Val66Met polymorphism in brain-derived neurotrophic factor (BDNF) gene, delivery method, birth weight, and lifestyle factors in Vietnamese primary school children...
May 4, 2017: Childhood Obesity
https://www.readbyqxmd.com/read/28465614/reconstructing-3d-deformation-dynamics-for-curved-epithelial-sheet-morphogenesis-from-positional-data-of-sparsely-labeled-cells
#11
Yoshihiro Morishita, Ken-Ichi Hironaka, Sang-Woo Lee, Takashi Jin, Daisuke Ohtsuka
Quantifying global tissue deformation patterns is essential for understanding how organ-specific morphology is generated during development and regeneration. However, due to imaging difficulties and complex morphology, little is known about deformation dynamics for most vertebrate organs such as the brain and heart. To better understand these dynamics, we propose a method to precisely reconstruct global deformation patterns for three-dimensional morphogenesis of curved epithelial sheets using positional data from labeled cells representing only 1-10% of the entire tissue with limited resolution...
May 2, 2017: Nature Communications
https://www.readbyqxmd.com/read/28463113/saccadic-suppression-as-a-perceptual-consequence-of-efficient-sensorimotor-estimation
#12
Frederic Crevecoeur, Konrad P Kording
Humans perform saccadic eye movements two to three times per second. When doing so, the nervous system strongly suppresses sensory feedback for extended periods of time in comparison to movement time. Why does the brain discard so much visual information? Here we suggest that perceptual suppression may arise from efficient sensorimotor computations, assuming that perception and control are fundamentally linked. More precisely, we show theoretically that a Bayesian estimator should reduce the weight of sensory information around the time of saccades, as a result of signal dependent noise and of sensorimotor delays...
May 2, 2017: ELife
https://www.readbyqxmd.com/read/28456584/inference-in-the-age-of-big-data-future-perspectives-on-neuroscience
#13
REVIEW
Danilo Bzdok, B T Thomas Yeo
Neuroscience is undergoing faster changes than ever before. Over 100 years our field qualitatively described and invasively manipulated single or few organisms to gain anatomical, physiological, and pharmacological insights. In the last 10 years neuroscience spawned quantitative datasets of unprecedented breadth (e.g., microanatomy, synaptic connections, and optogenetic brain-behavior assays) and size (e.g., cognition, brain imaging, and genetics). While growing data availability and information granularity have been amply discussed, we direct attention to a less explored question: How will the unprecedented data richness shape data analysis practices? Statistical reasoning is becoming more important to distill neurobiological knowledge from healthy and pathological brain measurements...
April 26, 2017: NeuroImage
https://www.readbyqxmd.com/read/28455815/perfusion-abnormalities-are-frequently-detected-by-early-ct-perfusion-and-predict-unfavourable-outcome-following-severe-traumatic-brain-injury
#14
Cino Bendinelli, Shannon Cooper, Tiffany Evans, Andrew Bivard, Dianne Pacey, Mark Parson, Zsolt J Balogh
BACKGROUND: In patients with severe traumatic brain injury (TBI), early CT perfusion (CTP) provides additional information beyond the non-contrast CT (NCCT) and may alter clinical management. We hypothesized that this information may prognosticate functional outcome. METHODS: Five-year prospective observational study was performed in a level-1 trauma centre on consecutive severe TBI patients. CTP (obtained in conjunction with first routine NCCT) was interpreted as: abnormal, area of altered perfusion more extensive than on NCCT, and the presence of ischaemia...
April 28, 2017: World Journal of Surgery
https://www.readbyqxmd.com/read/28450541/spatial-attention-motor-intention-and-bayesian-cue-predictability-in-the-human-brain
#15
Anna B Kuhns, Pascasie L Dombert, Paola Mengotti, Gereon R Fink, Simone Vossel
Predictions about upcoming events influence how we perceive and respond to our environment. There is increasing evidence that predictions may be generated based upon previous observations following Bayesian principles, but little is known about the underlying cortical mechanisms and their specificity for different cognitive subsystems. The present study aimed at identifying common and distinct neural signatures of predictive processing in the spatial attentional and motor intentional systems. Twenty-three female and male healthy human volunteers performed two probabilistic cueing tasks with either spatial or motor cues while lying in the fMRI scanner...
April 27, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28419235/a-bayesian-group-sparse-multi-task-regression-model-for-imaging-genetics
#16
Keelin Greenlaw, Elena Szefer, Jinko Graham, Mary Lesperance, Farouk S Nathoo
Motivation: Recent advances in technology for brain imaging and high-throughput genotyping have motivated studies examining the influence of genetic variation on brain structure. Wang et al. (Bioinformatics, 2012) have developed an approach for the analysis of imaging genomic studies using penalized multi-task regression with regularization based on a novel group l2,1-norm penalty which encourages structured sparsity at both the gene level and SNP level. While incorporating a number of useful features, the proposed method only furnishes a point estimate of the regression coefficients; techniques for conducting statistical inference are not provided...
April 13, 2017: Bioinformatics
https://www.readbyqxmd.com/read/28408150/adaptive-and-maladaptive-neural-compensatory-consequences-of-sensory-deprivation-from-a-phantom-percept-perspective
#17
REVIEW
Anusha Mohan, Sven Vanneste
It is suggested that the brain undergoes plastic changes in order to adapt to changing environmental needs. Sensory deprivation results in decreased input to the brain leading to adaptive or maladaptive changes. Although several theories hypothesize the mechanism of these adaptive and maladaptive changes, the course of action taken by the brain heavily depends on the age of incidence of damage. The growing body of literature on the topic proposes that maladaptive changes in the brain are instrumental in creating phantom percepts, defined as the perception of a sensory experience in the absence of a physical stimulus...
April 11, 2017: Progress in Neurobiology
https://www.readbyqxmd.com/read/28402428/bayesian-mapping-reveals-that-attention-boosts-neural-responses-to-predicted-and-unpredicted-stimuli
#18
Marta I Garrido, Elise G Rowe, Veronika Halász, Jason B Mattingley
Predictive coding posits that the human brain continually monitors the environment for regularities and detects inconsistencies. It is unclear, however, what effect attention has on expectation processes, as there have been relatively few studies and the results of these have yielded contradictory findings. Here, we employed Bayesian model comparison to adjudicate between 2 alternative computational models. The "Opposition" model states that attention boosts neural responses equally to predicted and unpredicted stimuli, whereas the "Interaction" model assumes that attentional boosting of neural signals depends on the level of predictability...
April 10, 2017: Cerebral Cortex
https://www.readbyqxmd.com/read/28399440/altered-effective-brain-connectivity-at-early-response-of-antipsychotics-in-first-episode-schizophrenia-with-auditory-hallucinations
#19
Leilei Zheng, Weibo Liu, Wei He, Shaohua Yu, Guodong Zhong
OBJECTIVE: This study aimed to examine the alterations of cortical connectivity in first-episode schizophrenia (FES) with auditory hallucinations at early response of antipsychotics. METHODS: This was a nonexperimental control of medication study. We measured the cortical activity of 20 medicated patients with FES (medicated group), 19 nonmedicated patients with FES (nonmedicated group), and 22 healthy controls using electroencephalogram during eye-open resting state...
June 2017: Clinical Neurophysiology: Official Journal of the International Federation of Clinical Neurophysiology
https://www.readbyqxmd.com/read/28389385/automatized-set-up-procedure-for-transcranial-magnetic-stimulation-protocols
#20
S Harquel, J Diard, E Raffin, B Passera, G Dall'Igna, C Marendaz, O David, A Chauvin
Transcranial Magnetic Stimulation (TMS) established itself as a powerful technique for probing and treating the human brain. Major technological evolutions, such as neuronavigation and robotized systems, have continuously increased the spatial reliability and reproducibility of TMS, by minimizing the influence of human and experimental factors. However, there is still a lack of efficient set-up procedure, which prevents the automation of TMS protocols. For example, the set-up procedure for defining the stimulation intensity specific to each subject is classically done manually by experienced practitioners, by assessing the motor cortical excitability level over the motor hotspot (HS) of a targeted muscle...
April 4, 2017: NeuroImage
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