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https://www.readbyqxmd.com/read/29220726/monte-carlo-calculations-of-electrons-impinging-on-a-copper-target-a-comparison-of-egsnrc-geant4-and-mcnp5
#1
John Paul Archambault
A simple geometry is used to compare several of the available Monte Carlo software codes for radiation transport. EGSnrc, Geant4 and MCNP5 are all used to calculate the photon fluence produced from electrons incident on a copper target. Four energies for the isotropic point source are chosen to simulate the average and maximum emission energies of 32P and 90Y: (0.7, 1.71)MeV and (0.93, 2.28)MeV, respectively. The energy deposition in the copper target, the electron current at the target and the computational efficiency are also calculated...
November 27, 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/29220695/altered-resting-state-functional-connectivity-in-early-course-schizophrenia
#2
Aastha Sharma, Arvind Kumar, Sadhana Singh, Triptish Bhatia, R P Beniwal, Subash Khushu, Konasale M Prasad, Smita N Deshpande
Impaired connectivity is proposed to underlie pathophysiology of schizophrenia. Existing studies on functional connectivity show inconsistent results. We examined functional connectivity in a clinically homogenous sample of 34 early course schizophrenia patients compared with/to 19 healthy controls using resting state functional magnetic resonance imaging (rsfMRI). Mean duration of illness for schizophrenia patients was 4 ± 1.78 years. Following a comprehensive clinical assessment, rsfMRI data were acquired using a 3...
November 22, 2017: Psychiatry Research
https://www.readbyqxmd.com/read/29213104/musical-imagery-involves-wernicke-s-area-in-bilateral-and-anti-correlated-network-interactions-in-musicians
#3
Yizhen Zhang, Gang Chen, Haiguang Wen, Kun-Han Lu, Zhongming Liu
Musical imagery is the human experience of imagining music without actually hearing it. The neural basis of this mental ability is unclear, especially for musicians capable of engaging in accurate and vivid musical imagery. Here, we created a visualization of an 8-minute symphony as a silent movie and used it as real-time cue for musicians to continuously imagine the music for repeated and synchronized sessions during functional magnetic resonance imaging (fMRI). The activations and networks evoked by musical imagery were compared with those elicited by the subjects directly listening to the same music...
December 6, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29211655/spectral-diversity-in-default-mode-network-connectivity-reflects-behavioral-state
#4
Michael M Craig, Anne E Manktelow, Barbara J Sahakian, David K Menon, Emmanuel A Stamatakis
Default mode network (DMN) functional connectivity is thought to occur primarily in low frequencies (<0.1 Hz), resulting in most studies removing high frequencies during data preprocessing. In contrast, subtractive task analyses include high frequencies, as these are thought to be task relevant. An emerging line of research explores resting fMRI data at higher-frequency bands, examining the possibility that functional connectivity is a multiband phenomenon. Furthermore, recent studies suggest DMN involvement in cognitive processing; however, without a systematic investigation of DMN connectivity during tasks, its functional contribution to cognition cannot be fully understood...
December 6, 2017: Journal of Cognitive Neuroscience
https://www.readbyqxmd.com/read/29209238/disrupted-control-related-functional-brain-networks-in-drug-naive-children-with-attention-deficit-hyperactivity-disorder
#5
Jiejie Tao, Xueyan Jiang, Xin Wang, Huiru Liu, Andan Qian, Chuang Yang, Hong Chen, Jiance Li, Qiong Ye, Jinhui Wang, Meihao Wang
Attention-deficit/hyperactivity disorder (ADHD) is a common neurodevelopmental disease featuring executive control deficits as a prominent neuropsychological trait. Executive functions are implicated in multiple sub-networks of the brain; however, few studies examine these sub-networks as a whole in ADHD. By combining resting-state functional MRI and graph-based approaches, we systematically investigated functional connectivity patterns among four control-related networks, including the frontoparietal network (FPN), cingulo-opercular network, cerebellar network, and default mode network (DMN), in 46 drug-naive children with ADHD and 31 age-, gender-, and intelligence quotient-matched healthy controls (HCs)...
2017: Frontiers in Psychiatry
https://www.readbyqxmd.com/read/29209203/linking-inter-individual-variability-in-functional-brain-connectivity-to-cognitive-ability-in-elderly-individuals
#6
Rui Li, Shufei Yin, Xinyi Zhu, Weicong Ren, Jing Yu, Pengyun Wang, Zhiwei Zheng, Ya-Nan Niu, Xin Huang, Juan Li
Increasing evidence suggests that functional brain connectivity is an important determinant of cognitive aging. However, the fundamental concept of inter-individual variations in functional connectivity in older individuals is not yet completely understood. It is essential to evaluate the extent to which inter-individual variability in connectivity impacts cognitive performance at an older age. In the current study, we aimed to characterize individual variability of functional connectivity in the elderly and to examine its significance to individual cognition...
2017: Frontiers in Aging Neuroscience
https://www.readbyqxmd.com/read/29208849/possessions-including-poltergeist-are-you-there-madness
#7
Olivier Walusinski
Beliefs involving the devil and possession figured in the nosography of mental illness that alienists gradually established during the 19th century. The description of this form of cenesthetic hallucination resulted in "the possessed" being viewed as patients, which protected them from the trials and punishments they so frequently faced in earlier centuries. According to psychologists, this illusion of mental duality is linked to impairment of introspective capacities. Current brain imaging suggests inappropriate activity of the default mode network, which interferes with attentional systems during the hallucinatory episode...
2018: Frontiers of Neurology and Neuroscience
https://www.readbyqxmd.com/read/29208422/support-vector-machine-based-classification-of-first-episode-drug-na%C3%A3-ve-schizophrenia-patients-and-healthy-controls-using-structural-mri
#8
Yuan Xiao, Zhihan Yan, Youjin Zhao, Bo Tao, Huaiqiang Sun, Fei Li, Li Yao, Wenjing Zhang, Shah Chandan, Jieke Liu, Qiyong Gong, John A Sweeney, Su Lui
Although regional brain deficits have been demonstrated in schizophrenia patients by structural MRI studies, one important question that remains largely unanswered is whether the complex and subtle deficits revealed by MRI could be used as objective biomarkers to discriminate patients from healthy controls individually. To address this question, a total of 326 right-handed participants were recruited, including 163 drug-naïve first-episode schizophrenia (FES) patients and 163 demographically matched healthy controls...
December 2, 2017: Schizophrenia Research
https://www.readbyqxmd.com/read/29206399/association-between-structural-and-functional-brain-alterations-in-drug-free-patients-with-schizophrenia-a-multimodal-meta-analysis
#9
Xin Gao, Wenjing Zhang, Li Yao, Yuan Xiao, Lu Liu, Jieke Liu, Siyi Li, Bo Tao, Chandan Shah, Qiyong Gong, John Sweeney, Su Lui
Background: Neuroimaging studies have shown both structural and functional abnormalities in patients with schizophrenia. Recently, studies have begun to explore the association between structural and functional grey matter abnormalities. By conducting a meta­-analysis on morphometric and functional imaging studies of grey matter alterations in drug-free patients, the present study aims to examine the degree of overlap between brain regions with anatomic and functional changes in patients with schizophrenia...
December 5, 2017: Journal of Psychiatry & Neuroscience: JPN
https://www.readbyqxmd.com/read/29205574/different-pre-scanning-instructions-induce-distinct-psychological-and-resting-brain-states-during-functional-magnetic-resonance-imaging
#10
Toshikazu Kawagoe, Keiichi Onoda, Shuhei Yamaguchi
Resting-state functional magnetic resonance imaging (rs-fMRI) is widely used to investigate functional brain network connectivity during rest or when the subject is not performing an explicit task. In the standard procedure, subjects are instructed to "let your mind wander" or "think of nothing." While these instructions appear appropriate to induce a "resting-state," they could induce distinct psychological and physiological states during the scan. In this study, we investigated whether different instructions affect mental state and functional connectivity (FC) (i...
December 4, 2017: European Journal of Neuroscience
https://www.readbyqxmd.com/read/29204113/effect-of-electro-acupuncture-and-moxibustion-on-brain-connectivity-in-patients-with-crohn-s-disease-a-resting-state-fmri-study
#11
Chunhui Bao, Di Wang, Peng Liu, Yin Shi, Xiaoming Jin, Luyi Wu, Xiaoqing Zeng, Jianye Zhang, Huirong Liu, Huangan Wu
Acupuncture and moxibustion have been shown to be effective in treating Crohn's disease (CD), but their therapeutic mechanisms remain unclear. Here we compared brain responses to either electro-acupuncture or moxibustion treatment in CD patients experiencing remission. A total of 65 patients were randomly divided into an electro-acupuncture group (n = 32) or a moxibustion group (n = 33), and treated for 12 weeks. Eighteen patients in the electro-acupuncture group and 20 patients in the moxibustion group underwent resting-state functional magnetic resonance imaging at baseline and after treatment...
2017: Frontiers in Human Neuroscience
https://www.readbyqxmd.com/read/29201281/graph-theoretical-approaches-towards-understanding-differences-in-frontoparietal-and-default-mode-networks-in-autism
#12
Brandalyn C Riedel, Neda Jahanshad, Paul M Thompson
Autism Spectrum Disorder is a complex developmental disorder affecting 1 in 68 children in the United States. While the prevalence may be on the rise, we currently lack a firm understanding of the etiology of the disease, and diagnosis is made purely on behavioral observation and informant report. As one method to improve our understanding of the disease, the current study took a systems-level approach by assessing the causal interactions among the frontoparietal and default mode networks using structural covariance of a large Autism dataset...
2017: Proceedings of the IEEE International Symposium on Biomedical Imaging: from Nano to Macro
https://www.readbyqxmd.com/read/29198443/how-the-human-brain-introspects-about-one-s-own-episodes-of-cognitive-control
#13
David Soto, Mona Theodoraki, Pedro M Paz-Alonso
Metacognition refers to our capacity to reflect upon our experiences, thoughts and actions. Metacognition processes are linked to cognitive control functions that allow keeping our actions on-task. But it is unclear how the human brain builds an internal model of one's cognition and behaviour. We conducted two functional magnetic resonance imaging (fMRI) experiments in which brain activity was recorded 'online' as participants engaged in a memory-guided search task and then later 'offline' when participants introspected about their prior experience and cognitive states during performance...
November 8, 2017: Cortex; a Journal Devoted to the Study of the Nervous System and Behavior
https://www.readbyqxmd.com/read/29197501/intuitive-physics-ability-in-systemizers-relies-on-differential-use-of-the-internalizing-system-and-long-term-spatial-representations
#14
Tapani Riekki, Juha Salmi, Annika M Svedholm-Häkkinen, Marjaana Lindeman
According to the Empathizing-Systemizing theory (E-S Theory), individual differences in how people understand the physical world (systemizing) and the social world (empathizing), are two continuums in the general population with several implications, from vocational interests to skills in the social and physical domains. The underlying mechanisms of intuitive physics performance among individuals with a strong systemizing and weak empathizing (systemizers) are, however, unknown. Our results affirm higher intuitive physics skills in healthy adult systemizers (N=36), and further reveal the brain mechanisms that are characteristic for those individuals in carrying out such tasks...
November 29, 2017: Neuropsychologia
https://www.readbyqxmd.com/read/29194517/a-switch-and-wave-of-neuronal-activity-in-the-cerebral-cortex-during-the-first-second-of-conscious-perception
#15
Wendy X Herman, Rachel E Smith, Sharif I Kronemer, Rebecca E Watsky, William C Chen, Leah M Gober, George J Touloumes, Meenakshi Khosla, Anusha Raja, Corey L Horien, Elliot C Morse, Katherine L Botta, Lawrence J Hirsch, Rafeed Alkawadri, Jason L Gerrard, Dennis D Spencer, Hal Blumenfeld
Conscious perception occurs within less than 1 s. To study events on this time scale we used direct electrical recordings from the human cerebral cortex during a conscious visual perception task. Faces were presented at individually titrated visual threshold for 9 subjects while measuring broadband 40-115 Hz gamma power in a total of 1621 intracranial electrodes widely distributed in both hemispheres. Surface maps and k-means clustering analysis showed initial activation of visual cortex for both perceived and non-perceived stimuli...
November 29, 2017: Cerebral Cortex
https://www.readbyqxmd.com/read/29193464/functional-connectivity-in-dementia-with-lewy-bodies-a-within-and-between-network-analysis
#16
Julia Schumacher, Luis R Peraza, Michael Firbank, Alan J Thomas, Marcus Kaiser, Peter Gallagher, John T O'Brien, Andrew M Blamire, John-Paul Taylor
Dementia with Lewy bodies (DLB) is a common form of dementia and is characterized by cognitive fluctuations, visual hallucinations, and Parkinsonism. The phenotypic expression of the disease may, in part, relate to alterations in functional connectivity within and between brain networks. This resting-state study sought to clarify this in DLB, how networks differed from Alzheimer's disease (AD), and whether they were related to clinical symptoms in DLB. Resting-state networks were estimated using independent component analysis...
November 29, 2017: Human Brain Mapping
https://www.readbyqxmd.com/read/29192865/electrocorticography-and-the-early-maturation-of-high-frequency-suppression-within-the-default-mode-network
#17
Kurt E Weaver, Andrew Poliakov, Edward J Novotny, Jared D Olson, Thomas J Grabowski, Jeffrey G Ojemann
OBJECTIVE The acquisition and refinement of cognitive and behavioral skills during development is associated with the maturation of various brain oscillatory activities. Most developmental investigations have identified distinct patterns of low-frequency electrophysiological activity that are characteristic of various behavioral milestones. In this investigation, the authors focused on the cross-sectional developmental properties of high-frequency spectral power from the brain's default mode network (DMN) during goal-directed behavior...
December 1, 2017: Journal of Neurosurgery. Pediatrics
https://www.readbyqxmd.com/read/29192157/linking-functional-connectivity-and-dynamic-properties-of-resting-state-networks
#18
Won Hee Lee, Sophia Frangou
Spontaneous brain activity is organized into resting-state networks (RSNs) involved in internally-guided, higher-order mental functions (default mode, central executive and salience networks) and externally-driven, specialized sensory and motor processing (auditory, visual and sensorimotor networks). RSNs are characterized by their functional connectivity in terms of within-network cohesion and between-network integration, and by their dynamic properties in terms of synchrony and metastability. We examined the relationship between functional connectivity and dynamic network features using fMRI data and an anatomically constrained Kuramoto model...
November 30, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29190989/aberrant-pattern-of-regional-cerebral-blood-flow-in-alzheimer-s-disease-a-voxel-wise-meta-analysis-of-arterial-spin-labeling-mr-imaging-studies
#19
Hai Rong Ma, Ping Lei Pan, Li Qin Sheng, Zhen Yu Dai, Gen Di Wang, Rong Luo, Jia Hui Chen, Pei Rong Xiao, Jian Guo Zhong, Hai Cun Shi
Many studies have applied arterial spin labeling (ASL) to characterize cerebral perfusion patterns of Alzheimer's disease (AD). However, findings across studies are not conclusive. A quantitatively voxel-wise meta-analysis to pool the resting-state ASL studies that measure regional cerebral blood flow (rCBF) alterations in AD was conducted to identify the most consistent and replicable perfusion pattern using seed-based d mapping. The meta-analysis, including 17 ASL studies encompassing 327 AD patients and 357 healthy controls, demonstrated that decreased rCBF in AD patients relative to healthy controls were consistently identified in the bilateral posterior cingulate cortices (PCC)/precuneus, bilateral inferior parietal lobules (IPLs), and left dorsolateral prefrontal cortex...
November 3, 2017: Oncotarget
https://www.readbyqxmd.com/read/29187817/predicting-long-term-cognitive-outcome-following-breast-cancer-with-pre-treatment-resting-state-fmri-and-random-forest-machine-learning
#20
Shelli R Kesler, Arvind Rao, Douglas W Blayney, Ingrid A Oakley-Girvan, Meghan Karuturi, Oxana Palesh
We aimed to determine if resting state functional magnetic resonance imaging (fMRI) acquired at pre-treatment baseline could accurately predict breast cancer-related cognitive impairment at long-term follow-up. We evaluated 31 patients with breast cancer (age 34-65) prior to any treatment, post-chemotherapy and 1 year later. Cognitive testing scores were normalized based on data obtained from 43 healthy female controls and then used to categorize patients as impaired or not based on longitudinal changes. We measured clustering coefficient, a measure of local connectivity, by applying graph theory to baseline resting state fMRI and entered these metrics along with relevant patient-related and medical variables into random forest classification...
2017: Frontiers in Human Neuroscience
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