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Cortical modeling

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https://www.readbyqxmd.com/read/28334915/salience-and-default-mode-network-dysregulation-in-chronic-cocaine-users-predict-treatment-outcome
#1
Xiujuan Geng, Yuzheng Hu, Hong Gu, Betty Jo Salmeron, Bryon Adinoff, Elliot A Stein, Yihong Yang
While chronic cocaine use is associated with abnormalities in both brain structure and function within and interactions between regions, previous studies have been limited to interrogating structure and function independently, and the detected neural differences have not been applied to independent samples to assess the clinical relevance of results. We investigated consequences of structural differences on resting-state functional connectivity in cocaine addiction and tested whether resting-state functional connectivity of the identified circuits predict relapse in an independent cohort...
February 20, 2017: Brain: a Journal of Neurology
https://www.readbyqxmd.com/read/28334882/decreased-integration-and-information-capacity-in-stroke-measured-by-whole-brain-models-of-resting-state-activity
#2
Mohit H Adhikari, Carl D Hacker, Josh S Siegel, Alessandra Griffa, Patric Hagmann, Gustavo Deco, Maurizio Corbetta
While several studies have shown that focal lesions affect the communication between structurally normal regions of the brain, and that these changes may correlate with behavioural deficits, their impact on brain's information processing capacity is currently unknown. Here we test the hypothesis that focal lesions decrease the brain's information processing capacity, of which changes in functional connectivity may be a measurable correlate. To measure processing capacity, we turned to whole brain computational modelling to estimate the integration and segregation of information in brain networks...
February 20, 2017: Brain: a Journal of Neurology
https://www.readbyqxmd.com/read/28334424/frequency-and-function-in-the-basal-ganglia-the-origins-of-beta-and-gamma-band-activity
#3
Alexander Blenkinsop, Sean Anderson, Kevin Gurney
Neural oscillations in the basal ganglia are well studied yet remain poorly understood. Behavioural correlates of spectral activity are well described, yet a quantitative hypothesis linking time domain dynamics and spectral properties to basal ganglia function has been lacking. We show, for the first time, that a unified description is possible by interpreting previously ignored structure in data describing GPi responses to cortical stimulation. These data were used to expose a pair of distinctive neuronal responses to the stimulation...
March 23, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28334401/vocal-tract-images-reveal-neural-representations-of-sensorimotor-transformation-during-speech-imitation
#4
Daniel Carey, Marc E Miquel, Bronwen G Evans, Patti Adank, Carolyn McGettigan
Imitating speech necessitates the transformation from sensory targets to vocal tract motor output, yet little is known about the representational basis of this process in the human brain. Here, we address this question by using real-time MR imaging (rtMRI) of the vocal tract and functional MRI (fMRI) of the brain in a speech imitation paradigm. Participants trained on imitating a native vowel and a similar nonnative vowel that required lip rounding. Later, participants imitated these vowels and an untrained vowel pair during separate fMRI and rtMRI runs...
March 18, 2017: Cerebral Cortex
https://www.readbyqxmd.com/read/28334181/uncovering-the-spatial-profile-of-contour-integration-from-fixational-saccades-evidence-for-widespread-processing-in-v1
#5
Ariel Gilad, Roy Oz, Hamutal Slovin
During contour integration, neuronal populations in the primary visual cortex (V1) enhance their responses to the contour while suppressing their responses to the noisy background. However, the spatial extent and profile of these responses are not fully understood. To investigate this question, 2 monkeys were trained on a contour detection task while we measured population responses in V1 using voltage-sensitive dyes. During stimulus presentation the animals made few fixational saccades, and we used their changing gaze position to image and analyze neuronal responses from large part of the stimulus, encoding multiple contour/background elements...
October 5, 2016: Cerebral Cortex
https://www.readbyqxmd.com/read/28334159/characterization-of-white-matter-tracts-by-diffusion-mr-tractography-in-cat-and-ferret-that-have-similar-gyral-patterns
#6
Avilash Das, Emi Takahashi
The developmental relationships between gyral structures and white matter tracts have long been debated, but it is still difficult to discern whether they influence each other's development or are causally related. To explore this topic, this study used cats and ferrets as models for species that share similar gyral folding patterns and imaged with diffusion magnetic resonance imaging to compare white matter innervations in homologous gyri and other brain regions. Adult cat and ferret brains were analyzed via diffusion spectrum imaging tractography and homologous regions of interest were compared...
March 1, 2017: Cerebral Cortex
https://www.readbyqxmd.com/read/28334142/layer-specific-organization-of-local-excitatory-and-inhibitory-synaptic-connectivity-in-the-rat-presubiculum
#7
Yangfan Peng, Federico J Barreda Tomás, Constantin Klisch, Imre Vida, Jörg R P Geiger
The presubiculum is part of the parahippocampal spatial navigation system and contains head direction and grid cells upstream of the medial entorhinal cortex. This position within the parahippocampal cortex renders the presubiculum uniquely suited for analyzing the circuit requirements underlying the emergence of spatially tuned neuronal activity. To identify the local circuit properties, we analyzed the topology of synaptic connections between pyramidal cells and interneurons in all layers of the presubiculum by testing 4250 potential synaptic connections using multiple whole-cell recordings of up to 8 cells simultaneously...
February 25, 2017: Cerebral Cortex
https://www.readbyqxmd.com/read/28333689/computational-modelling-of-the-cerebral-cortical-microvasculature-effect-of-x-ray-microbeams-versus-broad-beam-irradiation
#8
Andreas Merrem, Stefan Bartzsch, Jean Laissue, Uwe Oelfke
Microbeam Radiation Therapy is an innovative pre-clinical strategy which uses arrays of parallel, tens of micrometre wide kilo-voltage photon beams to treat tumours. These X-ray beams are typically generated on a synchrotron source. It was shown that these beam geometries allow exceptional normal tissue sparing from radiation damage while still being effective in tumour ablation. A final biological explanation for this enhanced therapeutic ratio has still not been found, some experimental data support an important role of the vasculature...
March 23, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28333588/multiassociative-memory-recurrent-synapses-increase-storage-capacity
#9
Marcelo Matheus Gauy, Florian Meier, Angelika Steger
The connection density of nearby neurons in the cortex has been observed to be around 0.1, whereas the longer-range connections are present with much sparser density (Kalisman, Silberberg, & Markram, 2005). We propose a memory association model that qualitatively explains these empirical observations. The model we consider is a multiassociative, sparse, Willshaw-like model consisting of binary threshold neurons and binary synapses. It uses recurrent synapses for iterative retrieval of stored memories. We quantify the usefulness of recurrent synapses by simulating the model for small network sizes and by doing a precise mathematical analysis for large network sizes...
March 23, 2017: Neural Computation
https://www.readbyqxmd.com/read/28333583/an-approximation-of-the-error-backpropagation-algorithm-in-a-predictive-coding-network-with-local-hebbian-synaptic-plasticity
#10
James C R Whittington, Rafal Bogacz
To efficiently learn from feedback, cortical networks need to update synaptic weights on multiple levels of cortical hierarchy. An effective and well-known algorithm for computing such changes in synaptic weights is the error backpropagation algorithm. However, in this algorithm, the change in synaptic weights is a complex function of weights and activities of neurons not directly connected with the synapse being modified, whereas the changes in biological synapses are determined only by the activity of presynaptic and postsynaptic neurons...
March 23, 2017: Neural Computation
https://www.readbyqxmd.com/read/28333275/anti-m%C3%A3-llerian-hormone-inhibits-activation-and-growth-of-bovine-ovarian-follicles-in-vitro-and-is-localized-to-growing-follicles
#11
M Y Yang, R A Cushman, J E Fortune
STUDY QUESTION: Does anti-Müllerian hormone (AMH) inhibit activation (initiation of growth) of primordial follicles and attenuate the growth of primary follicles in cattle, an excellent animal model for human ovarian follicular development? SUMMARY ANSWER: AMH inhibited activation of bovine primordial follicles and attenuated the growth of activated follicles in vitro. WHAT IS KNOWN ALREADY: In mice null mutant for AMH, the pool of primordial follicles is depleted prematurely and AMH inhibits follicle activation in vitro...
March 17, 2017: Molecular Human Reproduction
https://www.readbyqxmd.com/read/28333144/aberrant-ipsc-derived-human-astrocytes-in-alzheimer-s-disease
#12
V C Jones, R Atkinson-Dell, A Verkhratsky, L Mohamet
The pathological potential of human astroglia in Alzheimer's disease (AD) was analysed in vitro using induced pluripotent stem cell (iPSC) technology. Here, we report development of a human iPSC-derived astrocyte model created from healthy individuals and patients with either early-onset familial AD (FAD) or the late-onset sporadic form of AD (SAD). Our chemically defined and highly efficient model provides >95% homogeneous populations of human astrocytes within 30 days of differentiation from cortical neural progenitor cells (NPCs)...
March 23, 2017: Cell Death & Disease
https://www.readbyqxmd.com/read/28328700/lumbar-tactile-acuity-in-patients-with-low-back-pain-and-healthy-controls-systematic-review-and-meta-analysis
#13
Wacław Adamczyk, Kerstin Luedtke, Edward Saulicz
OBJECTIVE: Diminished tactile acuity in chronic non-neuropathic pain syndromes has been attributed to central pain processing and cortical reorganization. The latter was recently targeted in clinical trials that demonstrated no clear advantages over traditional approaches for the reduction of nonspecific low back pain (LBP). The aim of this systematic review and meta-analysis was to summarize the current evidence on tactile acuity in LBP and pain-free controls. METHODS: Six databases were independently searched by 2 researchers...
March 21, 2017: Clinical Journal of Pain
https://www.readbyqxmd.com/read/28327181/soluble-oligomeric-amyloid-%C3%AE-induces-calcium-dyshomeostasis-that-precedes-synapse-loss-in-the-living-mouse-brain
#14
Michal Arbel-Ornath, Eloise Hudry, Josiah R Boivin, Tadafumi Hashimoto, Shuko Takeda, Kishore V Kuchibhotla, Steven Hou, Carli R Lattarulo, Arianna M Belcher, Naomi Shakerdge, Pariss B Trujillo, Alona Muzikansky, Rebecca A Betensky, Bradley T Hyman, Brian J Bacskai
BACKGROUND: Amyloid-β oligomers (oAβ) are thought to mediate neurotoxicity in Alzheimer's disease (AD), and previous studies in AD transgenic mice suggest that calcium dysregulation may contribute to these pathological effects. Even though AD mouse models remain a valuable resource to investigate amyloid neurotoxicity, the concomitant presence of soluble Aβ species, fibrillar Aβ, and fragments of amyloid precursor protein (APP) complicate the interpretation of the phenotypes. METHOD: To explore the specific contribution of soluble oligomeric Aβ (oAβ) to calcium dyshomeostasis and synaptic morphological changes, we acutely exposed the healthy mouse brain, at 3 to 6 months of age, to naturally occurring soluble oligomers and investigated their effect on calcium levels using in vivo multiphoton imaging...
March 21, 2017: Molecular Neurodegeneration
https://www.readbyqxmd.com/read/28326625/alantolactone-and-isoalantolactone-prevent-amyloid-%C3%AE-25-35-induced-toxicity-in-mouse-cortical-neurons-and-scopolamine-induced-cognitive-impairment-in-mice
#15
Ji Yeon Seo, Soon Sung Lim, Jiyoung Kim, Ki Won Lee, Jong-Sang Kim
Given the evidence for detoxifying/antioxidant enzyme-inducing activities by alantolactone (AL) and isoalantolactone (IAL), the purpose of this study was to investigate the effects of AL and IAL on Aβ25-35 -induced cell death in mouse cortical neuron cells and to determine their effects on scopolamine-induced amnesia in mice. Our data demonstrated that both compounds effectively attenuated the cytotoxicity of Aβ25-35 (10 μM) in neuronal cells derived from the mouse cerebral cortex. It was also found that the production of intracellular reactive oxygen species, including superoxide anion induced by Aβ25-35 , was inhibited...
March 21, 2017: Phytotherapy Research: PTR
https://www.readbyqxmd.com/read/28326606/physical-activity-sedentary-time-and-bone-strength-from-childhood-to-early-adulthood-a-mixed-longitudinal-hr-pqct-study
#16
Leigh Gabel, Heather M Macdonald, Lindsay Nettlefold, Heather A McKay
Bone strength is influenced by bone geometry, density, and bone microarchitecture, which adapt to increased mechanical loads during growth. Physical activity (PA) is essential for optimal bone strength accrual; however, less is known about how sedentary time influences bone strength and its determinants. Thus, our aim was to investigate the prospective associations between PA, sedentary time, and bone strength and its determinants during adolescence. We used HR-pQCT at distal tibia (8% site) and radius (7% site) in 173 girls and 136 boys (aged 9 to 20 years at baseline)...
March 22, 2017: Journal of Bone and Mineral Research: the Official Journal of the American Society for Bone and Mineral Research
https://www.readbyqxmd.com/read/28326340/organ-and-tissue-level-properties-are-more-sensitive-to-age-than-osteocyte-lacunar-characteristics-in-rat-cortical-bone
#17
Nina Kølln Wittig, Fiona Linnea Bach-Gansmo, Mie Elholm Birkbak, Malene Laugesen, Annemarie Brüel, Jesper Skovhus Thomsen, Henrik Birkedal
Modeling and remodeling induce significant changes of bone structure and mechanical properties with age. Therefore, it is important to gain knowledge of the processes taking place in bone over time. The rat is a widely used animal model, where much data has been accumulated on age-related changes of bone on the organ and tissue level, whereas features on the nano- and micrometer scale are much less explored. We investigated the age-related development of organ and tissue level bone properties such as bone volume, bone mineral density, and load to fracture and correlated these with osteocyte lacunar properties in rat cortical bone...
June 2016: Bone Reports
https://www.readbyqxmd.com/read/28326054/dynamical-constants-and-time-universals-a-first-step-toward-a-metrical-definition-of-ordered-and-abnormal-cognition
#18
REVIEW
Mark A Elliott, Naomi du Bois
From the point of view of the cognitive dynamicist the organization of brain circuitry into assemblies defined by their synchrony at particular (and precise) oscillation frequencies is important for the correct correlation of all independent cortical responses to the different aspects of a given complex thought or object. From the point of view of anyone operating complex mechanical systems, i.e., those comprising independent components that are required to interact precisely in time, it follows that the precise timing of such a system is essential - not only essential but measurable, and scalable...
2017: Frontiers in Psychology
https://www.readbyqxmd.com/read/28326032/a-dynamic-circuit-hypothesis-for-the-pathogenesis-of-blepharospasm
#19
David A Peterson, Terrence J Sejnowski
Blepharospasm (sometimes called "benign essential blepharospasm," BEB) is one of the most common focal dystonias. It involves involuntary eyelid spasms, eye closure, and increased blinking. Despite the success of botulinum toxin injections and, in some cases, pharmacologic or surgical interventions, BEB treatments are not completely efficacious and only symptomatic. We could develop principled strategies for preventing and reversing the disease if we knew the pathogenesis of primary BEB. The objective of this study was to develop a conceptual framework and dynamic circuit hypothesis for the pathogenesis of BEB...
2017: Frontiers in Computational Neuroscience
https://www.readbyqxmd.com/read/28325671/accurate-fixation-of-plates-and-screws-for-the-treatment-of-acetabular-fractures-using-3d-printed-guiding-templates-an-experimental-study
#20
Xu Chen, Xuanhuang Chen, Guodong Zhang, Haibin Lin, Zhengxi Yu, Changfu Wu, Xing Li, Yijun Lin, Wenhua Huang
OBJECTIVE: To investigate the feasibility of the use of 3D-printed guiding templates for accurate placement of plates and screws for internal fixation of acetabular fractures. METHODS: 3D models of the pelvises of 14 adult cadavers were reconstructed using computed tomography (CT). Twenty-eight acetabular fractures were simulated and placement positions for plates and screw trajectories were designed. Bending module was obtained by 3D cutting; guiding template was manufactured using 3D printing, and the plate was pre-bent according to the bending module...
March 7, 2017: Injury
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