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https://www.readbyqxmd.com/read/29045569/altered-expression-of-reorganized-inputs-as-they-ascend-from-the-cuneate-nucleus-to-cortical-area-3b-in-monkeys-with-long-term-spinal-cord-injuries
#1
Priyabrata Halder, Niranjan Kambi, Prem Chand, Neeraj Jain
Chronic deafferentations in adult mammals result in reorganization of the brain. Lesions of the dorsal columns of the spinal cord at cervical levels in monkeys result in expansion of the intact chin inputs into the deafferented hand representation in area 3b, second somatosensory (S2) and parietal ventral (PV) areas of the somatosensory cortex, ventroposterior lateral nucleus (VPL) of the thalamus, and cuneate nucleus of the brainstem. Here, we describe the extent and nature of reorganization of the cuneate and gracile nuclei of adult macaque monkeys with chronic unilateral lesions of the dorsal columns, and compare it with the reorganization of area 3b in the same monkeys...
October 13, 2017: Cerebral Cortex
https://www.readbyqxmd.com/read/29045561/structural-variability-across-the-primate-brain-a-cross-species-comparison
#2
Paula L Croxson, Stephanie J Forkel, Leonardo Cerliani, Michel Thiebaut de Schotten
A large amount of variability exists across human brains; revealed initially on a small scale by postmortem studies and, more recently, on a larger scale with the advent of neuroimaging. Here we compared structural variability between human and macaque monkey brains using grey and white matter magnetic resonance imaging measures. The monkey brain was overall structurally as variable as the human brain, but variability had a distinct distribution pattern, with some key areas showing high variability. We also report the first evidence of a relationship between anatomical variability and evolutionary expansion in the primate brain...
October 13, 2017: Cerebral Cortex
https://www.readbyqxmd.com/read/29042433/serotonin-decreases-the-gain-of-visual-responses-in-awake-macaque-v1
#3
Lenka Seillier, Corinna Lorenz, Katsuhisa Kawaguchi, Torben Ott, Andreas Nieder, Paria Pourriahi, Hendrikje Nienborg
Serotonin (5HT) is an important neuromodulator in the brain implicated in affective and cognitive functions but its role even for basic cortical processes is controversial. For example, in the mammalian primary visual cortex heterogenous serotonergic modulation has been observed in anesthetized animals. Here, we combined extracellular single unit recordings with iontophoresis in awake animals. We examined the role of serotonin on well-defined tuning properties (orientation, spatial frequency, contrast and size) in the primary visual cortex (V1) of two male macaque monkeys...
October 17, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/29042259/widespread-optogenetic-expression-in-macaque-cortex-obtained-with-mr-guided-convection-enhanced-delivery-ced-of-aav-vector-to-the-thalamus
#4
Azadeh Yazdan-Shahmorad, Nan Tian, Viktor Kharazia, Lluis Samaranch, Adrian Kells, John Bringas, Jiwei He, Krystof Bankiewicz, Philip N Sabes
BACKGROUND: In non-human primate (NHP) optogenetics, infecting large cortical areas with viral vectors is often a difficult and time-consuming task. Previous work has shown that parenchymal delivery of adeno-associated virus (AAV) in the thalamus by convection-enhanced delivery (CED) can lead to large-scale transduction via axonal transport in distal areas including cortex. We used this approach to obtain widespread cortical expression of light-sensitive ion channels. NEW METHOD: AAV vectors co-expressing channelrhodopsin-2 (ChR2) and yellow fluorescent protein (YFP) genes were infused into thalamus of three rhesus macaques under MR-guided CED...
October 14, 2017: Journal of Neuroscience Methods
https://www.readbyqxmd.com/read/29035203/developing-a-nonstationary-computational-framework-with-application-to-modeling-dynamic-modulations-in-neural-spiking-responses
#5
Amir Akbarian, Kaiser Niknam, Mohammadbagher Parsa, Kelsey Clark, Behrad Noudoost, Neda Nategh
OBJECTIVE: This paper aims to develop a computational model that incorporates the functional effects of modulatory covariates (such as context, task, or behavior), which dynamically alter the relationship between the stimulus and the neural response. METHODS: We develop a general computational approach along with an efficient estimation procedure in the widely used generalized linear model (GLM) framework to characterize such nonstationary dynamics in spiking response and spatiotemporal characteristics of a neuron at the level of individual trials...
October 13, 2017: IEEE Transactions on Bio-medical Engineering
https://www.readbyqxmd.com/read/29033331/transcranial-direct-current-stimulation-facilitates-associative-learning-and-alters-functional-connectivity-in-the-primate-brain
#6
Matthew R Krause, Theodoros P Zanos, Bennett A Csorba, Praveen K Pilly, Jaehoon Choe, Matthew E Phillips, Abhishek Datta, Christopher C Pack
There has been growing interest in transcranial direct current stimulation (tDCS), a non-invasive technique purported to modulate neural activity via weak, externally applied electric fields. Although some promising preliminary data have been reported for applications ranging from stroke rehabilitation to cognitive enhancement, little is known about how tDCS affects the human brain, and some studies have concluded that it may have no effect at all. Here, we describe a macaque model of tDCS that allows us to simultaneously examine the effects of tDCS on brain activity and behavior...
October 11, 2017: Current Biology: CB
https://www.readbyqxmd.com/read/29030557/heading-representations-in-primates-are-compressed-by-saccades
#7
Frank Bremmer, Jan Churan, Markus Lappe
Perceptual illusions help to understand how sensory signals are decoded in the brain. Here we report that the opposite approach is also applicable, i.e., results from decoding neural activity from monkey extrastriate visual cortex correctly predict a hitherto unknown perceptual illusion in humans. We record neural activity from monkey medial superior temporal (MST) and ventral intraparietal (VIP) area during presentation of self-motion stimuli and concurrent reflexive eye movements. A heading-decoder performs veridically during slow eye movements...
October 13, 2017: Nature Communications
https://www.readbyqxmd.com/read/29030435/dissociation-of-self-motion-and-object-motion-by-linear-population-decoding-that-approximates-marginalization
#8
Ryo Sasaki, Dora E Angelaki, Gregory C DeAngelis
We use visual image motion to judge the movement of objects, as well as our own movements through the environment. Generally, image motion components caused by object motion and self-motion are confounded in the retinal image. Thus, to estimate heading, the brain would ideally marginalize out the effects of object motion (or vice-versa), but little is known about how this is accomplished neurally. Behavioral studies suggest that vestibular signals play a role in dissociating object motion and self-motion, and recent computational work suggests that a linear decoder can approximate marginalization by taking advantage of diverse multisensory representations...
October 13, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28986463/hebbian-learning-in-a-random-network-captures-selectivity-properties-of-prefrontal-cortex
#9
Grace W Lindsay, Mattia Rigotti, Melissa R Warden, Earl K Miller, Stefano Fusi
Complex cognitive behaviors, such as context-switching and rule-following, are thought to be supported by prefrontal cortex (PFC). Neural activity in PFC must thus be specialized to specific tasks while retaining flexibility. Nonlinear 'mixed' selectivity is an important neurophysiological trait for enabling complex and context-dependent behaviors. Here we investigate (1) the extent to which PFC exhibits computationally-relevant properties such as mixed selectivity and (2) how such properties could arise via circuit mechanisms...
October 6, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28983518/evidence-for-a-large-scale-brain-system-supporting-allostasis-and-interoception-in-humans
#10
Ian R Kleckner, Jiahe Zhang, Alexandra Touroutoglou, Lorena Chanes, Chenjie Xia, W Kyle Simmons, Karen S Quigley, Bradford C Dickerson, Lisa Feldman Barrett
Large-scale intrinsic brain systems have been identified for exteroceptive senses (e.g., sight, hearing, touch). We introduce an analogous system for representing sensations from within the body, called interoception, and demonstrate its relation to regulating peripheral systems in the body, called allostasis. Employing the recently introduced Embodied Predictive Interoception Coding (EPIC) model, we used tract-tracing studies of macaque monkeys, followed by two intrinsic functional magnetic resonance imaging samples (N = 280 and N = 270) to evaluate the existence of an intrinsic allostatic/interoceptive system in the human brain...
2017: Nature Human Behaviour
https://www.readbyqxmd.com/read/28975505/an-siv-macaque-model-targeted-to-study-hiv-associated-neurocognitive-disorders
#11
REVIEW
Sarah E Beck, Suzanne E Queen, Kelly A Metcalf Pate, Lisa M Mangus, Celina M Abreu, Lucio Gama, Kenneth W Witwer, Robert J Adams, M Christine Zink, Janice E Clements, Joseph L Mankowski
Simian immunodeficiency virus (SIV) infection of pigtailed macaques is a highly representative and well-characterized animal model for HIV neuropathogenesis studies that provides an excellent opportunity to study and develop prognostic markers of HIV-associated neurocognitive disorders (HAND) for HIV-infected individuals. SIV studies can be performed in a controlled setting that enhances reproducibility and offers high-translational value. Similar to observations in HIV-infected patients receiving antiretroviral therapy (ART), ongoing neurodegeneration and inflammation are present in SIV-infected pigtailed macaques treated with suppressive ART...
October 3, 2017: Journal of Neurovirology
https://www.readbyqxmd.com/read/28969320/isoflurane-exposure-for-three-hours-triggers-apoptotic-cell-death-in-neonatal-macaque-brain
#12
K K Noguchi, S A Johnson, G A Dissen, L D Martin, F M Manzella, K J Schenning, J W Olney, A M Brambrink
Background: Retrospective clinical studies suggest there is a risk for neurodevelopmental impairment following early childhood exposure to anaesthesia. In the developing animal brain, including those of non-human primates (NHPs), anaesthetics induce apoptotic cell death. We previously reported that a 5 h isoflurane (ISO) exposure in infant NHPs increases apoptosis 13-fold compared with control animals. However, the majority of paediatric surgeries requiring anaesthesia are of shorter durations...
September 1, 2017: British Journal of Anaesthesia
https://www.readbyqxmd.com/read/28968837/denser-growing-fiber-connections-induce-3-hinge-gyral-folding
#13
Fangfei Ge, Xiao Li, Mir Jalil Razavi, Hanbo Chen, Tuo Zhang, Shu Zhang, Lei Guo, Xiaoping Hu, Xianqiao Wang, Tianming Liu
Recent studies have shown that quantitative description of gyral shape patterns offers a novel window to examine the relationship between brain structure and function. Along this research line, this paper examines a unique and interesting type of cortical gyral region where 3 different gyral crests meet, termed 3-hinge gyral region. We extracted 3-hinge gyral regions in macaque/chimpanzee/human brains, quantified and compared the relevant DTI-derived fiber densities in 3-hinge and 2-hinge gyral regions. Our observations consistently showed that DTI-derived fiber densities in 3-hinge regions are much higher than those in 2-hinge regions...
August 30, 2017: Cerebral Cortex
https://www.readbyqxmd.com/read/28957679/high-level-prediction-signals-in-a-low-level-area-of-the-macaque-face-processing-hierarchy
#14
Caspar M Schwiedrzik, Winrich A Freiwald
Theories like predictive coding propose that lower-order brain areas compare their inputs to predictions derived from higher-order representations and signal their deviation as a prediction error. Here, we investigate whether the macaque face-processing system, a three-level hierarchy in the ventral stream, employs such a coding strategy. We show that after statistical learning of specific face sequences, the lower-level face area ML computes the deviation of actual from predicted stimuli. But these signals do not reflect the tuning characteristic of ML...
September 27, 2017: Neuron
https://www.readbyqxmd.com/read/28957019/neural-decoding-a-predictive-viewpoint
#15
Sonia Todorova, Valérie Ventura
Decoding in the context of brain-machine interface is a prediction problem, with the aim of retrieving the most accurate kinematic predictions attainable from the available neural signals. While selecting models that reduce the prediction error is done to various degrees, decoding has not received the attention that the fields of statistics and machine learning have lavished on the prediction problem in the past two decades. Here, we take a more systematic approach to the decoding prediction problem and search for risk-optimized reverse regression, optimal linear estimation (OLE), and Kalman filter models within a large model space composed of several nonlinear transformations of neural spike counts at multiple temporal lags...
September 28, 2017: Neural Computation
https://www.readbyqxmd.com/read/28935234/fractal-rules-in-brain-networks-signatures-of-self-organization
#16
Soibam Shyamchand Singh, Dineshchandra Haobijam, Md Zubbair Malik, Romana Ishrat, R K Brojen Singh
We study brain network data of three species, namely, C. elegans, cat and macaque monkey within the framework of network theory and Potts Hamiltonian model, and explore rich fractal nature in it, which could be an important signature of self-organization, and a simple rule to be obeyed in complex patterns of brain networks. Further, this fractal behaviors in topological parameters of brain networks at various network levels could be an indicator of systems level organization in complicated brain functionality...
September 18, 2017: Journal of Theoretical Biology
https://www.readbyqxmd.com/read/28926566/guidelines-for-the-management-of-a-brain-death-donor-in-the-rhesus-macaque-a-translational-transplant-model
#17
Tiffany J Zens, Juan S Danobeitia, Peter J Chlebeck, Laura J Zitur, Scott Odorico, Kevin Brunner, Jennifer Coonen, Saverio Capuano, Anthony M D'Alessandro, Kristina Matkowskyj, Weixiong Zhong, Jose Torrealba, Luis Fernandez
INTRODUCTION: The development of a translatable brain death animal model has significant potential to advance not only transplant research, but also the understanding of the pathophysiologic changes that occur in brain death and severe traumatic brain injury. The aim of this paper is to describe a rhesus macaque model of brain death designed to simulate the average time and medical management described in the human literature. METHODS: Following approval by the Institutional Animal Care and Use Committee, a brain death model was developed...
2017: PloS One
https://www.readbyqxmd.com/read/28924008/primary-generators-of-visually-evoked-field-potentials-recorded-in-the-macaque-auditory-cortex
#18
Yoshinao Kajikawa, John F Smiley, Charles E Schroeder
Prior studies have reported "local" field potential (LFP) responses to faces in the macaque auditory cortex and have suggested that such face-LFPs may be substrates of audiovisual integration. However, while field potentials (FPs) may reflect the synaptic currents of neurons near the recording electrode, due to the use of a distant reference electrode, they often reflect those of synaptic activity occurring in distant sites as well. Thus, FP recordings within a given brain region (e.g., auditory cortex) may be "contaminated" by activity generated elsewhere in the brain...
September 18, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28915311/can-increased-spatial-resolution-solve-the-crossing-fiber-problem-for-diffusion-mri
#19
Kurt Schilling, Yurui Gao, Vaibhav Janve, Iwona Stepniewska, Bennett A Landman, Adam W Anderson
It is now widely recognized that voxels with crossing fibers or complex geometrical configurations present a challenge for diffusion MRI (dMRI) reconstruction and fiber tracking, as well as microstructural modeling of brain tissues. This "crossing fiber" problem has been estimated to affect anywhere from 30% to as many as 90% of white matter voxels, and it is often assumed that increasing spatial resolution will decrease the prevalence of voxels containing multiple fiber populations. The aim of this study is to estimate the extent of the crossing fiber problem as we progressively increase the spatial resolution, with the goal of determining whether it is possible to mitigate this problem with higher resolution spatial sampling...
September 15, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28904101/methodological-considerations-for-a-chronic-neural-interface-with-the-cuneate-nucleus-of-macaques
#20
Aneesha K Suresh, Jeremy Winberry, Christopher Versteeg, Raeed H Chowdhury, Tucker Tomlinson, Joshua M Rosenow, Lee E Miller, Sliman J Bensmaia
While the response properties of neurons in the somatosensory nerves and anterior parietal cortex have been extensively studied, little is known about the encoding of tactile and proprioceptive information in the cuneate nucleus (CN) or external cuneate nucleus (ECN), the first recipients of upper limb somatosensory afferent signals. The major challenge in characterizing neural coding in CN/ECN has been to record from these tiny, difficult to access brainstem structures. Most previous investigations of CN response properties have been carried out in decerebrate or anesthetized animals, thereby eliminating the well-documented top-down signals from cortex, which likely exert a strong influence on CN responses...
September 13, 2017: Journal of Neurophysiology
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