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https://www.readbyqxmd.com/read/28230848/computational-approaches-to-fmri-analysis
#1
Jonathan D Cohen, Nathaniel Daw, Barbara Engelhardt, Uri Hasson, Kai Li, Yael Niv, Kenneth A Norman, Jonathan Pillow, Peter J Ramadge, Nicholas B Turk-Browne, Theodore L Willke
Analysis methods in cognitive neuroscience have not always matched the richness of fMRI data. Early methods focused on estimating neural activity within individual voxels or regions, averaged over trials or blocks and modeled separately in each participant. This approach mostly neglected the distributed nature of neural representations over voxels, the continuous dynamics of neural activity during tasks, the statistical benefits of performing joint inference over multiple participants and the value of using predictive models to constrain analysis...
February 23, 2017: Nature Neuroscience
https://www.readbyqxmd.com/read/28230845/dynamic-models-of-large-scale-brain-activity
#2
REVIEW
Michael Breakspear
Movement, cognition and perception arise from the collective activity of neurons within cortical circuits and across large-scale systems of the brain. While the causes of single neuron spikes have been understood for decades, the processes that support collective neural behavior in large-scale cortical systems are less clear and have been at times the subject of contention. Modeling large-scale brain activity with nonlinear dynamical systems theory allows the integration of experimental data from multiple modalities into a common framework that facilitates prediction, testing and possible refutation...
February 23, 2017: Nature Neuroscience
https://www.readbyqxmd.com/read/28230841/magnetoencephalography-for-brain-electrophysiology-and-imaging
#3
REVIEW
Sylvain Baillet
We review the aspects that uniquely characterize magnetoencephalography (MEG) among the techniques available to explore and resolve brain function and dysfunction. While emphasizing its specific strengths in terms of millisecond source imaging, we also identify and discuss current practical challenges, in particular in signal extraction and interpretation. We also take issue with some perceived disadvantages of MEG, including the misconception that the technique is redundant with electroencephalography. Overall, MEG contributes uniquely to our deeper comprehension of both regional and large-scale brain dynamics: from the functions of neural oscillations and the nature of event-related brain activation, to the mechanisms of functional connectivity between regions and the emergence of modes of network communication in brain systems...
February 23, 2017: Nature Neuroscience
https://www.readbyqxmd.com/read/28230528/biologically-plausible-learning-in-recurrent-neural-networks-reproduces-neural-dynamics-observed-during-cognitive-tasks
#4
Thomas Miconi
Neural activity during cognitive tasks exhibits complex dynamics that flexibly encode task-relevant variables. Chaotic recurrent networks, which spontaneously generate rich dynamics, have been proposed as a model of cortical computation during cognitive tasks. However, existing methods for training these networks are either biologically implausible, and/or require a continuous, real-time error signal to guide learning. Here we show that a biologically plausible learning rule can train such recurrent networks, guided solely by delayed, phasic rewards at the end of each trial...
February 23, 2017: ELife
https://www.readbyqxmd.com/read/28230106/longitudinal-assessments-of-normal-and-perilesional-tissues-in-focal-brain-ischemia-and-partial-optic-nerve-injury-with-manganese-enhanced-mri
#5
Kevin C Chan, Iris Y Zhou, Stanley S Liu, Yolandi van der Merwe, Shu-Juan Fan, Victor K Hung, Sookja K Chung, Wu-Tian Wu, Kwok-Fai So, Ed X Wu
Although manganese (Mn) can enhance brain tissues for improving magnetic resonance imaging (MRI) assessments, the underlying neural mechanisms of Mn detection remain unclear. In this study, we used Mn-enhanced MRI to test the hypothesis that different Mn entry routes and spatiotemporal Mn distributions can reflect different mechanisms of neural circuitry and neurodegeneration in normal and injured brains. Upon systemic administration, exogenous Mn exhibited varying transport rates and continuous redistribution across healthy rodent brain nuclei over a 2-week timeframe, whereas in rodents following photothrombotic cortical injury, transient middle cerebral artery occlusion, or neonatal hypoxic-ischemic brain injury, Mn preferentially accumulated in perilesional tissues expressing gliosis or oxidative stress within days...
February 23, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28230085/dynamics-of-contextual-modulation-of-perceived-shape-in-human-vision
#6
Elena Gheorghiu, Frederick A A Kingdom
In biological vision, contextual modulation refers to the influence of a surround pattern on either the perception of, or the neural responses to, a target pattern. One studied form of contextual modulation deals with the effect of a surround texture on the perceived shape of a contour, in the context of the phenomenon known as the shape aftereffect. In the shape aftereffect, prolonged viewing, or adaptation to a particular contour's shape causes a shift in the perceived shape of a subsequently viewed contour...
February 23, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28229308/eeg-signatures-of-dynamic-functional-network-connectivity-states
#7
E A Allen, E Damaraju, T Eichele, L Wu, V D Calhoun
The human brain operates by dynamically modulating different neural populations to enable goal directed behavior. The synchrony or lack thereof between different brain regions is thought to correspond to observed functional connectivity dynamics in resting state brain imaging data. In a large sample of healthy human adult subjects and utilizing a sliding windowed correlation method on functional imaging data, earlier we demonstrated the presence of seven distinct functional connectivity states/patterns between different brain networks that reliably occur across time and subjects...
February 22, 2017: Brain Topography
https://www.readbyqxmd.com/read/28228741/perception-and-modeling-of-affective-qualities-of-musical-instrument-sounds-across-pitch-registers
#8
Stephen McAdams, Chelsea Douglas, Naresh N Vempala
Composers often pick specific instruments to convey a given emotional tone in their music, partly due to their expressive possibilities, but also due to their timbres in specific registers and at given dynamic markings. Of interest to both music psychology and music informatics from a computational point of view is the relation between the acoustic properties that give rise to the timbre at a given pitch and the perceived emotional quality of the tone. Musician and nonmusician listeners were presented with 137 tones produced at a fixed dynamic marking (forte) playing tones at pitch class D# across each instrument's entire pitch range and with different playing techniques for standard orchestral instruments drawn from the brass, woodwind, string, and pitched percussion families...
2017: Frontiers in Psychology
https://www.readbyqxmd.com/read/28227964/cross-entropy-optimization-for-neuromodulation
#9
Harleen K Brar, Yunpeng Pan, Babak Mahmoudi, Evangelos A Theodorou, Harleen K Brar, Yunpeng Pan, Babak Mahmoudi, Evangelos A Theodorou, Yunpeng Pan, Harleen K Brar, Babak Mahmoudi, Evangelos A Theodorou
This study presents a reinforcement learning approach for the optimization of the proportional-integral gains of the feedback controller represented in a computational model of epilepsy. The chaotic oscillator model provides a feedback control systems view of the dynamics of an epileptic brain with an internal feedback controller representative of the natural seizure suppression mechanism within the brain circuitry. Normal and pathological brain activity is simulated in this model by adjusting the feedback gain values of the internal controller...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28227924/a-hybrid-hardware-and-software-approach-for-cancelling-stimulus-artifacts-during-same-electrode-neural-stimulation-and-recording
#10
Stanislav Culaclii, Brian Kim, Yi-Kai Lo, Wentai Liu, Stanislav Culaclii, Brian Kim, Yi-Kai Lo, Wentai Liu, Brian Kim, Yi-Kai Lo, Wentai Liu, Stanislav Culaclii
Recovering neural responses from electrode recordings is fundamental for understanding the dynamics of neural networks. This effort is often obscured by stimulus artifacts in the recordings, which result from stimuli injected into the electrode-tissue interface. Stimulus artifacts, which can be orders of magnitude larger than the neural responses of interest, can mask short-latency evoked responses. Furthermore, simultaneous neural stimulation and recording on the same electrode generates artifacts with larger amplitudes compared to a separate electrode setup, which inevitably overwhelm the amplifier operation and cause unrecoverable neural signal loss...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28227907/understanding-the-role-of-astrocytic-gaba-in-simulated-neural-networks
#11
Kerstin Lenk, Eero Raisanen, Jari A K Hyttinen, Kerstin Lenk, Eero Raisanen, Jari A K Hyttinen, Kerstin Lenk, Jari Ak Hyttinen, Eero Raisanen
Astrocytes actively influence the behavior of the surrounding neuronal network including changes of the synaptic plasticity and neuronal excitability. These dynamics are altered in diseases like Alzheimer's, where the release of the gliotransmitter GABA is increased by affected, so called reactive astrocytes. In this paper, we aim to simulate a neural network with altered astrocytic GABA release. Therefore, we use our developed neuron-astrocyte model, called INEXA, which includes astrocyte controlled tripartite synapses and the astrocyte-astrocyte interaction...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28227834/development-of-semi-chronic-microdrive-system-for-large-scale-circuit-mapping-in-macaque-mesolimbic-and-basal-ganglia-systems
#12
Shaoyu Qiao, Kevin A Brown, Amy L Orsborn, Breonna Ferrentino, Bijan Pesaran, Shaoyu Qiao, Kevin A Brown, Amy L Orsborn, Breonna Ferrentino, Bijan Pesaran, Shaoyu Qiao, Amy L Orsborn, Breonna Ferrentino, Kevin A Brown, Bijan Pesaran
The development of novel neurotechnologies for treating refractory neuropsychiatry disorders depends on understanding and manipulating the dynamics of neural circuits across large-scale brain networks. The mesolimbic pathway plays an essential role in reward processing and mood regulation and disorders of this pathway underlie many neuropsychiatric disorders. Here, we present the design of a customized semi-chronic microdrive array that precisely targets the anatomical structures of non-human primate (NHP) mesolimbic and basal ganglia systems...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28227759/mining-cross-frequency-coupling-microstates-cfc%C3%AE-states-from-eeg-recordings-during-resting-state-and-mental-arithmetic-tasks
#13
Stavros I Dimitriadis, Yu Sun, Nitish Thakor, Anastasios Bezerianos, Stavros I Dimitriadis, Yu Sun, Nitish Thakor, Anastasios Bezerianos, Stavros I Dimitriadis, Yu Sun, Nitish Thakor, Anastasios Bezerianos
The functional brain connectivity has been studied by analyzing synchronization between dynamic oscillations of identical frequency or between different frequencies of distinct brain areas. It has been hypothesized that cross-frequency coupling (CFC) between different frequency bands is the carrier mechanism for the coordination of global and local neural processes and hence supports the distributed information processing in the brain. In the present study, we attempt to study the dynamic evolution of CFC at resting-state and during a mental task...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28227324/analysis-of-the-non-stationarity-of-neural-activity-during-an-auditory-oddball-task-in-schizophrenia
#14
P Nunez, J Poza, J Gomez-Pilar, A Bachiller, C Gomez, A Lubeiro, V Molina, R Hornero, P Nunez, J Poza, J Gomez-Pilar, A Bachiller, C Gomez, A Lubeiro, V Molina, R Hornero, J Gomez-Pilar, A Bachiller, C Gomez, J Poza, P Nunez, A Lubeiro, V Molina, R Hornero
The aim of this study was to characterize brain dynamics during an auditory oddball task. For this purpose, a measure of the non-stationarity of a given time-frequency representation (TFR) was applied to electroencephalographic (EEG) signals. EEG activity was acquired from 20 schizophrenic (SCH) patients and 20 healthy controls while they underwent a three-stimulus auditory oddball task. The Degree of Stationarity (DS), a measure of the non-stationarity of the TFR, was computed using the continuous wavelet transform...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28227183/a-modular-closed-loop-platform-for-intracranial-stimulation-in-people-with-neurological-disorders
#15
Anish A Sarma, Britni Crocker, Sydney S Cash, Wilson Truccolo, Anish A Sarma, Britni Crocker, Sydney S Cash, Wilson Truccolo, Sydney S Cash, Wilson Truccolo, Anish A Sarma, Britni Crocker
Neuromodulation systems based on electrical stimulation can be used to investigate, probe, and potentially treat a range of neurological disorders. The effects of ongoing neural state and dynamics on stimulation response, and of stimulation parameters on neural state, have broad implications for the development of closed-loop neuro-modulation approaches. We describe the development of a modular, low-latency platform for pre-clinical, closed-loop neuromodulation studies with human participants. We illustrate the uses of the platform in a stimulation case study with a person with epilepsy undergoing neuro-monitoring prior to resective surgery...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28227164/dynamical-information-encoding-in-neural-adaptation
#16
Luozheng Li, Wenhao Zhang, Yuanyuan Mi, Dahui Wang, Xiaohan Lin, Si Wu, Luozheng Li, Wenhao Zhang, Yuanyuan Mi, Dahui Wang, Xiaohan Lin, Si Wu, Si Wu, Dahui Wang, Xiaohan Lin, Yuanyuan Mi, Wenhao Zhang, Luozheng Li
Adaptation refers to the general phenomenon that a neural system dynamically adjusts its response property according to the statistics of external inputs. In response to a prolonged constant stimulation, neuronal firing rates always first increase dramatically at the onset of the stimulation; and afterwards, they decrease rapidly to a low level close to background activity. This attenuation of neural activity seems to be contradictory to our experience that we can still sense the stimulus after the neural system is adapted...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28227133/comparison-between-k-nearest-neighbor-approaches-for-conditional-entropy-estimation-application-to-the-assessment-of-the-cardiac-control-in-amyotrophic-lateral-sclerosis-patients
#17
Alberto Porta, Beatrice De Maria, Vlasta Bari, Andrea Marchi, Kalliopi Marinou, Riccardo Sideri, Gabriele Mora, Laura Dalla Vecchia, Alberto Porta, Beatrice De Maria, Vlasta Bari, Andrea Marchi, Kalliopi Marinou, Riccardo Sideri, Gabriele Mora, Laura Dalla Vecchia, Kalliopi Marinou, Gabriele Mora, Alberto Porta, Laura Dalla Vecchia, Riccardo Sideri, Beatrice De Maria, Vlasta Bari, Andrea Marchi
The study evaluates the k-nearest-neighbor (KNN) strategy for the assessment of complexity of the cardiac neural control from spontaneous fluctuations of heart period (HP). Two different procedures were assessed: i) the KNN estimation of the conditional entropy (CE) proposed by Porta et al; ii) the KNN estimation of mutual information proposed by Kozachenko-Leonenko, refined by Kraskov-Stögbauer-Grassberger and here adapted for the CE estimation. The two procedures were compared over HP variability recordings obtained at rest in supine position and during head-up tilt (HUT) in amyotrophic lateral sclerosis patients and healthy subjects...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28227108/analysis-of-spontaneous-eeg-activity-in-alzheimer-s-disease-using-cross-sample-entropy-and-graph-theory
#18
Carlos Gomez, Jesus Poza, Javier Gomez-Pilar, Alejandro Bachiller, Celia Juan-Cruz, Miguel A Tola-Arribas, Alicia Carreres, Monica Cano, Roberto Hornero, Carlos Gomez, Jesus Poza, Javier Gomez-Pilar, Alejandro Bachiller, Celia Juan-Cruz, Miguel A Tola-Arribas, Alicia Carreres, Monica Cano, Roberto Hornero, Celia Juan-Cruz, Carlos Gomez, Alicia Carreres, Jesus Poza, Monica Cano, Roberto Hornero, Javier Gomez-Pilar, Alejandro Bachiller, Miguel A Tola-Arribas
The aim of this pilot study was to analyze spontaneous electroencephalography (EEG) activity in Alzheimer's disease (AD) by means of Cross-Sample Entropy (Cross-SampEn) and two local measures derived from graph theory: clustering coefficient (CC) and characteristic path length (PL). Five minutes of EEG activity were recorded from 37 patients with dementia due to AD and 29 elderly controls. Our results showed that Cross-SampEn values were lower in the AD group than in the control one for all the interactions among EEG channels...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28226966/measuring-the-quality-of-exercises
#19
Paritosh Parmar, Brendan Tran Morris, Paritosh Parmar, Brendan Tran Morris, Paritosh Parmar, Brendan Tran Morris
This work explores the problem of exercise quality measurement since it is essential for effective management of diseases like cerebral palsy (CP). This work examines the assessment of quality of large amplitude movement (LAM) exercises designed to treat CP in an automated fashion. Exercise data was collected by trained participants to generate ideal examples to use as a positive samples for machine learning. Following that, subjects were asked to deliberately make subtle errors during the exercise, such as restricting movements, as is commonly seen in cases of patients suffering from CP...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28226864/the-influence-of-the-pre-stimulation-neural-state-on-the-post-stimulation-neural-dynamics-via-distributed-microstimulation-of-the-hippocampus
#20
Mark J Connolly, Robert E Gross, Babak Mahmoudi, Mark J Connolly, Robert E Gross, Babak Mahmoudi, Mark J Connolly, Robert E Gross, Babak Mahmoudi
In this study we investigated how the neural state influences how the brain responds to electrical stimulation using a 16-channel microelectrode array with 8 stimulation and recording channels implanted in the rat hippocampus. In two experiments we identified the stimulation threshold at which the brain changes to an afterdischarge state. In one experiment a range of suprathreshold stimulations were applied, and in another the stimulation was not changed. The neural state was measured by the power spectral density prior to stimulation...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
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