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Nonlinear dynamics

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https://www.readbyqxmd.com/read/28230845/dynamic-models-of-large-scale-brain-activity
#1
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/28230528/biologically-plausible-learning-in-recurrent-neural-networks-reproduces-neural-dynamics-observed-during-cognitive-tasks
#2
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/28228741/perception-and-modeling-of-affective-qualities-of-musical-instrument-sounds-across-pitch-registers
#3
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/28227931/long-range-correlations-in-amplitude-variability-of-hf-and-lf-components-of-heart-rate-variability
#4
Yuki Miki, Yasuyuki Suzuki, Eiichi Watanabe, Junichiro Hayano, Yoshiharu Yamamoto, Taishin Nomura, Ken Kiyono, Yuki Miki, Yasuyuki Suzuki, Eiichi Watanabe, Junichiro Hayano, Yoshiharu Yamamoto, Taishin Nomura, Ken Kiyono
For the assessment of autonomic nervous system activity based on heart rate variability (HRV) analysis, characteristics of high-frequency (HF; 0.15 to 0.4 Hz) and low-frequency (LF; 0.04 to 0.15 Hz) components have been widely employed. HF and LF band powers quantified by power spectral analysis have most commonly been used in the conventional studies; the physiological significance of these measures has also been extensively studied. However, nonlinear characteristics of HF and LF components have not been well established...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28227903/development-of-a-detailed-model-of-calcium-dynamics-at-the-postsynaptic-spine-of-an-excitatory-synapse
#5
Eric Y Hu, Jean-Marie C Bouteiller, Dong Song, Theodore W Berger, Eric Y Hu, Jean-Marie C Bouteiller, Dong Song, Theodore W Berger, Jean-Marie C Bouteiller, Eric Y Hu, Dong Song, Theodore W Berger
Postsynaptic calcium dynamics play a critical role in synaptic plasticity, but are often difficult to measure in experimental protocols due to their relatively fast rise and decay times, and the small spine dimensions. To circumvent these limitations, we propose to develop a computational model of calcium dynamics in the postsynaptic spine. This model integrates the main elements that participate in calcium concentration influx, efflux, diffusion and buffering. These consist of (i) spine geometry; (ii) calcium influx through NMDA receptors and voltage-dependent calcium channels (VDCC); (iii) calcium efflux with plasma membrane calcium pumps (PMCA) and sodium-calcium exchangers (NCX); (iv) intracellular calcium stores; and (v) calcium buffers...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28227852/non-linear-dynamic-modeling-of-glucose-in-type-1-diabetes-with-kernel-adaptive-filters
#6
Eleni I Georga, Jose C Principe, Demosthenes Polyzos, Dimitrios I Fotiadis, Eleni I Georga, Jose C Principe, Demosthenes Polyzos, Dimitrios I Fotiadis, Eleni I Georga, Demosthenes Polyzos, Jose C Principe, Dimitrios I Fotiadis
We propose a non-linear recursive solution to the problem of short-term prediction of glucose in type 1 diabetes. The Fixed Budget Quantized Kernel Least Mean Square (QKLMS-FB) algorithm is employed to construct a univariate model of subcutaneous glucose concentration, which: (i) handles nonlinearities by transforming the input space into a high-dimensional Reproducing Kernel Hilbert Space and, (ii) finds a sparse solution by retaining a representative subset of the training input vectors. The dataset comes from the continuous multi-day recordings of 15 type 1 patients in free-living conditions...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28227778/hybrid-automata-models-of-cardiac-ventricular-electrophysiology-for-real-time-computational-applications
#7
Sidharta Andalam, Harshavardhan Ramanna, Avinash Malik, Parthasarathi Roop, Nitish Patel, Mark L Trew, Sidharta Andalam, Harshavardhan Ramanna, Avinash Malik, Parthasarathi Roop, Nitish Patel, Mark L Trew, Nitish Patel, Avinash Malik, Parthasarathi Roop, Harshavardhan Ramanna, Mark L Trew, Sidharta Andalam
Virtual heart models have been proposed for closed loop validation of safety-critical embedded medical devices, such as pacemakers. These models must react in real-time to off-the-shelf medical devices. Real-time performance can be obtained by implementing models in computer hardware, and methods of compiling classes of Hybrid Automata (HA) onto FPGA have been developed. Models of ventricular cardiac cell electrophysiology have been described using HA which capture the complex nonlinear behavior of biological systems...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28227773/whole-heart-modeling-spatiotemporal-dynamics-of-electrical-wave-conduction-and-propagation
#8
Hui Yang, Yun Chen, Fabio M Leonelli, Hui Yang, Yun Chen, Fabio M Leonelli, Hui Yang, Fabio M Leonelli, Yun Chen
Cardiac electrical activities are varying in both space and time. Human heart consists of a fractal network of muscle cells, Purkinje fibers, arteries and veins. Whole-heart modeling of electrical wave conduction and propagation involves a greater level of complexity. Our previous work developed a computer model of the anatomically realistic heart and simulated the electrical conduction with the use of cellular automata. However, simplistic assumptions and rules limit its ability to provide an accurate approximation of real-world dynamics on the complex heart surface, due to sensitive dependence of nonlinear dynamical systems on initial conditions...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28227757/feasibility-study-for-the-assessment-of-cardio-respiratory-coupling-in-newborn-infants
#9
Maristella Lucchini, William P Fifer, Manuela Ferrario, Maria G Signorini, Maristella Lucchini, William P Fifer, Manuela Ferrario, Maria G Signorini, Maristella Lucchini, Maria G Signorini, William P Fifer, Manuela Ferrario
Cardio Respiratory Coupling (CRC) plays a key role during infant development. Nonetheless, mechanisms underlying it are still mostly unexplained and tools to assess it are often inadequate to understand its functioning. This study aims to evaluate the feasibility of CRC activity detection and quantification analyzing ECG and respiration of newborn healthy subjects. Cross-spectral analysis (coherence) and a novel application of a nonlinear method (Bivariate Phase Rectified Signal Averaging) were applied on 10 minutes recording from 4 subjects...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28227754/brain-heart-linear-and-nonlinear-dynamics-during-visual-emotional-elicitation-in-healthy-subjects
#10
G Valenza, A Greco, C Gentili, A Lanata, N Toschi, R Barbieri, L Sebastiani, D Menicucci, A Gemignani, E P Scilingo, G Valenza, A Greco, C Gentili, A Lanata, N Toschi, R Barbieri, L Sebastiani, D Menicucci, A Gemignani, E P Scilingo, A Lanata, A Gemignani, E P Scilingo, A Greco, D Menicucci, L Sebastiani, C Gentili, N Toschi, R Barbieri, G Valenza
This study investigates brain-heart dynamics during visual emotional elicitation in healthy subjects through linear and nonlinear coupling measures of EEG spectrogram and instantaneous heart rate estimates. To this extent, affective pictures including different combinations of arousal and valence levels, gathered from the International Affective Picture System, were administered to twenty-two healthy subjects. Time-varying maps of cortical activation were obtained through EEG spectral analysis, whereas the associated instantaneous heartbeat dynamics was estimated using inhomogeneous point-process linear models...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28227284/on-the-pleasantness-of-a-haptic-stimulation-how-different-textures-can-be-recognized-through-heart-rate-variability-nonlinear-analysis
#11
Mimma Nardelli, Alberto Greco, Matteo Bianchi, Enzo Pasquale Scilingo, Gaetano Valenza, Mimma Nardelli, Alberto Greco, Matteo Bianchi, Enzo Pasquale Scilingo, Gaetano Valenza, Gaetano Valenza, Mimma Nardelli, Alberto Greco, Matteo Bianchi
The hedonic attributes of cutaneous elicitation play a crucial role in everyday life, influencing our behavior and psychophysical state. However, the correlation between such a hedonic aspect of touch and the Autonomic Nervous System (ANS)-related physiological response, which is intimately connected to emotions, still needs to be deeply investigated. This study reports on caress-like stimuli conveyed to the forearm of 32 healthy subjects through different fabrics actuated by a haptic device, which can control both the strength (i...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28227271/comparison-of-three-nonlinear-filters-for-fault-detection-in-continuous-glucose-monitors
#12
Zeinab Mahmoudi, Sabrina Lyngbye Wendt, Dimitri Boiroux, Morten Hagdrup, Kirsten Norgaard, Niels Kjolstad Poulsen, Henrik Madsen, John Bagterp Jorgensen, Zeinab Mahmoudi, Sabrina Lyngbye Wendt, Dimitri Boiroux, Morten Hagdrup, Kirsten Norgaard, Niels Kjolstad Poulsen, Henrik Madsen, John Bagterp Jorgensen, Dimitri Boiroux, Morten Hagdrup, Kirsten Norgaard, Henrik Madsen, Zeinab Mahmoudi
The purpose of this study is to compare the performance of three nonlinear filters in online drift detection of continuous glucose monitors. The nonlinear filters are the extended Kalman filter (EKF), the unscented Kalman filter (UKF), and the particle filter (PF). They are all based on a nonlinear model of the glucose-insulin dynamics in people with type 1 diabetes. Drift is modelled by a Gaussian random walk and is detected based on the statistical tests of the 90-min prediction residuals of the filters. The unscented Kalman filter had the highest average F score of 85...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28227113/developmental-differences-of-dimension-complexity-of-hippocampal-eeg-during-rem-sleep
#13
Taikang Ning, J Harry Blaise, Mariam Avagyan, Prawesh Dahal, Taikang Ning, J Harry Blaise, Mariam Avagyan, Prawesh Dahal, J Harry Blaise, Taikang Ning, Mariam Avagyan, Prawesh Dahal
This paper uses spectral analysis and correlation dimension index to examine the developmental differences between the EEG measured from two hippocampal subfields, CA1 and the dentate gyrus. The study was focused on the hippocampal EEG during the vigilance state of REM sleep in freely moving rats of 15 and 90 days of age. Power spectra, magnitude-squared coherence, and correlation dimension were estimated. The correlation dimension adds a new interpretation from the nonlinear dynamics perspective, and we found that there are no significant developmental differences between the granule cells of the dentate gyrus and the pyramidal cells of area CA1 when the theta activity was present during REM sleep...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28226940/design-and-optimization-of-partner-a-parallel-actuated-robotic-trainer-for-neurorehabilitation
#14
Hossein Taheri, Stephen A Goodwin, James A Tigue, Joel C Perry, Eric T Wolbrecht, Hossein Taheri, Stephen A Goodwin, James A Tigue, Joel C Perry, Eric T Wolbrecht, James A Tigue, Joel C Perry, Hossein Taheri, Stephen A Goodwin, Eric T Wolbrecht
Robotic devices are a promising and dynamic tool in the realm of post-stroke rehabilitation. Researchers are still investigating how the use of robots affects motor learning and what design characteristics best encourage recovery. We present a parallel-actuated, end-effector robot designed to provide spatial assistance for upper-limb therapy while exhibiting low impedance and high backdrivability. A gradient based optimization was performed to find an optimal design that accounted for force isotropy, mechanical advantage, workspace size, and counter-balancing...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28226663/predicting-seizures-in-untreated-temporal-lobe-epilepsy-using-point-process-nonlinear-models-of-heartbeat-dynamics
#15
G Valenza, A Romigi, L Citi, F Placidi, F Izzi, M Albanese, E P Scilingo, M G Marciani, A Duggento, M Guerrisi, N Toschi, R Barbieri, G Valenza, A Romigi, L Citi, F Placidi, F Izzi, M Albanese, E P Scilingo, M G Marciani, A Duggento, M Guerrisi, N Toschi, R Barbieri, M Guerrisi, F Izzi, F Placidi, A Romigi, E P Scilingo, A Duggento, M Albanese, N Toschi, M G Marciani, R Barbieri, G Valenza, L Citi
Symptoms of temporal lobe epilepsy (TLE) are frequently associated with autonomic dysregulation, whose underlying biological processes are thought to strongly contribute to sudden unexpected death in epilepsy (SUDEP). While abnormal cardiovascular patterns commonly occur during ictal events, putative patterns of autonomic cardiac effects during pre-ictal (PRE) periods (i.e. periods preceding seizures) are still unknown. In this study, we investigated TLE-related heart rate variability (HRV) through instantaneous, nonlinear estimates of cardiovascular oscillations during inter-ictal (INT) and PRE periods...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28226601/exploratory-analysis-of-nonlinear-coupling-between-eeg-global-field-power-and-end-tidal-carbon-dioxide-in-free-breathing-and-breath-hold-tasks
#16
Maria Sole Morelli, Gaetano Valenza, Alberto Greco, Alberto Giannoni, Claudio Passino, Michele Emdin, Enzo Pasquale Scilingo, Nicola Vanello, Maria Sole Morelli, Gaetano Valenza, Alberto Greco, Alberto Giannoni, Claudio Passino, Michele Emdin, Enzo Pasquale Scilingo, Nicola Vanello, Maria Sole Morelli, Claudio Passino, Alberto Greco, Nicola Vanello, Gaetano Valenza, Alberto Giannoni, Michele Emdin, Enzo Pasquale Scilingo
Brain activations underlying control of breathing are not completely known. Furthermore, the coupling between neural and respiratory dynamics is usually estimated through linear correlation measures, thus totally disregarding possible underlying nonlinear interactions. To overcome these limitations, in this preliminary study we propose a nonlinear coupling analysis of simultaneous recordings of electroencephalographic (EEG) and respiratory signals at rest and after variation of carbon dioxide (CO2) level. Specifically, a CO2 increase was induced by a voluntary breath hold task...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28226599/identifying-glaucoma-patients-by-applying-multivariate-analyses-of-cardiovascular-signals
#17
Andreas Voss, Claudia Fischer, Cristina Gonzalez Martinez, Eva Koch, Niklas Plange, Kathleen Kunert, Andreas Voss, Claudia Fischer, Cristina Gonzalez Martinez, Eva Koch, Niklas Plange, Kathleen Kunert, Claudia Fischer, Kathleen Kunert, Niklas Plange, Cristina Gonzalez Martinez, Eva Koch, Andreas Voss
Glaucoma is a disease that damages the eye's optic nerve. However, the exact cause of this optic nerve damage is not yet fully understood. Besides the factors of age, genetics and others, such as obesity, medication and migraines, a vascular dysfunction is believed to be a significant factor leading to glaucoma. This study's objective was to investigate whether these vascular dysfunctions could be recognized by analyzing cardiovascular regulation in glaucoma patients. Linear and nonlinear methods were applied to the extracted heart rate (HR), and systolic/ diastolic blood pressure (DBP) time series to discriminate between 35 healthy controls and 20 glaucoma patients...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28226480/eeg-based-image-encryption-via-quantum-walks
#18
N Rawat, Y Shin, I Balasingham, N Rawat, Y Shin, I Balasingham, I Balasingham, N Rawat, Y Shin
An electroencephalogram (EEG) based image encryption combined with Quantum walks (QW) is encoded in Fresnel domain. The computational version of EEG randomizes the original plaintext whereas QW can serve as an excellent key generator due to its inherent nonlinear chaotic dynamic behavior. First, a spatially coherent monochromatic laser beam passes through an SLM, which introduces an arbitrary EEG phase-only mask. The modified beam is collected by a CCD. Further, the intensity is multiply with the QW digitally...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28225066/scanning-tunneling-microscopy-observation-of-phonon-condensate
#19
Igor Altfeder, Andrey A Voevodin, Michael H Check, Sarah M Eichfeld, Joshua A Robinson, Alexander V Balatsky
Using quantum tunneling of electrons into vibrating surface atoms, phonon oscillations can be observed on the atomic scale. Phonon interference patterns with unusually large signal amplitudes have been revealed by scanning tunneling microscopy in intercalated van der Waals heterostructures. Our results show that the effective radius of these phonon quasi-bound states, the real-space distribution of phonon standing wave amplitudes, the scattering phase shifts, and the nonlinear intermode coupling strongly depend on the presence of defect-induced scattering resonance...
February 22, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28224315/modeling-of-free-fatty-acid-dynamics-insulin-and-nicotinic-acid-resistance-under-acute-and-chronic-treatments
#20
Robert Andersson, Tobias Kroon, Joachim Almquist, Mats Jirstrand, Nicholas D Oakes, Neil D Evans, Michael J Chappel, Johan Gabrielsson
Nicotinic acid (NiAc) is a potent inhibitor of adipose tissue lipolysis. Acute administration results in a rapid reduction of plasma free fatty acid (FFA) concentrations. Sustained NiAc exposure is associated with tolerance development (drug resistance) and complete adaptation (FFA returning to pretreatment levels). We conducted a meta-analysis on a rich pre-clinical data set of the NiAc-FFA interaction to establish the acute and chronic exposure-response relations from a macro perspective. The data were analyzed using a nonlinear mixed-effects framework...
February 21, 2017: Journal of Pharmacokinetics and Pharmacodynamics
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