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https://www.readbyqxmd.com/read/28432303/closed-loop-deep-brain-stimulation-by-pulsatile-delayed-feedback-with-increased-gap-between-pulse-phases
#1
Oleksandr V Popovych, Borys Lysyansky, Peter A Tass
Computationally it was shown that desynchronizing delayed feedback stimulation methods are effective closed-loop techniques for the control of synchronization in ensembles of interacting oscillators. We here computationally design stimulation signals for electrical stimulation of neuronal tissue that preserve the desynchronizing delayed feedback characteristics and comply with mandatory charge deposit-related safety requirements. For this, the amplitude of the high-frequency (HF) train of biphasic charge-balanced pulses used by the standard HF deep brain stimulation (DBS) is modulated by the smooth feedback signals...
April 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28432140/visually-evoked-3-5-hz-membrane-potential-oscillations-reduce-the-responsiveness-of-visual-cortex-neurons-in-awake-behaving-mice
#2
Michael C Einstein, Pierre-Olivier Polack, Duy T Tran, Peyman Golshani
Low frequency membrane potential (Vm) oscillations were once thought to only occur in sleeping and anesthetized states. Recently, low frequency Vm oscillations have been described in inactive awake animals, but it is unclear if they shape sensory processing in neurons and whether they occur during active awake behavioral states. To answer these questions, we performed two-photon guided whole-cell Vm recordings from primary visual cortex layer 2/3 excitatory and inhibitory neurons in awake mice during passive visual stimulation and performance of visual and auditory discrimination tasks...
April 21, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28430635/unsuccessful-mitosis-in-multicellular-tumour-spheroids
#3
Annie Molla, Morgane Couvet, Jean-Luc Coll
Multicellular spheroids are very attractive models in oncology because they mimic the 3D organization of the tumour cells with their microenvironment. We show here using 3 different cell types (mammary TSA/pc, embryonic kidney Hek293 and cervical cancer HeLa), that when the cells are growing as spheroids the frequency of binucleated cells is augmented as occurs in some human tumours.We therefore describe mitosis in multicellular spheroids by following mitotic markers and by time-lapse experiments. Chromosomes alignment appears to be correct on the metaphasic plate and the passenger complex is well localized on centromere...
February 24, 2017: Oncotarget
https://www.readbyqxmd.com/read/28430213/high-peak-power-hybrid-mopa-laser-with-tunable-pulse-repetition-frequency-and-pulse-duration
#4
Mingming Nie, Qiang Liu, Encai Ji, Xuezhe Cao, Fu Xing, Mali Gong
In this paper, we demonstrated a hybrid master oscillator power amplifier (MOPA) laser with high peak power and widely tunable pulse repetition frequency (PRF) and pulse duration. The first-stage solid-state amplifier was carefully designed to keep good beam quality and supply high gain simultaneously. The maximum peak power of 760 kW was achieved with average power of 42 W, PRF of 50 kHz, pulse duration of 1.1 ns, and near-diffraction limited beam quality. The MOPA laser covers a broad tunable temporal range with 1-100 ns for pulse duration and 50 kHz-1 MHz for PRF...
April 20, 2017: Applied Optics
https://www.readbyqxmd.com/read/28430211/compact-high-power-high-beam-quality-quasi-cw-microsecond-five-pass-zigzag-slab-1319%C3%A2-%C3%A2-nm-amplifier
#5
Chuan Guo, Junwei Zuo, Qi Bian, Chang Xu, Qinshuang Zong, Yong Bo, Yu Shen, Nan Zong, Hongwei Gao, Yanyong Lin, Lei Yuan, Yang Liu, Dafu Cui, Qinjun Peng, Zuyan Xu
We demonstrate a compact, high-power, quasi-continuous-wave (QCW) end-pumped 1319 nm Nd:YAG slab amplifier laser with good beam quality. The laser is based on a QCW pulse Nd:YAG master oscillator and Nd:YAG slab amplifier with multi-pass zigzag architecture. The amplifier operates at a pulse repetition frequency of 500 Hz and pulse width of ∼105  μs, delivering a maximum output power of 51.5 W under absorbed pump power of 217.8 W and corresponding to an extraction efficiency of 14.2%. The beam quality factor is measured to be Mx2=1...
April 20, 2017: Applied Optics
https://www.readbyqxmd.com/read/28424599/electrophysiological-sequelae-of-hemispherotomy-in-ipsilateral-human-cortex
#6
Ammar H Hawasli, Ravi Chacko, Nicholas P Szrama, David T Bundy, Mrinal Pahwa, Chester K Yarbrough, Brian J Dlouhy, David D Limbrick, Dennis L Barbour, Matthew D Smyth, Eric C Leuthardt
Objectives: Hemispheric disconnection has been used as a treatment of medically refractory epilepsy and evolved from anatomic hemispherectomy to functional hemispherectomies to hemispherotomies. The hemispherotomy procedure involves disconnection of an entire hemisphere with limited tissue resection and is reserved for medically-refractory epilepsy due to diffuse hemispheric disease. Although it is thought to be effective by preventing seizures from spreading to the contralateral hemisphere, the electrophysiological effects of a hemispherotomy on the ipsilateral hemisphere remain poorly defined...
2017: Frontiers in Human Neuroscience
https://www.readbyqxmd.com/read/28424226/objective-measurement-of-adherence-to-out-patient-airway-clearance-therapy-by-high-frequency-chest-wall-compression-in-cystic-fibrosis
#7
Christina L Mikesell, Robert R Kempainen, Theresa A Laguna, Jeremiah S Menk, Andrew R Wey, Philippe R Gaillard, Warren E Regelmann
BACKGROUND: Objective measures of adherence to high-frequency chest wall compression (HFCWC, also known as high frequency chest wall oscillation, HFCWO), a form of airway clearance therapy for patients with cystic fibrosis, are lacking. We used a novel electronic monitoring device integrated into an HFCWC vest to measure adherence compared with self-reported adherence. We determined factors that influenced adherence and how adherence correlated with baseline pulmonary function and pulmonary exacerbations...
April 19, 2017: Respiratory Care
https://www.readbyqxmd.com/read/28420362/clinical-hemispheric-and-autonomic-changes-associated-with-use-of-closed-loop-allostatic-neurotechnology-by-a-case-series-of-individuals-with-self-reported-symptoms-of-post-traumatic-stress
#8
Charles H Tegeler, Jared F Cook, Catherine L Tegeler, Joshua R Hirsch, Hossam A Shaltout, Sean L Simpson, Brian C Fidali, Lee Gerdes, Sung W Lee
BACKGROUND: The objective of this pilot study was to explore the use of a closed-loop, allostatic, acoustic stimulation neurotechnology for individuals with self-reported symptoms of post-traumatic stress, as a potential means to impact symptomatology, temporal lobe high frequency asymmetry, heart rate variability (HRV), and baroreflex sensitivity (BRS). METHODS: From a cohort of individuals participating in a naturalistic study to evaluate use of allostatic neurotechnology for diverse clinical conditions, a subset was identified who reported high scores on the Posttraumatic Stress Disorder Checklist (PCL)...
April 19, 2017: BMC Psychiatry
https://www.readbyqxmd.com/read/28416442/allopregnanolone-decreases-interictal-spiking-and-fast-ripples-in-an-animal-model-of-mesial-temporal-lobe-epilepsy
#9
Maxime Lévesque, Rochelle Herrington, Leila Leclerc, Michael A Rogawski, Massimo Avoli
The objective of this study was to characterize the impact of allopregnanolone, a neurosteroid that acts as a positive allosteric modulator of synaptic and extrasynaptic GABAA receptors, on interictal spikes and high-frequency oscillations (ripples: 80-200 Hz, fast ripples: 250-500 Hz) in the pilocarpine model of mesial temporal lobe epilepsy. Seven out of 25 Sprague-Dawley rats experiencing 1 h of pilocarpine-induced status epilepticus (SE) began treatment with allopregnanolone (9.6-12.8 mg/kg/day) on the following day...
April 14, 2017: Neuropharmacology
https://www.readbyqxmd.com/read/28412559/interictal-ripples-nested-in-epileptiform-discharge-help-to-identify-the-epileptogenic-zone-in-neocortical-epilepsy
#10
Shuang Wang, Norman K So, Bo Jin, Irene Z Wang, Juan C Bulacio, Rei Enatsu, Shenyi Dai, Zhong Chen, Jorge Gonzalez-Martinez, Imad M Najm
OBJECTIVE: This study aimed to identify the subtype of interictal ripples that help delineate the epileptogenic zone in neocortical epilepsy. METHODS: Totally 25 patients with focal neocortical epilepsy who had invasive electroencephalography (EEG) evaluation and subsequent surgery were included. They were followed up for at least 2years. Interictal ripples (80-250Hz) and fast ripples (250-500Hz) during slow-wave sleep were identified. Neocortical ripples were defined as type I ripples when they were superimposed on epileptiform discharges, and as type II ripples when they occurred independently...
March 25, 2017: Clinical Neurophysiology: Official Journal of the International Federation of Clinical Neurophysiology
https://www.readbyqxmd.com/read/28412092/chaotic-oscillations-of-gas-bubbles-under-dual-frequency-acoustic-excitation
#11
Yuning Zhang, Yuning Zhang
Chaotic oscillation of bubbles in liquids reduces the efficiency of the sonochemical system and should be suppressed in the practical applications. In the present paper, a chaos control method based on the dual-frequency approach is numerically investigated and is proved to be an effective method even for cases with intensive energy input. It was found that the chaos could be successfully suppressed by the application of dual-frequency approach in a wide range of parameter zone (even with high acoustic pressure amplitude)...
April 9, 2017: Ultrasonics Sonochemistry
https://www.readbyqxmd.com/read/28411273/low-frequency-cortical-oscillations-entrain-to-sub-threshold-rhythmic-auditory-stimuli
#12
Sanne Ten Oever, Charles E Schroeder, David Poeppel, Nienke van Atteveldt, Ashesh D Mehta, Pierre Mégevand, David M Groppe, Elana Zion-Golumbic
Many environmental stimuli contain temporal regularities, a feature which can help predict forthcoming input. Phase-locking (entrainment) of ongoing low-frequency neuronal oscillations to rhythmic stimuli is proposed as a potential mechanism for enhancing neuronal responses and perceptual sensitivity, by aligning high-excitability phases to events within a stimulus stream. Previous experiments show that rhythmic structure has a behavioral benefit even when the rhythm itself is below perceptual detection thresholds (Ten Oever et al...
April 14, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28410534/comparison-of-operation-modes-for-spin-exchange-optically-pumped-spin-oscillators
#13
Zhiguo Wang, Xiang Peng, Hui Luo, Hong Guo
The nuclear spin precesses continually when a positive feedback nuclear magnetic resonance field is applied. The characteristics of this behaviour depend not only on the parameters of the spin ensemble but also on the type and parameters of the feedback loop. We theoretically analysed two types of feedback loops which use direct feedback and phase-lock feedback, respectively. We also compared the oscillating frequency of the spin oscillators using rotating and linear magnetic fields, respectively. Some interesting results on the frequency and start-time of the oscillator were found...
March 30, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/28409815/high-frequency-continuous-birefringence-induced-oscillations-in-spin-polarized-vertical-cavity-surface-emitting-lasers
#14
M S Torre, H Susanto, Nianqiang Li, K Schires, M F Salvide, I D Henning, M J Adams, A Hurtado
Sustained, large amplitude and tunable birefringence-induced oscillations are obtained in a spin-vertical cavity surface-emitting laser (spin-VCSEL). Experimental evidence is provided using a spin-VCSEL operating at 1300 nm, under continuous-wave optical pumping and at room temperature. Numerical and stability analyses are performed to interpret the experiments and to identify the combined effects of pump ellipticity, spin relaxation rate, and cavity birefringence. Importantly, the frequency of the induced oscillations is determined by the device's birefringence rate, which can be tuned to very large values...
April 15, 2017: Optics Letters
https://www.readbyqxmd.com/read/28406919/what-are-the-assets-and-weaknesses-of-hfo-detectors-a-benchmark-framework-based-on-realistic-simulations
#15
Nicolas Roehri, Francesca Pizzo, Fabrice Bartolomei, Fabrice Wendling, Christian-George Bénar
High-frequency oscillations (HFO) have been suggested as biomarkers of epileptic tissues. While visual marking of these short and small oscillations is tedious and time-consuming, automatic HFO detectors have not yet met a large consensus. Even though detectors have been shown to perform well when validated against visual marking, the large number of false detections due to their lack of robustness hinder their clinical application. In this study, we developed a validation framework based on realistic and controlled simulations to quantify precisely the assets and weaknesses of current detectors...
2017: PloS One
https://www.readbyqxmd.com/read/28399043/different-estimation-methods-of-spontaneous-baroreflex-sensitivity-have-different-predictive-value-in-heart-failure-patients
#16
Gian Domenico Pinna, Alberto Porta, Roberto Maestri, Beatrice De Maria, Laura Adelaide Dalla Vecchia, Maria Teresa La Rovere
OBJECTIVE: Several methods have been developed so far to estimate cardiac baroreflex sensitivity (BRS) through the analysis of spontaneous fluctuations of systolic arterial pressure (SAP) and R-R interval. Their relative performance in predicting cardiac mortality in heart failure patients is not known. The aim of this study was to compare the prognostic value of a set of representative indexes of spontaneous BRS in these patients. METHODS: We studied 228 stable, moderate-to-severe heart failure patients with reduced ejection fraction, in sinus rhythm, who underwent an 8-min supine recording of ECG, arterial blood pressure and respiration during paced breathing (15 breaths/min)...
April 10, 2017: Journal of Hypertension
https://www.readbyqxmd.com/read/28396622/transcranial-magnetic-stimulation-reveals-intrinsic-perceptual-and-attentional-rhythms
#17
REVIEW
Laura Dugué, Rufin VanRullen
Oscillatory brain activity has functional relevance for perceptual and cognitive processes, as proven by numerous electrophysiology studies accumulating over the years. However, only within the past two decades have researchers been able to study the causal role of such oscillations using transcranial magnetic stimulation (TMS) technology. Two complementary approaches exist. A majority of research employs rhythmic TMS (rTMS) to entrain oscillatory activity and investigate its effect on targeted brain functions...
2017: Frontiers in Neuroscience
https://www.readbyqxmd.com/read/28393884/novel-wavelet-real-time-analysis-of-neurovascular-coupling-in-neonatal-encephalopathy
#18
Lina F Chalak, Fenghua Tian, Beverley Adams-Huet, Diana Vasil, Abbot Laptook, Takashi Tarumi, Rong Zhang
Birth asphyxia constitutes a major global public health burden for millions of infants, despite hypothermia therapy. There is a critical need for real time surrogate markers of therapeutic success, to aid in patient selection and/or modification of interventions in neonatal encephalopathy (NE). This is a proof of concept study aiming to quantify neurovascular coupling (NVC) using wavelet analysis of the dynamic coherence between amplitude-integrated electroencephalography (aEEG) and near-infrared spectroscopy in NE...
April 10, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28390225/persistent-irregular-activity-is-a-result-of-rebound-and-coincident-detection-mechanisms-a-computational-study
#19
Mustafa Zeki, Ahmed A Moustafa
Persistent irregular activity is defined as elevated irregular neural discharges in the brain in such a way that while the average network activity displays high frequency oscillations, the participating neurons display irregular and low frequency oscillations. This type of activity is observed in many brain regions like prefrontal cortex that plays a role in working memory. Previous studies have shown that large networks with sparse connections, networks with strong noise and persistent inhibition and networks with structured synaptic connections display persistent-irregular activity...
March 22, 2017: Neural Networks: the Official Journal of the International Neural Network Society
https://www.readbyqxmd.com/read/28387588/modulation-of-oscillatory-power-and-connectivity-in-the-human-posterior-cingulate-cortex-supports-the-encoding-and-retrieval-of-episodic-memories
#20
Bradley Lega, James Germi, Michael Rugg
Existing data from noninvasive studies have led researchers to posit that the posterior cingulate cortex (PCC) supports mnemonic processes: It exhibits degeneration in memory disorders, and fMRI investigations have demonstrated memory-related activation principally during the retrieval of memory items. Despite these data, the role of the PCC in episodic memory has received only limited treatment using the spatial and temporal precision of intracranial EEG, with previous analyses focused on item retrieval. Using data gathered from 21 human participants who underwent stereo-EEG for seizure localization, we characterized oscillatory patterns in the PCC during the encoding and retrieval of episodic memories...
April 7, 2017: Journal of Cognitive Neuroscience
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