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depth electrodes

Pratik Rohatgi, Ryan J Jafrani, Nicholas J Brandmeir, Frank G Gilliam, Tiffany L Fisher, Michael D Sather
BACKGROUND: Patients with bitemporal lobe epilepsy are generally not considered for surgical resection. Fortunately, responsive neurostimulation proves another avenue for the management of this challenging disease process. In conjunction with our epileptologist, we consider responsive neurostimulation for patients who have clinical features of temporal lobe epilepsy without clear localization on imaging and stereo-EEG. METHODS: Here we describe our technique for implanting a responsive neurostimulator (NeuroPace, NeuroPace Inc...
November 14, 2017: World Neurosurgery
Dorothea Miller, Patrick Carney, John S Archer, Gregory J Fitt, Graeme D Jackson, Kristian J Bulluss
Bottom of sulcus dysplasias (BOSDs) are localized focal cortical dysplasias (FCDs) centred on the bottom of a sulcus that can be highly epileptogenic, but difficult to delineate intraoperatively. We report on a patient with refractory epilepsy due to a BOSD, successfully resected with the aid of a multimodal surgical approach using neuronavigation based on MRI and PET, intraoperative ultrasound (iUS) and electrocorticography (ECoG) using depth electrodes. The lesion could be visualized on iUS showing an increase in echogenicity at the grey-white matter junction...
November 11, 2017: Journal of Clinical Neuroscience: Official Journal of the Neurosurgical Society of Australasia
Yu-Jiao Zhang, Jin Qu, Shu-Meng Hao, Wei Chang, Qiu-Yu Ji, Zhong-Zhen Yu
Increasing demands for lithium-ion batteries (LIBs) with high energy density and high power density require highly reversible electrochemical reactions to enhance the cyclability and capacities of electrodes. As the reversible formation/decomposition of the solid electrolyte interface (SEI) film during the lithiation/delithiation process of Fe3S4 could bring about a higher capacity than its theoretical value, in the present work, synthesized Fe3S4 nanoparticles are sandwich-wrapped with reduced graphene oxide (RGO) to fabricate highly reversible and long cycling life anode materials for high-performance LIBs...
November 21, 2017: ACS Applied Materials & Interfaces
Kai Zhang, Fang Ren, Xuelong Wang, Enyuan Hu, Yahong Xu, Xiao-Qing Yang, Hong Li, Liquan Chen, Piero Pianetta, Apurva Mehta, Xiqian Yu, Yijin Liu
The in-depth understanding of the minority phases' roles in functional materials, e.g., batteries, is critical for optimizing the system performance and the operational efficiency. Although the visualization of battery electrode under operating conditions has been demonstrated, the development of advanced data-mining approaches is still needed in order to identify minority phases and to understand their functionalities. The present study uses nanoscale X-ray spectromicroscopy to study a functional LiCoO2/Li battery pouch cell...
November 10, 2017: Nano Letters
Hanna Ljung, Arto Nordlund, Maria Strandberg, Johan Bengzon, Kristina Källén
OBJECTIVE: To explore whether patients with refractory mesial temporal lobe epilepsy risk aggravated verbal memory loss from intracranial electroencephalography (EEG) recording with longitudinal hippocampal electrodes in the language-dominant hemisphere. METHODS: A long-term neuropsychological follow-up (mean 61.5 months, range 22-111 months) was performed in 40 patients after ictal registration with left hippocampal depth electrodes (study group, n = 16) or no invasive EEG, only extracranial registration (reference group, n = 24)...
November 3, 2017: Epilepsia
P Mittmann, A Ernst, I Todt
BACKGROUND: Preservation of residual hearing is one of the major goals in modern cochlear implant surgery. Intra-cochlear fluid pressure changes influence residual hearing, and should be kept low before, during and after cochlear implant insertion. METHODS: Experiments were performed in an artificial cochlear model. A pressure sensor was inserted in the apical part. Five insertions were performed on two electrode arrays. Each insertion was divided into three parts, and statistically evaluated in terms of pressure peak frequency and pressure peak amplitude...
November 6, 2017: Journal of Laryngology and Otology
Evangelos Kogias, Jan-Helge Klingler, Horst Urbach, Christian Scheiwe, Barbara Schmeiser, Soroush Doostkam, Josef Zentner, Dirk-Matthias Altenmüller
OBJECTIVE: To investigate presurgical diagnostic modalities, clinical and seizure outcome as well as predictive factors after resective epilepsy surgery in 3 Tesla MRI-negative focal epilepsies. PATIENTS AND METHODS: This retrospective study comprises 26 patients (11 males/15 females, mean age 34±12years, range 13-50 years) with 3 Tesla MRI-negative focal epilepsies who underwent resective epilepsy surgery. Non-invasive and invasive presurgical diagnostic modalities, type and localization of resection, clinical and epileptological outcome with a minimum follow-up of 1year (range 1-11 years, mean 2...
October 31, 2017: Clinical Neurology and Neurosurgery
Tomoko Ishihara, Takashi Tokushima, Yuka Horikawa, Masaru Kato, Ichizo Yagi
We developed a spectro-electrochemical cell for X-ray absorption and X-ray emission spectroscopy, which are element-specific methods to study local electronic structures in the soft X-ray region. In the usual electrochemical measurement setup, the electrode is placed in solution, and the surface/interface region of the electrode is not normally accessible by soft X-rays that have low penetration depth in liquids. To realize soft X-ray observation of electrochemical reactions, a 15-nm-thick Pt layer was deposited on a 150-nm-thick film window with an adhesive 3-nm-thick Ti layer for use as both the working electrode and the separator window between vacuum and a sample liquid under atmospheric pressure...
October 2017: Review of Scientific Instruments
Daniel Bush, James A Bisby, Chris M Bird, Stephanie Gollwitzer, Roman Rodionov, Beate Diehl, Andrew W McEvoy, Matthew C Walker, Neil Burgess
Theta frequency oscillations in the 6- to 10-Hz range dominate the rodent hippocampal local field potential during translational movement, suggesting that theta encodes self-motion. Increases in theta power have also been identified in the human hippocampus during both real and virtual movement but appear as transient bursts in distinct high- and low-frequency bands, and it is not yet clear how these bursts relate to the sustained oscillation observed in rodents. Here, we examine depth electrode recordings from the temporal lobe of 13 presurgical epilepsy patients performing a self-paced spatial memory task in a virtual environment...
October 24, 2017: Proceedings of the National Academy of Sciences of the United States of America
Jigang Zhou, Jian Wang, Yongfeng Hu, Mi Lu
The nanoscale interfacial inhomogeneity in a cycled large-format LiFePO4 (LFP) composite electrode has been studied by X-ray photoemission electron microscopy at single particle spatial resolution with a probe depth of ∼5 nm. The loss of active lithium in cycled LFP causes the coexsitence of fully delithiated LFP (FePO4) and partially delithiated LFP (Li0.6FePO4 or Li0.8FePO4) as a function of the extent of lithium loss. The distribution of various lithium loss phases along with local agglomeration of LFP and degradation of binder and carbon black are correlatively visualized...
November 2, 2017: ACS Applied Materials & Interfaces
Scott D Slotnick
In a discussion paper (Slotnick, this issue), I conducted a selective review of spatial attention studies to compare experimental parameters and determine whether particular stimulus, task, or analysis conditions were more likely to produce significant attentional modulation of the event-related potential (ERP) C1 component. It was concluded that to maximize C1 attention effects, stimuli should be in the upper visual field, there should be distractors, conditions should be high perceptual or attentional load, there should be exogenous cuing, and effects should be measured at midline parietal-occipital electrodes POz, Pz, and CPz...
October 25, 2017: Cognitive Neuroscience
Macauley S Breault, Pierre Sacre, Jacob J Johnson, Matthew Kerr, Matthew D Johnson, Juan Bulacio, Jorge Gonzalez-Martinez, Sridevi V Sarma, John T Gale
Sensorimotor control and the involvement of motor brain regions has been extensively studied, but the role nonmotor brain regions play during movements has been overlooked. This is particularly due to the difficulty of recording from multiple regions in the brain during motor control. In this study, we utilize stereoelectroencephalography (SEEG) recording techniques to explore the role nonmotor brain areas have on the way we move. Nine humans were implanted with SEEG depth electrodes for clinical purposes, which rendered access to local field potential (LFP) activity in deep and peripheral nonmotor structures...
July 2017: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Jacob J Johnson, Macauley S Breault, Pierre Sacre, Matthew S D Kerr, Mathew Johnson, Juan Bulacio, Jorge Gonzalez-Martinez, Sridevi V Sarma, John T Gale
Neural prostheses have generally relied on signals from cortical motor regions to control reaching movements of a robotic arm. However, little work has been done in exploring the involvement of nonmotor cortical and associative regions during motor tasks. In this study, we identify regions which may encode direction during planning and movement of a center-out motor task. Local field potentials were collected using stereoelectroencephalography (SEEG) from nine epilepsy patients implanted with multiple depth electrodes for clinical purposes...
July 2017: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Jungmin Seo, Gwang Jin Choi, Sangwan Park, Jihun Lee, Changhoon Baek, Jungwoo Jang, Jaegook Lim, Soowon Shin, Kangmoon Seo, Jong-Mo Seo, Yoon-Kyu Song, Sung June Kim
A polymer-based implantable stimulator for wirelessly navigating pigeons was conceptually suggested and a pilot study using depth electrodes was conducted. In this study, depth electrodes based on liquid crystal polymer (LCP) with eight channels were designed and fabricated. Electrochemical impedance spectrum (EIS) assessments were performed to measure impedances of the electrodes. The average value of the measured impedances was 16.8∠15.8 ° kμ. The electrodes were then advanced to a target nucleus (formatio reticularis medialis mesencephalic, FRM) of a pigeon to prove their in vivo feasibilities...
July 2017: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Danyi Zhu, Xiunan Fang, Calvin Eiber, James Avery, David Holder, Alistair McEwan
Electrical Impedance Tomography has been recently applied to image fast neural activity in the somatosensory cerebral cortex. This non-invasive imaging modality has the unique advantage of high spatial-temporal resolution in millimeters over milliseconds. This work was designed to test an existing 32-channel EIT system, a modified UCL ScouseTom, and to discuss the feasibility of imaging neural activity in retinal tissue through computer simulation. The finite element method was used to model a retinal slice with a realistic conductivity-depth profile of the macaque eye...
July 2017: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Antje Aschendorff, Robert Briggs, Goetz Brademann, Silke Helbig, Joachim Hornung, Thomas Lenarz, Mathieu Marx, Angel Ramos, Timo Stöver, Bernard Escudé, Chris J James
AIMS: The Nucleus CI532 cochlear implant incorporates a new precurved electrode array, i.e., the Slim Modiolar electrode (SME), which is designed to bring electrode contacts close to the medial wall of the cochlea while avoiding trauma due to scalar dislocation or contact with the lateral wall during insertion. The primary aim of this prospective study was to determine the final position of the electrode array in clinical cases as evaluated using flat-panel volume computed tomography...
2017: Audiology & Neuro-otology
Shirin Mahdavi, Farzad Towhidkhah
Despite increasing attention to the application of transcranial Direct Current Stimulation (tDCS) for enhancing cognitive functions in subjects exposing to varying degree of cerebral atrophy such as Alzheimer's disease (AD), aging, and mild cognitive impairment (MCI), there is no general information for customizing stimulation protocol. OBJECTIVE: The objective of this study is to examine how cerebral shrinkage associated with cognitive impairment and aging can perturb current density distribution through the brain...
September 28, 2017: Brain Stimulation
Guilherme Barros, Michael J Lang, Nikolaos Mouchtouris, Ashwini D Sharan, Chengyuan Wu
BACKGROUND: While T1-weighted gadolinium-enhanced (T1-Gd) magnetic resonance imaging (MRI) is the standard imaging sequence for trajectory planning of stereotactic procedures, including deep brain stimulation, stereoelectroencephalography, and laser interstitial thermal therapy, susceptibility-weighted imaging (SWI) has been reported to demonstrate increased sensitivity for the visualization of microvasculature. OBJECTIVE: To determine the impact of SWI visualization on trajectory planning for electrode implantation and evaluate the relationship between the rate of vessel-electrode intersections and intracerebral hemorrhage (ICH)...
October 18, 2017: Operative Neurosurgery (Hagerstown, Md.)
Niels Hansen, Leila Chaieb, Marlene Derner, Kevin G Hampel, Christian E Elger, Rainer Surges, Bernhard Staresina, Nikolai Axmacher, Juergen Fell
BACKGROUND: Deep brain stimulation (DBS) of the human entorhinal area using 50 Hz pulses has revealed conflicting results regarding memory performance. Moreover, its impact on memory-related hippocampal potentials has not yet been investigated. METHODS: We recorded data from seven epilepsy patients implanted with depth electrodes in the entorhinal cortex, hippocampus, amygdala and parahippocampal cortex. Entorhinal DBS (bipolar, biphasic 50 Hz pulses, on- and off-cycles of 15 s) was applied with low amplitude (0...
October 16, 2017: Hippocampus
Giulia Liberati, Anne Klöcker, Maxime Algoet, Dounia Mulders, Marta Maia Safronova, Susana Ferrao Santos, José-Géraldo Ribeiro Vaz, Christian Raftopoulos, André Mouraux
Transient nociceptive stimuli elicit robust phase-locked local field potentials (LFPs) in the human insula. However, these responses are not preferential for nociception, as they are also elicited by transient non-nociceptive vibrotactile, auditory, and visual stimuli. Here, we investigated whether another feature of insular activity, namely gamma-band oscillations (GBOs), is preferentially observed in response to nociceptive stimuli. Although nociception-evoked GBOs have never been explored in the insula, previous scalp electroencephalography and magnetoencephalography studies suggest that nociceptive stimuli elicit GBOs in other areas such as the primary somatosensory and prefrontal cortices, and that this activity could be closely related to pain perception...
September 25, 2017: Cerebral Cortex
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