Frontiers in neuroengineering最新文献

{"title":"Deep brain stimulation macroelectrodes compared to multiple microelectrodes in rat hippocampus.","authors":"Sharanya Arcot Desai,&nbsp;Claire-Anne Gutekunst,&nbsp;Steve M Potter,&nbsp;Robert E Gross","doi":"10.3389/fneng.2014.00016","DOIUrl":"https://doi.org/10.3389/fneng.2014.00016","url":null,"abstract":"<p><p>Microelectrode arrays (wire diameter <50 μm) were compared to traditional macroelectrodes for deep brain stimulation (DBS). Understanding the neuronal activation volume may help solve some of the mysteries associated with DBS, e.g., its mechanisms of action. We used c-fos immunohistochemistry to investigate neuronal activation in the rat hippocampus caused by multi-micro- and macroelectrode stimulation. At ± 1V stimulation at 25 Hz, microelectrodes (33 μm diameter) had a radius of activation of 100 μm, which is 50% of that seen with 150 μm diameter macroelectrode stimulation. Macroelectrodes activated about 5.8 times more neurons than a single microelectrode, but displaced ~20 times more neural tissue. The sphere of influence of stimulating electrodes can be significantly increased by reducing their impedance. By ultrasonic electroplating (sonicoplating) the microelectrodes with platinum to increase their surface area and reduce their impedance by an order of magnitude, the radius of activation increased by 50 μm and more than twice the number of neurons were activated within this increased radius compared to unplated microelectrodes. We suggest that a new approach to DBS, one that uses multiple high-surface area microelectrodes, may be more therapeutically effective due to increased neuronal activation. </p>","PeriodicalId":73093,"journal":{"name":"Frontiers in neuroengineering","volume":" ","pages":"16"},"PeriodicalIF":0.0,"publicationDate":"2014-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3389/fneng.2014.00016","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"32458985","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nanocrystalline diamond surfaces for adhesion and growth of primary neurons, conflicting results and rational explanation.","authors":"Silviya M Ojovan,&nbsp;Matthew McDonald,&nbsp;Mathew McDonald,&nbsp;Noha Rabieh,&nbsp;Nava Shmuel,&nbsp;Hadas Erez,&nbsp;Milos Nesladek,&nbsp;Micha E Spira","doi":"10.3389/fneng.2014.00017","DOIUrl":"https://doi.org/10.3389/fneng.2014.00017","url":null,"abstract":"<p><p>Using a variety of proliferating cell types, it was shown that the surface of nanocrystalline diamond (NCD) provides a permissive substrate for cell adhesion and development without the need of complex chemical functionalization prior to cell seeding. In an extensive series of experiments we found that, unlike proliferating cells, post-mitotic primary neurons do not adhere to bare NCD surfaces when cultured in defined medium. These observations raise questions on the potential use of bare NCD as an interfacing layer for neuronal devices. Nevertheless, we also found that classical chemical functionalization methods render the \"hostile\" bare NCD surfaces with adhesive properties that match those of classically functionalized substrates used extensively in biomedical research and applications. Based on the results, we propose a mechanism that accounts for the conflicting results; which on one hand claim that un-functionalized NCD provides a permissive substrate for cell adhesion and growth, while other reports demonstrate the opposite. </p>","PeriodicalId":73093,"journal":{"name":"Frontiers in neuroengineering","volume":" ","pages":"17"},"PeriodicalIF":0.0,"publicationDate":"2014-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3389/fneng.2014.00017","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"32455573","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Organic electrode coatings for next-generation neural interfaces.","authors":"Ulises A Aregueta-Robles, Andrew J Woolley, Laura A Poole-Warren, Nigel H Lovell, Rylie A Green","doi":"10.3389/fneng.2014.00015","DOIUrl":"10.3389/fneng.2014.00015","url":null,"abstract":"<p><p>Traditional neuronal interfaces utilize metallic electrodes which in recent years have reached a plateau in terms of the ability to provide safe stimulation at high resolution or rather with high densities of microelectrodes with improved spatial selectivity. To achieve higher resolution it has become clear that reducing the size of electrodes is required to enable higher electrode counts from the implant device. The limitations of interfacing electrodes including low charge injection limits, mechanical mismatch and foreign body response can be addressed through the use of organic electrode coatings which typically provide a softer, more roughened surface to enable both improved charge transfer and lower mechanical mismatch with neural tissue. Coating electrodes with conductive polymers or carbon nanotubes offers a substantial increase in charge transfer area compared to conventional platinum electrodes. These organic conductors provide safe electrical stimulation of tissue while avoiding undesirable chemical reactions and cell damage. However, the mechanical properties of conductive polymers are not ideal, as they are quite brittle. Hydrogel polymers present a versatile coating option for electrodes as they can be chemically modified to provide a soft and conductive scaffold. However, the in vivo chronic inflammatory response of these conductive hydrogels remains unknown. A more recent approach proposes tissue engineering the electrode interface through the use of encapsulated neurons within hydrogel coatings. This approach may provide a method for activating tissue at the cellular scale, however, several technological challenges must be addressed to demonstrate feasibility of this innovative idea. The review focuses on the various organic coatings which have been investigated to improve neural interface electrodes. </p>","PeriodicalId":73093,"journal":{"name":"Frontiers in neuroengineering","volume":" ","pages":"15"},"PeriodicalIF":0.0,"publicationDate":"2014-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3389/fneng.2014.00015","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"32403208","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Decoding spectrotemporal features of overt and covert speech from the human cortex.","authors":"Stéphanie Martin,&nbsp;Peter Brunner,&nbsp;Chris Holdgraf,&nbsp;Hans-Jochen Heinze,&nbsp;Nathan E Crone,&nbsp;Jochem Rieger,&nbsp;Gerwin Schalk,&nbsp;Robert T Knight,&nbsp;Brian N Pasley","doi":"10.3389/fneng.2014.00014","DOIUrl":"https://doi.org/10.3389/fneng.2014.00014","url":null,"abstract":"<p><p>Auditory perception and auditory imagery have been shown to activate overlapping brain regions. We hypothesized that these phenomena also share a common underlying neural representation. To assess this, we used electrocorticography intracranial recordings from epileptic patients performing an out loud or a silent reading task. In these tasks, short stories scrolled across a video screen in two conditions: subjects read the same stories both aloud (overt) and silently (covert). In a control condition the subject remained in a resting state. We first built a high gamma (70-150 Hz) neural decoding model to reconstruct spectrotemporal auditory features of self-generated overt speech. We then evaluated whether this same model could reconstruct auditory speech features in the covert speech condition. Two speech models were tested: a spectrogram and a modulation-based feature space. For the overt condition, reconstruction accuracy was evaluated as the correlation between original and predicted speech features, and was significant in each subject (p < 10(-5); paired two-sample t-test). For the covert speech condition, dynamic time warping was first used to realign the covert speech reconstruction with the corresponding original speech from the overt condition. Reconstruction accuracy was then evaluated as the correlation between original and reconstructed speech features. Covert reconstruction accuracy was compared to the accuracy obtained from reconstructions in the baseline control condition. Reconstruction accuracy for the covert condition was significantly better than for the control condition (p < 0.005; paired two-sample t-test). The superior temporal gyrus, pre- and post-central gyrus provided the highest reconstruction information. The relationship between overt and covert speech reconstruction depended on anatomy. These results provide evidence that auditory representations of covert speech can be reconstructed from models that are built from an overt speech data set, supporting a partially shared neural substrate. </p>","PeriodicalId":73093,"journal":{"name":"Frontiers in neuroengineering","volume":" ","pages":"14"},"PeriodicalIF":0.0,"publicationDate":"2014-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3389/fneng.2014.00014","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"32403207","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Anti-inflammatory polymer electrodes for glial scar treatment: bringing the conceptual idea to future results.","authors":"Maria Asplund,&nbsp;Christian Boehler,&nbsp;Thomas Stieglitz","doi":"10.3389/fneng.2014.00009","DOIUrl":"https://doi.org/10.3389/fneng.2014.00009","url":null,"abstract":"<p><p>Conducting polymer films offer a convenient route for the functionalization of implantable microelectrodes without compromising their performance as excellent recording units. A micron thick coating, deposited on the surface of a regular metallic electrode, can elute anti-inflammatory drugs for the treatment of glial scarring as well as growth factors for the support of surrounding neurons. Electro-activation of the polymer drives the release of the substance and should ideally provide a reliable method for controlling quantity and timing of release. Driving signals in the form of a constant potential (CP), a slow redox sweep or a fast pulse are all represented in literature. Few studies present such release in vivo from actual recording and stimulating microelectronic devices. It is essential to bridge the gap between studies based on release in vitro, and the intended application, which would mean release into living and highly delicate tissue. In the biological setting, signals are limited both by available electronics and by the biological safety. Driving signals must not be harmful to tissue and also not activate the tissue in an uncontrolled manner. This review aims at shedding more light on how to select appropriate driving parameters for the polymer electrodes for the in vivo setting. It brings together information regarding activation thresholds for neurons, as well as injury thresholds, and puts this into context with what is known about efficient driving of release from conducting polymer films. </p>","PeriodicalId":73093,"journal":{"name":"Frontiers in neuroengineering","volume":" ","pages":"9"},"PeriodicalIF":0.0,"publicationDate":"2014-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3389/fneng.2014.00009","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"32366266","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Electrode impedance analysis of chronic tungsten microwire neural implants: understanding abiotic vs. biotic contributions.","authors":"Viswanath Sankar,&nbsp;Erin Patrick,&nbsp;Robert Dieme,&nbsp;Justin C Sanchez,&nbsp;Abhishek Prasad,&nbsp;Toshikazu Nishida","doi":"10.3389/fneng.2014.00013","DOIUrl":"https://doi.org/10.3389/fneng.2014.00013","url":null,"abstract":"<p><p>Changes in biotic and abiotic factors can be reflected in the complex impedance spectrum of the microelectrodes chronically implanted into the neural tissue. The recording surface of the tungsten electrode in vivo undergoes abiotic changes due to recording site corrosion and insulation delamination as well as biotic changes due to tissue encapsulation as a result of the foreign body immune response. We reported earlier that large changes in electrode impedance measured at 1 kHz were correlated with poor electrode functional performance, quantified through electrophysiological recordings during the chronic lifetime of the electrode. There is a need to identity the factors that contribute to the chronic impedance variation. In this work, we use numerical simulation and regression to equivalent circuit models to evaluate both the abiotic and biotic contributions to the impedance response over chronic implant duration. COMSOL® simulation of abiotic electrode morphology changes provide a possible explanation for the decrease in the electrode impedance at long implant duration while biotic changes play an important role in the large increase in impedance observed initially. </p>","PeriodicalId":73093,"journal":{"name":"Frontiers in neuroengineering","volume":" ","pages":"13"},"PeriodicalIF":0.0,"publicationDate":"2014-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3389/fneng.2014.00013","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"32356429","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effectiveness of the P3-speller in brain-computer interfaces for amyotrophic lateral sclerosis patients: a systematic review and meta-analysis.","authors":"Mauro Marchetti,&nbsp;Konstantinos Priftis","doi":"10.3389/fneng.2014.00012","DOIUrl":"https://doi.org/10.3389/fneng.2014.00012","url":null,"abstract":"<p><p>A quarter of century ago, Farwell and Donchin (1988) described their mental prosthesis for \"talking off the top of your head.\" This innovative communication system, later named P3-speller, has been the most investigated and tested brain-computer interface (BCI) system, to date. A main goal of the research on P3-spellers was the development of an effective assistive device for patients with severe motor diseases. Among these patients are those affected by amyotrophic lateral sclerosis (ALS). ALS patients have become a target population in P3-speller (and more generally in BCI) research. The P3-speller relies on the visual sensory modality, and it can be controlled by requiring users to actively move their eyes. Unfortunately, eye-movement control is usually not spared in the last stages of ALS, and, then, it is definitively lost in the case of complete paralysis. We reviewed the literature on ALS patients tested by means of P3-speller systems. Our aim was to investigate the evidence available to date of the P3-spellers effectiveness in ALS patients. To address this goal, a meta-analytic approach was adopted. The pooled classification accuracy performance, among retrieved studies, was about 74%. This estimation, however, was affected by significant heterogeneity and inconsistency among studies. This fact makes this percentage estimation (i.e., 74%) unreliable. Nowadays, the conclusion is that the initial hopes posed on P3-speller for ALS patients have not been met yet. In addition, no trials in which the P3-speller has been compared to current assistive technologies for communication (e.g., eye-trackers) are available. In conclusion, further studies are required to obtain a reliable index of P3-speller effectiveness in ALS. Furthermore, comparisons of P3-speller systems with the available assistive technologies are needed to assess the P3-speller usefulness with non-completely paralyzed ALS-patients. </p>","PeriodicalId":73093,"journal":{"name":"Frontiers in neuroengineering","volume":" ","pages":"12"},"PeriodicalIF":0.0,"publicationDate":"2014-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3389/fneng.2014.00012","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"32357543","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A polymer-based interface restores light sensitivity in blind rats","authors":"D. Ghezzi, M. Antognazza, Mattia Di Paolo, M. Mete, R. Maccarone, S. Bisti, G. Pertile, G. Lanzani, F. Benfenati","doi":"10.3389/CONF.FNENG.2014.11.00002","DOIUrl":"https://doi.org/10.3389/CONF.FNENG.2014.11.00002","url":null,"abstract":"Purpose: Sight restoration is one of the new frontiers for prosthetic devices that enable the electrical stimulation of neurons. In particular, diseases affecting the retinal pigment epithelium and photoreceptors but preserve the inner retinal layers are preferential targets for implantation of visual prostheses. We recently discovered that primary neurons can be successfully grown onto a photovoltaic organic polymer and electrically stimulated by light. This result was confirmed by restoring light sensitivity in retinas explanted from albino rats with light-induced degeneration of the photoreceptor layer. After implantation of the interface in Royal College of Surgeons rats, we are now evaluating the efficacy of the implant in restoring light sensitivity in-vivo. Methods: Experiments were performed on Royal College of Surgeons (RCS) rats and the non-dystrophic congenic animals (RCS-rdy). 2-3 months old animals were implanted with the prosthesis and let to recover for at least 3 weeks before experimentation. Pupillary light reflex, electroretinogram, visually evoked field potentials, and behavioral tests were performed in both implanted and not implanted rats (either RCS or RCS-rdy). Optical coherence tomography and immunofluorescence assays were performed to verify the correct positioning of the prosthesis after the surgery and its long-term tolerability. Results: We demonstrated the long-term tolerability (up to 5 months) of the organic prosthesis by monitoring the expression of inflammatory markers on retinas from RCS (GFAP) and RCS-rdy animals (FGF and GFAP) after implantation; Electroretinogram in implanted RCS-rdy animals confirmed that the prosthesis is not altering the functioning of healthy retinas. Moreover, electrophysiological and behavioral techniques on RCS rats suggest the possibility to partially restore light sensitivity in-vivo. We found: a statistically significant improvement in the pupillary light reflex (in 54% of the tested animals), the recovery of the visually evoked field potentials (in 50% of the tested animals), and a behavior in the Dark/Light test statistically comparable with the non-dystrophic animals (in 59% of the tested animals). Conclusions: In conclusion, our in-vitro and in-vivo results demonstrate the potential application of an optoelectronic polymer as substrate for the generation of a photovoltaic retinal prosthesis.","PeriodicalId":73093,"journal":{"name":"Frontiers in neuroengineering","volume":"7 1","pages":"2157-2157"},"PeriodicalIF":0.0,"publicationDate":"2014-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69611357","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Controlling neural network responsiveness: tradeoffs and constraints.","authors":"Hanna Keren,&nbsp;Shimon Marom","doi":"10.3389/fneng.2014.00011","DOIUrl":"https://doi.org/10.3389/fneng.2014.00011","url":null,"abstract":"<p><p>In recent years much effort is invested in means to control neural population responses at the whole brain level, within the context of developing advanced medical applications. The tradeoffs and constraints involved, however, remain elusive due to obvious complications entailed by studying whole brain dynamics. Here, we present effective control of response features (probability and latency) of cortical networks in vitro over many hours, and offer this approach as an experimental toy for studying controllability of neural networks in the wider context. Exercising this approach we show that enforcement of stable high activity rates by means of closed loop control may enhance alteration of underlying global input-output relations and activity dependent dispersion of neuronal pair-wise correlations across the network. </p>","PeriodicalId":73093,"journal":{"name":"Frontiers in neuroengineering","volume":" ","pages":"11"},"PeriodicalIF":0.0,"publicationDate":"2014-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3389/fneng.2014.00011","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"32324710","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Smaller, softer, lower-impedance electrodes for human neuroprosthesis: a pragmatic approach.","authors":"Elisa Castagnola,&nbsp;Alberto Ansaldo,&nbsp;Emma Maggiolini,&nbsp;Tamara Ius,&nbsp;Miran Skrap,&nbsp;Davide Ricci,&nbsp;Luciano Fadiga","doi":"10.3389/fneng.2014.00008","DOIUrl":"https://doi.org/10.3389/fneng.2014.00008","url":null,"abstract":"<p><p>Finding the most appropriate technology for building electrodes to be used for long term implants in humans is a challenging issue. What are the most appropriate technologies? How could one achieve robustness, stability, compatibility, efficacy, and versatility, for both recording and stimulation? There are no easy answers to these questions as even the most fundamental and apparently obvious factors to be taken into account, such as the necessary mechanical, electrical and biological properties, and their interplay, are under debate. We present here our approach along three fundamental parallel pathways: we reduced electrode invasiveness and size without impairing signal-to-noise ratio, we increased electrode active surface area by depositing nanostructured materials, and we protected the brain from direct contact with the electrode without compromising performance. Altogether, these results converge toward high-resolution ECoG arrays that are soft and adaptable to cortical folds, and have been proven to provide high spatial and temporal resolution. This method provides a piece of work which, in our view, makes several steps ahead in bringing such novel devices into clinical settings, opening new avenues in diagnostics of brain diseases, and neuroprosthetic applications. </p>","PeriodicalId":73093,"journal":{"name":"Frontiers in neuroengineering","volume":" ","pages":"8"},"PeriodicalIF":0.0,"publicationDate":"2014-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3389/fneng.2014.00008","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"32313070","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}