Binocular 3D otolith-ocular reflexes: responses of chinchillas to prosthetic electrical stimulation targeting the utricle and saccule.

From animal experiments by Cohen and Suzuki et al. in the 1960s to the first-in-human clinical trials now in progress, prosthetic electrical stimulation targeting semicircular canal branches of the vestibular nerve has proven effective at driving directionally appropriate vestibulo-ocular reflex eye movements, postural responses, and perception. That work was considerably facilitated by the fact that all hair cells and primary afferent neurons in each canal have the same directional sensitivity to head rotation, the three canals' ampullary nerves are geometrically distinct from one another, and electrically evoked three-dimensional (3D) canal-ocular reflex responses approximate a simple vector sum of linearly independent components representing relative excitation of each of the three canals. In contrast, selective prosthetic stimulation of the utricle and saccule has been difficult to achieve, because hair cells and afferents with many different directional sensitivities are densely packed in those endorgans and the relationship between 3D otolith-ocular reflex responses and the natural and/or prosthetic stimuli that elicit them is more complex. As a result, controversy exists regarding whether selective, controllable stimulation of electrically evoked otolith-ocular reflexes (eeOOR) is possible. Using micromachined, planar arrays of electrodes implanted in the labyrinth, we quantified 3D, binocular eeOOR responses to prosthetic electrical stimulation targeting the utricle, saccule, and semicircular canals of alert chinchillas. Stimuli delivered via near-bipolar electrode pairs near the maculae elicited sustained ocular countertilt responses that grew reliably with pulse rate and pulse amplitude, varied in direction according to which stimulating electrode was employed, and exhibited temporal dynamics consistent with responses expected for isolated macular stimulation.NEW & NOTEWORTHY As the second in a pair of papers on Binocular 3D Otolith-Ocular Reflexes, this paper describes new planar electrode arrays and vestibular prosthesis architecture designed to target the three semicircular canals and the utricle and saccule. With this technological advancement, electrically evoked otolith-ocular reflexes due to stimulation via utricle- and saccule-targeted electrodes were recorded in chinchillas. Results demonstrate advances toward achieving selective stimulation of the utricle and saccule.

In situ process quality monitoring and defect detection for direct metal laser melting.

Quality control and quality assurance are challenges in direct metal laser melting (DMLM). Intermittent machine diagnostics and downstream part inspections catch problems after undue cost has been incurred processing defective parts. In this paper we demonstrate two methodologies for in-process fault detection and part quality prediction that leverage existing commercial DMLM systems with minimal hardware modification. Novel features were derived from the time series of common photodiode sensors along with standard machine control signals. In one methodology, a Bayesian approach attributes measurements to one of multiple process states as a means of classifying process deviations. In a second approach, a least squares regression model predicts severity of certain material defects.

A Fully Automated Approach to Spike Sorting.

Understanding the detailed dynamics of neuronal networks will require the simultaneous measurement of spike trains from hundreds of neurons (or more). Currently, approaches to extracting spike times and labels from raw data are time consuming, lack standardization, and involve manual intervention, making it difficult to maintain data provenance and assess the quality of scientific results. Here, we describe an automated clustering approach and associated software package that addresses these problems and provides novel cluster quality metrics. We show that our approach has accuracy comparable to or exceeding that achieved using manual or semi-manual techniques with desktop central processing unit (CPU) runtimes faster than acquisition time for up to hundreds of electrodes. Moreover, a single choice of parameters in the algorithm is effective for a variety of electrode geometries and across multiple brain regions. This algorithm has the potential to enable reproducible and automated spike sorting of larger scale recordings than is currently possible.

Thin-film, high-density micro-electrocorticographic decoding of a human cortical gyrus.

High-density electrocorticography (ECoG) arrays are promising interfaces for high-resolution neural recording from the cortical surface. Commercial options for high-density arrays are limited, and historically tradeoffs must be made between spatial coverage and electrode density. However, thin-film technology is a promising alternative for generating electrode arrays capable of large area coverage and high channel count, with resolution on the order of cortical columns in the functional surface unit of a human gyrus. Here, we evaluate the sensing performance of a high-density thin-film 128-electrode array designed specifically for recording the distributed neural activity of a single human cortical gyrus. We found robust field potential responses throughout the superior temporal gyrus evoked by speech sounds, and clear phonetic feature selectivity at the resolution of 2 mm inter-electrode distance. Decoding accuracy improved with increasing density of electrodes over all three patients tested. Thin-film ECoG has significant potential for high-density neural interface applications at the scale of a human gyrus.

Reflexos de um processo de qualificação da Atenção Primária à Saúde na rotina e no cuidado produzido por seus trabalhadores / Reflections of a qualification process of Primary Health Care in the routine and care provided by its workers

Resumo Estudo qualitativo, exploratório, do tipo estudo de caso, que objetivou compreender os reflexos de um programa de qualificação da Atenção Primária à Saúde no processo de trabalho e no cuidado ofertado. A coleta de dados ocorreu de julho de 2018 a abril de 2019, utilizando observação-participante e entrevista semiestruturada com trabalhadores de uma Unidade de Saúde da Família. Os resultados apontaram a organização do processo de trabalho, sobrecarga física e mental dos profissionais, ênfase em questões burocráticas em detrimento do cuidado e dificuldade do processo em contemplar as singularidades do território. Apesar disso, oportunizou a reflexão sobre a prática profissional. Processos verticalizados e descontextualizados dificultam a compreensão da realidade e, por isso, a importância de práticas de Educação Permanente em Saúde como espaços de diálogo e problematização sobre o vivido, de forma a adequar os processos da macropolítica à realidade local.

Abstract An exploratory, qualitative research, case study type, that aimed to comprehend the reflections of a qualification process of the Primary Health Care in the work process and in the health care offered. Data were collected from July of 2018 to April of 2019, using the observation-participant study tool and semi-structed interviews with health workers of Family Health Unit. The results pointed out the work process organization, physical and mental overload, emphasis on bureaucratic issues in detriment of patient care, difficulties in the process of considering the territory uniqueness. Nevertheless, it provided the opportunity to reflect over the professional practice. Vertical and out of context processes hamper the understanding of the reality and because of that the practice of continuing health education is important so it can give space for dialog and problematize the experiences lived to suit the macro-politics to the local reality.

Diffusion-bonded electrodes for chronic neural stimulation.

We report a novel method to fabricate chronic neural interfaces with the intent to combine the reliability and lifetime of bulk metal electrodes, with the miniaturization and mechanical flexibility of thin-film polymer microelectrode arrays. 10 µm thick platinum discs were laser cut from a foil into the shape of individual electrodes, and coated with gold on the backside. The discs were bonded to a microelectrode array with gold bond pads via gold-gold inter-diffusion using a flipchip bonder. Electrode bonding and adhesion was characterized using mechanical shear testing and electrical testing. Electrode performance was characterized in vitro using electrochemical impedance spectroscopy and cyclic voltammetry. Biphasic electrical pulsing experiments were conducted on the bonded electrodes to study degradation of the electrode; the preliminary results show that the electrodes can withstand at least 4,900 million pulses with no adverse electrochemical or visual degradation. Overall, this is a promising new method for fabricating chronic neural electrodes for stimulation or recording that combines the reliability of commercial bulk electrodes with the miniaturization and versatility of microfabricated technologies.

Chronic, percutaneous connector for electrical recording and stimulation with microelectrode arrays.

The translation of advances in neural stimulation and recording research into clinical practice hinges on the ability to perform chronic experiments in awake and behaving animal models. Advances in microelectrode array technology, most notably flexible polymer arrays, have significantly improved reliability of the neural interface. However, electrical connector technology has lagged and is prone to failure from non-biocompatibility, large size, contamination, corrosion, and difficulty of use. We present a novel chronic, percutaneous electrical connector system that is suitable for neural stimulation and recording. This system features biocompatible materials, low connect and disconnect forces, passive alignment, and a protective cap during non-use. We have successfully designed, assembled, and tested in vitro both a 16-channel system and a high density 64-channel system. Custom, polyimide, 16-channel, microelectrode arrays were electrically assembled with the connector system and tested using cyclic voltammetry and electrochemical impedance spectroscopy. This connector system is versatile and can be used with a variety of microelectrode array technologies for chronic studies.

Towards a large-scale recording system: demonstration of polymer-based penetrating array for chronic neural recording.

The brain is a massively interconnected network of specialized circuits. Even primary sensory areas, once thought to support relatively simple, feed-forward processing, are now known to be parts of complex feedback circuits. All brain functions depend on millisecond timescale interactions across these brain networks. Current approaches cannot measure or manipulate such large-scale interactions. Here we demonstrate that polymer-based, penetrating, micro-electrode arrays can provide high quality neural recordings from awake, behaving animals over periods of months. Our results indicate that polymer electrodes are a viable substrate for the development of systems that can record from thousands of channels across months to years. This is our first step towards developing a 1000+ electrode system capable of providing high-quality, long-term neural recordings.

Improved chronic neural stimulation using high surface area platinum electrodes.

We report a novel nano-cluster platinum (NCPt) film that exhibits enhanced performance as an electrode material for neural stimulation applications. Nano-cluster films were deposited using a custom physical vapor deposition process and patterned on a flexible polyimide microelectrode array using semiconductor processing technology. Electrode performance was characterized in vitro using electrochemical impedance spectroscopy and compared with sputtered thinfilm platinum (TFPt) electrodes. We characterized electrode impedance, charge storage capacity, voltage transient properties, and relative surface area enhancement in vitro. Preliminary lifetime testing of the electrode reveals that the NCPt electrodes degrade more slowly than TFPt electrodes. The combination of material biocompatibility, electrochemical performance, and preliminary lifetime results point to a promising new electrode material for neural interface devices.

Insertion of flexible neural probes using rigid stiffeners attached with biodissolvable adhesive.

Microelectrode arrays for neural interface devices that are made of biocompatible thin-film polymer are expected to have extended functional lifetime because the flexible material may minimize adverse tissue response caused by micromotion. However, their flexibility prevents them from being accurately inserted into neural tissue. This article demonstrates a method to temporarily attach a flexible microelectrode probe to a rigid stiffener using biodissolvable polyethylene glycol (PEG) to facilitate precise, surgical insertion of the probe. A unique stiffener design allows for uniform distribution of the PEG adhesive along the length of the probe. Flip-chip bonding, a common tool used in microelectronics packaging, enables accurate and repeatable alignment and attachment of the probe to the stiffener. The probe and stiffener are surgically implanted together, then the PEG is allowed to dissolve so that the stiffener can be extracted leaving the probe in place. Finally, an in vitro test method is used to evaluate stiffener extraction in an agarose gel model of brain tissue. This approach to implantation has proven particularly advantageous for longer flexible probes (>3 mm). It also provides a feasible method to implant dual-sided flexible probes. To date, the technique has been used to obtain various in vivo recording data from the rat cortex.

Microfabricated polymer-based neural interface for electrical stimulation/recording, drug delivery, and chemical sensing--development.

We present here a microfabricated, multi-functional neural interface with the ability to selectively apply electrical and chemical stimuli, while simultaneously monitoring both electrical and chemical activity in the brain. Such a comprehensive approach is required to understand and treat neuropsychiatric disorders, such as major depressive disorder (MDD), and to understand the mechanisms underlying treatments, such as pharmaceutical therapies and deep brain stimulation (DBS). The polymer-based, multi-functional neural interface is capable of electrical stimulation and recording, targeted drug delivery, and electrochemical sensing. A variety of different electrode and fluidic channel arrangements are possible with this fabrication process. Preliminary testing has shown the suitability of these neural interfaces for in vivo electrical stimulation and recording, as well as in vitro chemical sensing. Testing of the in vitro drug delivery and combined in vivo functionalities this neural interface are currently underway.

Polymer neural interface with dual-sided electrodes for neural stimulation and recording.

We present here a demonstration of a dual-sided, 4-layer metal, polyimide-based electrode array suitable for neural stimulation and recording. The fabrication process outlined here utilizes simple polymer and metal deposition and etching steps, with no potentially harmful backside etches or long exposures to extremely toxic chemicals. These polyimide-based electrode arrays have been tested to ensure they are fully biocompatible and suitable for long-term implantation; their flexibility minimizes the injury and glial scarring that can occur at the implantation site. The creation of dual-side electrode arrays with more than two layers of trace metal enables the fabrication of neural probes with more electrodes without a significant increase in probe size. This allows for more stimulation/recording sites without inducing additional injury and glial scarring.

Optimization of multi-layer metal neural probe design.

We present here a microfabrication process for multi-layer metal, multi-site, polymer-based neural probes. The process has been used to generate 1-, 2-, and 4-layer trace metal neural probes with highly uniform and reproducible electrode characteristics. Typically, increasing the number of metal layers is assumed to both reduce the width of the neural probes and minimize the injury and glial scarring caused at the implantation site. We show, however, that increasing the number of trace metal layers does not always result in the minimal probe cross-sectional area. A thorough design analysis reveals that the electrode size, along with other design parameters, have interacting effects on the probe cross-sectional area. Moreover, increasing the trace metal layers in the neural probes also increases the design and fabrication cost/time, as well as the likelihood of probe failure. Consequently, all of these factors must be considered when designing a multi-site, neural probe with the objective of minimizing tissue damage.

Removable silicon insertion stiffeners for neural probes using polyethylene glycol as a biodissolvable adhesive.

Flexible polymer probes are expected to enable extended interaction with neural tissue by minimizing damage from micromotion and reducing inflammatory tissue response. However, their flexibility prevents them from being easily inserted into the tissue. This paper describes an approach for temporarily attaching a silicon stiffener with biodissolvable polyethylene glycol (PEG) so that the stiffener can be released from the probe and extracted shortly after probe placement. A novel stiffener design with wicking channels, along with flip-chip technology, enable accurate alignment of the probe to the stiffener, as well as uniform distribution of the PEG adhesive. Insertion, extraction, and electrode function were tested in both agarose gel and a rat brain. Several geometric and material parameters were tested to minimize probe displacement during stiffener extraction. We demonstrated average probe displacement of 28 ± 9 µm.

Influência de políticas públicas e sociais na vida das pessoas em situação de rua e consequências no processo de rualização / Influence of public and social policies on the life of homeless people and consequences in the homelessness process

O objetivo do estudo foi conhecer a influência de políticas públicas e sociais na vida das pessoas em situação de rua e as consequências destas no processo de rualização. Trata-se de revisão integrativa de artigos pesquisados na base de dados PUBMED, utilizando os descritores "Homeless person" e "social welfare". Os critérios de inclusão foram: idioma português, inglês e espanhol, publicados entre 2010-2016, disponíveis na íntegra, pautando políticas voltadas à população em situação de rua. Dos 535 artigos encontrados, 11 foram incluídos e abordavam programas norte-americanos, canadenses e ingleses; orfanatos quenianos e assistência social brasileira. Os resultados apontam que o uso de substâncias ilícitas e rualização ocorre mesmo em indivíduos acompanhados desde a infância, e as políticas amparam principalmente necessidades materiais, acarretando consequências que sustentam a necessidade de manutenção destas políticas não cumprindo o papel de emancipação de direitos individuais (AU).

The objective of the study was to know the influence of public and social policies on the lives of street homeless people, and their consequences in the process of street living. It is an integrative review of articles researched in the PUBMED database, using the descriptors "Homeless person" and "social welfare". The inclusion criteria were: texts in Portuguese, English and Spanish, published between 2010-2016, fully available, guiding policies aimed at the population living in the street. From 535 articles found, 11 were included and covered North American, Canadian and English programs; Kenyan orphanages, and Brazilian social assistance. The results indicate that the use of illicit substances and street living situation occur even in individuals followed since childhood, and policies support mainly material needs, leading to consequences that sustain the need to keep these policies, not fulfilling the role of emancipation of individual rights (AU).