Biology subjects

Talbot, N.

Publications and source records attributed to Talbot, N..

3 recordsLinked to original sources

bioRxiv2020

A vision prosthesis based on electrical stimulation of the primary visual cortex using epicortical microelectrodes

Prostheses that can restore limited vision in the profoundly blind have been under investigation for several decades. Studies using epicortical macroelectrodes and intracortical microelectrodes have validated that electrical stimulation of primary visual cortical can serve as the basis for a vision prosthesis. However, neither of these approaches has resulted in a clinically viable vision prosthesis. Epicortical macroelectrodes required high levels of electrical current to evoke visual percepts, while intracortical microelectrodes faced challenges with longevity and stability. We hypothesized that epicortical microelectrodes could evoke visual percepts at lower currents than macroelectrodes and provide improved longevity and stability compared with intracortical microelectrodes. To test this hypotheses we implanted epicortical microelectrode arrays over the primary visual cortex of a nonhuman primate. Electrical stimulation via this array was used to evaluate the ability of epicortical microstimulation to evoke differentiable visual percepts. Visual percepts were evoked using the epicortical microelectrode array, and at electrical currents notably lower than those required to evoke visual percepts on macroelectrode arrays. The electrical current thresholds for evoking visual percepts on the epicortical microelectrode array were consistent across multiple array implants and over several months. Normal vision of light perception was not impaired by multiple array implants or chronic electrical stimulation, demonstrating that no gross visual deficit resulted from the experiments. We specifically demonstrate that epicortical microelectrode interfaces can serve as the basis for a vision prosthesis and more generally may provide an approach to evoking perception in multiple sensory modalities. One Sentence SummaryElectrical stimulation of the brain via microelectrodes resting on the surface of primary visual cortex can evoke multiple differentiable visual percepts.

bioengineering↗

bioRxiv2020

Hybrid Chemomechanical Promotion of PEDOT Adhesion onto Flexible Microelectrode Arrays for Chronic Neural Stimulation

Advances in neural prosthetic technologies demand ever increasing novelty in material composition to enhance the mechanical and electrochemical properties of existing microelectrode arrays. Conductive polymers present advantages such as mechanical flexibility, outstanding biocompatibility, remarkable electrical properties and, most of all, cellular agreement. However, for long-term chronic applications, they fall short in their electrochemical endurance and mechanical adhesion to their substrate materials. Multiple electrochemical approaches have been investigated to improve the adherence of Poly(3,4-ethylenedioxythiophene) (PEDOT) to underlying metallic thin films. In this work, an electrochemical treatment of diazonium salt on platinum microelectrodes is incorporated as an electrochemical adhesion promoter for PEDOT and it is further combined with using the highly microporous geometry of Platinum Grey (Pt-Grey); a technology developed by Second Sight Medical Products Inc (SSMP). The intertwined mechanical integration of Pt-Grey and PEDOT molecules together with the covalent binding agency of diazonium salt demostrate a composite coating technology with long-term stability of more than 452 days while providing >70x enhancement to the interfacial capacitive impedance.

bioengineering↗

bioRxiv2017

Gene flow between divergent cereal- and grass-specific lineages of the rice blast fungus Magnaporthe oryzae

Delineating species and epidemic lineages in fungal plant pathogens is critical to our understanding of disease emergence and the structure of fungal biodiversity, and also informs international regulatory decisions. Pyricularia oryzae (syn. Magnaporthe oryzae) is a multi-host pathogen that infects multiple grasses and cereals, is responsible for the most damaging rice disease (rice blast), and of growing concern due to the recent introduction of wheat blast to Bangladesh from South America. However, the genetic structure and evolutionary history of M. oryzae, including the possible existence of cryptic phylogenetic species, remain poorly defined. Here, we use whole-genome sequence information for 76 M. oryzae isolates sampled from 12 grass and cereal genera to infer the population structure of M. oryzae, and to reassess the species status of wheat-infecting populations of the fungus. Species recognition based on genealogical concordance, using published data or extracting previously-used loci from genome assemblies, failed to confirm a prior assignment of wheat blast isolates to a new species (Pyricularia graminis tritici). Inference of population subdivisions revealed multiple divergent lineages within M. oryzae, each preferentially associated with one host genus, suggesting incipient speciation following host shift or host range expansion. Analyses of gene flow, taking into account the possibility of incomplete lineage sorting, revealed that genetic exchanges have contributed to the makeup of multiple lineages within M. oryzae. These findings provide greater understanding of the eco-evolutionary factors that underlie the diversification of M. oryzae and highlight the practicality of genomic data for epidemiological surveillance in this important multi-host pathogen.\n\nImportanceInfection of novel hosts is a major route for disease emergence by pathogenic micro-organisms. Understanding the evolutionary history of multi-host pathogens is therefore important to better predict the likely spread and emergence of new diseases. Magnaporthe oryzae is a multi-host fungus that causes serious cereal diseases, including the devastating rice blast disease, and wheat blast, a cause of growing concern due to its recent spread from South America to Asia. Using whole genome analysis of 76 fungal strains from different hosts, we have documented the divergence of M. oryzae into numerous lineages, each infecting a limited number of host species. Our analyses provide evidence that inter-lineage gene flow has contributed to the genetic makeup of multiple M. oryzae lineages within the same species. Plant health surveillance is therefore warranted to safeguard against disease emergence in regions where multiple lineages of the fungus are in contact with one another.

microbiology↗