Laser ablation of the pia mater for insertion of high-density microelectrode arrays in a translational sheep model

AbstractThe safe insertion of high density intracortical electrode arrays has been a long-standing practical challenge for neural interface engineering and applications such as brain-computer interfaces (BCIs). Here we describe a surgical procedure, inspired by laser corneal ablation, that can be used in large mammals to thin the pia mater, the innermost meningeal layer encapsulating the brain. This procedure allows for microelectrode arrays to be inserted into the cortex with less force, thus reducing deformation of underlying tissue during placement of the microelectrodes. We demonstrate that controlled pia removal over a small area of cortex allows for insertion of high-density electrode arrays and subsequent acute recordings of spiking neuron activity in sheep cortex. We also show histological and electrophysiological evidence that laser removal of the pia does not acutely affect neuronal viability in the region. This approach suggests a promising new path for clinical BCI with high-density microelectrode arrays.

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Quantitative Determination and Subcellular Imaging of Cu in Single Cells via Laser Ablation-ICP-Mass Spectrometry Using High-Density Microarray Gelatin Standards

Analytical Chemistry ◽

10.1021/acs.analchem.6b00334 ◽

2016 ◽

Vol 88 (11) ◽

pp. 5783-5789 ◽

Cited By ~ 35

Author(s):

Stijn J. M. Van Malderen ◽

Eva Vergucht ◽

Maarten De Rijcke ◽

Colin Janssen ◽

Laszlo Vincze ◽

...

Keyword(s):

Mass Spectrometry ◽

Laser Ablation ◽

Quantitative Determination ◽

Single Cells ◽

High Density ◽

Icp Mass Spectrometry ◽

Subcellular Imaging

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Why ‘the bigger the better’ is not always the case when utilising microelectrode arrays: high density vs. low density arrays for the electroanalytical sensing of chromium(vi)

The Analyst ◽

10.1039/b911507b ◽

2009 ◽

Vol 134 (11) ◽

pp. 2301 ◽

Cited By ~ 27

Author(s):

Sebastian J. Hood ◽

Dimitrios. K. Kampouris ◽

Rashid O. Kadara ◽

Norman Jenkinson ◽

F. Javier del Campo ◽

...

Keyword(s):

Microelectrode Arrays ◽

High Density ◽

Low Density ◽

Chromium Vi

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Spike detection methods for polytrodes and high density microelectrode arrays

Journal of Computational Neuroscience ◽

10.1007/s10827-014-0539-z ◽

2014 ◽

Vol 38 (2) ◽

pp. 249-261 ◽

Cited By ~ 8

Author(s):

Nicholas V. Swindale ◽

Martin A. Spacek

Keyword(s):

Microelectrode Arrays ◽

High Density ◽

Detection Methods ◽

Spike Detection

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Mesenchymal Stem Cell-Seeded High-Density Collagen Gel for Annular Repair: 6-Week Results From In Vivo Sheep Models

Neurosurgery ◽

10.1093/neuros/nyy523 ◽

2018 ◽

Vol 85 (2) ◽

pp. E350-E359 ◽

Cited By ~ 9

Author(s):

Ibrahim Hussain ◽

Stephen R Sloan ◽

Christoph Wipplinger ◽

Rodrigo Navarro-Ramirez ◽

Micaella Zubkov ◽

...

Keyword(s):

Nucleus Pulposus ◽

Annulus Fibrosus ◽

Perioperative Complications ◽

Collagen Gel ◽

Intervertebral Discs ◽

High Density ◽

Sheep Model ◽

Gel Treatment ◽

Pfirrmann Grade

AbstractBACKGROUNDOur group has previously demonstrated in vivo annulus fibrosus repair in animal models using an acellular, riboflavin crosslinked, high-density collagen (HDC) gel.OBJECTIVETo assess if seeding allogenic mesenchymal stem cells (MSCs) into this gel yields improved histological and radiographic benefits in an in vivo sheep model of annular injury.METHODSFifteen lumbar intervertebral discs (IVDs) were randomized into 4 groups: intact, injury only, injury + acellular gel treatment, or injury + MSC-seeded gel treatment. Sheep were sacrificed at 6 wk. Disc height index (DHI), Pfirrmann grade, nucleus pulposus area, and T2 relaxation time (T2-RT) were calculated for each IVD and standardized to healthy controls from the same sheep. Quantitative histological assessment was also performed using the Han scoring system.RESULTSAll treated IVDs retained gel plugs on gross assessment and there were no adverse perioperative complications. The MSC-seeded gel treatment group demonstrated statistically significant improvement over other experimental groups in DHI (P = .002), Pfirrmann grade (P < .001), and T2-RT (P = .015). There was a trend for greater Han scores in the MSC-seeded gel-treated discs compared with injury only and acellular gel-treated IVDs (P = .246).CONCLUSIONMSC-seeded HDC gel can be delivered into injured IVDs and maintained safely in live sheep to 6 wk. Compared with no treatment and acellular HDC gel, our data show that MSC-seeded HDC gel improves outcomes in DHI, Pfirrmann grade, and T2-RT. Histological analysis shows improved annulus fibrosus and nucleus pulposus reconstitution and organization over other experimental groups as well.

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Production of high-density single-walled nanotube material by a simple laser-ablation method

Chemical Physics Letters ◽

10.1016/s0009-2614(98)00776-3 ◽

1998 ◽

Vol 292 (4-6) ◽

pp. 587-593 ◽

Cited By ~ 169

Author(s):

W.K. Maser ◽

E. Muñoz ◽

A.M. Benito ◽

M.T. Martı́nez ◽

G.F. de la Fuente ◽

...

Keyword(s):

Laser Ablation ◽

High Density ◽

Laser Ablation Method

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Automatic spike sorting for high-density microelectrode arrays

Journal of Neurophysiology ◽

10.1152/jn.00803.2017 ◽

2018 ◽

Vol 120 (6) ◽

pp. 3155-3171 ◽

Cited By ~ 13

Author(s):

Roland Diggelmann ◽

Michele Fiscella ◽

Andreas Hierlemann ◽

Felix Franke

Keyword(s):

Principal Component Analysis ◽

Clustering Algorithm ◽

State Of The Art ◽

Microelectrode Arrays ◽

Principal Component ◽

Component Analysis ◽

High Density ◽

Sorting Algorithm ◽

Spike Sorting ◽

Recording Electrodes

High-density microelectrode arrays can be used to record extracellular action potentials from hundreds to thousands of neurons simultaneously. Efficient spike sorters must be developed to cope with such large data volumes. Most existing spike sorting methods for single electrodes or small multielectrodes, however, suffer from the “curse of dimensionality” and cannot be directly applied to recordings with hundreds of electrodes. This holds particularly true for the standard reference spike sorting algorithm, principal component analysis-based feature extraction, followed by k-means or expectation maximization clustering, against which most spike sorters are evaluated. We present a spike sorting algorithm that circumvents the dimensionality problem by sorting local groups of electrodes independently with classical spike sorting approaches. It is scalable to any number of recording electrodes and well suited for parallel computing. The combination of data prewhitening before the principal component analysis-based extraction and a parameter-free clustering algorithm obviated the need for parameter adjustments. We evaluated its performance using surrogate data in which we systematically varied spike amplitudes and spike rates and that were generated by inserting template spikes into the voltage traces of real recordings. In a direct comparison, our algorithm could compete with existing state-of-the-art spike sorters in terms of sensitivity and precision, while parameter adjustment or manual cluster curation was not required. NEW & NOTEWORTHY We present an automatic spike sorting algorithm that combines three strategies to scale classical spike sorting techniques for high-density microelectrode arrays: 1) splitting the recording electrodes into small groups and sorting them independently; 2) clustering a subset of spikes and classifying the rest to limit computation time; and 3) prewhitening the spike waveforms to enable the use of parameter-free clustering. Finally, we combined these strategies into an automatic spike sorter that is competitive with state-of-the-art spike sorters.

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