Multimodal, longitudinal assessment of intracortical microstimulation

Koivuniemi, Andrew S.; Wilks, Seth J.; Woolley, Andrew J.; Otto, Kevin J.

doi:10.1016/b978-0-444-53815-4.00011-x

Cited by 45 publications

(56 citation statements)

References 47 publications

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“…Statistical analysis showed that site size was a statistically significant factor ( p < 0.01), while post-implant time was not. While microstimulation studies have revealed a pattern of a sharp increase in impedance within the first 2–3 weeks post-implantation followed by a decay to some baseline (18, 21, 31, 32), the findings here follow impedance patterns shown in long-term implantation studies applying microelectrode arrays solely for neural recording (17, 20). …”

Section: Discussionsupporting

confidence: 72%

Microelectrode Array Recordings from the Ventral Roots in Chronically Implanted Cats

et al. 2014

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The ventral spinal roots contain the axons of spinal motoneurons and provide the only location in the peripheral nervous system where recorded neural activity can be assured to be motor rather than sensory. This study demonstrates recordings of single unit activity from these ventral root axons using floating microelectrode arrays (FMAs). Ventral root recordings were characterized by examining single unit yield and signal-to-noise ratios (SNR) with 32-channel FMAs implanted chronically in the L6 and L7 spinal roots of nine cats. Single unit recordings were performed for implant periods of up to 12 weeks. Motor units were identified based on active discharge during locomotion and inactivity under anesthesia. Motor unit yield and SNR were calculated for each electrode, and results were grouped by electrode site size, which were varied systematically between 25 and 160 μm to determine effects on signal quality. The unit yields and SNR did not differ significantly across this wide range of electrode sizes. Both SNR and yield decayed over time, but electrodes were able to record spikes with SNR >2 up to 12 weeks post-implant. These results demonstrate that it is feasible to record single unit activity from multiple isolated motor units with penetrating microelectrode arrays implanted chronically in the ventral spinal roots. This approach could be useful for creating a spinal nerve interface for advanced neural prostheses, and results of this study will be used to improve design of microelectrodes for chronic neural recording in the ventral spinal roots.

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Section: Discussionsupporting

confidence: 72%

Microelectrode Array Recordings from the Ventral Roots in Chronically Implanted Cats

et al. 2014

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“…A recent study from our lab investigating the depth-dependency of microstimulation-induced behavioral responses found that, over time, the most superficial electrode sites along a linear microelectrode array required the greatest increase in stimulation current to effectively drive a behavioral response (Koivuniemi et al ., 2011). Detailed histological analysis of tissue around intact devices used for depth-depended behavioral studies may clarify this link.…”

Section: Discussionmentioning

confidence: 99%

Chronic intracortical microelectrode arrays induce non-uniform, depth-related tissue responses

Woolley¹,

Desai²,

Otto³

2013

J. Neural Eng.

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Objective Brain-implanted microelectrode arrays show promise as future clinical devices. However, biological responses to various designs, compositions, and locations of these implants have not been fully characterized, and may impact the long term functionality of these devices. In order to improve our understanding of the tissue conditions at the interface of chronic brain-implanted microdevices, we proposed utilizing advanced histology and microscopy techniques to image implanted devices and surrounding tissue intact within brain slices. We then proposed utilizing these methods to examine whether depth within the cerebral cortex affected tissue conditions around implants. Approach Histological data was collected from rodent brain slices containing intact, intracortical microdevices 4 weeks after implantation surgery. Thick tissue sections containing the chronic implants were processed with fluorescent antibody labels, and imaged in an optical clearing solution using laser confocal microscopy. Main Results Tissue surrounding microdevices exhibited two major depth-related phenomena: a non-uniform microglial coating along the device length and a dense mass of cells surrounding the implant in cerebral cortical layers I and II. Detailed views of the monocyte-derived immune cells improve our understanding of the close and complex association that immune cells have with chronic brain-implants, and illuminated a possible relationship between cortical depth and the intensity of a chronic monocyte response penetrating microdevices. The dense mass of cells contained Vimentin, a protein typically expressed highly in non-CNS cells, evidence that non-CNS cells likely descended down the face of the penetrating devices from the pial surface. Significance Image data of highly non-uniform and depth-dependent biological responses along a device provides novel insight into the complexity of the tissue response to penetrating brain-implanted microdevices. The presented work also demonstrates the value of in situ histological collection of brain-implants for studying the complex tissue changes that occur, and the utility of pairing thick-tissue histology with appropriate optical clearing solutions.

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“…Excluding effects of the instrumentation, which are unlikely given that five different stimulators were used in this study, there are (at least) four mechanisms that would lead to a decrease in impedance: (1) an electrical 'loosening' of the glial and/or other tissue encapsulation (cf [27,28,30,34,38]); (2) the formation of iridium oxide or other electrochemical effects at the metal interface (cf [27,38]); (3) failure of the insulation of the electrode (cf [42]); (4) failure of the electrode substrate or other aspect of the device (i.e., wire bonds or connector) (cf [35]).…”

Section: Mechanisms Underlying the Effect Of Chronic Icms On The Elecmentioning

confidence: 99%

The effect of chronic intracortical microstimulation on the electrode–tissue interface

Chen¹,

Dammann²,

Boback³

et al. 2014

J. Neural Eng.

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Multimodal, longitudinal assessment of intracortical microstimulation

Cited by 45 publications

References 47 publications

Microelectrode Array Recordings from the Ventral Roots in Chronically Implanted Cats

Microelectrode Array Recordings from the Ventral Roots in Chronically Implanted Cats

Chronic intracortical microelectrode arrays induce non-uniform, depth-related tissue responses

The effect of chronic intracortical microstimulation on the electrode–tissue interface

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