Imaging the Tissue Response Around Brain-Implanted Microdevices

Woolley, A.; Desai, Himanshi A.; Otto, Kevin J.

doi:10.1017/s1431927611001607

Cited by 2 publications

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“…The formation of scar tissue around chronically implanted neural micro-electrode arrays can significantly decrease the quality of the recorded signals, often rendering the devices unusable (Szarowski et al, 2003; Williams et al, 1999; Woolley et al, 2011). This well-known problem has led to a push towards less invasive neural implants, such as electrocorticography (ECoG), and more recently, micro-ECoG (Figure 1), which sit on top of the cortical surface rather than penetrating into it (Gierthmuehlen et al, 2011; Kitzmiller et al, 2006; Thongpang et al, 2011; Viventi et al, 2011; Wang et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

“…However, although there has been extensive research into in vivo biological responses to penetrating neural micro-electrode arrays (MEAs) (Williams et al, 2007; Woolley et al, 2011), there has been little investigation into tissue responses to MEAs implanted on the surface of the cerebral cortex. The assumption that these devices elicit little tissue response is based on results from traditional histological studies of brains implanted with surface electrode arrays (Henle et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

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A cranial window imaging method for monitoring vascular growth around chronically implanted micro-ECoG devices

Schendel

Thongpang

Brodnick

et al. 2013

Journal of Neuroscience Methods

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Implantable neural micro-electrode arrays have the potential to restore lost sensory or motor function to many different areas of the body. However, the invasiveness of these implants often results in scar tissue formation, which can have detrimental effects on recorded signal quality and longevity. Traditional histological techniques can be employed to study the tissue reaction to implanted micro-electrode arrays, but these techniques require removal of the brain from the skull, often causing damage to the meninges and cortical surface. This is especially unfavorable when studying the tissue response to electrode arrays such as the micro-electrocorticography (micro-ECoG) device, which sits on the surface of the cerebral cortex. In order to better understand the biological changes occurring around these types of devices, a cranial window implantation scheme has been developed, through which the tissue response can be studied in vivo over the entire implantation period. Rats were implanted with epidural micro-ECoG arrays, over which glass coverslips were placed and sealed to the skull, creating cranial windows. Vascular growth around the devices was monitored for one month after implantation. It was found that blood vessels grew through holes in the micro-ECoG substrate, spreading over the top of the device. Micro-hematomas were observed at varying time points after device implantation in every animal, and tissue growth between the micro-ECoG array and the window occurred in several cases. Use of the cranial window imaging technique with these devices enabled the observation of tissue changes that would normally go unnoticed with a standard device implantation scheme.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A cranial window imaging method for monitoring vascular growth around chronically implanted micro-ECoG devices

Schendel

Thongpang

Brodnick

et al. 2013

Journal of Neuroscience Methods

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Glial cells, but not neurons, exhibit a controllable response to a localized inflammatory microenvironment in vitro

2014

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The ability to design long-lasting intracortical implants hinges on understanding the factors leading to the loss of neuronal density and the formation of the glial scar. In this study, we modify a common in vitro mixed cortical culture model using lipopolysaccharide (LPS) to examine the responses of microglia, astrocytes, and neurons to microwire segments. We also use dip-coated polyethylene glycol (PEG), which we have previously shown can modulate impedance changes to neural microelectrodes, to control the cellular responses. We find that microglia, as expected, exhibit an elevated response to LPS-coated microwire for distances of up to 150 μm, and that this elevated response can be mitigated by co-depositing PEG with LPS. Astrocytes exhibit a more complex, distance-dependent response, whereas neurons do not appear to be affected by the type or magnitude of glial response within this in vitro model. The discrepancy between our in vitro responses and typically observed in vivo responses suggest the importance of using a systems approach to understand the responses of the various brain cell types in a chronic in vivo setting, as well as the necessity of studying the roles of cell types not native to the brain. Our results further indicate that the loss of neuronal density observed in vivo is not a necessary consequence of elevated glial activation.

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Imaging the Tissue Response Around Brain-Implanted Microdevices

Abstract: Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.

Cited by 2 publications

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A cranial window imaging method for monitoring vascular growth around chronically implanted micro-ECoG devices

A cranial window imaging method for monitoring vascular growth around chronically implanted micro-ECoG devices

Glial cells, but not neurons, exhibit a controllable response to a localized inflammatory microenvironment in vitro

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