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Distribution and Morphology of Calcium-Binding Proteins Immunoreactive Neurons following Chronic Tungsten Multielectrode Implants.

Freire MA, Faber J, Lemos NA, Santos JR, Cavalcanti PF, Lima RH, Morya E - PLoS ONE (2015)

Bottom Line: Our results revealed that chronic microelectrode arrays were well tolerated by the nervous tissue, with recordings remaining viable for up to 6 months after implantation.Furthermore, neither the morphology nor the distribution of inhibitory neurons were broadly impacted.On the whole, our results confirm and expand the notion that tungsten multielectrodes can be deemed as a feasible candidate to future human BMI studies.

View Article: PubMed Central - PubMed

Affiliation: Edmond and Lily Safra International Institute of Neurosciences (ELS-IIN), Santos Dumont Institute, Macaiba, RN, Brazil.

ABSTRACT
The development of therapeutic approaches to improve the life quality of people suffering from different types of body paralysis is a current major medical challenge. Brain-machine interface (BMI) can potentially help reestablishing lost sensory and motor functions, allowing patients to use their own brain activity to restore sensorimotor control of paralyzed body parts. Chronic implants of multielectrodes, employed to record neural activity directly from the brain parenchyma, constitute the fundamental component of a BMI. However, before this technique may be effectively available to human clinical trials, it is essential to characterize its long-term impact on the nervous tissue in animal models. In the present study we evaluated how chronic implanted tungsten microelectrode arrays impact the distribution and morphology of interneurons reactive to calcium-binding proteins calbindin (CB), calretinin (CR) and parvalbumin (PV) across the rat's motor cortex. Our results revealed that chronic microelectrode arrays were well tolerated by the nervous tissue, with recordings remaining viable for up to 6 months after implantation. Furthermore, neither the morphology nor the distribution of inhibitory neurons were broadly impacted. Moreover, restricted microglial activation was observed on the implanted sites. On the whole, our results confirm and expand the notion that tungsten multielectrodes can be deemed as a feasible candidate to future human BMI studies.

No MeSH data available.


Related in: MedlinePlus

Microglial immunoreactivity across electrode tracks.(a). Electrode implantation sites (arrows) were identified as a well-defined strip of microglial labeling, especially in latter survival time point. (b). Iba1-reactive microglial cells with a hypertrophic morphology were observed only in the vicinity of implants, whilst microglial cells presented a non-activated morphology in the contralateral hemisphere, possessing stellate non-hypertrophic cell bodies and thin and elongated processes. Activated microglial cells were not observed far from implant sites neither in contralateral hemispheres. White squares in lower magnification pictures indicate the regions where enlargements were obtained in all groups. Left column of the figure: implanted hemisphere; right column of the figure: contralateral hemisphere, adopted as control. Scale bar: 100 μm (lower magnification); 25 μm (enlargements).
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pone.0130354.g007: Microglial immunoreactivity across electrode tracks.(a). Electrode implantation sites (arrows) were identified as a well-defined strip of microglial labeling, especially in latter survival time point. (b). Iba1-reactive microglial cells with a hypertrophic morphology were observed only in the vicinity of implants, whilst microglial cells presented a non-activated morphology in the contralateral hemisphere, possessing stellate non-hypertrophic cell bodies and thin and elongated processes. Activated microglial cells were not observed far from implant sites neither in contralateral hemispheres. White squares in lower magnification pictures indicate the regions where enlargements were obtained in all groups. Left column of the figure: implanted hemisphere; right column of the figure: contralateral hemisphere, adopted as control. Scale bar: 100 μm (lower magnification); 25 μm (enlargements).

Mentions: Microglial activation was observed around the electrode tracks, mainly after 6 months of implant, appearing as a stripe of labeling circumscribing the implant site (Fig 7A). Activated microglial cells around implanted regions were characterized by hypertrophic cell bodies and thicker and shortened processes, whilst in the contralateral hemisphere microglial cells possessed a non-activated morphology, with cells presenting stellate non-hypertrophic cell bodies and thin and elongated processes (Fig 7B). Activated microglial cells were not observed far from implant sites neither in contralateral hemispheres, suggesting that electrode implants did not alter the physiology of adjacent cortical regions.


Distribution and Morphology of Calcium-Binding Proteins Immunoreactive Neurons following Chronic Tungsten Multielectrode Implants.

Freire MA, Faber J, Lemos NA, Santos JR, Cavalcanti PF, Lima RH, Morya E - PLoS ONE (2015)

Microglial immunoreactivity across electrode tracks.(a). Electrode implantation sites (arrows) were identified as a well-defined strip of microglial labeling, especially in latter survival time point. (b). Iba1-reactive microglial cells with a hypertrophic morphology were observed only in the vicinity of implants, whilst microglial cells presented a non-activated morphology in the contralateral hemisphere, possessing stellate non-hypertrophic cell bodies and thin and elongated processes. Activated microglial cells were not observed far from implant sites neither in contralateral hemispheres. White squares in lower magnification pictures indicate the regions where enlargements were obtained in all groups. Left column of the figure: implanted hemisphere; right column of the figure: contralateral hemisphere, adopted as control. Scale bar: 100 μm (lower magnification); 25 μm (enlargements).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4476592&req=5

pone.0130354.g007: Microglial immunoreactivity across electrode tracks.(a). Electrode implantation sites (arrows) were identified as a well-defined strip of microglial labeling, especially in latter survival time point. (b). Iba1-reactive microglial cells with a hypertrophic morphology were observed only in the vicinity of implants, whilst microglial cells presented a non-activated morphology in the contralateral hemisphere, possessing stellate non-hypertrophic cell bodies and thin and elongated processes. Activated microglial cells were not observed far from implant sites neither in contralateral hemispheres. White squares in lower magnification pictures indicate the regions where enlargements were obtained in all groups. Left column of the figure: implanted hemisphere; right column of the figure: contralateral hemisphere, adopted as control. Scale bar: 100 μm (lower magnification); 25 μm (enlargements).
Mentions: Microglial activation was observed around the electrode tracks, mainly after 6 months of implant, appearing as a stripe of labeling circumscribing the implant site (Fig 7A). Activated microglial cells around implanted regions were characterized by hypertrophic cell bodies and thicker and shortened processes, whilst in the contralateral hemisphere microglial cells possessed a non-activated morphology, with cells presenting stellate non-hypertrophic cell bodies and thin and elongated processes (Fig 7B). Activated microglial cells were not observed far from implant sites neither in contralateral hemispheres, suggesting that electrode implants did not alter the physiology of adjacent cortical regions.

Bottom Line: Our results revealed that chronic microelectrode arrays were well tolerated by the nervous tissue, with recordings remaining viable for up to 6 months after implantation.Furthermore, neither the morphology nor the distribution of inhibitory neurons were broadly impacted.On the whole, our results confirm and expand the notion that tungsten multielectrodes can be deemed as a feasible candidate to future human BMI studies.

View Article: PubMed Central - PubMed

Affiliation: Edmond and Lily Safra International Institute of Neurosciences (ELS-IIN), Santos Dumont Institute, Macaiba, RN, Brazil.

ABSTRACT
The development of therapeutic approaches to improve the life quality of people suffering from different types of body paralysis is a current major medical challenge. Brain-machine interface (BMI) can potentially help reestablishing lost sensory and motor functions, allowing patients to use their own brain activity to restore sensorimotor control of paralyzed body parts. Chronic implants of multielectrodes, employed to record neural activity directly from the brain parenchyma, constitute the fundamental component of a BMI. However, before this technique may be effectively available to human clinical trials, it is essential to characterize its long-term impact on the nervous tissue in animal models. In the present study we evaluated how chronic implanted tungsten microelectrode arrays impact the distribution and morphology of interneurons reactive to calcium-binding proteins calbindin (CB), calretinin (CR) and parvalbumin (PV) across the rat's motor cortex. Our results revealed that chronic microelectrode arrays were well tolerated by the nervous tissue, with recordings remaining viable for up to 6 months after implantation. Furthermore, neither the morphology nor the distribution of inhibitory neurons were broadly impacted. Moreover, restricted microglial activation was observed on the implanted sites. On the whole, our results confirm and expand the notion that tungsten multielectrodes can be deemed as a feasible candidate to future human BMI studies.

No MeSH data available.


Related in: MedlinePlus