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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

Signal-to-noise ratio (SNR) of cortical neurons recorded from all animals across distinct survival times.(a). Measurement of the SNR average among all time points revealed an increase in this parameter after 3 months of implant as compared to 1 month of implantation. In latter survival time (6 months after the array implant), quality of recordings decreased as compared to previous time point, though a good SNR still had been identified (standard deviation threshold: SNR>std(SNR) = 1; and SNR<std(SNR) = 0) (n = 5 animals by time point); values expressed as mean ± SEM. (b). Temporal variation of the neuronal number in each group during its time of implant, comparing the first and the last week of array implantation in all survival times, in relationship to Threshold rate (Hz) adopted to assess SNR (see Material and Methods). There was an improvement in the number of neuronal units from 1 month to 3 months of implant. In latter survival time (6 months of implant) number of recorded cells decreased (n = 5 animals by time point).
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pone.0130354.g002: Signal-to-noise ratio (SNR) of cortical neurons recorded from all animals across distinct survival times.(a). Measurement of the SNR average among all time points revealed an increase in this parameter after 3 months of implant as compared to 1 month of implantation. In latter survival time (6 months after the array implant), quality of recordings decreased as compared to previous time point, though a good SNR still had been identified (standard deviation threshold: SNR>std(SNR) = 1; and SNR<std(SNR) = 0) (n = 5 animals by time point); values expressed as mean ± SEM. (b). Temporal variation of the neuronal number in each group during its time of implant, comparing the first and the last week of array implantation in all survival times, in relationship to Threshold rate (Hz) adopted to assess SNR (see Material and Methods). There was an improvement in the number of neuronal units from 1 month to 3 months of implant. In latter survival time (6 months of implant) number of recorded cells decreased (n = 5 animals by time point).

Mentions: There was an increase in SNR after 3 months of implant as compared to 1 month of implantation (Fig 2). In latter survival time (6 months after the array implant), there was a trend towards a decrease in the recording quality as compared to 3 months survival time, although a good SNR could still be obtained (Fig 2A). We also evaluated the temporal variation of the neuronal number in each group during its time of implantation, comparing the first and the last week of implant in all survival times. There was an improvement of the number of neuronal units recorded 3 months after implant as compared to 1 month of implant. In latter survival time (6 months of implant) the number of recorded cells decreased (Fig 2B).


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)

Signal-to-noise ratio (SNR) of cortical neurons recorded from all animals across distinct survival times.(a). Measurement of the SNR average among all time points revealed an increase in this parameter after 3 months of implant as compared to 1 month of implantation. In latter survival time (6 months after the array implant), quality of recordings decreased as compared to previous time point, though a good SNR still had been identified (standard deviation threshold: SNR>std(SNR) = 1; and SNR<std(SNR) = 0) (n = 5 animals by time point); values expressed as mean ± SEM. (b). Temporal variation of the neuronal number in each group during its time of implant, comparing the first and the last week of array implantation in all survival times, in relationship to Threshold rate (Hz) adopted to assess SNR (see Material and Methods). There was an improvement in the number of neuronal units from 1 month to 3 months of implant. In latter survival time (6 months of implant) number of recorded cells decreased (n = 5 animals by time point).
© Copyright Policy
Related In: Results  -  Collection

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

pone.0130354.g002: Signal-to-noise ratio (SNR) of cortical neurons recorded from all animals across distinct survival times.(a). Measurement of the SNR average among all time points revealed an increase in this parameter after 3 months of implant as compared to 1 month of implantation. In latter survival time (6 months after the array implant), quality of recordings decreased as compared to previous time point, though a good SNR still had been identified (standard deviation threshold: SNR>std(SNR) = 1; and SNR<std(SNR) = 0) (n = 5 animals by time point); values expressed as mean ± SEM. (b). Temporal variation of the neuronal number in each group during its time of implant, comparing the first and the last week of array implantation in all survival times, in relationship to Threshold rate (Hz) adopted to assess SNR (see Material and Methods). There was an improvement in the number of neuronal units from 1 month to 3 months of implant. In latter survival time (6 months of implant) number of recorded cells decreased (n = 5 animals by time point).
Mentions: There was an increase in SNR after 3 months of implant as compared to 1 month of implantation (Fig 2). In latter survival time (6 months after the array implant), there was a trend towards a decrease in the recording quality as compared to 3 months survival time, although a good SNR could still be obtained (Fig 2A). We also evaluated the temporal variation of the neuronal number in each group during its time of implantation, comparing the first and the last week of implant in all survival times. There was an improvement of the number of neuronal units recorded 3 months after implant as compared to 1 month of implant. In latter survival time (6 months of implant) the number of recorded cells decreased (Fig 2B).

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