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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

Multielectrode apparatus, coordinates adopted to implant and surgical procedure.(a). General aspect of a 32 channel microelectrode array. (b). Details of the electrode array being implanted through the skull window on primary motor cortex, relative to bregma (marked with a black dot). Scale bars: 3.5 mm (a and b).
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pone.0130354.g001: Multielectrode apparatus, coordinates adopted to implant and surgical procedure.(a). General aspect of a 32 channel microelectrode array. (b). Details of the electrode array being implanted through the skull window on primary motor cortex, relative to bregma (marked with a black dot). Scale bars: 3.5 mm (a and b).

Mentions: The present study follows the same proposal adopted in our previous report concerning a suitable understanding on the impact of multielectrodes arrays in the rat’s brain [22]. Accordingly, the experimental design was quite similar. In brief, surgeries for multielectrode implantation were performed in rats deeply anesthetized with 100 mg/kg of ketamine chlorhydrate and 5 mg/kg xylazine chlorhydrate (i.p.). The animals were placed in a stereotaxic head holder, and a small craniotomy was made over the implant target area (primary motor cortex) (Fig 1). Each animal was slowly implanted with multielectrode arrays, manufactured as follows: Insulated tungsten wires (50-μm microwire diameter, 1.5 MOhm at 1.0 KHz, California Fine Wire Co., Grover Beach, CA, USA; Catalog number #100211, IS coating) were cut into 32, 5-cm segments. Each wire was soldered into separate slots in an Omnetics connector (Omnetics Connector Corp., Minneapolis, MN, USA) using a digital soldering station with a micro soldering pencil (Weller WD1, 0.25mm tip) in order to assemble an array of 4x8, with 500 μm spacing (Fig 1). The tip of the electrode was cut with a stainless steel precision surgical scissor, being visualized in a surgical magnifier (Zeiss Stemi 2000 Stereo Microscope, Carl Zeiss, Göttingen, Germany). The array was subsequently implanted in the motor cortex using the following coordinates (in millimeters relative to bregma): 0.5–4.0, anteroposterior (AP); 1.5–3.0, mediolateral (ML); 1.8–2.0, dorsoventral (DV) [24]. Stainless steel screws and dental acrylic were used to hold the implant. The ground stainless steel wire was soldered to a screw. After 7 days to surgical recovery, animals started to be recorded weekly. Three survival time groups were then defined, according to the total time of recording: 1, 3, and 6 months after initial implantation.


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)

Multielectrode apparatus, coordinates adopted to implant and surgical procedure.(a). General aspect of a 32 channel microelectrode array. (b). Details of the electrode array being implanted through the skull window on primary motor cortex, relative to bregma (marked with a black dot). Scale bars: 3.5 mm (a and b).
© Copyright Policy
Related In: Results  -  Collection

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

pone.0130354.g001: Multielectrode apparatus, coordinates adopted to implant and surgical procedure.(a). General aspect of a 32 channel microelectrode array. (b). Details of the electrode array being implanted through the skull window on primary motor cortex, relative to bregma (marked with a black dot). Scale bars: 3.5 mm (a and b).
Mentions: The present study follows the same proposal adopted in our previous report concerning a suitable understanding on the impact of multielectrodes arrays in the rat’s brain [22]. Accordingly, the experimental design was quite similar. In brief, surgeries for multielectrode implantation were performed in rats deeply anesthetized with 100 mg/kg of ketamine chlorhydrate and 5 mg/kg xylazine chlorhydrate (i.p.). The animals were placed in a stereotaxic head holder, and a small craniotomy was made over the implant target area (primary motor cortex) (Fig 1). Each animal was slowly implanted with multielectrode arrays, manufactured as follows: Insulated tungsten wires (50-μm microwire diameter, 1.5 MOhm at 1.0 KHz, California Fine Wire Co., Grover Beach, CA, USA; Catalog number #100211, IS coating) were cut into 32, 5-cm segments. Each wire was soldered into separate slots in an Omnetics connector (Omnetics Connector Corp., Minneapolis, MN, USA) using a digital soldering station with a micro soldering pencil (Weller WD1, 0.25mm tip) in order to assemble an array of 4x8, with 500 μm spacing (Fig 1). The tip of the electrode was cut with a stainless steel precision surgical scissor, being visualized in a surgical magnifier (Zeiss Stemi 2000 Stereo Microscope, Carl Zeiss, Göttingen, Germany). The array was subsequently implanted in the motor cortex using the following coordinates (in millimeters relative to bregma): 0.5–4.0, anteroposterior (AP); 1.5–3.0, mediolateral (ML); 1.8–2.0, dorsoventral (DV) [24]. Stainless steel screws and dental acrylic were used to hold the implant. The ground stainless steel wire was soldered to a screw. After 7 days to surgical recovery, animals started to be recorded weekly. Three survival time groups were then defined, according to the total time of recording: 1, 3, and 6 months after initial implantation.

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