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Multiple implants do not aggravate the tissue reaction in rat brain.

Lind G, Gällentoft L, Danielsen N, Schouenborg J, Pettersson LM - PLoS ONE (2012)

Bottom Line: This possible interaction was only seen between implants within the same hemisphere, no interaction with the contralateral hemisphere was found.More importantly, we found no aggravation of tissue reactions as a result of a larger number of implants.These results highlight the possibility of implanting multiple electrodes without aggravating the glial scar surrounding each implant.

View Article: PubMed Central - PubMed

Affiliation: Department of Experimental Medical Sciences, Neuronano Research Center, Medical Faculty, Lund University, Lund, Sweden. gustav.lind@med.lu.se

ABSTRACT
Chronically implanted microelectrodes are an invaluable tool for neuroscientific research, allowing long term recordings in awake and behaving animals. It is known that all such electrodes will evoke a tissue reaction affected by its' size, shape, surface structure, fixation mode and implantation method. However, the possible correlation between tissue reactions and the number of implanted electrodes is not clear. We implanted multiple wire bundles into the brain of rats and studied the correlation between the astrocytic and microglial reaction and the positioning of the electrode in relation to surrounding electrodes. We found that an electrode implanted in the middle of a row of implants is surrounded by a significantly smaller astrocytic scar than single ones. This possible interaction was only seen between implants within the same hemisphere, no interaction with the contralateral hemisphere was found. More importantly, we found no aggravation of tissue reactions as a result of a larger number of implants. These results highlight the possibility of implanting multiple electrodes without aggravating the glial scar surrounding each implant.

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Related in: MedlinePlus

Schematic overview of implant locations in the different study groups.Dorsal view of the cerebral cortex with implant locations indicated by black dots. The implant in the left hemisphere of Group 1 & 3 is referred to as the contralateral implant; the implants in the right hemisphere in group 1 & 3 are referred to as middle and outer implants respectively; the implant in the right hemisphere of group 2 & 4 is referred to as the solitary implant and has no contralateral counterpart. Distances between implants in the right hemisphere of group 1 & 3 are 1 mm. Unnamed implants are not analyzed.
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pone-0047509-g001: Schematic overview of implant locations in the different study groups.Dorsal view of the cerebral cortex with implant locations indicated by black dots. The implant in the left hemisphere of Group 1 & 3 is referred to as the contralateral implant; the implants in the right hemisphere in group 1 & 3 are referred to as middle and outer implants respectively; the implant in the right hemisphere of group 2 & 4 is referred to as the solitary implant and has no contralateral counterpart. Distances between implants in the right hemisphere of group 1 & 3 are 1 mm. Unnamed implants are not analyzed.

Mentions: The implants in this study were identical to the gelatine embedded wire bundles used in a previous study in our laboratory [25]. Implants consist of a wire bundle of 32 tungsten wires with a diameter of 7.5 µm and an insulation layer of 3 µm polyimide,moulded into a gelatine needle (gelatine type B, VWR BDH, Sweden) resulting in a final diameter of 300 µm. The gelatine is intended to give stability to the highly flexible wires while penetrating the meninges. It dissolves during, or soon after, implantation leaving only the wire bundle in place in the cortex. The wire bundle have an approximate diameter of 180 µm. Animals were kept for one or six weeks and were divided into the following experimental groups; 1) killed after one week, implanted with five wire bundles in the left hemisphere with 1 mm between each bundle, and one wire bundle in the right hemisphere (n = 6); 2) killed after one week, implanted with one wire bundle in the left hemisphere, and no implant in the right hemisphere (n = 6); 3) killed after six weeks, implanted with five wire bundles in the left hemisphere, with 1 mm between each bundle, and one wire bundle in the right hemisphere (n = 6); 4) killed after six weeks, implanted with one wire bundle in the left hemisphere, and no implants in the right hemisphere (n = 5). A schematic overview of the groups is presented in Figure 1.


Multiple implants do not aggravate the tissue reaction in rat brain.

Lind G, Gällentoft L, Danielsen N, Schouenborg J, Pettersson LM - PLoS ONE (2012)

Schematic overview of implant locations in the different study groups.Dorsal view of the cerebral cortex with implant locations indicated by black dots. The implant in the left hemisphere of Group 1 & 3 is referred to as the contralateral implant; the implants in the right hemisphere in group 1 & 3 are referred to as middle and outer implants respectively; the implant in the right hemisphere of group 2 & 4 is referred to as the solitary implant and has no contralateral counterpart. Distances between implants in the right hemisphere of group 1 & 3 are 1 mm. Unnamed implants are not analyzed.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3472973&req=5

pone-0047509-g001: Schematic overview of implant locations in the different study groups.Dorsal view of the cerebral cortex with implant locations indicated by black dots. The implant in the left hemisphere of Group 1 & 3 is referred to as the contralateral implant; the implants in the right hemisphere in group 1 & 3 are referred to as middle and outer implants respectively; the implant in the right hemisphere of group 2 & 4 is referred to as the solitary implant and has no contralateral counterpart. Distances between implants in the right hemisphere of group 1 & 3 are 1 mm. Unnamed implants are not analyzed.
Mentions: The implants in this study were identical to the gelatine embedded wire bundles used in a previous study in our laboratory [25]. Implants consist of a wire bundle of 32 tungsten wires with a diameter of 7.5 µm and an insulation layer of 3 µm polyimide,moulded into a gelatine needle (gelatine type B, VWR BDH, Sweden) resulting in a final diameter of 300 µm. The gelatine is intended to give stability to the highly flexible wires while penetrating the meninges. It dissolves during, or soon after, implantation leaving only the wire bundle in place in the cortex. The wire bundle have an approximate diameter of 180 µm. Animals were kept for one or six weeks and were divided into the following experimental groups; 1) killed after one week, implanted with five wire bundles in the left hemisphere with 1 mm between each bundle, and one wire bundle in the right hemisphere (n = 6); 2) killed after one week, implanted with one wire bundle in the left hemisphere, and no implant in the right hemisphere (n = 6); 3) killed after six weeks, implanted with five wire bundles in the left hemisphere, with 1 mm between each bundle, and one wire bundle in the right hemisphere (n = 6); 4) killed after six weeks, implanted with one wire bundle in the left hemisphere, and no implants in the right hemisphere (n = 5). A schematic overview of the groups is presented in Figure 1.

Bottom Line: This possible interaction was only seen between implants within the same hemisphere, no interaction with the contralateral hemisphere was found.More importantly, we found no aggravation of tissue reactions as a result of a larger number of implants.These results highlight the possibility of implanting multiple electrodes without aggravating the glial scar surrounding each implant.

View Article: PubMed Central - PubMed

Affiliation: Department of Experimental Medical Sciences, Neuronano Research Center, Medical Faculty, Lund University, Lund, Sweden. gustav.lind@med.lu.se

ABSTRACT
Chronically implanted microelectrodes are an invaluable tool for neuroscientific research, allowing long term recordings in awake and behaving animals. It is known that all such electrodes will evoke a tissue reaction affected by its' size, shape, surface structure, fixation mode and implantation method. However, the possible correlation between tissue reactions and the number of implanted electrodes is not clear. We implanted multiple wire bundles into the brain of rats and studied the correlation between the astrocytic and microglial reaction and the positioning of the electrode in relation to surrounding electrodes. We found that an electrode implanted in the middle of a row of implants is surrounded by a significantly smaller astrocytic scar than single ones. This possible interaction was only seen between implants within the same hemisphere, no interaction with the contralateral hemisphere was found. More importantly, we found no aggravation of tissue reactions as a result of a larger number of implants. These results highlight the possibility of implanting multiple electrodes without aggravating the glial scar surrounding each implant.

Show MeSH
Related in: MedlinePlus