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A reliable method for intracranial electrode implantation and chronic electrical stimulation in the mouse brain.

Jeffrey M, Lang M, Gane J, Wu C, Burnham WM, Zhang L - BMC Neurosci (2013)

Bottom Line: A daily stimulation protocol was used to induce electrographic discharges and motor seizures.Electrographic discharges and motor seizures were successfully induced via hippocampal electrical kindling.Importantly, no animal encountered infection in the implanted area or a loss of implanted electrodes after 4-6 months of repetitive stimulation/recording.

View Article: PubMed Central - HTML - PubMed

Affiliation: Toronto Western Research Institute, University Health Network, Toronto, Ontario, Canada.

ABSTRACT

Background: Electrical stimulation of brain structures has been widely used in rodent models for kindling or modeling deep brain stimulation used clinically. This requires surgical implantation of intracranial electrodes and subsequent chronic stimulation in individual animals for several weeks. Anchoring screws and dental acrylic have long been used to secure implanted intracranial electrodes in rats. However, such an approach is limited when carried out in mouse models as the thin mouse skull may not be strong enough to accommodate the anchoring screws. We describe here a screw-free, glue-based method for implanting bipolar stimulating electrodes in the mouse brain and validate this method in a mouse model of hippocampal electrical kindling.

Methods: Male C57 black mice (initial ages of 6-8 months) were used in the present experiments. Bipolar electrodes were implanted bilaterally in the hippocampal CA3 area for electrical stimulation and electroencephalographic recordings. The electrodes were secured onto the skull via glue and dental acrylic but without anchoring screws. A daily stimulation protocol was used to induce electrographic discharges and motor seizures. The locations of implanted electrodes were verified by hippocampal electrographic activities and later histological assessments.

Results: Using the glue-based implantation method, we implanted bilateral bipolar electrodes in 25 mice. Electrographic discharges and motor seizures were successfully induced via hippocampal electrical kindling. Importantly, no animal encountered infection in the implanted area or a loss of implanted electrodes after 4-6 months of repetitive stimulation/recording.

Conclusion: We suggest that the glue-based, screw-free method is reliable for chronic brain stimulation and high-quality electroencephalographic recordings in mice. The technical aspects described this study may help future studies in mouse models.

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Illustration of connecting pins and mounted electrodes. A, a schematic illustration of electrode mounting and an image of connecting pins and a bipolar electrode. B, a photograph of a subject implanted. C-D, images of adjacent brain sections collected from a mouse. The animal was euthanized 3 months after electrode implantation. Note the track of an implanted CA3 electrode (arrowed, C) and densely packed hippocampal neurons in the area near the implanted electrode and in the adjacent section (D). Calibrations: 5 mm in A and 1 mm in C-D.
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Figure 1: Illustration of connecting pins and mounted electrodes. A, a schematic illustration of electrode mounting and an image of connecting pins and a bipolar electrode. B, a photograph of a subject implanted. C-D, images of adjacent brain sections collected from a mouse. The animal was euthanized 3 months after electrode implantation. Note the track of an implanted CA3 electrode (arrowed, C) and densely packed hippocampal neurons in the area near the implanted electrode and in the adjacent section (D). Calibrations: 5 mm in A and 1 mm in C-D.

Mentions: 25 adult male mice (initial ages of 6–8 month-old) underwent implantation of bipolar electrodes in bilateral hippocampal CA3 (Cornu Ammonis area 3). These electrodes were secured onto the skull with a modified version of the screw-free and glue-based method [14,21]. Electrode construction, assembly and mounting are schematically illustrated in Figure 1A. The surgical procedure for electrode implantation is detailed in the Methods. Of the 25 animals implanted, we observed no evident behavioral abnormalities or spontaneous seizures in the absence of kindling stimulations. Importantly, no animal encountered local infection in the implanted area or a loss of implanted electrodes after 4–6 months of repetitive stimulation and recordings.


A reliable method for intracranial electrode implantation and chronic electrical stimulation in the mouse brain.

Jeffrey M, Lang M, Gane J, Wu C, Burnham WM, Zhang L - BMC Neurosci (2013)

Illustration of connecting pins and mounted electrodes. A, a schematic illustration of electrode mounting and an image of connecting pins and a bipolar electrode. B, a photograph of a subject implanted. C-D, images of adjacent brain sections collected from a mouse. The animal was euthanized 3 months after electrode implantation. Note the track of an implanted CA3 electrode (arrowed, C) and densely packed hippocampal neurons in the area near the implanted electrode and in the adjacent section (D). Calibrations: 5 mm in A and 1 mm in C-D.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3750568&req=5

Figure 1: Illustration of connecting pins and mounted electrodes. A, a schematic illustration of electrode mounting and an image of connecting pins and a bipolar electrode. B, a photograph of a subject implanted. C-D, images of adjacent brain sections collected from a mouse. The animal was euthanized 3 months after electrode implantation. Note the track of an implanted CA3 electrode (arrowed, C) and densely packed hippocampal neurons in the area near the implanted electrode and in the adjacent section (D). Calibrations: 5 mm in A and 1 mm in C-D.
Mentions: 25 adult male mice (initial ages of 6–8 month-old) underwent implantation of bipolar electrodes in bilateral hippocampal CA3 (Cornu Ammonis area 3). These electrodes were secured onto the skull with a modified version of the screw-free and glue-based method [14,21]. Electrode construction, assembly and mounting are schematically illustrated in Figure 1A. The surgical procedure for electrode implantation is detailed in the Methods. Of the 25 animals implanted, we observed no evident behavioral abnormalities or spontaneous seizures in the absence of kindling stimulations. Importantly, no animal encountered local infection in the implanted area or a loss of implanted electrodes after 4–6 months of repetitive stimulation and recordings.

Bottom Line: A daily stimulation protocol was used to induce electrographic discharges and motor seizures.Electrographic discharges and motor seizures were successfully induced via hippocampal electrical kindling.Importantly, no animal encountered infection in the implanted area or a loss of implanted electrodes after 4-6 months of repetitive stimulation/recording.

View Article: PubMed Central - HTML - PubMed

Affiliation: Toronto Western Research Institute, University Health Network, Toronto, Ontario, Canada.

ABSTRACT

Background: Electrical stimulation of brain structures has been widely used in rodent models for kindling or modeling deep brain stimulation used clinically. This requires surgical implantation of intracranial electrodes and subsequent chronic stimulation in individual animals for several weeks. Anchoring screws and dental acrylic have long been used to secure implanted intracranial electrodes in rats. However, such an approach is limited when carried out in mouse models as the thin mouse skull may not be strong enough to accommodate the anchoring screws. We describe here a screw-free, glue-based method for implanting bipolar stimulating electrodes in the mouse brain and validate this method in a mouse model of hippocampal electrical kindling.

Methods: Male C57 black mice (initial ages of 6-8 months) were used in the present experiments. Bipolar electrodes were implanted bilaterally in the hippocampal CA3 area for electrical stimulation and electroencephalographic recordings. The electrodes were secured onto the skull via glue and dental acrylic but without anchoring screws. A daily stimulation protocol was used to induce electrographic discharges and motor seizures. The locations of implanted electrodes were verified by hippocampal electrographic activities and later histological assessments.

Results: Using the glue-based implantation method, we implanted bilateral bipolar electrodes in 25 mice. Electrographic discharges and motor seizures were successfully induced via hippocampal electrical kindling. Importantly, no animal encountered infection in the implanted area or a loss of implanted electrodes after 4-6 months of repetitive stimulation/recording.

Conclusion: We suggest that the glue-based, screw-free method is reliable for chronic brain stimulation and high-quality electroencephalographic recordings in mice. The technical aspects described this study may help future studies in mouse models.

Show MeSH
Related in: MedlinePlus