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An array of highly flexible electrodes with a tailored configuration locked by gelatin during implantation-initial evaluation in cortex cerebri of awake rats.

Agorelius J, Tsanakalis F, Friberg A, Thorbergsson PT, Pettersson LM, Schouenborg J - Front Neurosci (2015)

Bottom Line: The structure of the electrode array was well preserved 3 weeks after implantation.A new implantable multichannel neural interface, comprising electrodes individually flexible in 3D that retain its architecture and functionality after implantation has been developed.Since the new neural interface design is adaptable, it offers a versatile tool to explore the function of various brain structures.

View Article: PubMed Central - PubMed

Affiliation: Department of Experimental Medical Science, Neuronano Research Centre, Lund University Lund, Sweden ; The Nanometer Structure Consortium, Lund University Lund, Sweden.

ABSTRACT

Background: A major challenge in the field of neural interfaces is to overcome the problem of poor stability of neuronal recordings, which impedes long-term studies of individual neurons in the brain. Conceivably, unstable recordings reflect relative movements between electrode and tissue. To address this challenge, we have developed a new ultra-flexible electrode array and evaluated its performance in awake non-restrained animals.

Methods: An array of eight separated gold leads (4 × 10 μm), individually flexible in 3D, were cut from a gold sheet using laser milling and insulated with Parylene C. To provide structural support during implantation into rat cortex, the electrode array was embedded in a hard gelatin based material, which dissolves after implantation. Recordings were made during 3 weeks. At termination, the animals were perfused with fixative and frozen to prevent dislocation of the implanted electrodes. A thick slice of brain tissue, with the electrode array still in situ, was made transparent using methyl salicylate to evaluate the conformation of the implanted electrode array.

Results: Median noise levels and signal/noise remained relatively stable during the 3 week observation period; 4.3-5.9 μV and 2.8-4.2, respectively. The spike amplitudes were often quite stable within recording sessions and for 15% of recordings where single-units were identified, the highest-SNR unit had an amplitude higher than 150 μV. In addition, high correlations (>0.96) between unit waveforms recorded at different time points were obtained for 58% of the electrode sites. The structure of the electrode array was well preserved 3 weeks after implantation.

Conclusions: A new implantable multichannel neural interface, comprising electrodes individually flexible in 3D that retain its architecture and functionality after implantation has been developed. Since the new neural interface design is adaptable, it offers a versatile tool to explore the function of various brain structures.

No MeSH data available.


Related in: MedlinePlus

Photograph taken 3.5 h after implantation of the gelatin embedded electrode, showing that the gelatin has dissolved and the brain surface contracted around the electrode array.
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Figure 2: Photograph taken 3.5 h after implantation of the gelatin embedded electrode, showing that the gelatin has dissolved and the brain surface contracted around the electrode array.

Mentions: The implantation into rat cortex proved to be smooth, without bleeding (n = 15) or visible conformational changes of the flexible electrode array. The gelatin matrix remained stiff enough to withstand implantation to the intended depth of 1800 μm. To investigate whether any gelatin is likely to remain non-dissolved around the implanted electrode array, gelatin embedded electrode arrays were implanted into the brains of four animals. The brain surface was kept exposed and monitored for 3.5 h. During this time the brain surface was covered by a thin layer of saline to mimic the conditions of the normal implantation procedure in which the skull opening is sealed with dental cement. These experiments showed that the brain surface had contracted around the implant with no visual trace of gelatin in any of the four animals after 3.5 h (Figure 2). Clarification of brain tissue slices with the electrode array still in situ (3 rats) confirmed that the electrode array could be implanted into the brain and remain in the brain for 3 weeks with preserved conformation (Figure 3).


An array of highly flexible electrodes with a tailored configuration locked by gelatin during implantation-initial evaluation in cortex cerebri of awake rats.

Agorelius J, Tsanakalis F, Friberg A, Thorbergsson PT, Pettersson LM, Schouenborg J - Front Neurosci (2015)

Photograph taken 3.5 h after implantation of the gelatin embedded electrode, showing that the gelatin has dissolved and the brain surface contracted around the electrode array.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4585103&req=5

Figure 2: Photograph taken 3.5 h after implantation of the gelatin embedded electrode, showing that the gelatin has dissolved and the brain surface contracted around the electrode array.
Mentions: The implantation into rat cortex proved to be smooth, without bleeding (n = 15) or visible conformational changes of the flexible electrode array. The gelatin matrix remained stiff enough to withstand implantation to the intended depth of 1800 μm. To investigate whether any gelatin is likely to remain non-dissolved around the implanted electrode array, gelatin embedded electrode arrays were implanted into the brains of four animals. The brain surface was kept exposed and monitored for 3.5 h. During this time the brain surface was covered by a thin layer of saline to mimic the conditions of the normal implantation procedure in which the skull opening is sealed with dental cement. These experiments showed that the brain surface had contracted around the implant with no visual trace of gelatin in any of the four animals after 3.5 h (Figure 2). Clarification of brain tissue slices with the electrode array still in situ (3 rats) confirmed that the electrode array could be implanted into the brain and remain in the brain for 3 weeks with preserved conformation (Figure 3).

Bottom Line: The structure of the electrode array was well preserved 3 weeks after implantation.A new implantable multichannel neural interface, comprising electrodes individually flexible in 3D that retain its architecture and functionality after implantation has been developed.Since the new neural interface design is adaptable, it offers a versatile tool to explore the function of various brain structures.

View Article: PubMed Central - PubMed

Affiliation: Department of Experimental Medical Science, Neuronano Research Centre, Lund University Lund, Sweden ; The Nanometer Structure Consortium, Lund University Lund, Sweden.

ABSTRACT

Background: A major challenge in the field of neural interfaces is to overcome the problem of poor stability of neuronal recordings, which impedes long-term studies of individual neurons in the brain. Conceivably, unstable recordings reflect relative movements between electrode and tissue. To address this challenge, we have developed a new ultra-flexible electrode array and evaluated its performance in awake non-restrained animals.

Methods: An array of eight separated gold leads (4 × 10 μm), individually flexible in 3D, were cut from a gold sheet using laser milling and insulated with Parylene C. To provide structural support during implantation into rat cortex, the electrode array was embedded in a hard gelatin based material, which dissolves after implantation. Recordings were made during 3 weeks. At termination, the animals were perfused with fixative and frozen to prevent dislocation of the implanted electrodes. A thick slice of brain tissue, with the electrode array still in situ, was made transparent using methyl salicylate to evaluate the conformation of the implanted electrode array.

Results: Median noise levels and signal/noise remained relatively stable during the 3 week observation period; 4.3-5.9 μV and 2.8-4.2, respectively. The spike amplitudes were often quite stable within recording sessions and for 15% of recordings where single-units were identified, the highest-SNR unit had an amplitude higher than 150 μV. In addition, high correlations (>0.96) between unit waveforms recorded at different time points were obtained for 58% of the electrode sites. The structure of the electrode array was well preserved 3 weeks after implantation.

Conclusions: A new implantable multichannel neural interface, comprising electrodes individually flexible in 3D that retain its architecture and functionality after implantation has been developed. Since the new neural interface design is adaptable, it offers a versatile tool to explore the function of various brain structures.

No MeSH data available.


Related in: MedlinePlus