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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

Samples of 1 s long recordings extracted at 0, 29, and 52 min from one electrode channel in an awake non-restrained rat. The unit spike with the highest signal to noise ratio in each segment is shown to the right of respective sample (mean waveform ± standard deviation). Note the high level of stability of the recordings with respect to spike-waveforms (waveform correlation > 0.99 between the indicated unit waveforms of all three segments) and amplitude, as well as the overall recording qualities. The spike-times of the indicated single-unit are marked in red below the sweeps.
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Figure 4: Samples of 1 s long recordings extracted at 0, 29, and 52 min from one electrode channel in an awake non-restrained rat. The unit spike with the highest signal to noise ratio in each segment is shown to the right of respective sample (mean waveform ± standard deviation). Note the high level of stability of the recordings with respect to spike-waveforms (waveform correlation > 0.99 between the indicated unit waveforms of all three segments) and amplitude, as well as the overall recording qualities. The spike-times of the indicated single-unit are marked in red below the sweeps.

Mentions: Evaluation of electrode functionality showed that single unit activity was readily recorded during the full length of the experiment (3 weeks in 3 rats). Single units often remained quite stable both in amplitude and waveform during individual recording sessions (up to 50 min) as shown in Figure 4, indicating that the electrode recording sites remained relatively stable in the tissue during the time-course of individual recordings.


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)

Samples of 1 s long recordings extracted at 0, 29, and 52 min from one electrode channel in an awake non-restrained rat. The unit spike with the highest signal to noise ratio in each segment is shown to the right of respective sample (mean waveform ± standard deviation). Note the high level of stability of the recordings with respect to spike-waveforms (waveform correlation > 0.99 between the indicated unit waveforms of all three segments) and amplitude, as well as the overall recording qualities. The spike-times of the indicated single-unit are marked in red below the sweeps.
© Copyright Policy
Related In: Results  -  Collection

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

Figure 4: Samples of 1 s long recordings extracted at 0, 29, and 52 min from one electrode channel in an awake non-restrained rat. The unit spike with the highest signal to noise ratio in each segment is shown to the right of respective sample (mean waveform ± standard deviation). Note the high level of stability of the recordings with respect to spike-waveforms (waveform correlation > 0.99 between the indicated unit waveforms of all three segments) and amplitude, as well as the overall recording qualities. The spike-times of the indicated single-unit are marked in red below the sweeps.
Mentions: Evaluation of electrode functionality showed that single unit activity was readily recorded during the full length of the experiment (3 weeks in 3 rats). Single units often remained quite stable both in amplitude and waveform during individual recording sessions (up to 50 min) as shown in Figure 4, indicating that the electrode recording sites remained relatively stable in the tissue during the time-course of individual recordings.

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