Mechanical Flexibility Reduces the Foreign Body Response to Long-Term Implanted Microelectrodes in Rabbit Cortex.

Area of Science:

• Neuroscience
• Biomedical Engineering
• Materials Science

Background:

• Micromotion between brain tissue and implanted electrodes causes recording instability and failure.
• Sustained mechanical trauma from electrodes triggers glial cell activation, leading to signal decline over time.

Purpose of the Study:

• To compare the long-term glial response to novel flexible electrodes versus traditional microwires in rabbit cortex.
• To evaluate the impact of electrode design on neural recording stability and tissue response over extended implantation periods (26-96 weeks).

Main Methods:

• Implantation of microwires and flexible electrodes in rabbit cortex.
• Histological analysis of brain tissue, including depth profiling of microglia, astrocytes, and neurofilament.
• Quantitative assessment of glial response (gliosis) and neuronal density around implants.

Main Results:

• Flexible electrodes exhibited significantly decreased gliosis compared to microwires over 26-96 weeks.
• Reduced microgliosis and enhanced neuronal density were observed around the flexible probe, particularly at longer implantation durations.
• Flexible electrodes demonstrated improved biocompatibility and reduced tissue trauma.

Conclusions:

• Flexible electrodes offer a promising alternative to microwires for long-term neural implantation due to reduced glial response.
• The improved biocompatibility of flexible electrodes may lead to more stable and reliable neural recordings.
• Minimizing mechanical trauma through electrode design is crucial for mitigating glial activation and ensuring long-term device function.