Chronic subdural electrocorticography in nonhuman primates by an implantable wireless device for brain-machine...

Area of Science:

• Neuroscience
• Biomedical Engineering
• Implantable Devices

Background:

• Subdural electrocorticography (ECoG) offers higher resolution than EEG for brain-machine interfaces (BMIs).
• Long-term ECoG implantation can be limited by inflammatory reactions and tissue encapsulation, potentially degrading signal quality.
• The impact of surrounding tissue on chronic ECoG signal recording and device function remains under-investigated.

Purpose of the Study:

• To evaluate the long-term stability and quality of subdural ECoG signals in nonhuman primates.
• To investigate the chronic tissue reactions around subdural ECoG electrodes.
• To assess the effect of tissue encapsulation on signal recording and device functionality.

Main Methods:

• A wireless 32-electrode ECoG array was implanted subdurally in two nonhuman primates for 15 months.
• Neural activity was recorded and wirelessly transmitted, alongside evaluation of chronic tissue reactions.
• The gain factor of newly formed ventral fibrous tissue was measured in vivo.

Main Results:

• Signal features remained consistent between acute and chronic phases, with stable root mean square voltage and power spectral density.
• Histological analysis showed thickened reactive tissue around the electrodes but no cortical inflammation.
• Tissue proliferation beneath the electrodes was found to reduce signal amplitude power.

Conclusions:

• Subdural ECoG demonstrates potential for chronic signal recording in clinical applications and neuroscience research.
• Reducing reactive tissue proliferation ventral to electrodes is crucial for enhancing long-term signal stability.
• Further research is needed to optimize ECoG device design for sustained performance.