In vivo Recording Quality of Mechanically Decoupled Floating Versus Skull-Fixed Silicon-Based Neural Probes

Area of Science:

• Neural Engineering
• Neuroscience
• Biomedical Engineering

Background:

• Silicon-based neural probes with integrated CMOS electronics are crucial for neural recording.
• Chronic implantation requires mechanical anchoring, but brain-implant motion causes signal instability and tissue scarring.

Purpose of the Study:

• To compare the performance of mechanically fixed versus floating silicon neural probes for chronic neural recording.
• To evaluate the impact of probe fixation on neural signal quality over time in non-human primates.

Main Methods:

• Chronic implantation of both fixed and floating silicon neural probes into the non-human primate cortex.
• Long-term monitoring and comparison of neural signal quality, including spiking activity and local field potentials (LFPs).
• Assessment of signal quality in relation to probe mechanical stability and control of brain pulsations.

Main Results:

• Floating probes initially demonstrated superior neural signal quality (spiking and LFP) compared to fixed probes.
• Skull-fixed probes allowed for long-term recording of multi-unit activity (MUA) and low-frequency signals over several months.
• Controlling brain pulsations significantly improved the long-term recording capabilities of skull-fixed probes.

Conclusions:

• Probe fixation strategy impacts initial neural signal quality, with floating probes showing an advantage.
• Mechanically fixed probes can achieve stable long-term neural recordings, particularly when physiological motion is mitigated.
• This study provides insights into optimizing neural probe design and implantation for chronic recordings.