An Ultraflexible Electrode Array for Large-Scale Chronic Recording in the Nonhuman Primate Brain

Area of Science:

• Neuroscience
• Biomedical Engineering
• Materials Science

Background:

• Single-unit recording in nonhuman primates is crucial for understanding brain function.
• Current electrodes face limitations in signal longevity, stability, and spatial coverage.
• There is a need for advanced neural recording tools in primate models.

Purpose of the Study:

• To develop a mechanically robust, ultraflexible microelectrode array for chronic neural recording in nonhuman primates.
• To overcome the limitations of existing electrodes for high-density, large-scale, and long-term neural recordings.
• To explore applications in basic neuroscience and brain-machine interfaces.

Main Methods:

• Fabrication of a 1 µm thin, ultraflexible microelectrode array (MERF) using novel structural materials and microfabrication techniques.
• Development of penetration techniques for pial insertion into the nonhuman primate brain.
• Chronic recording of neural activity from the primary visual cortex (V1) and primary motor cortex (M1) in three monkeys.

Main Results:

• Successful chronic recording of 2,913 single units from 1,065 channels over 240 days, with some units tracked for up to 2 months.
• Demonstrated high-density, large-scale recording along vertical and horizontal cortical axes.
• Observed higher spike correlation between neurons with similar orientation preferences in V1.
• Identified preferential firing patterns of neurons in different M1 layers corresponding to hand movement directions.
• Achieved on-line control of cursor movement using a linear decoder trained on M1 neural activity.

Conclusions:

• The MERF electrode array provides a robust tool for high-density, large-scale, and chronic neural recording in the nonhuman primate brain.
• This technology facilitates detailed investigation of neural circuits and dynamics in both sensory and motor cortices.
• MERF opens new avenues for advanced brain-machine interface applications in primate models.