A low-cost, scalable, current-sensing digital headstage for high channel count μECoG

Area of Science:

• Neuroscience
• Biomedical Engineering
• Signal Processing

Background:

• High-channel count electrode arrays are crucial for monitoring large-scale neural activity with high spatial resolution.
• Implantable neural recording systems require compact, high-bandwidth front-end electronics to manage numerous recording sites.

Purpose of the Study:

• To investigate the efficacy of a novel digital current-sensing integrated circuit for acquiring cortical surface signals from a 61-channel micro-electrocorticographic (μECoG) array.
• To evaluate the performance of this new digital headstage compared to traditional analog voltage-based systems.

Main Methods:

• Recorded acute and chronic μECoG signals from rat auditory cortex using the novel digital current-sensing headstage.
• Performed parallel recordings using a conventional analog voltage headstage for direct comparison.
• Developed an electrode impedance model to relate current- and voltage-sensed signals and reconstruct cortical potential.

Main Results:

• The digital current headstage yielded neural signals with comparable spatiotemporal statistics and auditory frequency tuning to voltage signals.
• Auditory evoked responses (AERs) exhibited a significantly higher signal-to-noise ratio (SNR) with the current-sensing headstage.
• Stimulus decoding performance was not significantly different between true and reconstructed voltage signals.
• Implanted systems demonstrated detectable and decodable AERs for up to 52 days, with noise mitigation and SNR enhancement via a reconstruction filter.

Conclusions:

• A novel digital current-sensing approach for μECoG headstage acquisition was developed and validated.
• These low-cost, current-input circuits provide sensitive and specific cortical field measurements, comparable to traditional voltage headstages.
• The resulting headstage is small, lightweight, and scalable for recording from hundreds of channels, offering a significant advancement for neural monitoring.