Biomimetic stimulation patterns drive natural artificial touch percepts using intracortical microstimulation in...

Area of Science:

• Neuroscience
• Biomedical Engineering
• Rehabilitation Medicine

Background:

• Intracortical microstimulation (ICMS) in the human somatosensory cortex can evoke tactile percepts, but these artificial sensations often lack naturalness.
• Optimizing ICMS parameters to increase the naturalness of evoked sensations is crucial for developing effective neuroprosthetics and sensory feedback systems.

Purpose of the Study:

• To investigate whether biomimetic stimulation patterns, which replicate natural neural activity features, enhance the perceived naturalness of ICMS-evoked tactile sensations compared to non-biomimetic patterns.
• To assess the efficacy of both simple (single-electrode amplitude modulation) and advanced (multi-electrode spatiotemporal dynamics) biomimetic ICMS schemes.

Main Methods:

• Three individuals with cervical spinal cord injuries and implanted somatosensory cortex electrode arrays participated.
• Participants compared ICMS-evoked percepts with natural tactile percepts from mechanical indentation on their hand.
• Biomimetic and non-biomimetic ICMS patterns were systematically evaluated for perceived naturalness and charge efficiency.

Main Results:

• A simple biomimetic ICMS strategy (single-electrode amplitude modulation) was perceived as more natural than non-biomimetic patterns for 32% of electrodes.
• An advanced biomimetic scheme, capturing spatiotemporal dynamics across four electrodes, was perceived as more natural for 75% of electrode groups.
• Biomimetic stimulus trains required less electrical charge to achieve intensity-matched sensations compared to non-biomimetic patterns.

Conclusions:

• ICMS encoding schemes that mimic natural somatosensory cortical spatiotemporal activation patterns lead to more natural-feeling artificial tactile sensations.
• Biomimetic approaches offer a promising strategy for improving sensory feedback in neuroprosthetics and may guide future stimulation parameter optimization.
• This research suggests that incorporating principles of natural neural activity can enhance the efficacy and efficiency of ICMS for sensory restoration.