The frequency of cortical microstimulation shapes artificial touch

Area of Science:

• Neuroscience
• Biomedical Engineering
• Sensory Feedback

Background:

• Intracortical microstimulation (ICMS) provides tactile sensations for bionic devices.
• Limited understanding exists regarding ICMS frequency discrimination and its sensory correlates.
• Previous studies focused on low frequencies, leaving higher ranges unexplored.

Purpose of the Study:

• To investigate the discriminability of ICMS pulse train frequency over a wide range (10–400 Hz).
• To determine if ICMS frequency changes sensation magnitude or quality.
• To explore electrode-dependent sensory correlates of ICMS frequency.

Main Methods:

• Monkeys were trained to discriminate ICMS frequencies.
• Stimuli varied in amplitude to isolate frequency perception.
• Wide frequency ranges (10–400 Hz) were tested.

Main Results:

• Frequency discrimination was consistent up to approximately 200 Hz.
• Sensory correlates of frequency were highly electrode-dependent.
• On some electrodes, frequency changes altered perceived sensation quality, distinct from amplitude changes.

Conclusions:

• ICMS frequency can be reliably discriminated within a specific range for sensory feedback.
• Electrode-specific neural coding influences the perception of ICMS frequency.
• Findings have implications for optimizing neural coding strategies in brain-controlled prosthetics.