Somatosensory Evoked Potentials following upper limb noninvasive electrical stimulation: a case study

Area of Science:

• Neuroscience
• Biomedical Engineering
• Rehabilitation Technology

Background:

• Lack of sensory feedback limits control and embodiment in upper-limb prostheses.
• Noninvasive nerve stimulation offers potential for somatotopic feedback in amputees.
• Previous research focused on median nerve stimulation, neglecting ulnar and bipolar approaches.

Purpose of the Study:

• To characterize neural correlates of monopolar and bipolar transcutaneous electrical nerve stimulation (TENS) on the ulnar and median nerves.
• To investigate the potential of bipolar TENS for improving tactile feedback in prosthetic devices.

Main Methods:

• Monopolar and bipolar TENS applied to ulnar and median nerves.
• Somatosensory Evoked Potentials (SEPs) recorded using electroencephalography (EEG).
• Analysis of SEPs' latencies, amplitudes, and scalp topographies.

Main Results:

• Distinct P50, P150, and P270 SEPs identified with significant amplitude differences between stimulation configurations.
• Early phase (40-100 ms) showed strong contralateral activation, consistent with somatosensory cortex activity.
• Late phase (130-190 ms) exhibited a frontal-central distribution.

Conclusions:

• Bipolar TENS effectively elicits SEPs with distinct characteristics.
• Findings suggest bipolar TENS has potential for enhancing tactile feedback in upper-limb prostheses.
• Further validation with larger subject groups is recommended.