Could cortical signals control intraspinal stimulators? A theoretical evaluation.

Area of Science:

• Neuroscience
• Biomedical Engineering
• Spinal Cord Injury Research

Background:

• Spinal cord injury (SCI) often leads to paralysis and loss of motor function.
• Intraspinal microstimulation (ISMS) is a technique that can activate neural circuits in the spinal cord.
• Restoring locomotion after SCI is a major goal in neurorehabilitation.

Purpose of the Study:

• To investigate the control signals needed for ISMS-evoked stepping.
• To compare two ISMS paradigms: tonic and phasic stimulation.
• To assess the feasibility of using a brain-computer interface (BCI) to control ISMS-induced stepping.

Main Methods:

• Two ISMS protocols, tonic (constant amplitude) and phasic (modulated amplitude), were applied to the hind limbs of paralyzed cats.
• The resulting hind limb movements and coordination were analyzed.
• The study discusses the theoretical requirements for BCI control of these ISMS paradigms.

Main Results:

• Low-amplitude tonic ISMS activated a spinal locomotor network, producing bilateral hind limb stepping.
• Phasic ISMS generated coordinated stepping by activating flexor and extensor muscle synergies in a limb-alternating pattern.
• The findings suggest that one or two independent cortical signals could control ISMS-induced stepping.

Conclusions:

• Both tonic and phasic ISMS paradigms can effectively generate stepping in paralyzed animals.
• ISMS-evoked stepping shows potential for restoring hind limb locomotion after SCI.
• BCI control of ISMS is theoretically feasible, offering a potential pathway for volitional control of movement post-injury.