Paired motor cortex and cervical epidural electrical stimulation timed to converge in the spinal cord promotes lasting increases in motor responses

The study explores how pairing stimulation of the motor cortex and cervical spinal cord can strengthen motor responses. The researchers hypothesized that this pairing would enhance motor responses due to the convergence of these stimulations. Epidural electrodes were placed over the motor cortex and dorsal cervical spinal cord in rats. The researchers measured motor evoked potentials (MEPs) from the biceps muscle to assess the impact of the paired stimulation. The findings suggest that the immediate and lasting effects of paired stimulation are likely due to the convergence of descending motor circuits and large diameter afferents onto common interneurons in the cervical spinal cord.

• 1
  Pairing motor cortex stimulation with spinal cord epidural stimulation significantly augmented motor cortex evoked potentials, but only when timed to converge in the spinal cord.
• 2
  The modulation of cortical evoked potentials by spinal cord stimulation was most pronounced when spinal electrodes were placed over the dorsal root entry zone.
• 3
  Repeated pairing of motor cortex and spinal cord stimulation led to lasting increases in evoked potentials from both sites, but only with optimal timing between stimuli.