Mapping of the Spinal Sensorimotor Network by Transvertebral and Transcutaneous Spinal Cord Stimulation

Polina Shkorbatova; Vsevolod Lyakhovetskii; Natalia Pavlova; Alexander Popov; Elena Bazhenova; Daria Kalinina; Oleg Gorskii; Pavel Musienko

doi:10.3389/fnsys.2020.555593

Mapping of the Spinal Sensorimotor Network by Transvertebral and Transcutaneous Spinal Cord Stimulation

Front Syst Neurosci. 2020 Oct 9:14:555593. doi: 10.3389/fnsys.2020.555593. eCollection 2020.

Authors

Polina Shkorbatova^{1

2}, Vsevolod Lyakhovetskii^{2

3}, Natalia Pavlova^{1

2}, Alexander Popov², Elena Bazhenova^{1

2}, Daria Kalinina¹, Oleg Gorskii^{1

2

3}, Pavel Musienko^{1

2

3

4}

Affiliations

¹ Institute of Translational Biomedicine, Saint Petersburg State University, Saint Petersburg, Russia.
² Pavlov Institute of Physiology Russian Academy of Sciences, Saint Petersburg, Russia.
³ Russian Research Center of Radiology and Surgical Technologies, Ministry of Health of the Russian Federation, Saint Petersburg, Russia.
⁴ Children's Surgery and Orthopedic Clinic, Department of Non-pulmonary Tuberculosis, Institute of Phthysiopulmonology, Saint Petersburg, Russia.

Abstract

Transcutaneous stimulation is a neuromodulation method that is efficiently used for recovery after spinal cord injury and other disorders that are accompanied by motor and sensory deficits. Multiple aspects of transcutaneous stimulation optimization still require testing in animal experiments including the use of pharmacological agents, spinal lesions, cell recording, etc. This need initially motivated us to develop a new approach of transvertebral spinal cord stimulation (SCS) and to test its feasibility in acute and chronic experiments on rats. The aims of the current work were to study the selectivity of muscle activation over the lower thoracic and lumbosacral spinal cord when the stimulating electrode was located intravertebrally and to compare its effectiveness to that of the clinically used transcutaneous stimulation. In decerebrated rats, electromyographic activity was recorded in the muscles of the back (m. longissimus dorsi), tail (m. abductor caudae dorsalis), and hindlimb (mm. iliacus, adductor magnus, vastus lateralis, semitendinosus, tibialis anterior, gastrocnemius medialis, soleus, and flexor hallucis longus) during SCS with an electrode placed alternately in one of the spinous processes of the VT12-VS1 vertebrae. The recruitment curves for motor and sensory components of the evoked potentials (separated from each other by means of double-pulse stimulation) were plotted for each muscle; their slopes characterized the effectiveness of the muscle activation. The electrophysiological mapping demonstrated that transvertebral SCS has specific effects to the rostrocaudally distributed sensorimotor network of the lower thoracic and lumbosacral cord, mainly by stimulation of the roots that carry the sensory and motor spinal pathways. These effects were compared in the same animals when mapping was performed by transcutaneous stimulation, and similar distribution of muscle activity and underlying neuroanatomical mechanisms were found. The experiments on chronic rats validated the feasibility of the proposed stimulation approach of transvertebral SCS for further studies.

Keywords: decerebrated rat; neuromodulation; sensorimotor network; spinal cord; transcutaneous stimulation; transvertebral spinal cord stimulation.