title: Integration of sensory, spinal, and volitional descending inputs in regulation of human locomotion.
abstract: We reported previously that both transcutaneous electrical spinal cord stimulation and direct pressure stimulation of the plantar surfaces of the feet can elicit rhythmic involuntary step-like movements in noninjured subjects with their legs in a gravity-neutral apparatus. The present experiments investigated the convergence of spinal and plantar pressure stimulation and voluntary effort in the activation of locomotor movements in uninjured subjects under full body weight support in a vertical position. For all conditions, leg movements were analyzed using electromyographic (EMG) recordings and optical motion capture of joint kinematics. Spinal cord stimulation elicited rhythmic hip and knee flexion movements accompanied by EMG bursting activity in the hamstrings of 6/6 subjects. Similarly, plantar stimulation induced bursting EMG activity in the ankle flexor and extensor muscles in 5/6 subjects. Moreover, the combination of spinal and plantar stimulation exhibited a synergistic effect in all six subjects, eliciting greater motor responses than either modality alone. While the motor responses to spinal vs. plantar stimulation seems to activate distinct but overlapping spinal neural networks, when engaged simultaneously, the stepping responses were functionally complementary. As observed during induced (involuntary) stepping, the most significant modulation of voluntary stepping occurred in response to the combination of spinal and plantar stimulation. In light of the known automaticity and plasticity of spinal networks in absence of supraspinal input, these findings support the hypothesis that spinal and plantar stimulation may be effective tools for enhancing the recovery of motor control in individuals with neurological injuries and disorders.
authors.affiliation: Pavlov Institute of Physiology, Russian Academy of Sciences, St. Petersburg, Russia; Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, California; yuryg@ucla.edu.
authors.forename: Yury
authors.initials: Y
authors.lastname: Gerasimenko
authors.affiliation: Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, California;
authors.forename: Parag
authors.initials: P
authors.lastname: Gad
authors.affiliation: Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, California;
authors.forename: Dimitry
authors.initials: D
authors.lastname: Sayenko
authors.affiliation: Department of Bioengineering, University of California, Los Angeles, Los Angeles, California;
authors.forename: Zach
authors.initials: Z
authors.lastname: McKinney
authors.affiliation: Velikiye Luki State Academy of Physical Education and Sport, Velikiye Luki, Russia;
authors.forename: Ruslan
authors.initials: R
authors.lastname: Gorodnichev
authors.affiliation: Velikiye Luki State Academy of Physical Education and Sport, Velikiye Luki, Russia;
authors.forename: Aleksandr
authors.initials: A
authors.lastname: Puhov
authors.affiliation: Pavlov Institute of Physiology, Russian Academy of Sciences, St. Petersburg, Russia;
authors.forename: Tatiana
authors.initials: T
authors.lastname: Moshonkina
authors.affiliation: Pavlov Institute of Physiology, Russian Academy of Sciences, St. Petersburg, Russia;
authors.forename: Aleksandr
authors.initials: A
authors.lastname: Savochin
authors.affiliation: Institute for Information Transmission Problems, Russian Academy of Science, Moscow, Russia; and.
authors.forename: Victor
authors.initials: V
authors.lastname: Selionov
authors.affiliation: Russian Federation State Scientific Center-Institute for Bio-Medical Problems, Russian Academy of Sciences, Moscow, Russia.
authors.forename: Tatiana
authors.initials: T
authors.lastname: Shigueva
authors.affiliation: Russian Federation State Scientific Center-Institute for Bio-Medical Problems, Russian Academy of Sciences, Moscow, Russia.
authors.forename: Elena
authors.initials: E
authors.lastname: Tomilovskaya
authors.affiliation: Russian Federation State Scientific Center-Institute for Bio-Medical Problems, Russian Academy of Sciences, Moscow, Russia.
authors.forename: Inessa
authors.initials: I
authors.lastname: Kozlovskaya
authors.affiliation: Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, California;
authors.forename: V Reggie
authors.initials: VR
authors.lastname: Edgerton
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D004576:Electromyography; D006801:Humans; D007866:Leg / Q000502:physiology*; D008124:Locomotion / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D061848:Optical Imaging; D010812:Physical Stimulation; D011312:Pressure; D012677:Sensation / Q000502:physiology*; D013116:Spinal Cord / Q000502:physiology*; D004561:Transcutaneous Electric Nerve Stimulation; D014836:Volition; D055815:Young Adult
keywords: central pattern generator; sensory stimulation of sole; spinal cord locomotion; spinal cord stimulation