scholarly journals Different phase delays of peripheral input to primate motor cortex and spinal cord promote cancellation at physiological tremor frequencies

2014 ◽  
Vol 111 (10) ◽  
pp. 2001-2016 ◽  
Author(s):  
Saša Koželj ◽  
Stuart N. Baker
Keyword(s):  
Spinal Cord ◽  
Motor Cortex ◽  
Motor Behavior ◽  
Cervical Spinal Cord ◽  
Late Response ◽  
Physiological Tremor ◽  
Phase Cancellation ◽  
Overall Stability ◽  
Response Onset ◽  
Frequency Relationship

Neurons in the spinal cord and motor cortex (M1) are partially phase-locked to cycles of physiological tremor, but with opposite phases. Convergence of spinal and cortical activity onto motoneurons may thus produce phase cancellation and a reduction in tremor amplitude. The mechanisms underlying this phase difference are unknown. We investigated coherence between spinal and M1 activity with sensory input. In two anesthetized monkeys, we electrically stimulated the medial, ulnar, deep radial, and superficial radial nerves; stimuli were timed as independent Poisson processes (rate 10 Hz). Single units were recorded from M1 (147 cells) or cervical spinal cord (61 cells). Ninety M1 cells were antidromically identified as pyramidal tract neurons (PTNs); M1 neurons were additionally classified according to M1 subdivision (rostral/caudal, M1r/c). Spike-stimulus coherence analysis revealed significant coupling over a broad range of frequencies, with the strongest coherence at <50 Hz. Delays implied by the slope of the coherence phase-frequency relationship were greater than the response onset latency, reflecting the importance of late response components for the transmission of oscillatory inputs. The spike-stimulus coherence phase over the 6–13 Hz physiological tremor band differed significantly between M1 and spinal cells (phase differences relative to the cord of 2.72 ± 0.29 and 1.72 ± 0.37 radians for PTNs from M1c and M1r, respectively). We conclude that different phases of the response to peripheral input could partially underlie antiphase M1 and spinal cord activity during motor behavior. The coordinated action of spinal and cortical feedback will act to reduce tremulous oscillations, possibly improving the overall stability and precision of motor control.

Spinal cord representation of motor cortex plasticity reflects corticospinal tract LTP

2021 ◽  
Vol 118 (52) ◽  
pp. e2113192118
Author(s):  
Alzahraa Amer ◽  
Jianxun Xia ◽  
Michael Smith ◽  
John H. Martin
Keyword(s):  
Spinal Cord ◽  
Motor Cortex ◽  
Corticospinal Tract ◽  
Cervical Spinal Cord ◽  
Long Term Potentiation ◽  
Dependent Manner ◽  
Term Potentiation ◽  
Spinal Cord Segment ◽  
Spinal Interneuron ◽  
Activity Dependent

Although it is well known that activity-dependent motor cortex (MCX) plasticity produces long-term potentiation (LTP) of local cortical circuits, leading to enhanced muscle function, the effects on the corticospinal projection to spinal neurons has not yet been thoroughly studied. Here, we investigate a spinal locus for corticospinal tract (CST) plasticity in anesthetized rats using multichannel recording of motor-evoked, intraspinal local field potentials (LFPs) at the sixth cervical spinal cord segment. We produced LTP by intermittent theta burst electrical stimulation (iTBS) of the wrist area of MCX. Approximately 3 min of MCX iTBS potentiated the monosynaptic excitatory LFP recorded within the CST termination field in the dorsal horn and intermediate zone for at least 15 min after stimulation. Ventrolaterally, in the spinal cord gray matter, which is outside the CST termination field in rats, iTBS potentiated an oligosynaptic negative LFP that was localized to the wrist muscle motor pool. Spinal LTP remained robust, despite pharmacological blockade of iTBS-induced LTP within MCX using MK801, showing that activity-dependent spinal plasticity can be induced without concurrent MCX LTP. Pyramidal tract iTBS, which preferentially activates the CST, also produced significant spinal LTP, indicating the capacity for plasticity at the CST–spinal interneuron synapse. Our findings show CST monosynaptic LTP in spinal interneurons and demonstrate that spinal premotor circuits are capable of further modifying descending MCX control signals in an activity-dependent manner.

Adaptation in the motor cortex following cervical spinal cord injury

Neurology ◽  
2002 ◽  
Vol 58 (5) ◽  
pp. 794-801 ◽  
Author(s):  
D. J. Mikulis ◽  
M. T. Jurkiewicz ◽  
W. E. McIlroy ◽  
W. R. Staines ◽  
L. Rickards ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Motor Cortex ◽  
Cervical Spinal Cord ◽  
Cervical Spinal Cord Injury ◽  
Cord Injury

scholarly journals Different contributions of primary motor cortex, reticular formation, and spinal cord to fractionated muscle activation

2018 ◽  
Vol 119 (1) ◽  
pp. 235-250 ◽  
Author(s):  
Boubker Zaaimi ◽  
Lauren R. Dean ◽  
Stuart N. Baker
Keyword(s):  
Spinal Cord ◽  
Motor Cortex ◽  
Reticular Formation ◽  
Upper Limb ◽  
Muscle Activation ◽  
Primary Motor Cortex ◽  
Cervical Spinal Cord ◽  
Motor Output ◽  
Natural Activity ◽  
Limb Muscles

Coordinated movement requires patterned activation of muscles. In this study, we examined differences in selective activation of primate upper limb muscles by cortical and subcortical regions. Five macaque monkeys were trained to perform a reach and grasp task, and electromyogram (EMG) was recorded from 10 to 24 muscles while weak single-pulse stimuli were delivered through microelectrodes inserted in the motor cortex (M1), reticular formation (RF), or cervical spinal cord (SC). Stimulus intensity was adjusted to a level just above threshold. Stimulus-evoked effects were assessed from averages of rectified EMG. M1, RF, and SC activated 1.5 ± 0.9, 1.9 ± 0.8, and 2.5 ± 1.6 muscles per site (means ± SD); only M1 and SC differed significantly. In between recording sessions, natural muscle activity in the home cage was recorded using a miniature data logger. A novel analysis assessed how well natural activity could be reconstructed by stimulus-evoked responses. This provided two measures: normalized vector length L, reflecting how closely aligned natural and stimulus-evoked activity were, and normalized residual R, measuring the fraction of natural activity not reachable using stimulus-evoked patterns. Average values for M1, RF, and SC were L = 119.1 ± 9.6, 105.9 ± 6.2, and 109.3 ± 8.4% and R = 50.3 ± 4.9, 56.4 ± 3.5, and 51.5 ± 4.8%, respectively. RF was significantly different from M1 and SC on both measurements. RF is thus able to generate an approximation to the motor output with less activation than required by M1 and SC, but M1 and SC are more precise in reaching the exact activation pattern required. Cortical, brainstem, and spinal centers likely play distinct roles, as they cooperate to generate voluntary movements. NEW & NOTEWORTHY Brainstem reticular formation, primary motor cortex, and cervical spinal cord intermediate zone can all activate primate upper limb muscles. However, brainstem output is more efficient but less precise in producing natural patterns of motor output than motor cortex or spinal cord. We suggest that gross muscle synergies from the reticular formation are sculpted and refined by motor cortex and spinal circuits to reach the finely fractionated output characteristic of dexterous primate upper limb movements.

Changes in motor cortex activation after recovery from spinal cord inflammation

2001 ◽  
Vol 7 (6) ◽  
pp. 364-370 ◽  
Author(s):  
S C Cramer ◽  
E Fray ◽  
A Tievsky ◽  
R A Parker ◽  
P N Riskind ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Motor Cortex ◽  
Activation Volume ◽  
Cervical Spinal Cord ◽  
Premotor Cortex ◽  
Left Index Finger ◽  
Control Group ◽  
Cortical Motor ◽  
Motor Improvement ◽  
Contralateral Motor

Diseases of the spinal cord are associated with reactive changes in cerebral cortex organization. Many studies in this area have examined spinal cord conditions not associated with recovery, making it difficult to consider the value of these cortical events in the restoration of neurological function. We studied patients with myelitis, a syndrome of transient spinal cord inflammation, in order to probe cortical changes that might contribute to recovery after disease of the spinal cord. Seven patients, each of whom showed improvement in hand motor function after a diagnosis of myelitis involving cervical spinal cord, were clinically evaluated then studied with functional MRI. During right and left index finger tapping, activation volumes were assessed in three cortical motor regions within each hemisphere. Results were compared with findings in nine control subjects. Compared to the control group, myelitis patients had larger activation volumes within contralateral sensorimotor as well as contralateral premotor cortex. The degree of daily hand use showed a significant correlation with the volume of activation in contralateral sensorimotor cortex. Recovery from myelitis is associated with an enlarged activation volume in contralateral motor cortices. This change in motor cortex function is related to behavioral experience, and thus may contribute to motor improvement. The expanded activation in motor cortex, seen with several forms of spinal cord insult, may have maximal utility when corticospinal tract axons are preserved.

scholarly journals Posteroanterior Cervical Transcutaneous Spinal Cord Stimulation: Interactions with Cortical and Peripheral Nerve Stimulation

2021 ◽  
Vol 10 (22) ◽  
pp. 5304
Author(s):  
Jaclyn R. Wecht ◽  
William M. Savage ◽  
Grace O. Famodimu ◽  
Gregory A. Mendez ◽  
Jonah M. Levine ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Motor Cortex ◽  
Motor Neurons ◽  
Nerve Stimulation ◽  
Spinal Cord Stimulation ◽  
Cervical Spinal Cord ◽  
Hand Function ◽  
Median Nerve Stimulation ◽  
Cord Injury ◽  
Transcutaneous Spinal Cord Stimulation

Transcutaneous spinal cord stimulation (TSCS) has demonstrated potential to beneficially modulate spinal cord motor and autonomic circuitry. We are interested in pairing cervical TSCS with other forms of nervous system stimulation to enhance synaptic plasticity in circuits serving hand function. We use a novel configuration for cervical TSCS in which the anode is placed anteriorly over ~C4–C5 and the cathode posteriorly over ~T2–T4. We measured the effects of single pulses of TSCS paired with single pulses of motor cortex or median nerve stimulation timed to arrive at the cervical spinal cord at varying intervals. In 13 participants with and 15 participants without chronic cervical spinal cord injury, we observed that subthreshold TSCS facilitates hand muscle responses to motor cortex stimulation, with a tendency toward greater facilitation when TSCS is timed to arrive at cervical synapses simultaneously or up to 10 milliseconds after cortical stimulus arrival. Single pulses of subthreshold TSCS had no effect on the amplitudes of median H-reflex responses or F-wave responses. These findings support a model in which TSCS paired with appropriately timed cortical stimulation has the potential to facilitate convergent transmission between descending motor circuits, segmental afferents, and spinal motor neurons serving the hand. Studies with larger numbers of participants and repetitively paired cortical and spinal stimulation are needed.

Transcranial stimulation measures explored by epidural spinal cord recordings

2012 ◽  
Author(s):  
Vicenzo Di Lazzaro
Keyword(s):  
Spinal Cord ◽  
Motor Cortex ◽  
Cervical Spinal Cord ◽  
Electrical Stimulus ◽  
Transcranial Electrical Stimulation ◽  
Transcranial Stimulation ◽  
Human Motor Cortex ◽  
Direct Recording ◽  
High Frequency Waves ◽  
Medullary Pyramid

In response to a single-electrical stimulus to the motor cortex an electrode placed in the medullary pyramid or on the dorsolateral surface of the cervical spinal cord records a series of high-frequency waves. This has been shown by various studies conducted on animals. Recording from the surface of the spinal cord during spinal cord surgery has provided evidence for the action of transcranial magnetic stimulation (TMS) and transcranial electrical stimulation (TES) on the human motor cortex. However, the interpretation of this data has been limited. This article explains both types of transcranial stimulation (magnetic or electrical) the direct recording of which shows that transcranial stimulation can evoke several different kinds of descending activities. The output also depends upon the representation of the motor cortex being stimulated.

Motor cortex excitability changes following a lesion in the posterior columns of the cervical spinal cord

2008 ◽  
Vol 434 (1) ◽  
pp. 119-123 ◽  
Author(s):  
Raffaele Nardone ◽  
Stefan Golaszewski ◽  
Jürgen Bergmann ◽  
Alessandro Venturi ◽  
Igor Prünster ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Motor Cortex ◽  
Cervical Spinal Cord ◽  
Motor Cortex Excitability

scholarly journals Nicotinic signaling is required for motor learning but not rehabilitation after spinal cord injury

2022 ◽  
Author(s):  
Yue Li ◽  
Edmund Hollis
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Motor Learning ◽  
Molecular Mechanisms ◽  
Motor Behavior ◽  
Cervical Spinal Cord ◽  
Compensatory Strategies ◽  
Nicotinic Acetylcholine ◽  
Motor Circuits ◽  
Cord Injury

Currently, therapeutic intervention for spinal cord injury is limited. Many approaches rely on strengthening the remaining substrate and driving recovery through rehabilitative training. As compared to learning novel compensatory strategies, rehabilitation focuses on restoring movements lost to injury. Whether rehabilitation of previously learned movements after spinal cord injury requires the molecular mechanisms of motor learning, or if it engages previously trained motor circuits without requiring novel learning. Our findings implicate the latter mechanism, as we demonstrate that nicotinic acetylcholine signaling is required for motor learning but is dispensable for the recovery of previously trained motor behavior after cervical spinal cord injury.

Sign in / Sign up

Export Citation Format

Share Document