Reliability in the location of hindlimb motor representations in Fischer-344 rats

Frost, Shawn B.; Iliakova, Maria; Dunham, Caleb; Barbay, Scott; Arnold, Paul M.; Nudo, Randolph J.

doi:10.3171/2013.4.spine12961

Cited by 24 publications

(37 citation statements)

References 26 publications

(44 reference statements)

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“…Subsequently, current intensity was increased in 1 µA increments not exceeding 80 µA until a consistent movement was evoked with every stimulus train. The lowest stimulation current that evoked a visible and consistent joint displacement was defined as the movement threshold (Frost, Iliakova et al 2013). …”

Section: Methodsmentioning

confidence: 99%

A 3D map of the hindlimb motor representation in the lumbar spinal cord in Sprague Dawley rats

et al. 2016

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Objective Spinal cord injury (SCI) is a devastating neurological trauma with a prevalence of about 282,000 people living with an SCI in the United States in 2016. Advances in neuromodulatory devices hold promise for restoring function by incorporating the delivery of electrical current directly into the spinal cord grey matter via intraspinal microstimulation (ISMS). In such designs, detailed topographic maps of spinal cord outputs are needed to determine ISMS locations for eliciting hindlimb movements. The primary goal of the present study was to derive a topographic map of functional motor outputs in the lumbar spinal cord to hindlimb skeletal muscles as defined by ISMS in a rat model. Approach Experiments were carried out in nine healthy, adult, male, Sprague Dawley rats. After a laminectomy of the T13-L1 vertebrae and removal of the dura mater, a four-shank, 16-channel microelectrode array was inserted along a three-dimensional (200 µm) stimulation grid. Trains of three biphasic current pulses were used to determine evoked movements and EMG activity. Via fine wire electromyographic (EMG) electrodes, Stimulus-Triggered Averaging (StTA) was used on rectified EMG data to determine response latency. Main results Hindlimb movements were elicited at a median current intensity of 6 µA, and thresholds were significantly lower in ventrolateral sites. Movements typically consisted of whole leg, hip, knee, ankle, toe, and trunk movements. Hip movements dominated rostral to the T13 vertebral segment, knee movements were evoked at the T13-L1 vertebral junction, while ankle and digit movements were found near the rostral L1 vertebra. Whole leg movements spanned the entire rostrocaudal region explored, while trunk movements dominated medially. StTAs of EMG activity demonstrated a latency of ~4 ms. Significance The derived motor map provides insight into the parameters needed for future neuromodulatory devices.

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Section: Methodsmentioning

confidence: 99%

A 3D map of the hindlimb motor representation in the lumbar spinal cord in Sprague Dawley rats

et al. 2016

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“…26–28 Two recent neurophysiological studies using ICMS techniques reported that the hindlimb motor area in rodents was, on average, 1–3.25 mm and 0.75–2.75 mm lateral to midline in rats 27 (Figure 2) and mice, 29 respectively. Following traumatic brain injury in rats, ICMS stimulation in the MC contralateral to the injury (the non-injured MC) elicited more ipsilateral hindlimb movements than sham operated (uninjured rats).…”

Section: Interhemispheric Communication Between the Leg Motor Corticamentioning

confidence: 98%

Motor Cortex and Motor Cortical Interhemispheric Communication in Walking After Stroke

Charalambous

Bowden

Adkins

2015

Neurorehabil Neural Repair

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Despite the plethora of human neurophysiological research, the bilateral involvement of the leg motor cortical areas and their interhemispheric interaction during both normal and impaired human walking is poorly understood. Using transcranial magnetic stimulation (TMS), we have expanded our understanding of the role upper-extremity motor cortical areas play in normal movements and how stroke alters this role, and probe the efficacy of interventions to improve post-stroke arm function. However, similar investigations of the legs have lagged behind, in part, due to the anatomical difficulty in using TMS to stimulate the leg motor cortical areas. Additionally, leg movements are predominately bilaterally controlled and require interlimb coordination that may involve both hemispheres. The sensitive, but invasive, tools used in animal models of locomotion hold great potential for increasing our understanding of the bihemispheric motor cortical control of walking. In this review, we discuss three themes associated with the bihemispheric motor cortical control of walking after stroke: 1) what is known about the role of the bihemispheric motor cortical control in healthy and post-stroke leg movements, 2) how the neural remodeling of the contralesional hemisphere can affect walking recovery after a stroke, and 3) what is the effect of behavioral rehabilitation training of walking on the neural remodeling of the motor cortical areas bilaterally. For each theme, we discuss how rodent models can enhance the present knowledge on human walking by testing hypotheses that cannot be investigated in humans, and how these findings can then be back-translated into the neurorehabilitation of post-stroke walking.

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“…A craniectomy was performed over the motor cortex. The general location of the craniectomy was guided by previous motor mapping studies in the rat (Frost et al, 2013;Frost et al, 2015). The dura over the cranial opening was incised and the opening was filled with warm, medical grade, sterile, silicone oil (50% Medical Silicone Fluid 12,500, 50% MDM Silicone Fluid 1000, Applied Silicone Corp., Santa Paula, CA) to prevent desiccation during the experiment.…”

Section: Hfrugmentioning

confidence: 99%

Activity Dependent Stimulation Increases Synaptic Efficacy In Spared Pathways In An Anesthetized Rat Model Of Spinal Cord Contusion Injury

Krizsan-Agbas

Nudo

et al. 2020

Preprint

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Objective. The purpose of this study was to assess the ability of intraspinal microstimulation, triggered by action potentials (spikes) recorded in motor cortex, to alter synaptic efficacy in descending motor pathways in an anesthetized rat model of spinal cord injury. Approach. Experiments were carried out in adult, male, Sprague Dawley rats with a moderate contusion injury at T8. Four weeks after SCI, and under ketamine/xylazine anesthesia, fine wire electromyographic (EMG) electrodes were implanted into four muscles of the right hindlimb. After exposure of the left motor cortex hindlimb area and laminectomy of the T13-L1 vertebrae, intracortical microstimulation (ICMS) and intraspinal microstimulation (ISMS) were used to determine the location of evoked hip movements in cortex and spinal cord, respectively. For activity-dependent stimulation sessions, a single shank, 16-channel, recording microelectrode was used to detect neuronal spikes in motor cortex that triggered ISMS in the spinal cord grey matter. Spinal cord injured rats were randomly assigned to one of four experimental groups differing by: a) cortical spike-ISMS stimulus delay (10 or 25 ms) and b) number of ISMS pulses (1 or 3). Activity-dependent stimulation sessions were conducted in three consecutive 1-hour conditioning bouts for a total of 3 hours. At the end of each conditioning bout, changes in synaptic efficacy were assessed using ICMS to examine the number of spikes evoked in spinal cord neurons during five minute test bouts. Evoked spikes were recorded, sorted, and displayed in post-stimulus spike histograms in 1ms bins. Post-stimulus spike histograms and EMG recordings were characterized using stimulus triggered averaging techniques. Main results. The results showed that activity-dependent stimulation resulted in an increase in cortically-evoked spikes in spinal cord neurons at specific combinations of spike-ISMS delays and numbers of pulses. Efficacy in descending motor pathways was increased throughout all dorsoventral depths of the hindlimb spinal cord, including the ventral horn, in the vicinity of motor neurons. Changes were evident in some conditions as early as 1 hour after conditioning. EMG responses were never evoked with ICMS pre-or post-conditioning. Significance. These results show that after a spinal cord contusion injury, activity-dependent stimulation, consisting of cortical spike-driven ISMS, can increase synaptic efficacy in spared pathways between motor cortex and spinal cord. This suggests that activity-dependent stimulation may serve as an effective therapeutic approach for enhancing descending motor control after spinal cord injury. Muscle EMG Wires ICMS RecordRecord ISMS Catch Trial: ADS:

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Reliability in the location of hindlimb motor representations in Fischer-344 rats

Cited by 24 publications

References 26 publications

A 3D map of the hindlimb motor representation in the lumbar spinal cord in Sprague Dawley rats

A 3D map of the hindlimb motor representation in the lumbar spinal cord in Sprague Dawley rats

Motor Cortex and Motor Cortical Interhemispheric Communication in Walking After Stroke

Activity Dependent Stimulation Increases Synaptic Efficacy In Spared Pathways In An Anesthetized Rat Model Of Spinal Cord Contusion Injury

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