A5064515031- Spinal Cord Injury Research
- Muscle activation and electromyography studies
- Transcranial Magnetic Stimulation Studies
- Cerebral Palsy and Movement Disorders
- Stroke Rehabilitation and Recovery
- Neuroscience and Neural Engineering
- Botulinum Toxin and Related Neurological Disorders
- Motor Control and Adaptation
- Pain Mechanisms and Treatments
- Ion channel regulation and function
- Neuroscience and Neuropharmacology Research
- Neural dynamics and brain function
- Neonatal and fetal brain pathology
- EEG and Brain-Computer Interfaces
- Vestibular and auditory disorders
- Infant Development and Preterm Care
- Photoreceptor and optogenetics research
- Musculoskeletal pain and rehabilitation
- Neuroscience of respiration and sleep
- Neurological disorders and treatments
- Temporomandibular Joint Disorders
- Advanced Sensor and Energy Harvesting Materials
- Genetic Neurodegenerative Diseases
- Balance, Gait, and Falls Prevention
- Veterinary Orthopedics and Neurology
University of Alberta
2015-2025
Women and Children’s Health Research Institute
2015-2024
University of Copenhagen
1998-2000
After chronic spinal injury, motoneurons spontaneously develop two persistent inward currents (PICs): a TTX-sensitive sodium current (sodium PIC) and nimodipine-sensitive calcium (calcium PIC). In the present paper, we examined how these PICs contributed to motoneuron firing. Adult rats were spinalized at S 2 sacral level, after months intracellular recordings made from sacrocaudal in vitro. The repetitive firing measured with slow triangular voltage ramps, respectively. PIC was blocking...
Bennett, David J., Hans Hultborn, Brent Fedirchuk, and Monica Gorassini. Synaptic activation of plateaus in hindlimb motoneurons decerebrate cats. J. Neurophysiol. 80: 2023–2037, 1998. Intracellular recordings were made from cats to study how synaptic inputs could affect the threshold at which plateau potentials are activated with current injections through recording microelectrode cell body. This was prompted by recent evidence that noninactivating inward currents regeneratively produce...
In this study, we examined if several months of intensive locomotor training increases the function spared corticospinal tract pathways after chronic spinal cord injury (SCI) in association with recovery function. Transcranial magnetic stimulation (TMS) at incrementing levels intensity was applied over motor cortex supplying either tibialis anterior or vastus lateralis muscles, and resulting peak-to-peak amplitude motor-evoked potentials (MEPs) were measured to obtain a recruitment curve...
The main purpose of this study was to estimate the contribution intrinsic activation human motoneurons (e.g., by plateau potentials) during voluntary and reflexive muscle contractions. Pairs motor units were recorded from either tibialis anterior or soleus three different conditions: 1) a brief vibration followed slow relaxation steady isometric contraction; 2) triangular torque 3) passive sinusoidal stretch superimposed on contraction. In each case, firing rate tonically control unit used...
Motor units of segmental tail muscles were recorded in awake rats following acute (1–2 days) and chronic (>30 sacral spinal cord transection to determine whether plateau potentials contributed sustained motor-unit discharges after injury. This study was motivated by a companion vitro that indicated injury, the motoneurons sacrocaudal exhibit persistent inward currents ( I PIC ) cause intrinsically depolarizations potentials) firing self-sustained firing). Importantly, this study, plateaus...
Motoneurons in the spinal cord have intrinsic voltage-dependent persistent inward currents (PICs; e.g. calcium currents) that amplify synaptic inputs by three- to five-fold addition providing a sustained excitatory drive allows motoneurons fire repetitively following brief excitation. In this study, we examined whether prolonged involuntary muscle spasms subjects with long-term injury are mediated activation of PICs motoneuron. To examine human, used paired motor unit analysis technique...
We have investigated sacral spinal cord lesions in rats with the goal of developing a rat model muscular spasticity that is minimally disruptive, not interfering bladder, bowel, or hindlimb locomotor function. Spinal transections were made at S2 level and, thus, only affected tail musculature. After transection, muscles inactive for 2 weeks. Following this initial period, hypertonia, hyperreflexia, and clonus developed tail, grew more pronounced time. These changes assessed awake rat, since...
In human spinal cord injury, the neuronal mechanisms mediating improvement of locomotor function in response to intensive treadmill training are not well understood. this study, we examined if such recovery is mediated, part, by increases residual corticospinal drive muscles leg during walking. To do this, measured coherence electromyogram (EMG) activity between two antagonist (intermuscular coherence), specifically at frequencies 24 and 40 Hz, which thought indicate common from inputs. 12...
Non-invasive brain stimulation is being increasingly used to interrogate neurophysiology and modulate function. Despite the high scientific therapeutic potential of non-invasive stimulation, experience in developing has been limited.To determine safety tolerability neurostimulation children across diverse modalities pediatric populations.A program was established 2008 at our pediatric, academic institution. Multi-disciplinary neurophysiological studies included single- paired-pulse...
A new method of estimating synaptic drive to multiple, simultaneously recorded motor units provides evidence that the portion depolarizing from persistent inward currents contributes self-sustained firing is similar across motoneurons different sizes.
The main purpose of this study was to collate population data on the firing characteristics muscle afferents recorded chronically during normal stepping in cats. Ensemble profiles forty‐seven spindle and tendon organ were compiled from stored data. relationships between displacement force signals analysed with help mathematical models response primary secondary organs. Whereas hamstring could be predicted reasonable accuracy length velocity alone, triceps surae deviated profiles,...
Following chronic sacral spinal cord transection in rats the affected tail muscles exhibit marked spasticity, with characteristic long-lasting spasms evoked by mild stimulation. The purpose of present paper was to characterize reflex seen response electrical stimulation nerves awake spastic rat, including its development time and relation spasticity. Before after transection, surface electrodes were placed on for caudal nerve trunk (mixed nerve) recording EMG from segmental muscles. In...
The aim of this work was to compare the ability several mathematical models predict firing characteristics muscle spindle primary afferents recorded chronically during normal stepping in cats. Ensemble profiles nine hamstring (presumed group Ia) were compiled from stored data 132 step cycles. Three sets corresponding slow, medium and fast steps generated by averaging groups cycles aligned peak length each cycle. Five obtained literature compared. Each these used averaged signals. also...
1. In the cat step cycle electromyographic (EMG) activity in ankle extensor muscles commences approximately 70 ms before foot contact. There is a sharp peak between 10 and 25 after contact EMG then declines for remainder of stance phase. It has been posited that abrupt transition consequence reflexes elicited by large barrage afferent input signals touchdown. However, it also possible basic profile might be generated within CNS, with little modification input. 2. These ideas were tested 11...
The main purpose of this study was to examine whether facilitation human motor unit recruitment by repeated voluntary contractions is mediated, in part, time and activity-dependent increases the intrinsic excitability parent motoneuron. To do this, pairs tibialis anterior or soleus units were recorded during slowly increasing then decreasing contractions. firing rate lower-threshold pair (control unit) used as a measure effective synaptic excitation (i.e., drive) motoneurons. This estimate...
Stroke survivors often exhibit abnormal motoneuron excitability, manifested clinically as spasticity with exaggerated stretch reflexes in resting muscles. We examined whether this excitability is a result of increased activation intrinsic voltage-dependent persistent inward currents (PICs) or it enhanced synaptic inputs to the motoneuron. This distinction was made by recording firing rate profiles pairs motor units during isometric contractions elbow flexor To estimate PIC amplitude,...
Following spinal cord injury (SCI), prolonged muscle spasms are readily triggered by brief sensory stimuli. Animal and indirect human studies have shown that a substantial portion of the depolarization motoneurons during spasm comes from activation persistent inward currents (PICs). The (single pulse) stimuli trigger PICs in chronically spinalized animals evoke excitatory post-synaptic potentials (EPSPs) broadened to more than 500 ms, duration required activate PIC motoneuron. Thus, humans,...