A5076514163- Zebrafish Biomedical Research Applications
- Neuroscience and Neuropharmacology Research
- Neurogenesis and neuroplasticity mechanisms
- Neuroscience of respiration and sleep
- Muscle activation and electromyography studies
- Neuroscience and Neural Engineering
- Neural dynamics and brain function
- Photoreceptor and optogenetics research
- Congenital heart defects research
- Ion channel regulation and function
- Spinal Cord Injury Research
- Neuroendocrine regulation and behavior
- Advanced MRI Techniques and Applications
- NMR spectroscopy and applications
- Neurobiology and Insect Physiology Research
- Sleep and Wakefulness Research
- Advanced Neuroimaging Techniques and Applications
- Developmental Biology and Gene Regulation
- Neonatal and fetal brain pathology
- Hemispheric Asymmetry in Neuroscience
- Nerve injury and regeneration
- Genetics, Aging, and Longevity in Model Organisms
- Muscle Physiology and Disorders
- Amyotrophic Lateral Sclerosis Research
- Transcranial Magnetic Stimulation Studies
National Institute of Neurological Disorders and Stroke
2012-2023
National Institutes of Health
2012-2023
Cardiff University
2019
Combat Capabilities Development Command Soldier Center
2015
United States Department of the Army
2014
Institute of Developmental Physiology
2012
Wright State University
2005
University of Calgary
2002
National Institute of Diabetes and Digestive and Kidney Diseases
1997
Simon Fraser University
1995
We examined the ability of isolated lumbosacral spinal cord neonatal mouse (P0–7) to generate rhythmic motor activity under several different conditions. In absence electrical or pharmacological stimulation, we recorded patterns spontaneous ventral root depolarization and discharge. Spontaneous, alternating discharge between contralateral roots could occur two three times over a 10-min interval. also observed other patterns, including left-right synchrony restricted one side cord. Trains...
1. The properties of fifty-seven motor units in human medial gastrocnemius have been studied using controlled intramuscular microstimulation, glycogen depletion and muscle biopsy. 2. Motor could be divided into three classes on the basis their mechanical properties. Type S were slow, small fatigue resistant. FR fast, intermediate size, FF large fatigable. 3. Glycogen a number type revealed them to composed 1 2b fibres respectively. 4. results suggest that during slowly increasing voluntary...
Cat sartorius has two distinct anatomical portions, anterior (SA-a) and medial (SA-m). SA-a acts to extend the knee also flex hip. SA-m both The objective of this study was investigate how a "single motoneuron pool" is used control at least three separate functions mediated by portions one muscle. Discharge patterns single motoneurons projecting muscle were recorded using floating microelectrodes implanted in L5 ventral root cats. electromyographic activity generated with chronically...
Spontaneous episodic activity is a general feature of developing neural networks. In the chick spinal cord, comprises episodes rhythmic discharge (duration 5-90 sec; cycle rate 0.1-2 Hz) that recur every 2-30 min. The does not depend on specialized connectivity or intrinsic bursting neurons and generated by network functionally excitatory connections. Here, we develop an idealized, qualitative model homogeneous, recurrent could account for multiple time-scale spontaneous in embryonic cord....
The dimensions of the somata and stem dendrites 57 alpha- three gamma-motoneurons, identified as to motor unit type labeled by intracellular injection horseradish peroxidase, were measured in triceps surae plantaris pools. S motoneurons tended be smaller (mean diameter 47.9 micrometers) than those FF FR units (52.5 53.1 micrometer, respectively) but these mean values not significantly different data distributions showed considerable overlap between types. numbers diameters exhibited somewhat...
1. By spike‐triggered averaging of intracellular synaptic noise it has been shown in pentobarbitone anaesthetized cats that jaw elevator muscle spindle afferents with their cell bodies the mid‐brain have a relatively weak monosynaptic projection to masseter and temporalis motoneurones. 2. Extending method recording extracellular excitatory field potentials virtually all spindles do project monosynaptically motoneurone pool. It is concluded general weakness due its restriction small...
Muscle activation patterns of embryonic chick hind limb muscles were determined from electromyographic (e.m.g.) recordings in an isolated spinal cord/hind preparation stage 34‐36 embryos, and compared with ovo e.m.g. activity similarly staged embryos. consisted periodically recurring sequences bursts during which antagonistic often alternated synergistic co‐active, as compatible their mature function. However, more variable behaviour was also observed. Burst initiated by a short‐duration,...
Activity patterns were recorded from 51 motoneurons in the fifth lumbar ventral root of cats walking on a motorized treadmill at range speeds between 0.1 and 1.3 m/s. The muscle destination was identified by spike-triggered averaging EMG recordings each anterior thigh muscles. Forty-three projected to one quadriceps (vastus medialis, vastus lateralis, intermedius, or rectus femoris) sartorius (anterior medial) muscles thigh. Anterior always discharged single burst action potentials per step...
We studied the regulation of spontaneous activity in embryonic (day 10–11) chick spinal cord. After bath application either an excitatory amino acid (AP-5 or CNQX) and a nicotinic cholinergic (DHβE mecamylamine) antagonist, glycine GABA receptor (bicuculline, 2-hydroxysaclofen, strychnine) antagonists, was blocked for period (30–90 min) but then reappeared presence drugs. The efficacy antagonists assessed by their continued ability to block reflex pathways during reappearance activity....
Mammalian spinal motoneurons are considered to be output elements of the cord that generate exclusively cholinergic actions on Renshaw cells, their intraspinal synaptic targets. Here, we show antidromic stimulation motor axons evokes depolarizing monosynaptic potentials in cells depressed, but not abolished, by antagonists. This residual potential was abolished 2-amino-5-phosphonovaleric acid and 6-cyano-7-nitroquinoxaline-2,3-dione. In presence antagonists, axon triggered locomotor-like...
We have examined the regionalization and coordination of rhythm- generating networks in isolated spinal cord chick embryo between embryonic days 9 13, by recording pattern rhythmic activity recorded from muscle nerves ventral roots following a variety lesions. found that capacity for is distributed along rostrocaudal axis but can be expressed single, segment. Specializations within lumbosacral were investigated isolating particular regions their motor output. The rostral part generates more...
The development of hindlimb motor activity was studied in an isolated preparation the chick spinal cord. output from lumbosacral segments characterized by recording pattern ventral root and muscle nerve discharge 6-14-d-old embryos. In addition, synaptic drive underlying motoneuron monitored electrotonically roots. Spontaneous consisted recurring episodes cyclical discharge. During development, both number cycles each episode intensity cycle progressively increased. Monophasic, positive...
Spontaneous episodic activity occurs throughout the developing nervous system because immature circuits are hyperexcitable. It is not fully understood how temporal pattern of this regulated. Here, we study role activity-dependent depression network excitability in generation and regulation spontaneous embryonic chick spinal cord. We demonstrate that duration an episode depends on at beginning episode. found a positive correlation between preceding inter-episode interval, but with following...
Long-term recording from single lumbar motoneurons of intact cats revealed activation patterns fundamentally different those seen in decerebrate preparations. In cats, motoneuron bursts showed marked rate modulation without initial doublets. Each unit's frequencygram generally resembled the envelope gross electromyogram simultaneously recorded corresponding muscle. Average and peak discharge rates increased for faster gaits. These findings suggest that, cat locomotion, is a more important...
Video-rate imaging of spinal neurons loaded with calcium-sensitive dyes was used to investigate the calcium dynamics and cellular organization spontaneously active rhythm-generating networks in cord E9-E12 chick embryos. Spinal were bath-applied fura-2am. Motoneurons also by retrograde labeling dextran-conjugated, dyes. Dye-filled motoneurons exhibited large fluorescent changes during antidromic stimulation motor nerves, an increase 340/380 fura fluorescence ratio that is indicative...
We have examined the development of synaptic connections between afferents and motoneurons in lumbosacral spinal cord chick embryo stages 28 39. The central projection was visualized following injection dorsal root ganglia with HRP. Afferent fibers first entered gray matter 29 31. They grew a ventrolateral direction, reaching motoneuron dendrites by stage 32. Quantitative analysis axon numbers suggested that individual axons did not begin to branch extensively until they approached lateral...
We develop magnetic resonance (MR) methods for real-time measurement of tissue microstructure and membrane permeability live fixed excised neonatal mouse spinal cords. Diffusion exchange MR measurements are performed using the strong static gradient produced by a single-sided permanent magnet. Using delipidation methods, we show that water diffusion is restricted solely lipid membranes. Most signal can be assigned to in which far from The remaining 25% on length scales roughly micron or...
For its size, the brain is most metabolically active organ in body. Most of energy demand used to maintain stable homeostatic physiological conditions. Altered homeostasis and states are hallmarks many diseases disorders. Yet there currently no direct reliable method assess absolute basal activity cells tissue noninvasively without exogenous tracers or contrast agents. We propose a novel low-field, high-gradient diffusion exchange nuclear magnetic resonance (NMR) capable directly measuring...