Changes in motoneuron excitability during postnatal life in the mouse

Chandran, A. P.; Oda, Kenichiro; Shibasaki, Hiroshi

doi:10.1016/s0387-7604(12)80026-x

Cited by 5 publications

(4 citation statements)

References 14 publications

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“…At different spinal cord levels, two or three distinct responses were observed. These findings closely mirror results reported previously in a study using conventional spinal cord recording electrodes [6].…”

Section: Transducers and Eurosensors '07supporting

confidence: 91%

High-Density Flexible Parylene-Based Multielectrode Arrays for Retinal and Spinal Cord Stimulation

Rodger

Fong

et al. 2007

TRANSDUCERS 2007 - 2007 International Solid-State Sensors, Actuators and Microsystems Conference

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Novel flexible parylene-based high-density electrode arrays have been developed for functional electrical stimulation in retinal and spinal cord applications. These electrode arrays are microfabricated according to single-metal-layer and, most recently, dual-metal-layer processes. A new heat-molding process has been implemented to conform electrode arrays to approximate the curvature of canine retinas, and chronic implantation studies have been undertaken to study the mechanical effects of parylene-based prostheses on the retina, with excellent results to date. Electrode arrays have also been implanted and tested on the spinal cords of murine models, with the ultimate goal of facilitation of locomotion after spinal cord injury; these arrays provide a higher density and better spatial control of stimulation and recording than is typically possible using traditional fine-wire electrodes. Spinal cord stimulation typically elicited three muscle responses, an early (direct), a middle (monosynaptic), and a late (polysynaptic) response, classified based on latency after stimulation. Stimulation at different rostrocaudal levels of the cord yielded markedly different muscle responses, highlighting the need for such high-density arrays.

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Section: Transducers and Eurosensors '07supporting

confidence: 91%

High-Density Flexible Parylene-Based Multielectrode Arrays for Retinal and Spinal Cord Stimulation

Rodger

Fong

et al. 2007

TRANSDUCERS 2007 - 2007 International Solid-State Sensors, Actuators and Microsystems Conference

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show abstract

“…The percentage of SOL muscle fibers with myosin heavy chain type I (i.e., slow-twitch) varies from 20 to 70% among other strains of mice (Carlson et al, 1999;Stelzer and Widrick, 2003). Thus, inter-strain and/or inter-muscle differences in motor unit type distribution could account for the observed difference in the HR:MR ratio between the present study and that of Chandran et al (1991).…”

Section: Discussionmentioning

confidence: 50%

“…Thus, direct comparisons cannot readily be made between the present study and previous studies in mice, all of which describe H-reflex recordings from other muscles in anesthetized or sedated and restrained mice (Chandran et al, 1991;Elias et al, 1998;Turski and Stephens, 1993). For example, the ratio of the maximum HR to the maximum MR in the present study in SOL (0.22) was lower than that reported previously for intrinsic muscles of the foot in mice (0.61 in Chandran et al, 1991). The HR:MR ratio can vary widely among muscles, typically being higher in muscles with a higher proportion of slow-twitch fibers (Messina and Cotrufo, 1976;Palmieri et al, 2002).…”

Section: Discussionmentioning

confidence: 76%

Long-term spinal reflex studies in awake behaving mice

Carp

Tennissen

Chen

et al. 2005

Journal of Neuroscience Methods

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“…Well‐coordinated locomotor function of the hind limbs develops within a few weeks in the PN rat because of the rapid maturation of motor systems. There is a comprehensive morphological change of almost every structure of the motor pathway during development, including elevated excitability of cortical motor neurons (Chandran et al, ), increased elongation and density of the brain–spinal projections (Armand et al, ), and establishment and maturation of synapses and neuromuscular junctions (Slater, ; Ching et al, ; Nishimaru and Kudo, ).…”

Section: Discussionmentioning

confidence: 99%

Correlation between electrophysiological properties, morphological maturation, and olig gene changes during postnatal motor tract development

Cai

Shields

Zhang

et al. 2013

Developmental Neurobiology

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Background Functional maturation of the nervous system in postnatal (PN) animals is a progressive process that may be assessed using evoked potentials of the auditory, visual, or somatosensory systems. This study investigated electrophysiological and histological changes as well as alterations of myelin relevant proteins of descending motor tracts in rat pups. MEP responses were recorded bi-weekly from postnatal (PN) week-1 to week-9 (adult). Results MEP latencies in PN week-1 rats averaged 23.7 milliseconds and became shorter during early maturation, stabilizing at 6.6 milliseconds at PN week-4. During maturation there was a rapid increase in the conduction velocity (CV). The CV increased from 2.8 ± 0.2 at PN week-1 to 35.2 ± 3.1 mm/ms at PN week-8 which represented functional maturation. Histology of the spinal cord and sciatic nerves revealed progressive axonal myelination. Expression of the oligodendrocyte precursor markers PDGFRα and NG2 were gradually down-regulated in spinal cords, and myelin-relevant proteins such as GalC, CNP, and MBP were increased during maturation. Oligodendrocyte-lineage markers Olig2 and MOG, specifically expressed in myelinated oligodendrocytes, peaked at approximately PN week-3 and were down-regulated thereafter. A similar expression pattern was also observed in neurofilament M/H subunits (NF-M/H). Noticeably, NF-M/H was extensively phosphorylated in adult spinal cords but not in neonatal spinal cords, suggesting an increase in axon diameter and myelin formation. Ultra-structural morphology of axon and myelin sheaths in the ventrolateral funiculus (VLF) showed axon myelination of the VLF axons (99.3%) at PN week-2, while only 44.6% were sheathed at PN week-1. Furthermore, increased axon diameter and myelin thickness in both the VLF and sciatic nerves were highly correlated to the CV (rs>0.95). Conclusions Results from this study indicate that MEPs may be a predicator for the morphological maturity and integrity of myelinated axons in descending motor tracts.

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Changes in motoneuron excitability during postnatal life in the mouse

Cited by 5 publications

References 14 publications

High-Density Flexible Parylene-Based Multielectrode Arrays for Retinal and Spinal Cord Stimulation

High-Density Flexible Parylene-Based Multielectrode Arrays for Retinal and Spinal Cord Stimulation

Long-term spinal reflex studies in awake behaving mice

Correlation between electrophysiological properties, morphological maturation, and olig gene changes during postnatal motor tract development

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