scholarly journals A Functional Motor Unit in the Culture Dish: Co-culture of Spinal Cord Explants and Muscle Cells

10.3791/3616 ◽  
2012 ◽  
Author(s):  
Anne-Sophie Arnold ◽  
Martine Christe ◽  
Christoph Handschin
Keyword(s):  
Spinal Cord ◽  
Motor Unit ◽  
Muscle Cells ◽  
Culture Dish

Reduction of Common Synaptic Drive to Ankle Dorsiflexor Motoneurons During Walking in Patients With Spinal Cord Lesion

2005 ◽  
Vol 94 (2) ◽  
pp. 934-942 ◽  
Author(s):  
N. L. Hansen ◽  
B. A. Conway ◽  
D. M. Halliday ◽  
S. Hansen ◽  
H. S. Pyndt ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Motor Unit ◽  
Healthy Subjects ◽  
Motor Units ◽  
Central Peak ◽  
Spinal Cord Lesion ◽  
Short Term ◽  
Physiological Markers ◽  
Synaptic Drive ◽  
Cord Lesion

It is possible to obtain information about the synaptic drive to motoneurons during walking by analyzing motor-unit coupling in the time and frequency domains. The purpose of the present study was to compare motor-unit coupling during walking in healthy subjects and patients with incomplete spinal cord lesion to obtain evidence of differences in the motoneuronal drive that result from the lesion. Such information is of importance for development of new strategies for gait restoration. Twenty patients with incomplete spinal cord lesion (SCL) participated in the study. Control experiments were performed in 11 healthy subjects. In all healthy subjects, short-term synchronization was evident in the discharge of tibialis anterior (TA) motor units during the swing phase of treadmill walking. This was identified from the presence of a narrow central peak in cumulant densities constructed from paired EMG recordings and from the presence of significant coherence between these signals in the 10- to 20-Hz band. Such indicators of short-term synchrony were either absent or very small in the patient group. The relationship between the amount of short-term synchrony and the magnitude of the 10- to 20-Hz coherence in the patients is discussed in relation to gait ability. It is suggested that supraspinal drive to the spinal cord is responsible for short-term synchrony and coherence in the 10- to 20-Hz frequency band during walking in healthy subjects. Absence or reduction of these features may serve as physiological markers of impaired supraspinal control of gait in SCL patients. Such markers could have diagnostic and prognostic value in relation to the recovery of locomotion in patients with central motor lesions.

Development of neuromuscular synapses

1983 ◽  
Vol 63 (3) ◽  
pp. 915-1048 ◽  
Author(s):  
M. R. Bennett
Keyword(s):  
Motor Unit ◽  
Muscle Cells ◽  
Terminal Branch ◽  
Quantal Release ◽  
Synaptic Site ◽  
Neuromuscular Synapses ◽  
A Site ◽  
Threshold Amount ◽  
Neuron Soma ◽  
Secretory Capacity

Quantal secretion at nerve terminals in mature muscles depends on the number of terminal branches and the size of release sites (sect. VB4). The physical length of SBL determines the length of terminal branch that can be laid down in a reinnervation experiment (sect. IVA4). A limit is set on the total length of terminal branches formed by a motoneuron; this limit is determined by the amount of TF (sect. IVB) made available from the neuron soma to the peripheral branches of the neuron (sect. VC). As a result of this limit, not all SBL needs to be occupied at a site by terminal branches. The SBL eventually disappears if it is not occupied by terminal branches (sect. IVA2). If a muscle is relatively inactive, it synthesizes and releases at synaptic sites additional amounts of NGF, which stimulates the growth of additional terminal branches. These may secrete sufficient amounts of AF to induce the formation of new SRs with associated SBL. In these circumstances a new synaptic site is formed or an extension of an existing site is created. If the size of a motor unit is decreased, the enhanced release of TF at the remaining terminals ensures that each occupies all the SBL at the synaptic site. Furthermore the enhanced release of AF per terminal induces more SBL, allowing additional terminal branches on the muscle cells to be established. Neither of these changes occurs unless the threshold amount of NGF is available from the muscle to stabilize the terminals. If this condition is met, an increase in quantal release per terminal occurs after reducing the size of a motor unit (sect. VC). An increase in quantal release per terminal also occurs after inactivation of a muscle. Such inactivation leads to an enhanced release of NGF per synaptic site (sect. VA4). Extra terminals may then form if sufficient TF is available; these may innervate existing but empty synaptic sites. In rare circumstances the extra terminal may induce SBL and innervate these new sites if sufficient AF is available. In both cases the quantal release per terminal increases. During development the secretory capacity of the axon terminal depends on the muscle cells with which it synapses. This secretory capacity can be enhanced either by increasing the number of terminal branch pairs or by increasing the secretory capacity of individual release sites. If two terminals innervate a synaptic site, their individual secretory capacity is reduced--in these circumstances the terminal's secretory capacity depends on the amount of NGF available to the terminal; two terminals must share their NGF.

A soluble factor (<4000 Da) from chick spinal cord blocks slow hyperpolarizing afterpotentials in cultured rat muscle cells

1986 ◽  
Vol 30 (2) ◽  
pp. 274-277 ◽  
Author(s):  
Benjamin A. Suarez-Isla ◽  
James W. Cosgrove ◽  
Jeffrey M. Thompson ◽  
Stanley I. Rapoport
Keyword(s):  
Spinal Cord ◽  
Muscle Cells ◽  
Soluble Factor ◽  
Rat Muscle ◽  
Chick Spinal Cord
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