scholarly journals In Vivo Recording of Nerve Conduction Velocity of Spinal CNS Fibers in the Mouse

2017 ◽  
pp. 545-548
Author(s):  
P. DIBAJ ◽  
E. D. SCHOMBURG
Keyword(s):  
Spinal Cord ◽  
Conduction Velocity ◽  
Nerve Conduction ◽  
Nerve Conduction Velocity ◽  
Compound Action Potential ◽  
Lumbar Spinal Cord ◽  
Measured Distance ◽  
Spinal Cord Level ◽  
Lumbar Spinal

Anesthetic and surgical procedures and an electrophysiological method were developed for recording nerve conduction velocity (NCV) of CNS fibers in the murine spinal cord. Under intravenous anesthesia and artificial ventilation the lumbar spinal cord segments L1 to L4 and dorsal roots L3 to L5 on the left side were exposed by laminectomy. After stimulation of the dorsal root L4, a compound action potential (CAP) was recorded at the ipsilateral left fasciculus gracilis at the spinal cord level L1. The latency from stimulation to the CAP together with the measured distance between the electrodes was used for the determination of the NCV. NCV of the fastest fibers in the fasciculus gracilis was observed to be approximately 28 m/s. Reversible decrease of the NCV was measured, in vivo, under general hypothermia. The technique described serves for in vivo electrophysiological investigations of spinal central fibers in wildtype and mutant mice.

Active Dendritic Integration of Inhibitory Synaptic Inputs In Vivo

2003 ◽  
Vol 90 (6) ◽  
pp. 3617-3624 ◽  
Author(s):  
Jason J. Kuo ◽  
Robert H. Lee ◽  
Michael D. Johnson ◽  
Heather M. Heckman ◽  
C. J. Heckman
Keyword(s):  
Spinal Cord ◽  
Lumbar Spinal Cord ◽  
Standard State ◽  
Dendritic Integration ◽  
Local Inhibition ◽  
Highly Active ◽  
Linear Integration ◽  
Inward Currents ◽  
Lumbar Spinal

Synaptic integration in vivo often involves activation of many afferent inputs whose firing patterns modulate over time. In spinal motoneurons, sustained excitatory inputs undergo enormous enhancement due to persistent inward currents (PICs) that are generated primarily in the dendrites and are dependent on monoaminergic neuromodulatory input from the brain stem to the spinal cord. We measured the interaction between dendritic PICs and inhibition generated by tonic electrical stimulation of nerves to antagonist muscles during voltage clamp in motoneurons in the lumbar spinal cord of the cat. Separate samples of cells were obtained for two different states of monoaminergic input: standard (provided by the decerebrate preparation, which has tonic activity in monoaminergic axons) and minimal (the chloralose anesthetized preparation, which lacks tonic monoaminergic input). In the standard state, steady inhibition that increased the input conductance of the motoneurons by an average of 38% reduced the PIC by 69%. The range of this reduction, from <10% to >100%, was proportional to the magnitude of the applied inhibition. Thus nearly linear integration of synaptic inhibition may occur in these highly active dendrites. In the minimal state, PICs were much smaller, being approximately equal to inhibition-suppressed PICs in the standard state. Inhibition did not further reduce these already small PICs. Overall, these results demonstrate that inhibition from local spinal circuits can oppose the facilitation of dendritic PICs by descending monoaminergic inputs. As a result, local inhibition may also suppress active dendritic integration of excitatory inputs.

scholarly journals Characterization of DTI Indices in the Cervical, Thoracic, and Lumbar Spinal Cord in Healthy Humans

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Rachael L. Bosma ◽  
Patrick W. Stroman
Keyword(s):  
Spinal Cord ◽  
Mean Diffusivity ◽  
Lumbar Spinal Cord ◽  
Single Shot ◽  
Tissue Properties ◽  
Healthy Humans ◽  
Diffusion Weighted Images ◽  
Lumbar Spinal

The aim of this study was to characterizein vivomeasurements of diffusion along the length of the entire healthy spinal cord and to compare DTI indices, including fractional anisotropy (FA) and mean diffusivity (MD), between cord regions. The objective is to determine whether or not there are significant differences in DTI indices along the cord that must be considered for future applications of characterizing the effects of injury or disease. A cardiac gated, single-shot EPI sequence was used to acquire diffusion-weighted images of the cervical, thoracic, and lumbar regions of the spinal cord in nine neurologically intact subjects (19 to 22 years). For each cord section, FA versus MD values were plotted, and a k-means clustering method was applied to partition the data according to tissue properties. FA and MD values from both white matter (averageFA=0.69, averageMD=0.93×10−3 mm2/s) and grey matter (averageFA=0.44, averageMD=1.8×10−3 mm2/s) were relatively consistent along the length of the cord.

scholarly journals Functional and Structural Changes in the Corticospinal Tract of Streptozotocin-Induced Diabetic Rats

2021 ◽  
Vol 22 (18) ◽  
pp. 10123
Author(s):  
Ken Muramatsu ◽  
Satoshi Shimo ◽  
Toru Tamaki ◽  
Masako Ikutomo ◽  
Masatoshi Niwa
Keyword(s):  
Spinal Cord ◽  
Conduction Velocity ◽  
Corticospinal Tract ◽  
Morphological Changes ◽  
Cervical Spinal Cord ◽  
Diabetic Animal ◽  
Lumbar Spinal Cord ◽  
Dorsal Funiculus ◽  
Lumbar Spinal ◽  
G Ratio

This study aimed to reveal functional and morphological changes in the corticospinal tract, a pathway shown to be susceptible to diabetes. Type 1 diabetes was induced in 13-week-old male Wistar rats administered streptozotocin. Twenty-three weeks after streptozotocin injection, diabetic animals and age-matched control animals were used to demonstrate the conduction velocity of the corticospinal tract. Other animals were used for morphometric analyses of the base of the dorsal funiculus of the corticospinal tract in the spinal cord using both optical and electron microscopy. The conduction velocity of the corticospinal tract decreased in the lumbar spinal cord in the diabetic animal, although it did not decrease in the cervical spinal cord. Furthermore, atrophy of the fibers of the base of the dorsal funiculus was observed along their entire length, with an increase in the g-ratio in the lumbar spinal cord in the diabetic animal. This study indicates that the corticospinal tract fibers projecting to the lumbar spinal cord experience a decrease in conduction velocity at the lumbar spinal cord of these axons in diabetic animals, likely caused by a combination of axonal atrophy and an increased g-ratio due to thinning of the myelin sheath.

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