Enhancement of voluntary motor function following spinal cord stimulation--case study

One patient with an incomplete traumatic myelopathy underwent epidural spinal cord stimulation for the management of severe intractable spasms, which were abolished by the stimulation. After several months of stimulation, the patient regained some voluntary motor function in the lower extremities. Voluntary motor control of the left quadriceps was present only when spinal cord stimulation was activated and stopped immediately after it was turned off. The effects could be consistently reproduced. EMG polygraphic recordings confirmed the results.     

Dynamics of changes in somatosensory input to the motor cortex following lesion of somatosensory cortical areas in dogs

The pattern of change produced in somatosensory evoked potential (EP) in the forelimb projection area within the motor cortex (MI) following lesion of the projection area of the same limb in the somatosensory cortex (SI) or in parietal cortex area 5 was investigated during chronic experiments on waking dogs. Amplitude of the initial positive — negative wave of EP declined to 28–63% of preoperational level in all cases. No significant recovery of EP was noted for three weeks. Thus, a correlation between change in EP and spontaneous recuperation of the precision motor response occurring within two weeks after lesion of the SI did not exist. Nor was EP reinstated in the MI after ablation of area 5, despite complete but gradual reinstatement of EP (after an initial decline to 53%) in the nearby SI region. This protracted depression of EP seems to have been associated with breakdown of somatotopic sensory input from the SI or from area 5 to the MI, since EP in the motor cortex of the intact hemisphere and the hindlimb projection area within the MI on the lesioned side either remained unchanged or recovered within a week or two.Institute of Higher Nervous Activity and Neurophysiology, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 22, No. 1, pp. 61–68, January–February, 1990.     

The neurite growth stimulating effect of terrilytin on sensory neurons and the spinal cord in tissue culture

Terrilytin (a protease) was found to promote neurite extension in chick embryo dorsal root ganglia and spinal cord in vitro. This protease was active at the concentration 10-50 ng/ml, which provided extensive neurite outgrowth in the bioassay, compared to the control. Terrilytin may be used for stimulating regenerating processes in nervous tissue.     

Assessment of the functional state of the cerebral cortex in rabbits according to electroencephalographic findings using a computer diagnostic system]

Computer estimation of the current functional state of the cerebral cortex in rabbits by the EEG data permitted to distinguish its peculiarities in dark and light adaptation of different duration under the action of nembutal; individual peculiarities of the cerebral cortex activity were revealed in various rabbits. The automatic converter system and that of recording and analysis of multiprocess information (apromin system) and computer diagnostic system (mds) were used in complex for the multistage processing of the multiprocess information. Final results are presented on the plane as points reflecting multidimentional images of the current functional states of the cerebral cortex in animals.     

Motor training induces experience-specific patterns of plasticity across motor cortex and spinal cord.

The motor cortex and spinal cord possess the remarkable ability to alter structure and function in response to differential motor training. Here we review the evidence that the corticospinal system is not only plastic but that the nature and locus of this plasticity is dictated by the specifics of the motor experience. Skill training induces synaptogenesis, synaptic potentiation, and reorganization of movement representations within motor cortex. Endurance training induces angiogenesis in motor cortex, but it does not alter motor map organization or synapse number. Strength training alters spinal motoneuron excitability and induces synaptogenesis within spinal cord, but it does not alter motor map organization. All three training experiences induce changes in spinal reflexes that are dependent on the specific behavioral demands of the task. These results demonstrate that the acquisition of skilled movement induces a reorganization of neural circuitry within motor cortex that supports the production and refinement of skilled movement sequences. We present data that suggest increases in strength may be mediated by an increased capacity for activation and/or recruitment of spinal motoneurons while the increased metabolic demands associated with endurance training induce cortical angiogenesis. Together these results show the robust pattern of anatomic and physiological plasticity that occurs within the corticospinal system in response to differential motor experience. The consequences of such distributed, experience-specific plasticity for the encoding of motor experience by the motor system are discussed.     

Granulocyte-colony stimulating factor (G-CSF) improves motor recovery in the rat impactor model for spinal cord injury

Granulocyte-colony stimulating factor (G-CSF) improves outcome after experimental SCI by counteracting apoptosis, and enhancing connectivity in the injured spinal cord. Previously we have employed the mouse hemisection SCI model and studied motor function after subcutaneous or transgenic delivery of the protein. To further broaden confidence in animal efficacy data we sought to determine efficacy in a different model and a different species. Here we investigated the effects of G-CSF in Wistar rats using the New York University Impactor. In this model, corroborating our previous data, rats treated subcutaneously with G-CSF over 2 weeks show significant improvement of motor function.     

Neuronal correlates of the motor function of the cerebral motor cortex

Modern ideas about the motor cortex neuronal mechanisms ensuring the initiation and correction of the instrumental manipulational movements in mammals have been analysed. A close correlation has been established to exist between the neuronal activity and various characteristics of movement including those that are not induced by muscle force. The role of somatic afferentation in the formation and realization of the movement programme is analysed as well as in motor output modulation by means of fast feedback.     

Functional consequences of motor unit recruitment order reversals following spinal cord transection in cat

Motoneuron recruitment order determinations were made for acute, 2-week chronic, and 3-month chronic spinal cats by comparing cutaneous nerve stimulation thresholds for evoking single unit tibialis anterior (TA) electromyogram (EMG) spikes of different sizes. Recruitment order was largely ( approximately 80%) orderly (small spikes recruited at lower stimulus intensities than large spikes) in acute and 3-month chronic spinal animals. However, in 2-week chronic spinal animals recruitment order was reversed, with large units more often recruited at lower stimulus intensities than small units ( approximately 65%). Morphological analyses of TA muscle fibers suggested that fiber size changes were unlikely to account for the dramatic alterations in recruitment order results of the 2-week chronic spinal animals. Additional studies suggested that the recruitment order reversal in the 2-week chronic animals coincided with an enhanced reflex neural output (increased recruitment or reflex gain) for the flexion reflex which compensated for disuse atrophy related decreases in flexor muscle force generation capability in these animals. The data from 2-week chronic spinal animals represent a functionally significant example of deviation from the normal size principle of motoneuron recruitment order as the corresponding reflex gain increases can enhance the rapidity of motor function recovery (standing, locomotion) following spinal injury.     

Amino acid incorporation into the protein of mitochondrial preparations from cerebral cortex and spinal cord

1. Washed guinea-pig cerebral-cortex mitochondria incorporate [(14)C]leucine into their protein at a rate comparable with the rates reported for liver or heart mitochondria only if the mitochondria are separated from myelin and nerve endings by density-gradient centrifugation. 2. The non-mitochondrial components (myelin and nerve endings) of brain mitochondrial preparations incorporated [(14)C]leucine at a negligible rate. 3. The mitochondria do not require an exogenous supply of energy or a full supply of amino acids to support the process. 4. The incorporation rate was linear up to 2hr. aerobic incubation at 30 degrees and was inhibited by chloramphenicol, only slightly by actinomycin D and not by penicillin or pretreatment with ribonuclease. The observed incorporation is considered to be unlikely to be due to contaminating cytoplasmic ribosomes or bacteria. 5. The process was also studied in mitochondrial preparations from rabbit cerebral cortex and spinal cord.