[The enhancement of the reflex reactions of the rat spinal cord after ablation of the cerebellum]. / Usilenie reflektornykh reaktsii spinnogo mozga krys posle udaleniia mozzhechka.

The character of evoked monosynaptic responses of spinal cord 3 weeks after total or partial ablation of cerebellum was studied on white rats. There was a substantial increase of amplitude of this response on the side of hemicerebellectomy and of animals with total cerebellectomy. In acute experiments cutting of spinal cord does not remove hyperreflexia.

[Effect of various neurotropic drugs on chronic hyperreflexia in rats after cordotomy]. / Vplyv deiakykh neirotropnykh rechovyn na hiperrefleksiiu u khronichno spinalizovanykh shchuriv.

Substances modulating calcium permeability of cell membrane (verapamil imidazol, 4-aminopyridine), decreasing motor activity (meprobamate) and blocking adrenoreceptors (clophelin, propranolol, droperidol, aminazine++ have been studied for their action on the monosynaptic discharge of the ventral roots (MD VR) reinforced due to chronic cutting of the spinal cord. It is found that verapamil and meprobamate depress more strongly MD VR of rats with chronic cutting of the spinal cord than of those with the acute one. Imidazol and 4-aminopyridine reinforcing MD VR of rats with acute cutting of the spinal cord have no influence on the analogous index of rats with chronic cutting of the spinal cord. Adrenoblockers do not change the amplitude of MD VR in both groups of the animals.

[Change in the background afferent influx to the spinal cord after transsecting the sciatic nerve and early enhancement of monosynaptic reflexes]. / Izmenenie fonovogo afferentnogo pritoka k spinnomu mozgu posle pererezki sedalishchnogo nerva i rannee usilenie monosinapticheskikh refleksov.

Background impulse activity (BIA) of separate fibres of dorsal roots of 5 lumbar segment of rats after one-sided cutting of the sciatic nerve which caused early enhancement of monosynaptic segmental reflexes (5 days after operation) has been recorded. It is revealed that afferent fibres with BIA are found more rarely on side of cutting than on the opposite side and frequency of background activity is lower than in the opposite root. It is concluded that development of spontaneous activity of the spinal ganglion neurons after cutting nerves does not ensure a higher BIA level in afferent fibres. The given phenomenon cannot be a reason of early enhancement of monosynaptic reflexes after the nerve cutting.

[Evoked activity of spinal cord neurons in the early period after cutting the sciatic nerve]. / Vyzvannaia aktivnost' neironov spinnogo mozga v rannie sroki posle pererezki sedalishchnogo nerva.

The character of evoked activity of motoneurons, interneurons and Renshaw cells of white rats in low lumbar segments of the spinal cord was studied 5 days after cutting of sciatic nerves. A trustworthy rise of the amplitude of the excited postsynaptic potential (EPSP) of motoneurons on the side of nerve cutting was found. No reliable change of the membrane potential and threshold of the action potential emergence in these motoneurones was observed. Character of evoked activity of the Renshaw cells and interneurons did not differ essentially from the same of animals with the intact nerve. Possible mechanisms taking part in rising of the EPSP amplitude after cutting of the nerve are discussed.

[The possible role of changes in calcium conduction in the early enhancement of spinal reflex responses after dissection of the sciatic nerve]. / Vozmozhnaia rol' izmenenii kal'tsievoi provodimosti v rannem usilenii spinal'nykh reflektornykh otvetov posle pererezki sedalishchnogo nerva.

Effects of imidazol, 4-aminopyridin and verapamil on evoked monosynaptic responses 5-7 days after cutting of the sciatic nerve have been studied in white rats. Imidazol induced no changes for certain 4-aminopyridin increased and verapamil decreased amplitude of responses on the side of cutting nerve.

[Excitation and inhibition of highly excitable reflex curves in chronically denervated albino rats]. / Vozbuzhdenie i tormozhenie v povyshenno vozbudimykh reflektornykh dugakh u khronicheski spinalizirovannykh belykh krys.

The animals were selected with spastic syndrome and enlarged amplitude of monosynaptic segmental reflex responses in 2-4 weeks after cutting of spinal cord at Th10 level. The processes of excitation and inhibition in lumbar segments of these animals were investigated. A reliable decrease of the presynaptic inhibition intensity was found after cutting of spinal cord. It is supposed that reduction of presynaptic inhibition plays a definite but not determinant role in developing hyperreflexia in chronically spinal white rat.

[Monosynaptic reflex responses of the spinal cord after the removal of the bones of the shin and thigh in white rats]. / Monosinapticheskie reflektornye otvety spinnogo mozga posle udaleniia kostei goleni i bedra u belykh krys.

To analyse the mechanisms of the increase of excitability of the spinal cord neurons after division of a nerve, the author studied the character of changes of the monosynaptic responses (MSR) of the ventral spinal cord root in albino rats 5 days and 4 weeks after removal of the bones of one hind limb. The MSR did not change in 5 days but intensified significantly in 4 weeks as compared to the monosynaptic responses on the contralateral side. The possible mechanisms of the increase of MSR after osteotomy and division of a nerve are discussed.

[Effect of tractotomy on the reflex activity of the lumbar segment of the spinal cord severed after sectioning of the sciatic nerve in the rat]. / Vliianie khordotomii na reflektornuiu aktivnost' poiasnichnogo otdela spinnogo mozga krys, narushennuiu posle pererezki sedalishchnogo nerva.

Electrical responses of the spinal cord roots of rats evoked by the preliminary cutting of nerve were investigated in 1, 3, 7 and 14 days after tractotomy. Mean amplitude of the monosynaptic reflex discharges in ventral roots on the side of nerve section is substantially higher 7 and 14 days after the tractotomy, than that of these responses 1 and 3 days after it.

[Characteristics of the potential of the dorsal surface of the spinal cord in a chronic deficit of afferent influences]. / K kharakteristikke potentsiala dorsal'noi poverkhnosti spinnogo mozga v usloviiakh khronicheskogo defitsita afferentnykh vliianii.

The changes of spinal cord dorsal potential (SCDP) has been studied on white rats to the posterior root stimulation at different intervals after sciatic nerve cutting. The increase of threshold, the decrease of amplitude, the growth of duration in some components of SCDP have been revealed on the site of the cutting. These changes were manifested at a less degree on the contralateral cutting site. A conclusion concerning the relative resistance of the spinal cord afferent system to the prolonged absence of peripheral afferent influence has been drawn.

[Changes in the evoked activity of the spinal cord after subarachnoidal administration of different amounts of colchicine]. / Izmenenie vyzvannoi aktivnosti spinnogo mozga posle subarakhnoidal'nogo vvedeniia razlichnykh kontsentratsii kolkhitsina.

Colchicine solution (0.3-0.01%) depressed the motor activity and evoked potentials of the spinal cord within 1-7 days after subarachnoidal injection of 0.05 ml in white rats. Monosynaptic response of the ventral root was more depressed than the spinal cord dorsum potential.

[Possible participation of nonimpulse factors in the increased excitability of partially deafferentated motor neurons]. / O vozmozhnosti uchastiia neimpul'snykh faktorov v povyshenii vozbudimosti chastichno deafferentirovannykh motoneironov.

The dynamics of strengthening of monosynaptic segmental response (MSR) in white rats has been studied after bilateral sciatic nerves cuts nearer to the spinal cord (high cut) and farther from it (low cut). 24 hours after the operation the irritation of the posterior root on the side of the high cut stimulates anterior root MSR of authentically larger amplitude than on the side of the low cut and much greater than in intact animals. 48 h, 72 h and 120 h after the operation MSR amplitude on both sides is considerably increased in comparison with the intact animals amplitude but authentically does not differ on the side of the low and high cuts. A connection may be suggested between the excitability increase process of partially deafferented motoneurons with the disturbance of axoplasmatic flow in central sections of the cut afferent fibres.

[Dynamics of monosynaptic response potentiation after nerve section at different distances from the spinal cord]. / Dinamika usileniia monosinapticheskikh otvetov posle pererezki nerva na razlichnom rasstoianii ot spinnogo mozga.

The nature of increase in amplitude of monosynaptic reaction of the anterior root to stimulation of the posterior root was studied in 18, 24 and 48 hrs after preliminary cutting of the sciatic nerve in rats. After a close to spinal cord nerve cutting the amplitude of monosynaptic reaction on the side of the cutting increased within 18 hrs whereas after the distant cutting the monosynaptic reaction increase only occurred within 24 hrs. The increase in sensitivity to nerve impulses of the partially deafferented motoneurons is due not to the switching off the background impulsation but to the impairment of the nonimpulse influence on motoneurons.