[Experimental spinal cord contusion. I. An assessment of the state of the conductivity of different funiculi]. / Eksperimental'naia kontuziia spinnogo mozga. I. Otsenka sostoianiia provodimosti razlichnykh kanatikov.

Experiments were conducted on albino rats to study the changes of the amplitude and latency of maxima tract and synaptic components of the dorsal surface potential before and after spinal cord injury at the level of Th9. Dorsal surface potentials were recorded from L4 after stimulation in C2. The amplitude of tract and synaptic component maxima of the short latency potential were found to be considerably reduced after the injury. The latency of both components increased after the injury. The changes of the amplitude or latency of potentials evoked from different stimulated points of the cord were analysed. The possible mechanism of the revealed changes is discussed.

[Status of the spinal inhibitory reactions in humans subjected to hyperbaric oxygenation]. / Sostoianie spinal'nykh tormoziashchikh reaktsii v usloviiakh giperbaricheskogo vozdeistviia na cheloveka.

The state of human spinal inhibition responses under normo- and hyperbaric pressure (6.5 ata) was comparatively studied. The paired stimulation method has been used to estimate resetting of tested monosynaptic reflex in the 20-900 ms interval of paired stimulation at rest or against the background of supraspinal modulation of spinal reflective processes (Jendrassik manoeuvre, voluntary plantar flexion) were studied. The depression of inhibition reactions under hyperbaric pressure identical to that during the supraspinal modulation under normobaric conditions is shown. It is supposed that these influences on spinal reflection processes are caused by the same neuronal mechanism.

[Load dynamics on the extremities during locomotion in rats before and after deafferentation]. / Dinamika nagruzki na konechnosti pri lokomotsii u krys do i posle deafferentatsii.

Stepping of an intact animal was characterized by a fast rise to maxima, maintenance on this level and fast decay of limbs' loading in the stance phase. In deafferentated rats a slow rise without maintenance in that phase was found. The role of afferent input intensity in reflex control of movements is discussed.

[Descending modulation of monosynaptic reflexes after traumatic injury of the cat spinal cord]. / Niskhodiashchaia moduliatsiia monosinapticheskikh refleksov posle travmaticheskogo povrezhdeniia spinnogo mozga u koshek.

Studies of the descending modulation of monosynaptic reflex responses have revealed that electrical stimulation of dorsolateral, ventrolateral and ventral funiculi in C2 facilitated and suppressed test responses of intact animals, but evoked only suppression of spinal reflexes after injury of the spinal cord. The obtained data have shown that descending pathways which transmit facilitatory influences are more vulnerable to injury of the spinal cord.

[Modulation of the segmental reflex reactions during real locomotion in rats]. / Moduliatsiia segmentarnykh reflektornykh reaktsii vo vremia real'noi lokomotsii krys.

Studies of low- and high-threshold reflex reactions evoked by dorsal root stimulation in different phases of real locomotion (swimming) in rat were performed. The pronounced facilitation of low- and high-threshold muscle responses in the period of particular muscle activity and their extensive depression in the period coupled with antagonist muscle activity were revealed. The low-threshold stimulation did not change the temporal and amplitude parameters of locomotor movements, but high-threshold one influenced the amplitude and frequency of locomotor movements. The functional significance and possible mechanisms of modulation of the influence of peripheral afferents are discussed.

[Phase-dependent changes in the posterior root potentials during real locomotion in rats]. / Fazozavisimye izmeneniia zadnekoreshkovykh potentsialov vo vremia real'noi lokomotsii krys.

Dorsal root potentials (DRP) were studied during two kinds of the real locomotion (swimming and stepping) of rats. Two negative DRP waves were observed in one locomotor cycle. One wave coincided with stance on extension, while the other one--with swing phase. Dependence between the DRP amplitude and intensity of afferent input during the real locomotion and passive movements of hind limbs was established. It is concluded that wave-like changes of DRP in the real locomotion are mainly due to the influences from peripheral afferents.

[Descending modulation of the reflex reactions of the spinal motor neurons in human spinal cord damage]. / Issledovanie niskhodiashchei moduliatsii reflektornykh reaktsii spinal'nykh motoneironov pri povrezhdeniiakh spinnogo mozga u liudei.

Changes of H-reflexes amplitude and Ia-inhibition intensity before, during and after voluntary contractions of skeletal muscles were studied in healthy subjects and patients with midthoracic injury of the spinal cord. The voluntary actions induced facilitation of H-reflexes and suppression of Ia inhibition in healthy people and in patients with paraparesis. In patients with paraplegia these voluntary actions induced either the depression of H-reflexes and increase of Ia inhibition intensity or caused no effect on these reactions. A relation between reflex reaction changes and posttraumatic structural and functional disturbance of descending paths were discussed.

[Antidromic impulsation of the dorsal roots at the time of real locomotion in rats]. / Issledovanie antidromnoi impul'satsii dorsal'nykh koreshkov vo vremia real'noi lokomotsii krys.

The antidromic activity of dorsal roots during swimming and stepping of rats was studied. It consisted of phase-dependent and tonic components of antidromic potentials. The most pronounced correlation was found between the intensity of antidromic activity and afferent input while the relation between the antidromic activity and efferent output was less appreciable. Possible sources for the initiation of antidromic activity and the significance of presynaptic depolarization in the spinal reflex control are discussed.

[Kinematic analysis of the different types of locomotor movement in rats after deafferentation]. / Analiz kinematiki razlichnykh vidov lokomotornykh dvizhenii u krys posle deafferentatsii.

Comparative analysis of kinematics of rat hindlimb movements during different kind of locomotion (swimming, walking, hindlimb swimming but forelimb walking) was performed. After deafferentation an increase of the locomotor rhythm frequency and a decrease of the movement amplitude of hindlimb joints were common features for all kinds of the locomotion. This indicates that the above parameters of locomotor movements were formed by afferent influences. A decrease of the movement amplitude and of the EMG activity which were evoked after deafferentation were minimal for swimming and maximal for walking. The role of afferent influences in formation of different locomotion patterns is discussed.

[Reflex component of the swing phase: a comparative analysis of locomotion in intact and deafferentated rats]. / Reflektornyi komponent fazy perenosa: sravnitel'nyi analiz lokomot sii intaktnykh i deafferentirovannykh krys.

Comparative analysis of hindlimb biomechanics and EMG activity with different kinds of locomotion before and after bilateral LI-S2 spinal cord deafferentation were performed in rats. A delay of the onset and increase of duration of knee and ankle joint flexion, but not hip joint flexion were revealed after deafferentation. It was accompanied by reinforcing of the F-period of the swing phase which was more prominent during walking than swimming. The amplitude and duration of the muscle activity decreased, in particular, during the F-period of the swing phase. The role of afferent inflow in the formation of the F-phase of the locomotor cycle is discussed.

[Phase-modulated antidromic action potentials in the dorsal root of the rat during locomotion]. / Faznomodulirovannye antidromnye potentsialy deistviia v dorsal'nom koreshke krysy vo vremia lokomotsii.

Discharges of antidromic spike potentials (ASP) were recorded from the rat dorsal root during locomotion. Tonic and phasic components were revealed in discharges of ASP. The phase-dependent modulation of phasic component was observed during locomotion. The role of ASP as a possible mechanism for restriction of afferent input was discussed.

[Uncoupling of modulation of the afferent flow and phasic activity of muscles during a period of unstable locomotion in the rat]. / Nesopriazhennost' moduliatsii afferentnogo pritoka i faznoi aktivnosti myshts v period nestabil'noi lokomotsii u krys.

During unstable locomotion which is characterised by irregular, low-amplitude movements different types of uncoupling between modulation of the amplitude and temporal characteristics of the afferent influx and efferent activity were revealed.

[Comparative analysis of the kinematics of hindlimb movements in different forms of locomotion in the rat]. / Sravnitel'nyi analiz kinematiki dvizhenii zadnei konechnostei krysy pri razlichnykh vidakh lokomotsii.

Changes in the locomotor cycles and joint angles during walking and swimming were comparatively analyzed in rats. Differences in hindlimb movements with or without participation of the forelimb were shown as well as differences between swing phases during walking and swimming. The role of central spinal processes and effects of peripheral afferents in organization of the different kind of locomotions is discussed.

[Changes in spino-bulbo-spinal reflexes during activation and inactivation of the locus coeruleus in the cat]. / Izmenenie spino-bul'bo-spinal'nykh refleksov pri aktivatsii ili inaktivatsii golubogo piatna u koshki.

In cats anesthetized with chloralose the long lasting depression of spino-bulbo-spinal (SBS) discharges following short repetitive stimulation of the locus coeruleus (LC) was revealed. Inactivation of LC by procaine microinjections resulted in remarkable enhancement of SBS discharges. These data evidence for prominent inhibitory modulatory influences from locus coeruleus on SBS reflexes which are presumably performed mainly on supraspinal level.

[Neuronal organization of coeruleo-spinal connections in the cat]. / Neironnaia organizatsiia tseruleo-spinal'nykh sviazei u koshki.

Electrical stimulation of locus coeruleus in anesthetized cats was accompanied by a decrease in the inhibitory action of flexor reflex afferents (FRA) on extensor motoneurons. No changes in excitatory reactions of spinal motoneurons were observed. Microinjections of aspartic acid or chlorpromazine depressed FRA inhibitory action; injection of procaine and noradrenaline potentiated this action. The responses of differente spinal interneurons during activation of locus coeruleus were also studied. A conclusion is made that the inhibitory action of FRA is depressed by coeruleo-spinal influences on the level of the last-order inhibitory interneuron of the FRA system.

[Changes in inhibitory responses in the spinal cord of the cat induced by stimulation of suprasegmental structures during rhythmic stimulation of the locus coeruleus]. / Izmeneniia tormoziashchikh reaktii v spinnom mozge koshki, vyzvannykh stimuliatsiei nadsegmentarnykh struktur, pri ritmicheskom razdrazhenii golubogo piatna.

Effects of rhythmic locus coeruleus stimulation on spinal reactions evoked by cortico-, reticulo- and vestibulospinal influences were studied in anesthetized decerebellized cats. Two-component inhibitory reactions in extensor and excitatory-inhibitory reactions in flexor motoneurons were found after the stimulation of the motor cortex or the medullary reticular formation. The locus coeruleus stimulation depressed the late component of responses in both group of motoneurons but had a less influence on the early inhibitory and excitatory components. No changes were observed in reactions evoked by vestibulospinal influences in the extensor and flexor motoneurons. Mechanisms of descending influences of locus coeruleus on spinal reactions evoked by primary afferents and supraspinal structures are discussed.

[Changes in the postsynaptic responses of spinal cord motor neurons against a background of rhythmic stimulation of the locus coeruleus]. / Issledovanie izmenenii postsinapticheskikh reaktsii v motoneironakh spinnogo mozga na fone ritmicheskoi stimuliatsii golubogo piatna.

Influences of locus coeruleus rhythmical stimulation on the postsynaptic reactions of spinal motoneurons were studied in chloralose anesthetized cats. IPSPs evoked by flexor reflex afferent (FRA) stimulation were inhibited, but EPSPs evoked by FRA and PSPs evoked by low-threshold muscle afferents stimulation were unchanged under these conditions. The inhibition of IPSPs disappeared in reserpine-pretreated animals. Both IPSPs and EPSPs evoked by FRA stimulation were diminished also during rhythmical stimulation of nucleus reticularis pontis oralis. However this effect was not of monoaminergic nature because it was present in reserpine-pretreated animals.

[Effect of drugs potentiating or inhibiting the activity of locus coeruleus neurons on various types of spinal inhibition in the cat]. / Vliianie veshchestv, potentsiruiushchikh ili ugnetaiushchikh aktivnost' neironov golubogo piatna, na nekotorye vidy spinal'nogo tormozheniia u koshki.

Microinjections of aspartate or chlorpromazine (which increase the background firing of many central neurons) into region of locus coeruleus of decerebellized cats anaesthetized with chloralose diminished the inhibitory action of flexor reflex afferents on the extensor monosynaptic reflexes but had no effect on the excitatory action from these afferents on the flexor reflexes. In some experiments the injections of these drugs decreased also recurrent inhibition of extensor motoneurons. Microinjections of procaine or norepinephrine (which reduce the background of firing of central neurons) in the same region increased the inhibitory action of the flexor reflex afferents and the recurrent inhibition of the extensor monosynaptic reflexes and had no effect on their excitatory action on the flexor reflex. The role of tonic activity of locus coeruleus in controlling the spinal inhibition evoked from the flexor reflex afferents is discussed.