[Isometric forces generated by the human wrist: force trajectories with and without a visual target]. / Izometricheskie usiliia, razvivaemye zapiast'em cheloveka: silovye traektorii pri nalichii i otsutstvii vizual'noi tseli.

The force trajectories of isometric wrist flexor efforts and corresponding EMG activity of forearm muscles were studied in healthy subjects. A target effort of 50 N was developed after the sound signal: the target level and force trajectory were displayed on the TV indicator. Force trajectories under conditions of visual control, kinesthetic control (without a visual target) and with random alternation of these regimens were compared. Wrist flexor EMG latencies were approximately equal under visual and kinesthetic control and noticeably longer when these conditions were alternated randomly. Relative error of the target effort reproduction and duration of late components of force trajectories were higher in absence of the visual target. When visual and kinesthetic regimes were alternated randomly the delay between EMG onset and force trajectory initiation increased; its values correlated positively with the duration of the first force derivative increase. Formation of different strategies for force trajectory correction under different experimental conditions is discussed.

[Deterministic and stochastic identification of neurophysiologic systems]. / Deterministicheskaia i stokhasticheskaia identifikatsiia neirofiziologicheskikh sistem.

The paper deals with deterministic and stochastic identification methods applied to the concrete neurophysiological systems. The deterministic identification was carried out for the system: efferent fibres-muscle. The obtained transition characteristics demonstrated dynamic nonlinearity of the system. Identification of the neuronal model and the "afferent fibres-synapses-neuron" system in mollusc Planorbis corneus was carried out using the stochastic methods. For these purpose the Wiener method of stochastic identification was expanded for the case of pulse trains as input and output signals. The weight of the nonlinear component in the Wiener model and accuracy of the model prediction were quantitatively estimated. The results obtained proves the possibility of using these identification methods for various neurophysiological systems.

[Wiener analysis of transmission of signals of identified mollusk neurons]. / Vinerovskii analiz peredachi signalov identifitsirovannymi neironami molliuskov.

Mathematical model of spike train transmission by identified neurons of the mollusc Planorbis corneus was obtained by means of Wiener analysis. Poisson distributed sequences of near-threshold stimuli were used as input trains for construction and testing. It was shown that addition of terms sensitive to the nonlinear properties of the synapse-neuron system to the model decreased the model error from 25% to 16%. When comparing the mean square error value of the predicted model responses to testing stimuli and the real neuron responses to the same stimuli, the prediction error with allowance for nonlinear properties was established not to exceed 21%. Some questions connected with choosing adequate criteria for comparing model and experimental results are discussed.

[Determination of the topical organization of the discharges of identified mollusk neurons]. / Opredelenie topicheskoi organizatsii vykhodov identifitsirovannykh neironov molliuska.

Identified RPa1, RPa2 neurons of the right parietal ganglion of Planorbis corneus were investigated. Coherent analysis of accumulated electrical activity in periferal nerves and spike discharges in identified neurons was done. Using this analysis, the presence of axon processes of RPa1 and RPa2 cells in the left and right pallial nerves was determined. Some polysynaptic pathways activated by discharges of these neurons were demonstrated. It is shown that the topical organization of the outputs of the investigated neurons remains invariant for different preparations.

[Effect of blockers of pre- and post-synaptic inhibition on processes of habituation in the system of cutaneous sensitivity]. / Vliianie blokatorov pre- i postsinapticheskogo tormozheniia na protsessy privykaniia v sisteme kozhnoi chuvstvitel'nosti.

The role of pre- and postsynaptic inhibition in the habituation of spinal ascending neurons transmitting cutaneous sensory signals was studied in cat. Pharmacological blockade of these types of inhibition by strychnine, bicuculline and picrotoxin did not evoke substantial changes in initial suppression of neuronal discharges during prolonged high-frequency (more than 50 per s) stimulation. Neuronal responses to stimulation of a cutaneous nerve fibres were not influenced during habituation of the neuron evoked by stimulation of other converging cutaneous nerve fibres.

[Analysis of the spike activity of pairs of caudate nucleus neurons in cats]. / Analiz impul'snoi aktivnosti par neironov khvostatogo iadra koshki.

Spike activity of pairs of neurons was recorded simultaneously with a single microelectrode in the caudate nucleus of lightly anaesthetized immobilized cats. A high time correlation was observed in discharges of two neurons when their background activity showed group discharges. In case of unitary background activity, correlation between spike trains was observed only in 50% of the cells; it could be both of excitatory and inhibitory type. Many neuronal pairs exhibited negative short latency correlation in the 0--4 ms range. Electrical stimulation of different afferent inputs of the caudate nucleus caused minimal correlation between neuronal discharges and, on the contrary, abolished correlation between spontaneous discharges of the same pair of neurons. The presented results are discussed from the point of view of the caudate nucleus as an associative cerebral nucleus.

[Study of the natural activity of nerve fibers using the method of multi-channel coherent recording]. / Issledovanie estestvennoi aktivnosti nervnykh volokon s pomoshch'iu metoda mnogokanal'nogo kogerentnogo priema.

Spontaneous electrical activity was recorded with a six channel amplifier from the intact vagal nerve (cervical area) of the cat in acute experiments. The records obtained were summated using different delays between them induced by a computer for differentiation of the afferent activity from the efferent one and estimation of the proper conduction velocity. It is found that the most active afferent fibres have conduction velocity about 25 m/s.