[A biomechanical invariant of automated movement]. / O biomekhanicheskom invariante avtomatizirovannogo dvizheniia.

Trained arm movements and two-link arm dynamics and control of arm movements model are investigated. It is found that for these movements the component of the movements energy dissipations in the control force potential is invariable during the outer force actions.

[Electrical activity of muscles during disturbances in the trajectory of single-joint motion in the arm]. / Elektricheskaia aktivnost' myshts pri vozmushchenii traektorii odnosustavnogo dvizheniia ruki.

Horizontal "extension-flexion" movement of human arm at the elbow joint was studied. Humans performed movements in accordance with the instruction to ignore sudden trajectory changes that arose by the arm during lengthening of different elastic rods with friction. It was shown by multi-dimension regression analysis that the electric activity of biceps and triceps muscles of the shoulder was correlated first of all with the work of load and then with loading force, muscle work and other mechanic and myographic characteristics. One could suppose that information on energy quantities was contained in afferentation signals of the nervous system to correct the program commands on the spinal level. The purpose of correction was to preserve constant quantity of energy expenditure, as well as accuracy and duration of movement.

[Clinical aspects, EEG and biophysical and biochemical parameters of the intracranial system in large fractionated-dose irradiation]. / Klinika, EEG i nekotorye biofizicheskie i biokhimicheskie parametry intrakranial'noi sistemy pri krupnofraktsionnom obluchenii.

Seven patients operated on for intracerebral tumors received a course of large fractionating irradiation during which the patients' clinical status, changes of the ventricular CSF pressure, intracerebral pressure of the interstitial liquid, biochemical parameters of the blood and CSF and the EEG summary rate were assessed over time. The patients' reaction was characterized by a moderately expressed change of the above parameters in response to irradiation which returned to normal within 12 hrs. following large fractionating irradiation.

[Pressure distribution in the cranial cavity]. / O raspredelenii davlenii v polosti cherepa.

Values of interstitial fluid pressure in surface layers of the human brain and of the pressure of the cerebrospinal fluid "bathing" the brain are presented. The results show a difference in these pressures. The analysis with a spherical model shows that intratissue structural (biomechanical) connections, and those between the brain, its membranes and cranium are extremely important in significantly weakening the transmission of the cerebrospinal fluid pressure to the cortex and surface layers of the brain.

[Response of cerebral bioelectrical activity to changes in the cerebrospinal fluid pressure of neurooncologic patients]. / Reaktsiia bioélektricheskoi aktivnosti mozga na izmenenie likvornogo davleniia u neiroonkologicheskikh bol'nykh.

The reaction of cerebral electric activity to induced changes in the cerebrospinal fluid pressure during examination of P-V dependence of the craniospinal cavity was appraised in 8 neuro-oncological patients in the postoperative period by means of spectral EEG analysis. Among 41 tests with artificial changes in CSF pressure decrease in CSF pressure was attended in 60 per cent of cases by an increase in the EEG p]ower by 6.4% on the average, while an increase in CSF pressure caused a decrease in EEG power by 8.6% on the average. In 40% of cases, however, a decrease in CSF pressure was attended not by an increase, but by a reduction of EEG power by 3.5% on the average; an increase in CSF pressure induced a rise in EEG power (by 3.7% on the average). The degree of the reactive changes in EEG power in response to induced CSF pressure fluctuations increased with deterioration of the patient's condition. Thus, rapid compression and decompression of the CSF system induces short-term (7 minutes at most) changes in EEG power. These changes are ambiguous both in direction and in degree of conspicuity.

[Intracerebral pressure and the EEG following graded changes in cerebrospinal fluid volume]. / Vnutrimozgovoe davlenie i EEG pri dozirovannom izmenenii ob"ema likvora.

The effect of graded change of the CSF amount on the clinical status, intracerebral pressure and brain bioelectrical activity was studied in 31 patients operated on for brain tumors of various sites. Normally, the graded change in the CSF amount made with an object of examining the biophysical characteristics of the intracranial system did not produce the impairment of the patients status. Discomfort sensation that occurred in rare cases was not a consequence of either hypo- or hypertension as such but of the absence of CNS ability to adapt rapidly to the changes of the pressure in the cranium. The graded change in the CSF amount and thus in the CSF pressure caused minimum transitory changes in the intracerebral pressure of interstitial liquid and in brain bioelectrical activity. The data obtained indicate the feasibility of studying the biophysic characteristics of the intracranial system by means of graded changes of the CSF amount in neurosurgical patients undergoing acute postoperative period.

[Pressure-volume relation in the craniospinal cavity in the presence of supra- and subtentorial pathology. II. Changes in local intracerebral pressure subsequent to cerebrospinal fluid compression and decompression of the brain]. / Sootnoshenie ob"em-davlenie v kraniospinal'noi polosti pri supra- i subtentorial'noi polosti pri supra- i subtentorial'noi patologii. Soobshchenie II. Izmenenie lokal'nogo vnutrimozgovogo davleniia pri likvornoi kompressii i dekompressii golovnogo mozga.

Comparative measurements of cerebrospinal fluid pressure (FP) and local intracerebral pressure of the interstitial fluid (ICPIF) both during their spontaneous changes and during artificial changes in cerebrospinal fluid volume were conducted in 15 neuro-oncological patients in the postoperative period. ICPIF pressure was measured by means of a double-layer perforated capsule perceiving pressure of the surrounding interstitial fluid. In patients who underwent removal of a tumor from the posterior cranial fossa ICPIF ranged from -15.8 to +9.5 mm Hg, and FP from 15 to 37.5 mm Hg. In patients subjected to removal of meningioma of the chiasmal-sellar area ICPIF ranged from -11.2 to +0.4 mm Hg, while FP ranged from 4 to 18.7 mm Hg. In artificial decrease in FP to 5 mm Hg and subsequent increase to 35-50 mm Hg, ICPIF changed as a rule, though only slightly (from 0.5 to 10 mm Hg), and often the changes in FP and ICPIF were opposite in direction. In approximately 1/3 of cases ICPIF did not change while the changes in FP ranged from 5 to 50 mm Hg. The possible causes of changes in intracerebral pressure in dosaged FP changes are discussed and a conclusion is drawn that the changes in ICPIF are not a simple reflection of FP dynamics but are linked with the effect exerted on the interstitial fluid by some factors among which are changes in intra-capillary pressure and tension in the cerebral tissue.

[Pressure-volume ratio in the craniospinal cavity in supra- and subtentorial pathology. I. Changes in cerebrospinal fluid pressure in cerebrospinal fluid compression and decompression of the brain]. / Sootnoshenie ob"em--davlenie v kraniospinal'noi polosti pri supra- i subtentorial'noi patologiii. Soobshchenie I. Izmenenie likvornogo davleniia pri likvornoi kompressii i dekompressii golovnogo mozga.

The p-V dependence in the craniospinal cavity was studied by the method of dosaged change in the cerebrospinal fluid volume in 15 neurooncological patients who underwent operation for tumor of the posterior cranial fossa in the chiasmal-sellar area. It is shown that this dependence, reflecting the biophysical properties of the intracranial system, has distinguishing features in patients with supra- and subtentorial pathology. For instance, in FP values close to zero the resilience of the intracranial system is higher in patients with supratentorial processes than in patients with subtentorial pathology. In artificial c.s.f. compression, intracranial system resilience grows gradually in patients with basal pathology and increases much more rapidly in patients with subtentorial pathology. The authors discuss the possible causes of the difference in P-V dependence in the groups of patients who were examined and the significance of the obtained information in substantiating intensive therapy in the immediate postoperative period.

[Comparative study of intracerebral and cerebrospinal fluid pressure in neurosurgical clinical practice]. / Sravnitel'noe izuchenie vnutrimozgovogo i likvornogo davlenii v neirokhirurgicheskoi klinike

Comparative measurements of cerebrospinal fluid pressure(CSPF), total local intrabrain pressure (IBP) and interstitial fluid pressure(ISFP) have been made in 32 neurosurgical patients in the postoperative period. The obtained data prove that IBP is almost twice higher than ISFP and 1.5 times higher than CSFP. The data of this study show that no direct hydrostatic relation exists between the cerebrospinal fluid and the interstitial fluid. The reasons of "negative" values of ISFP are also discussed. The intracranial pressure is to be considred as a combination of selective mechanical pressures of the main intracranial components. Therefore a more precise term "intracranial pressures" is suggested.

[Reproduction by means of a methematical model of the dynamic characteristics of human vertical posture maintenance]. / Vosproizvedenie nekotorykh osobennostei dinamiki podderzhaniia vertikal'noi pozy cheloveka s pomoshch'iu matematicheskoi modeli

Some peculiarities of invisible oscillations of man's body during his standing are reproduced using a mathematical model. The stability of the corresponding dynamic system with two delayed feedbacks and its behaviour in response to irregular and regular effects has been investigated. The results are compared with the experimental data. It is suggested that the mathematical model satisfactorily reflects principal peculiarities of the process of equilibrium support of man's body.