Functional organization of limbic brain structures during conditioned reflex activity in the dog

In experiments on 3 dogs it was shown that instrumental defensive conditioned reflex (CR) to electrical stimulation of the hippocampus is generalized within the limbic system (LS). The rate of generalization depended on the place of testing stimuli in LS. Stimulation of the medial parts of LS at the stage of stabilized initial reflex did not produce the generalized CRs, while they appeared distinctly in response to stimulation of the lateral parts of LS. In the process of elaboration of heterogeneous CRs (defensive and alimentary) to electrical stimulation of the hippocampus, generalized conditioned reactions from some brain structures appeared in both situations to the same degree while from other structures--with considerable differences. These data point to a possible participation in the genesis of the generalized CRs both of signal and reinforcing brain mechanisms.     

Thyroid effect on brain activity in adolescents during heart rhythm biofeedback session

Types of neurophysiologic and thyroid condition in 15-17-year old adolescents were studied for the purpose of heart rhythm biofeedback session effect by heart rhythm variability parameters. Changes of heart rhythm vegetative regulation activity modulate functional capacities of central vegetative regulation structures. The biofeedback training with heart rhythm variability parameters increases brain bioelectrical activity in different frequency ranges. The thyroid system modulates functional activity of vegetative regulation central structures uppermost at sympathotonic and thyreotropin increasing leads to increase of rhythm maker structure reactivity in brain.     

Functional dependence of single muscle receptors on muscle activity

In experiments on chloraloso-urethane anesthetized cats changes in spontaneous and induced spike activity of single muscle spindles and Golgi's receptors following a direct and/or indirect electrical stimulation of the muscle were studied. It was found that contractile activity of the plantar (phase) and heel (tonic) muscles decreased the spike activity of both muscle spindle and Golgi's receptors, the decrease in the phase muscle spindle activity being more considerable than in the tonic one.     

Effects of antiepileptic drugs on brain energy reserves during convulsions

Cerebral cortical ATP, P-creatine, glucose, and lactate were measured 6 sec after 1 sec of 150/sec rectangular pulses, at 0,20 v, 40 v, 60 v, 80 v, or 100 v, applied to the heads of intact mice which had been given either no drug, phenobarbitone (25 mg/kg), trimethadione (600 mg/kg), or diphenylhydantoin (40 mg/kg), intraperitoneally. In general, regardless of stimulus strength or drug used, animals which exhibited maximal (tonic-clonic) convulsions showed similar striking decreases in brain P-creatine, decreases in ATP and glucose, and increases in lactate. On the other hand, in animals which exhibited less than maximal clinical response, there was little or no change in these metabolites. An exception was the case of diphenylhydantoin. Tonic-clonic seizures did not occur after diphenylhydantoin administration, even with 100 v stimuli, but substrate changes at this voltage were, nevertheless, similar to those observed in brains of other mice undergoing maximal convulsions.     

Functional reserves and adaptive potential of various levels of habitual motor activity

On the basis of longitudinal studies in children of older preschool and early school-age boys and girls with low, medium and high habitual physical activity (NAPA, SPDA, VPDA) identified the basic characteristics of the cardiovascular system, physical capacity and the degree of tension of regulatory mechanisms at rest and during functional loading. Analysis of the statistical distribution of the trait given chi2 and lambda criteria and average data of various functional indicators in the total sample identified a fairly wide area and the divergent levels of physiological individuality in a healthy population and the desirability of allocating the three typological groups--functional types (FT-1 - NAPA, the FT-2 - SPDA, FT-3 - VPDA). Model parameters are allocated first and second order for each CFT, as well as performance tests of the third order, describing the current functional status. Determination of the physiological features of the FT-1 FT-2 FT-3 with the establishment of their functional reserves and adaptive capacity makes it possible to identify the different strategies of interaction with the environment, evaluate their advantages and disadvantages and a more grounded approach to the problem of optimization of physical condition and prenosological diagnosis.     

Functional reserves and adaptive capacity of subjects with different levels of habitual physical activity

The basic characteristics of the cardiovascular system, physical capacity, and the degree of tension of regulatory mechanisms in the state of rest and under functional loading were identified on the basis of longitudinal studies in children of senior preschool and junior school ages, including boys and girls with low, medium, and high habitual physical activity (LHPA, MHPA, and HHPA). Analysis of the statistical distribution of traits using the χ² and λ tests and the average statistical data on various functional indicators in the total sample identified a fairly wide area and qualitative differences in physiological individuality in a healthy population and the advisability of distinguishing three typological groups, i.e., functional types (FT-1, LHPA; FT-2, MHPA; FT-3, HHPA). The typological parameters of the first and second orders for each FT and performance test parameters of the third order describing the current functional state have been distinguished. Determination of the physiological features of FT-1, FT-2, and FT-3 with the establishment of their functional reserves and adaptive capacity permits the identification of different strategies of interaction between the body and the environment, estimation of their advantages and disadvantages, and a more reasonable approach to optimization of physical condition and premorbid diagnosis.     

Influence of aggressive computer games on the brain cortex activity level in adolescents

Dynamic changes in the activities of different areas of the brain cortex were studied in order to determine cortical structures responsible for playing aggressive computer games, with the degree of initial aggression of the adolescent subjects taken into account. Changes in anxiety and aggression produced by aggressive computer games were found to depend on the initial level of aggression of the subjects. In adolescents with a high baseline level of aggression, the amplitude of the N200 component increased in the frontal and decreased in the temporal areas of the cortex, whereas, in adolescents with a low baseline aggression level, N200 decreased in the frontal and increased in the temporal cortical areas.     

Changes in hexokinase activity during muscle alteration

Changes in extractability and activity of hexokinase (HK) were studied under the action of heating and of urea on skeletal muscles of Rana temporaria L., and besides the stability of this enzyme in muscle extract to those agents in vitro was examined. Under a 15 minutes heating of muscle, a decrease in extractability (the activity calculated for 1 g of tissue) and activity (the activity calculated for 1 mg of protein) of hexokinase is first revealed at 37 degrees C. Then the enzyme extractability decreases gradually in accordance to the decrease in extractability of the total water-soluble protein; the level of hexokinase activity attained at 37 degrees does not change up to 40 degrees. At 42 degrees the activity of the enzyme is completely inhibited. Under the heating of the muscle extract, the decrease of enzyme activity takes place at 36 degrees, the level achieved being stable up to 42 degrees C. Under the action of urea on the muscle at the reversible phase of alteration (1 M urea from 5 minutes to 2 hours at room temperature, 1 M urea for 9 hours at + 4 degrees C), hexokinase activity increases, calculated for 1 g of tissue and for 1 mg of protein. Under the irreversible disappearance of muscle excitability (1 M urea during 9 hours, 2 M urea during 2 hours at room temperature) no hexokinase activity was revealed. The activation of the enzyme is discussed in connection with the data on the increase of ATP content in muscle under the urea alteration. The treatment of the enzyme in muscle extract with 1 M urea decreases its activity in 30 minutes down to 67%; the level achieved does not change during 20 hours.     

Functional subdivision of the upper trapezius muscle during maximal isometric contractions

The electromyographic (EMG) activity pattern across the upper trapezius of 22 healthy subjects was investigated during maximal isometric contractions. Eight bipolar surface electrodes with 10 mm distance between adjacent electrode pairs were placed on a line from the clavicle to the scapula. At the region near the clavicle the highest EMG amplitudes were recorded during 90 ° arm abduction. At the more posterior parts the highest amplitudes were found both during arm abduction and shoulder elevation. A double differential recording technique which reduced the EMG cross-talk contribution supported the finding that the upper trapezius was differently activated when the arm posture was changed. The normalized EMG amplitude-force relationship during the shoulder elevation showed a curvilinear relationship on the anterior part of the upper trapezius with a slower increase in EMG amplitude than force at low force. The slope of the curve, at low force, increased gradually in the posterior direction on the upper trapezius. The EMG activity patterns across the upper trapezius indicate a flexibility in motor activation which maybe reflects a functional optimization of the contractions performed by this muscle.