A mathematical model is proposed to analyze the spinal strain-deformation condition resulting from axial and lateral g-loads that are generated by changes in the gravity field and/or pilot’s actions during high-performance aircraft maneuvering under flight overload conditions. An algorithm of solution has been developed, which takes into account changes in the intervertebral disk pressure and the fibrous ring shape at the time when loading reaches close-to-critical g-values. Calculation of the spinal-strain deformation condition was implemented using the SPLEN computer system (KOMMEK, Russia). Analysis of the spinal straindeformation condition was made for two types of external loads: normal load and unilateral load with the bending moment. Maximum permissible loads on the spinal segment were evaluated, and a pattern of distribution of strain intensity and mean strains, spinal deformation, and the destruction field was described. The developed computer models can be used as a basis for developing a technique of predicting characteristic spinal injuries due to different extreme loads and pathologies.
The review considers the roles cortisol (Crt), dehydroepiandrosterone (DHEA), and DHEA sul fate (DHEAS) play in the stress response. Agerelated, sexrelated, and circadian fluctuations in normal conditions and in acute or chronic stress are described for Crt, DHEA, and DHEAS. The main techniques used to estimate the Crt level in the blood, urine, and saliva are described, and approaches to the interpretation of the results discussed. Special attention is paid to Crt assays in anthropological and psychological studies.
We investigated cognitive functions of attention and decision-making in 18 healthy subjects and 15 schizophrenia patients using an experimental design with consecutive presentation of two short visual stimuli (double-step). In patients with schizophrenia, an increase in the number of errors and change in the pattern of saccadic responses have been found: an increase of the number of two-saccade responses to each stimulus and a decrease in the number of single-saccade responses to the second stimulus. In schizophrenia patients, the latent period of the first of a pair of saccades has been shorter; and the latent period of single saccade has been increased in comparison with healthy subjects. Opposite lateral differences in latent periods of saccades in healthy subjects and schizophrenia patients have been found. Our results show the deficit of cognitive oculomotor control and a decrease in prognostic processes of saccade programming in schizophrenia patients. © 2015, Pleiades Publishing, Inc.
This study is focused on changes in the brain function throughout the adulthood in healthy men and women performing task switching (TS) in the visual modality. One hundred and forty healthy subjects aged 20 to 65 years (69 men) participated in the experiments. In the fMRI study, the subjects performed a test that required switching attention between two objectives (classifying figures according to their form or number). Using the voxel-based morphometry (VBM), we calculated the volumes of gray and white matter in the whole brain and in selected areas. The results showed that a common feature of different age and sex groups performing the TS was bilateral activation of the dorsolateral prefrontal areas, the inferior parietal lobes and the inferior occipital gyrus. We also found a transition from local to diffuse activation occurring with age. In young men (20 to 30 years of age) compared to women, a greater increase in theBOLD signal was found in the prefrontal areas bilaterally, the right parietal lobe and insula, and, in addition, bilateral activation in the supplementary motor area which were not observed in women. Older men and women (51 to 65 years) had no significant differences. The study of the BOLD signal correlations with age in women at the age from 20 to 40 and men from 20 to 55 years showed no significant changes. With further increase of age in both groups we found a consequent increase in the number of brain areas which are activated. The VBM analysis showed a significant decrease in the volume of gray, but not white, matter with age. No significant correlations between age-related changes in the gray matter volume (both in the whole brain and in the specific areas) and BOLD signal in this age group were detected.
The purpose of the research was to study effect of longterm isolation on night sleep. The data were collected during international ground simulation of an interplanetary manned flight – “Mars500”. The polysomno graphic recordings of six healthy men were performed before, four times during and after 520days confine ment. During the isolation sleep efficiency and deltalatency decreased, while sleep latency increased. Post hoc analysis demonstrate significant differences between background and the last (1.5 months before the end of the experiment) measure during isolation. Frequency of nights with low sleep efficiency rose on the eve of the important for the crew events (simulation of Mars landing and the end of the confinement). Two weeks after the landing simulation, amount of the nights with a low sleep efficiency significantly decreased. There fore, anticipation of significant event under condition of longterm isolation might result in sleep worsening in previously healthy men, predominantly difficulties getting to sleep.
The perception of spatial and successive contexts of auditory information develops during human ontogeny. We compared event-related potentials (ERPs) recorded in 5- to 6-year-old children (N = 15) and adults (N = 15) in response to a digital series with omitted digits to explore age differences in the perception of successive auditory information. In addition, ERPs in response to the sound of falling drops delivered binaurally were obtained to examine the spatial context of auditory information. The ERPs obtained from the omitted digits significantly differed in the amplitude and latency of the N200 and P300 components between adults and children, which supports the hypothesis that the perception of a successive auditory structure is less automated in children compared with adults. Although no significant differences were found in adults, the sound of falling drops presented to the left ears of children elicited ERPs with earlier latencies and higher amplitudes of P300 and N400 components in the right temporal area. Stimulation of the right ear caused increasing amplitude of the N100 component in children. Thus, the observed differences in auditory ERPs of children and adults reflect developmental changes in the perception of spatial and successive auditory information.
The role of cortisol (Crt), dehydroepiandrosterone (DHEA) and DHEAsulfate (DHEAS) in stress responses were shown. The fluctuations in concentration of Crt, DHEA and DHEAS depending on age, sex and time of the day in norm and under acute and chronic stress were quoted. The main techniques of assessment of serum, urine and saliva Crt concentrations were discussed. A special attention had been paid to the use of Crt concentration in anthropological and psychological research. Bibliography comprises 181 works.
We studied the features of cognitive functions of attention and decision making in 18 healthy subjects and 15 patients with schizophrenia with the use of pairs of two short visual stimuli (double step). In the group of patients with schizophrenia, we observed a higher number of errors and higher frequency of modified saccad ic pattern – two saccades to each stimulus instead of only one saccade to the second stimulus. In these pa tients, the latency period of the first saccade was shorter, while the latency period of a single saccade to the second stimulus was longer as compared with healthy subjects. The lateral differences in the saccade latency in schizophrenic and healthy subjects are opposite. The data provide an evidence of disorders in the cognitive control and prognostic processes of saccade pro gramming in schizophrenic patients.