Characteristics of the human EEG during cognitive-mnemenic activity under hypoxic conditions

The amplitude-frequency and spatiotemporal characteristics of the EEGs of subjects performing various cognitive-mnemenic activities under the conditions of graduated hypoxia were studied. The quickness and correctness of test performance were significantly decreased beginning from the sixth minute of hypoxia as compared to normoxic conditions. The amplitude and mean period of the dominant EEG activity in this functional state were higher than in the same tests performed under normoxic conditions and lower than in the case of hypoxia not accompanied by the performance of tests. The spatiotemporal characteristics of the EEG under hypoxic conditions displayed both the characteristics typical of hypoxia (a decrease in EEG cross-correlation within anterior cortical regions) and those typical of cognitive-mnemenic activity (an increase in the correlation between the EEGs of distant zones of anterior and posterior cortical regions). It is assumed that the “intermediate” EEG pattern observed in subjects performing cognitive-mnemenic tests under hypoxic conditions reflects opposite effects of hypoxia and intellectual effort on the functional activity of brain neurons.     

Use of backward masking test for the study of visual information processing in healthy subjects and schizophrenic patients

The study of 14 healthy subjects and 15 schizophrenic patients was conducted under visual backward masking conditions. Sensory thresholds were identified using the method of constant stimuli. A special modification of the backward masking technique with lateralized presentation of test and masking stimuli was used to study the lateral characteristics of visual attention. It was found that the thresholds of letter stimulus identification were significantly higher in patients with schizophrenia than in healthy subjects. Only in patients the asymmetry of visual perception was revealed with the higher recognition thresholds in the left visual hemifield. The overall data analysis suggests an association between increased recognition thresholds in schizophrenic patients and changes in the interruption mechanism functioning at the neocortex level.     

Adaptation of the circulatory system to frequently repeated submaximal workloads in the light of left ventricular contraction analysis

In two groups of healthy men aged 20-22 years the left ventricular systolic time intervals were evaluated by the method of Weissler et al. during frequently repeated workloads and restitution. Each exercise was carried out on a Zimmerman cycle ergometer during 10 minutes, and was repeated five times at 50-minutes intervals from 8.00 o'clock a.m. Group I (15 subjects) performed the exercise at a stable workload which produced during the first exercise heart rate acceleration to 170/min, but gave a successive further rise in the heart rate during consecutive exercises. Group II (11 subjects) performed all exercises to a stable rise in heart rate to 170/min with decreasing workloads. It was found that successive exercises caused in both groups a similar decrease of the left ventricular ejection time index (LVETI), pre-ejection period (PEP), isovolumetric contraction time (ICT), and decrease of the PEP/LVET index (p less than 0.05). Each successive exercise began with higher values of LVETI, PEP, ICT and PEP/LVET than the first one. No significant differences were found in the values of left ventricular systolic time intervals in both groups (p greater than 0.05). The duration of restitution of normal values of the left ventricular systolic time intervals after successive exercises was not changing but the tolerance of these exercises measured by heart rate increase and work performed decreased successively.     

Bisexual behavior in the male rat: Influence of masculine sexual activity on the display of lordosis behavior

Sexually inexperienced male Wistar rats (strain WI in our colony) known to very infrequently display spontaneous lordosis behavior (Schaeffer et al., 1990b) were used. A first group was tested four times at 5-day intervals for lordosis with vigorous stimulus males (heterotypic sexual behavior), immediately following testing for masculine sexual activity with highly receptive females (homotypic sexual behavior). A small number of animals displayed lordosis during the first test, but more and more animals displayed this behavior from the first to the fourth test. There was no relationship between the degree of masculine sexual activity--intromission without ejaculation or ejaculation--and the occurrence of lordosis behavior. A second group was tested only once for both masculine sexual activity and lordosis behavior as above and afterwards three times at 5-day intervals for lordosis behavior in the absence of any previous testing for masculine sexual activity. A few animals displayed lordosis during their first test. As compared to the first group, the animals which had not displayed lordosis in the first test never showed lordosis responses in the following tests. It is concluded that both homotypic and heterotypic sexual interactions are required for the display of lordosis behavior in the strain of Wistar rats used in this study.     

The lability of the human background alpha rhythm under functional loads

Some characteristics of electroencephalographic reaction (alpha frequency, whole alpha range power spectrum and alpha index) have been studied. In the first series the indifferent single, rhythmic and complex stimuli were presented to the test subjects, in another series a conditioned motor reflex was elaborated, in the third series the test subjects rhythmically reproduced fixed temporal interval. It has been shown that the functional loads lead to higher alpha frequency. The alpha rhythm frequency was higher in subjects verbally underestimating and reproducing intervals with some delay than in ones overestimating intervals and reproducing them in advance. It has been suggested that alpha rhythm instability is due to reorganization processes in neuronal complexes of different lability.     

Functional differences in the backward shifts of CA1 and CA3 place fields in novel and familiar environments

Insight into the processing dynamics and other neurophysiological properties of different hippocampal subfields is critically important for understanding hippocampal function. In this study, we compared shifts in the center of mass (COM) of CA3 and CA1 place fields in a familiar and completely novel environment. Place fields in CA1 and CA3 were simultaneously recorded as rats ran along a closed loop track in a familiar room followed by a session in a completely novel room. This process was repeated each day over a 4-day period. CA3 place fields shifted backward (opposite to the direction of motion of the rat) only in novel environments. This backward shift gradually diminished across days, as the novel environment became more familiar with repeated exposures. Conversely, CA1 place fields shifted backward across all days in both familiar and novel environments. Prior studies demonstrated that CA1 place fields on average do not exhibit a backward shift during the first exposure to an environment in which the familiar cues are rearranged into a novel configuration, although CA3 place fields showed a strong backward shift. Under the completely novel conditions of the present study, no dissociation was observed between CA3 and CA1 during the first novel session (although a strong dissociation was observed in the familiar sessions and the later novel sessions). In summary, this is the first study to use simultaneous recordings in CA1 and CA3 to compare place field COM shift and other associated properties in truly novel and familiar environments. This study further demonstrates functional differentiation between CA1 and CA3 as the plasticity of CA1 place fields is affected differently by exposure to a completely novel environment in comparison to an altered, familiar environment, whereas the plasticity of CA3 place fields is affected similarly during both types of environmental novelty.     

Periodic phenomenon in the ECoG of newborn rat pups and its correlation with spontaneous motor activity

In conscious 2-6-day rat puppies, studies have been made on the bioelectrical activity in the visual and sensorimotor cortex. ECG in newborn rat puppies exhibits characteristic intermittence of complexes of the electrical activity with intervals of partial or almost complete absence of the activity in a minute scale. This phenomenon reflects the ancient property of immature nervous system, i.e. a capacity to autogenic periodic excitation. The structure of these complexes may be different, since it reflects the condition of animals at the given moment, the degree of maturation of elements involved in realization of the bioelectrical activity and interrelationship with other parts of the brain. With respect to amplitude-frequency parameters, age dynamics and the relationship to the spontaneous motor activity, four distinct types of complexes were revealed in the ECG of rat puppies during the first week of their postnatal life.     

逐级递增负荷踏车试验测定最大耗氧量和无氧阈的重复性

本文目的旨在研究在逐级递增负荷踏车试驻中测定最大耗氧量和无氧阈的重复性。21名运动员各完成三次重复性递增负荷踏车试验。通过与Apple Ⅱ_E计算机辅助联机的Jaeger EOS自动分析系统,根据通气和气体交换参数的变化,对无氧阈及最大耗氧量进行无创性测定。结果表明,采用递增负荷踏车试验测定最大耗氧量时,有必要对不熟悉试验程序的受试者进行重复测定以提高准确性,无创性测定无氧阈具有令人满意的重复性,多次重复测定将可提高无氧阈测定的准确性。     

Establishing equivalence classes in preschool children with one-to-many and many-to-one training protocols

The present study set out to assess if the different probabilities reported in the literature of obtaining equivalence after baseline training with MTO and OTM protocols could be attributed to individual differences and, if so, whether equivalence formation could be facilitated by using familiar stimuli as nodes. In Experiment 1, 16 preschool children were trained on four sets of 2-choice match-to-sample tasks, eight with a OTM protocol (A-B, A-C, A-D, A-E) and eight with a MTO protocol (B-A, C-A, D-A, E-A). For four OTM and four MTO children only abstract stimuli were used. The other four OTM children and four MTO children received the same training but with familiar stimuli as nodes. All children received tests for equivalence (first) and symmetry (second). In Experiment 2, eight children who served in Experiment 1 participated again, four who had passed the equivalence test, and four who had failed that test. All children received the same baseline training as in Experiment 1 but with the opposite type of nodes (abstract instead of familiar, and vice versa) and training protocol (MTO instead of OTM, and vice versa). The results showed that (a) the children's performances (training and testing) were not affected by the training protocol; (b) equivalence formation occurred more readily when being trained with all abstract stimuli than when familiar stimuli served as nodes; and (c) most children who passed or did not pass the equivalence test in Experiment 1 repeated their performance in Experiment 2, irrespective of the conditions that were used.     

Taste threshold determination and side-preference in captive cockatiels (Nymphicus hollandicus)

The taste thresholds of caged cockatiels (Nymphicus hollandicus) for aqueous solutions of sodium chloride, citric acid, and sucrose were studied using two-choice taste-preference tests. The effects of location on the threshold were tested by putting the flavored solution in either the preferred or non-preferred locations (i.e. sides of cages) and offering water in the opposite location. Four parameters (total consumption, consumption from preferred side, consumption from non-preferred side, and proportion of test solution consumed) were measured at the end of 3-day test periods. Experiments were repeated with increasing concentration of test flavors until intake variables were significantly (p<0.05) affected. The results showed that birds distinguished (p<0.05) between purified water and 0.16 mol l(-1) sodium chloride, 0.36 mol l(-1) sucrose, or pH 5.5 citric acid. The likelihood of detecting a taste threshold was greater for sodium chloride and citric acid when these solutions were placed on the preferred side. In contrast, sucrose sensitivity was greater when this solution was offered on the non-preferred side.     

Evidence of social niche construction: persistent and repeated social interactions generate stronger personalities in a social spider

While there are now a number of theoretical models predicting how consistent individual differences in behaviour may be generated and maintained, so far, there are few empirical tests. The social niche specialization hypothesis predicts that repeated social interactions among individuals may generate among-individual differences and reinforce within-individual consistency through positive feedback mechanisms. Here, we test this hypothesis using groups of the social spider Stegodyphus mimosarum that differ in their level of familiarity. In support of the social niche specialization hypothesis, individuals in groups of spiders that were more familiar with each other showed greater repeatable among-individual variation in behaviour. Additionally, individuals that were more familiar with each other exhibited lower within-individual variation in behaviour, providing one of the first examples of how the social environment can influence behavioural consistency. Our study demonstrates the potential for the social environment to generate and reinforce consistent individual differences in behaviour and provides a potentially general mechanism to explain this type of behavioural variation in animals with stable social groups.     

Effects of repeated anthelmintic treatment on Enterobius vermicularis infection in chimpanzees

Effects of repeated treatment with pyrantel pamoate on Enterobius vermicularis infection in chimpanzees were assessed by observing worms discharged in the feces after administration of anthelmintic treatment. Three of 9 chimpanzees reared in a zoological garden in Japan were subjected to fecal worm count and morphometric observation, and all were given oral pyrantel pamoate 6 times at 10-day intervals simultaneously. Following the first and second treatments, more than 30,000 pinworms were discharged from 1 chimpanzee. The number of discharged worms abruptly decreased after the third treatment, and only a few worms were recovered after the fifth treatment, indicating that repeated treatment at short intervals was very effective. Complete eradication was not achieved, however, presumably because of reinfection. The female proportion among discharged worms tended to increase as the treatment was repeated.     

Female-female mounting among goats stimulates sexual performance in males

The hypothesis that female-female mounting is proceptivity in goats, in that male goats are aroused by the visual cues of this mounting behavior, was tested. Once a week, male goats were randomly selected and placed in a test pen in which they were allowed to observe one of six selected social or sexual stimulus conditions. The stimulus conditions were one familiar male with two estrous females (MEE); three estrous females that displayed female-female mounting (E(m)); three estrous females that did not mount (E(nm)); three non-estrous females (N(E)); three familiar males (M); and no animals in the pen (Empty). After 10 min, the stimulus animals were removed, and an estrous female was placed in the test pen with the male for a 20-min sexual performance test. During sexual performance tests, the frequencies and latencies of all sexual behaviors were recorded. This procedure was repeated so all males (n = 6) were tested once each test day, and all the stimulus conditions were presented each test day. This was repeated weekly until all males had been exposed to each stimulus condition. Viewing mounting behavior, whether male-female or female-female, increased the total number of sexual behaviors displayed, increased ejaculation frequency, and decreased latency to first mount and ejaculation, post-ejaculatory interval, and the interval between ejaculations. We conclude that male goats are aroused by the visual cues of mounting behavior, and that female-female mounting is proceptivity in goats.     

Effects of a Single Histoplasmin Skin Test on the Serological Diagnosis of Histoplasmosis

Numerous reports have indicated that a single histoplasmin skin test may stimulate humoral antibodies to Histoplasma capsulatum antigens in histoplasmin-hypersensitive individuals. Although these investigations concur that antibody elevations are evoked, they vary in the reported degree of incidence and response induced, and they cast doubt on the interpretation of serological tests in the diagnosis of histoplasmosis. Histoplasmin-hypersensitive subjects (114) were bled prior to administration of the skin test, 2 days later, at the time this test was read, and 15 and 30 days after testing. No significant antibody titers were observed at 2 days. At 15- and 30-day intervals, only 17 (15%) of the subjects demonstrated circulating antibodies. All 17 showed agar gel bands; 5 demonstrated no complement-fixation (CF) titers, 10 produced CF antibodies ranging from 1:8 to 1:16, and 2 demonstrated titers of 1:32. The data suggest that skin testing does not interfere significantly with antibody levels in sera drawn approximately 2 days after administration of antigen. However, since titers as high as 1:32 were obtained at later intervals, such reactions should be evaluated cautiously and only after consideration of clinical findings.     

Female health,attractiveness, and desirability for relationships: Role of breast asymmetry and waist-to-hip ratio

Fluctuating asymmetry (FA) of ordinarily bilaterally symmetrical traits in humans has been proposed to indicate developmental anomaly. Recent research has shown that individuals with minimal FA are judged to be attractive, and preferred as sexual partners (Thornhill and Gangestad 1993). Waist-to-hip ratios (WHR) have been also shown to reflect health and reproductive capability of woman and those with low WHRs are judged more attractive and healthy (Singh 1993a,b). The present study examines the relative roles of WHR and FA in female breasts in judgments of female attractiveness, health, and desirability for short-term and long-term relationships. Male college students were asked to judge attractiveness of female figures that differed in WHR (high and low) and breast symmetry (none, low, or high). In the first test, paired comparison method was used in which each figure was paired one at a time with all other figures. In the second test, subjects examined all figures simultaneously, estimated their age, and rated each figure for attractiveness, feminine looks, health, overall degree of body symmetry, and willingness to engage in short- and long-term relationship. Results from both tests show that figures with low WHRs were judged to be more attractive than figures with high WHRs, regardless of their degree of breast asymmetry. The figure with low WHR and symmetrical breasts was judged to be most attractive and youngest of all other figures. It appears that men use both WHR and breast asymmetry in judging attractiveness and being willing to develop romantic relationships. It is proposed that WHR and breast asymmetry may signal different aspects of overall female mate quality.     

Effects of dietary tin and aluminum on selenium utilization by adult males

The main purpose of these studies was to determine whether the amounts of tin and aluminum that can enter foods during processing and storage are sufficient to affect the utilization of selenium by human subjects. Two 40-day balance studies were conducted. The eight adult males who participated in the first study lost significantly more selenium in their feces when fed a test diet containing 50 mg tin daily than when fed the control diet containing 0.1 mg tin daily. During the first study subjects tended to excrete less selenium in the urine when fed the test diet rather than the control diet. In the second study, the dietary treatments (5 and 125 mg aluminum daily) had no effect on the excretion and apparent retention of selenium by eight adult males.     

The Response to Novel Foods in Common Marmoset (Callithrix jacchus): The Effects of Different Social Contexts

The main aim of this study was to verify if the response to novel foods in common marmoset (Callithrix jacchus) is influenced by different social settings. This question was tested in three tests involving four social groups. The data regarding the response to novel foods were collected from a total of eight food-naive young. In particular, we explored if direct contacts between food-naive and experienced individuals would have a different effect on the response to novel food by the first, in comparison with a situation in which only visual contacts were allowed. These two different social settings were then compared to a situation in which the response to novel food was not mediated by the experience of group-mates. The results showed a significantly higher number of intervals in which naive young, in social settings, were observed feeding compared with a control test. However, this result was confirmed only in the case of novel foods, not in the case of familiar foods. Furthermore, in the tests in which direct social contacts were allowed, naive young obtained food from group-mates significantly more often in the case of novel than familiar foods. This study suggests that although naive young, when left in pairs, responded quickly to novel foods without the need to observe or interact with experienced group-mates, a process of social facilitation was evident. Such a process was not observed in the case of familiar foods, confirming the hypothesis that social facilitation operates in order to acquire novel foods in the diet of the group in the long term.     

Mathematical modeling of ventricular disturbances following atrial fibrillation

The present study presents the results of mathematical and computer modeling of atrial fibrillation and ventricular disturbances following atrial fibrillation. The model is based on the assumption that electric impulsation arriving on the atrioventricular node during atrial fibrillation is sum of N independent pulse streams with various amplitude-frequency and phase characteristics. With this model it becomes possible to investigate the dependence of nonlinear dynamics of PP and RR intervals on amplitude-frequency and phase characteristics pulse streams. Results of computer experiments are compared with real physiological experiments on rabbits. Identification of model was carried out by means of least-squares procedure.     

Effect of Personality on Changes of Sleep Structure Caused by Emotional Stress

Effects of personality characteristics on the structure of sleep in ten normal subjects between the ages of 21–33 under stressors of various modalities were studied. Several psychological tests and polygraph recording of sleep during three nights (adaptation, background, and after emotional stress, which was modeled using the pretension level paradigm) were conducted. Statistical cluster analysis of the psychological test results revealed two groups of subjects. The first group predominantly used active coping mechanisms and was characterized by more pronounced alterations of sleep structure in response to adaptation stress (the first night in the laboratory). The second group used nonadaptation coping strategy. The sleep structure in these subjects more significantly changed in response to emotional stress.     

Development of an RSA calibration system with improved accuracy and precision

In this study, a new radiostereometric analysis (RSA) calibration cage was developed with the aim of improving the accuracy and precision of RSA. This development consisted of three steps: a numerical simulation technique was first used to design the new cage; a synthetic imaging method was then implemented to predict the performance of the designed cage before it was actually fabricated; and an experimental phantom test was finally conducted to verify the actual performance of the new cage and compare with two currently widely used cages. Accuracy was calculated as the 95% prediction intervals from regression analyses between the measured and actual displacements, and precision was defined as the standard deviation of repeated measurements. The final experimental phantom tests showed that the accuracy and precision of the new calibration cage were improved by about 40% over an existing biplanar cage and by about 70% compared to a uniplanar cage design. This new cage can be used with any skeletal joints, in either static or kinematic examination, which is helpful for the standardization of the RSA application.