Hemispheric interaction in man during perception of visual stimuli]

Averaged evoked potentials (AEP) to verbal (letters) and nonverbal (random shapes) stimuli exposed in the left and right visual fields were registered in healthy subjects with normal vision. Analysis of the later AEP latencies pointed to asymmetry in the temporal parameters of the interhemispheric interaction. The late AEP latency is shorter in the right hemisphere than in the left hemisphere. The difference is more pronounced in responses to nonverbal stimuli. The earlier development of the evoked potential in the right hemisphere (or the later one in the left hemisphere) accounts for the interhemispheric difference in the temporal parameters of the late AEP components. Comparison of the latency of the component P300 to verbal and nonverbal stimuli presented in the ipsilateral or the contralateral visual fields reveals a transfer of the results of the cortical processing of visual information in the course of interhemispheric interaction.     

Evoked activity of the human brain during perception of illusory stimuli

Evoked activity of the human brain was studied in 19 right-handed men during the perception of illusory images in Go/NoGo tasks. It was found that the recognition of illusory images was associated with changes in the amplitudes of both early (P1 and P2) and late (P3a and P3b) components of the evoked potentials and with an increase in the latencies of the late components recorded from the occipital, central, and frontal cortical areas, which could be explained by the necessity to store a template in the memory, compare a perceived image with the template, and prepare and execute (or inhibit) a motor response. At the same time, the operation of the brain was more differentiated during the NoGo task compared to the Go task.     

Complex perception of stimuli during conditioning

The review concerns the effects of a variety of stimuli on the reproduction of conditioned reflexes. By the literature data, during conditioning of any type, besides the single stimulus intentionally applied by an experimenter as a conditioned one, an animal perceives the whole complex of stimuli (acoustic, visual, olfactory, algesic, and other exteroceptive, proprioceptive, and interoceptive stimuli), including those of the environment and time of the day during training. Many of these stimuli are essential for the reproduction of the acquired habit. The complex of stimuli that act on an animal during the reproduction should in all parameters correspond to that perceived by the animal during training. If the complexes differ at least in one stimulus, the reproduction of the reflex may fail.     

Bioelectric brain activity during visual perception of verbalized and nonverbalized stimuli in seven-to eight-year-old schoolchildren

Neurophysiological mechanisms of visual perception of verbalized and nonverbalized stimuli have been studied in girls (n = 89) and boys (n = 109) aged seven to eight years. It has been shown that, in children of this age, neurophysiological mechanisms of the visual perception system during the selection of verbalized and nonverbalized stimuli have similar organizations of functional rearrangements and are characterized by the general involvement of cortical areas and by the lack of clear specialization of the cerebral hemispheres. However, the choice of nonverbalized visual stimuli is characterized by a more pronounced generalization of the functional interaction between cortical areas and by the increased spectral power of the EEG’s high-frequency components in anterior associative areas. The increased spatial synchronization in the EEG θ- and β bands in the frontal areas emphasizes the contribution of these structures to the analysis and processing of visual stimuli at this stage of development. Differences in the neurophysiological mechanisms of visual perception in boys and girls have been detected. Spatial and temporal organizations of bioelectric activity (BEA) of the brain in girls performing visual tasks is characterized by a stronger and more varied ipsi- and contralateral statistical relationships in the fronto-occipital direction and displacement of interaction centers to the left hemisphere. In boys perceiving verbalized and nonverbalized visual stimuli, a greater contribution of posterocentral cortical areas has been observed. The detected differences are considered to reflect a greater maturity of identification mechanisms in girls aged seven to eight years as compared to boys.     

Physiology of interdigestive motor activity in man

Aim of this work has been to investigate the pattern of interdigestive motility from the esophagus to the duodenum. Six human subjects have been studied by means of a manometric probe. The results are very similar to those described elsewhere, and show that a cyclic motor activity spreads down from the esophagus to the duodenum and that a district control of gastrointestinal motility exists.     

Maternal perception of fetal motor activity.

A technique using real-time ultrasound for comprehensive recording of fetal motor activity was used in 20 subjects in the third trimester of pregnancy. Maternal awareness of fetal movement correlated with the number of fetal parts contributing to the movement but not with maternal parity or obesity, gestational age, placental site, or duration of the fetal movement. Some subjects recorded fetal breathing, passive fetal displacement, and Braxton Hicks''s contractions as fetal movement. Most of our subjects were consistent and accurate in their perception of major fetal movements, but a few were inconsistent and one was completely unaware of major fetal movements. These results suggest that kick counts kept by most mothers will be accurate. Low counts of fetal movement should be an indication for fetal monitoring by other means and not, unconfirmed, for intervention.     

Role of voluntary motor activity on menthol-induced hyperthermia in mice

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This study tested the hypothesis that activating cutaneous TRPM8 receptors by menthol causes an increase in voluntary activity, because of a heat-seeking behavior, that contributes to menthol-induced hyperthermia in mice.     

The evoked cortical activity of the cerebral hemispheres in man during the active and passive perception of facial expression]

Twenty-two right-handed subjects were asked either to identify sad, neutral, or laughing faces presented on a computer monitor or to view passively the same pictures without classification. Visual evoked potentials were recorded from F3/4, C3/4, P3/4, O1/2, and T5/6 derivations. In comparison with the passive viewing, the emotion recognition was characterized by the higher level of cortical activity reflected in the higher N1, N2, N3 amplitudes and shortened latencies of N1, P2, and N2 waves. In contrast, the latencies of the later P3 and N3 waves were longer. During emotion recognition, the dynamical brain mapping technique revealed symmetrical activation of the frontocentral areas and only the right-side activation during the passive perception. Factor analysis demonstrated a complication of N2 structure in the task of face emotion recognition. A principal component corresponding to the descending part of the N2 wave was revealed, which probably reflected the stage of image classification.     

Differential sensitivity of the kinesthetic and visual sensory system during complex motor activity in man]

Sportsmen of different specialities were examined by the A. V. Zavyalov method (1962) for differential sensitivity of their kinesthetic and visual analysers. It has been shown that the characteristics of differential sensitivity of the analysers are dissimilar in representatives of different kinds of sport. For example, pentathlon and basketball sportsmen exhibit in their kinesthetic analyser the greatest number of minimum increases of sensation, namely 30.2 and 21.4 respectively, while those not engaged in any sport, 15.0. The characteristics of intersensory optico-kinesthetic relationships has been established. Closest correlation has been recorded among pentathlon sportmen, volley-ballers and fencers. The dynamics of differential sensitivity of analysers is differently manifested, depending on the subjects' age.     

Event-related synchronization and desynchronization of EEG during perception of emotional stimuli: association with autonomous nervous system activity

Up to now, mechanisms of neurovisceral integration are not clear. The main objective of the present investigation consisted in studying cortical concomitants of sympathetic activity during emotional perception. The 62-channel EEG and skin conductance response (SCR) were recorded while right-handed healthy participants (n-33) viewed sequentially presented neutral, pleasant, and unpleasant pictures. The event-related synchronization (ERS) and desynchronization were measured in different frequency bands. Relying on median split of SCR amplitudes elicited by the presented stimuli the participants were segregated into groups with low (SCR-) and high (SCR+) autonomous activity. In was revealed that group differences were associated with power changes in the low (4-6 Hz) theta band only. For both groups in the early test period (up to 1 s after stimulus onset), emotional vs. neutral stimuli induced larger theta-ERS over posterior cortical regions with greater impact on the right parieto-temporo-occipital regions. At the later phases (2-6 s after stimulus onset), only the SCR group retained emotion-related greater right hemisphere synchronization. It is concluded that the right parieto-temporo-occipital cortex mediates mechanisms of motivated attention and sympathetic activation.     

Nociceptive system response to repetitive painful stimuli during chronic psychoemotional stress in humans

Repeated nocigenic stimuli applied to the skin evoked a hyperalgesia in healthy subjects while in patients with neurasthenia which is a natural model of a chronic psychoemotional stress, they evoked a hyperalgesia accompanied by sensitization. The differences in the nociceptive system responses show particularities in reactivity (plasticity) of a wide dynamic range of the spinal neurons under chronic psychoemotional stress that is due to disorders in supraspinal descending modulation system of plasticity in the spinal nociceptive neurons.