The discrimination of time microintervals by emotionally excitable personalities

Function of time microintervals estimation was studied in emotionally excitable subjects (23 persons) as well as learning of this function by means of positive and negative reinforcements--words "good" and "error"--and interhemispheric relations. In excitable subjects, discerning is disturbed of short pauses between the visual stimuli, especially of 10 ms pause, presented in the right visual field. Deficit of learning of the intervals discerning is noted by reaction time parameter. There is no advantage of the left hemisphere in discerning the 10 ms pause from 60 ms, which is observed in healthy people.     

Spectral characteristics of EEG during formation a set to illusory length perception (Müller-Lyer illusion)

A cognitive set to illusory perception of linear relationships was formed in 56 young healthy subjects. After 10 presentations of Müller-Lyer figures, 39 subjects formed the stable set. In 17 subjects the unstable set was formed. The spectral power of the EEG led from different cortical areas was studied at different stages of set formation. Analysis of variance showed that the factors "set stage" and "group" x "set stage" x "hemisphere" exert significant influence on the EEG spectral power in the delta range in the frontal area. In the subjects with stable set, the power of this spectral component increased at the stages of set formation and actualization and returned to its initial values during set extinction. The between-group difference was more expressed in the left hemisphere. In subjects, which formed the stable set, the power of the occipitotemporal alpha rhythm in the reference state was higher than in subjects with the unstable set. In the process of set formation, the dynamics of the alpha spectral component (8-10 Hz) was more expressed in the stable group: its power increased to a greater extent at the stages of set actualization and extinction. In both groups, there were no significant changes in the alpha2 power over the course of the experiment.     

Learning with half a brain

Since the 1970s, human subjects that have undergone corpus callosotomy have provided important insights into neural mechanisms of perception, memory, and cognition. The ability to test the function of each hemisphere independently of the other offers unique advantages for investigating systems that are thought to underlie cognition. However, such approaches have been limited to mammals. Here we describe comparable experiments on an insect brain to demonstrate learning‐associated changes within one brain hemisphere. After training one half of their bisected brains, cockroaches learn to extend the antenna supplying that brain hemisphere towards an illuminated diode after this has been paired with an odor stimulus. The antenna supplying the naïve hemisphere shows no response. Cockroaches retain this ability for up to 24 h, during which, shortly after training, the mushroom body of the trained hemisphere alone undergoes specific post‐translational alterations of microglomerular synaptic complexes in its calyces. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2007.     

Metacognitive Confidence Increases with,but Does Not Determine,Visual Perceptual Learning

While perceptual learning increases objective sensitivity, the effects on the constant interaction of the process of perception and its metacognitive evaluation have been rarely investigated. Visual perception has been described as a process of probabilistic inference featuring metacognitive evaluations of choice certainty. For visual motion perception in healthy, naive human subjects here we show that perceptual sensitivity and confidence in it increased with training. The metacognitive sensitivity–estimated from certainty ratings by a bias-free signal detection theoretic approach–in contrast, did not. Concomitant 3Hz transcranial alternating current stimulation (tACS) was applied in compliance with previous findings on effective high-low cross-frequency coupling subserving signal detection. While perceptual accuracy and confidence in it improved with training, there were no statistically significant tACS effects. Neither metacognitive sensitivity in distinguishing between their own correct and incorrect stimulus classifications, nor decision confidence itself determined the subjects’ visual perceptual learning. Improvements of objective performance and the metacognitive confidence in it were rather determined by the perceptual sensitivity at the outset of the experiment. Post-decision certainty in visual perceptual learning was neither independent of objective performance, nor requisite for changes in sensitivity, but rather covaried with objective performance. The exact functional role of metacognitive confidence in human visual perception has yet to be determined.     

The function of the counting of time as the basis for the individual adaptive activity of the nervous system

An important role of time factor in adaptive process of organisms is shown on the basis of great literary material. The time perception is a result of the interrelationship of the so-called "biological clock" and learning during the whole ontogenesis. The hypothetical mechanisms of time perception are discussed. In own experiments the authors revealed more distinct expressiveness of high-frequency components in electroencephalogram spectrum and less expressiveness of low-frequency components in subjects underestimating time intervals compared with subjects overestimating them. A conception on the role of individual characteristics of nervous system in time perception is developed.     

Hemispheric lateralization in the processing of odor pleasantness versus odor names

It is well established that for most people linguistic processing is primarily a left hemisphere activity, whereas recent evidence has shown that basic odor perception is more lateralized to the right hemisphere. Importantly, under certain conditions, emotional responding also shows right hemisphere laterality. Hedonic (pleasantness) assessments constitute basic level emotional responses. Given that olfaction is predominantly ipsilateral in function, it was hypothesized that odor pleasantness evaluations may be accentuated by right nostril perception and that odor naming would be superior with left nostril perception. To test this prediction we presented eight familiar neutral-mildly pleasant odors for subjects to sniff through the left and right nostrils. Subjects smelled each odor twice (once through each nostril) at two different sessions, separated by 1 week. At each session subjects provided pleasantness, arousal and naming responses to each odorant. Results revealed that odors were rated as more pleasant when sniffed through the right nostril and named more correctly when sniffed through the left. No effects for arousal were obtained. These findings are consistent with previously demonstrated neural laterality in the processing of olfaction, emotion and language, and suggest that a local and functional convergence may exist between olfaction and emotional processing.     

Song perception in the European starling: hemispheric specialisation and individual variations

Hemispheric specialisation for speech in humans has been well documented. The lateralisation for song production observed in songbirds is reminiscent of this hemispheric dominance. In order to investigate whether song perception is also lateralised, we made multiunit recordings of the neuronal activity in the field L of starlings during the presentation of species-specific and artificial non-specific sounds. We observed a systematic stronger activation in one hemisphere than in the other one during the playback of species-specific sounds, with inter-subject variability in the predominant hemisphere for song perception. Such an asymmetry was not observed for artificial non-specific sounds. Thus, our results suggest that, at least at the individual level, the two hemispheres of the starlings' brain perceive and process conspecific signals differently.     

Deficit of learning of posture voluntary control in patients with cortical lesions of various locations: cortical mechanisms of posture regulation

Forty two hemiparetic patients after cerebrovascular accidents were trained to change the position of the center of pressure according to a target on the screen with the visual feedback control. The learning was substantially impaired in comparison with the group of healthy subjects. Patients with the right-hemispheric lesions showed somewhat greater learning deficit than patients with lesions in the left hemisphere. Lesion localization also affected the process of learning. The learning was disturbed to a greater extent in patients with lesions involving not only motor but also premotor and parietal cortical areas. In patients with parieto-temporal lesions the learning reached a very low level after three initial days of training, possibly, because of the deficit of sensory integration and of body scheme in the extra-personal space. Patients with combined lesions of the motor, premotor, and parietal areas showed the lowest results. The learning was shown to depend on the deficit of proprioception and extent of postural disturbances (asymmetry of body weight distribution and amplitude of the center of pressure oscillations) rather than on the extent of motor deficit (paresis and spasticity). However, the learning itself improved some motor disturbances.     

Change in parameters of interhemispheric asymmetry during simulation of a destructive action

Interhemispheric EEG asymmetry was studied in 26 male subjects aged 8-23 with different behavioral destructiveness levels. Subjects with higher destructiveness level in the state of rest had the focus of interhemispheric asymmetry in the temporal and frontal areas of the left hemisphere, whereas in subjects with lower destructiveness level the asymmetry focus was found in the same areas of the right hemisphere. Simulation of aggressive activity led to displacement of the asymmetry focus to the right hemisphere in both groups. However, in the group with higher destructiveness the changes in the focus were observed in the EEG theta band, which suggested the involvement of mainly stem oscillators of EEG activity in the destructive behavior. In the group with lower destructiveness changes were observed mainly in the alpha3 and beta1 bands, which indicated that cortical oscillators of EEG activity were involved in the control of the destructive behavior. The results suggest better perception and assessment of stimuli by subjects with lower aggressiveness and their choice of more adequate models of behavior.     

Hemispheric specialization in dogs for processing different acoustic stimuli

Considerable experimental evidence shows that functional cerebral asymmetries are widespread in animals. Activity of the right cerebral hemisphere has been associated with responses to novel stimuli and the expression of intense emotions, such as aggression, escape behaviour and fear. The left hemisphere uses learned patterns and responds to familiar stimuli. Although such lateralization has been studied mainly for visual responses, there is evidence in primates that auditory perception is lateralized and that vocal communication depends on differential processing by the hemispheres. The aim of the present work was to investigate whether dogs use different hemispheres to process different acoustic stimuli by presenting them with playbacks of a thunderstorm and their species-typical vocalizations. The results revealed that dogs usually process their species-typical vocalizations using the left hemisphere and the thunderstorm sounds using the right hemisphere. Nevertheless, conspecific vocalizations are not always processed by the left hemisphere, since the right hemisphere is used for processing vocalizations when they elicit intense emotion, including fear. These findings suggest that the specialisation of the left hemisphere for intraspecific communication is more ancient that previously thought, and so is specialisation of the right hemisphere for intense emotions.     

Specialization of cerebral hemispheres in the perception of Russian intonations

Relations between the brain hemispheres were studied during the human perception of various types of Russian intonations. Fifty healthy subjects with normal hearing took part in the tests based on the method of monaural presentation of stimuli—the sentences that represented the main kinds of Russian emotional and linguistic intonations. The linguistic intonations expressed: various communicative types of sentences; completeness/incompleteness of a statement; various types of the syntagmatic segmentation of the statements; various logical stress. Sentences that required the identification of the emotion quality were used to study the perception of emotional intonations. The results of statistical analysis of latent periods and errors made by the test subjects demonstrated a significant preference of theright hemisphere in perceiving emotional intonations and complete/incomplete sentences; sentences with different logical stress were perceived mainly by theleft hemisphere. No significant differences were found in the perception of various communicative types of sentences and statements with different syntagmatic segmentation. The obtained data also testify to a difference in the degree of the involvement of human hemispheres in the perception and analysis of prosodic characteristics of the speech in males and females.     

Sensory detection of food odour in relation to dental status,gender and age

The aim of this study was to investigate to what extent declining odour perception can be ascribed to dental status and oral hygiene habits, taking into account gender and age. Apparently healthy adults (n=182), ranging from 53 to 93 years (mean age=68.4) were tested. Information about oral hygiene habits (brushing teeth and cleaning dentures) and dental status was obtained by questionnaires. A validated objective procedure was used to measure sensory detection thresholds for isoamylacetate by an ascending method of limits. A significant negative correlation of odour perception with age was shown by the edentulous subjects which might reflect their wider age spread with many subjects over age 75. The evaluation of odour perception as a function of dental status shows no significant difference in odour perception between persons partial denture wearers, with natural teeth only or complete dentures. However, a tendency for lower odour perception was observed among male partial denture wearers, especially those reporting less frequent oral hygiene, which justifies further more detailed study.     

Lateralization of olfactory processes

Over the last ten years, methods of cerebral imaging have revolutionized our knowledge of cognitive processes in humans. An impressive number of papers dealing with cerebral imaging for olfaction have been published to date. Whereas the early works revealed those structures participating in the processing of odours presented passively to subjects, researchers later recorded brain activity when subjects performed specific olfactory tasks based on memory, emotion and identification. From these results, we suggest that there is a dissociation of olfactory processes, with involvement of the right hemisphere in memory processes and the left hemisphere in emotional processes. The review concludes with a summary of how these lateralized processes are consistent with the gestalt-nature of our olfactory perception.     

Motor Imagery Cognitive Network after Left Ischemic Stroke: Study of the Patients during Mental Rotation Task

Although motor imagery could improve motor rehabilitation, the detailed neural mechanisms of motor imagery cognitive process of stroke patients, particularly from functional network perspective, remain unclear. This study investigated functional brain network properties in each cognitive sub-stage of motor imagery of stroke patients with ischemic lesion in left hemisphere to reveal the impact of stroke on the cognition of motor imagery. Both stroke patients and control subjects participated in mental rotation task, which includes three cognitive sub-stages: visual stimulus perception, mental rotation and response cognitive process. Event-related electroencephalograph was recorded and interdependence between two different cortical areas was assessed by phase synchronization. Both global and nodal properties of functional networks in three sub-stages were statistically analyzed. Phase synchronization of stroke patients significantly reduced in mental rotation sub-stage. Longer characteristic path length and smaller global clustering coefficient of functional network were observed in patients in mental rotation sub-stage which implied the impaired segregation and integration. Larger nodal clustering coefficient and betweenness in contralesional occipitoparietal and frontal area respectively were observed in patients in all sub-stages. In addition, patients also showed smaller betweenness in ipsilesional central-parietal area in response sub-stage. The compensatory effects on local connectedness and centrality indicated the neuroplasticity in contralesional hemisphere. The functional brain networks of stroke patients demonstrated significant alterations and compensatory effects during motor imagery.     

Influence of informational oversaturation on the quality of creative activity and spatial organization of EEG

The features of the spatial organization of bioelectric potentials in the cases of successful and unsuccessful creative imagination (refusal or poor quality of the product) under conditions of informational oversaturation. Two groups of subjects were compared: professionals (23 healthy students of the Department of Graphic Arts) and non-professionals (34 persons whose specialties were not linked with systematic visual imagination). During the experiments, the subjects were asked to mentally create a visual image based on two simple graphic elements, a right angle and a diagonal; after recording the EEG, they had to draw the image on paper and give it a title. The total number of elements exceeded 7 ± 2; hence, information processing at the conscious level was impossible, which caused the necessity of involving the mechanisms of unconscious information processing. The quality of the created product was evaluated with regard to the degree of success of performing the task and the features of spatial EEG organization. The EEG was recorded from 24 scalp sites of a subject using a SIT-EEG portable telemetric device. In the case of the successful performance of the task by professionals, the parameters of spatial organization of bioelectric potentials, i.e., spatial synchronization (linear processes) and spatial disorder (non-linear process) were strengthened compared to the base-line level in the frontal temporal areas of the right hemisphere and parietal occipital areas of the left hemisphere. Conversely, in the nonprofessionals, these parameters increased in the frontal temporal areas of the left hemisphere and parietal occipital areas of the right hemisphere. In the case a task was not successfully performed by the professionals, the spatial disorder of bioelectric potentials increased in all the cortical areas; in the nonprofessionals, only weak changes were observed. In all situations, the groups differed also in the parameters of coherence (Coh), spectral power (Sp) of bioelectric potentials, and informational energy, which reflects the level of expenditure of the brain’s energy for information processing. The evidence obtained is interpreted in terms of electroencephalographic correlates of successful task performance by professionals and nonprofessionals, i.e., their creative imagination under the conditions of informational over-saturation.     

Behavioral responses to species-specific warning calls in infant squirrel monkeys reared in social isolation

Six infant squirrel monkeys were reared in social isolation. They responded differentially to playbacks of two species-specific alarm calls. The reaction to the alarm peep, the warning call to bird predators, was a prompt flight to the mother surrogate and essentially resembled the respective behavior of mother-reared infants. The responses to yapping, the alarm call to terrestrial predators, were less clear-cut and habituated soon. However, when yapping was played back in connection with the presentation of a reference object, both subjects tested in this way clearly avoided the object and preferred contact with the mother surrogate while they thoroughly explored an object presented with a control tone. From this it can be concluded that the perception of both alarm calls is innate. In addition, the method of behavior-contingent playback of vocalizations simulates the learning process by which the visual perception of terrestrial predators of the habitat is acquired.     

Functional Cerebral Asymmetry and Its Possible Evolution in Historical Times

The paper addresses problems of the development of visual spatial functions of the right hemisphere of the human brain in ontogeny and phylogeny. The problem is being treated as an interdisciplinary one, and its potential as evidence of significant changes in cerebral asymmetry in historical times is discussed. Data from evolutionary physiology, anthropology, neuropsychology, and visual art history beginning with the Paleolithic are considered together. The authors pay special attention to such functions as perception of volume of objects and depth of three-dimensional visual scenery as well as perception of the face and emotional expressiveness both in clinical pathology and in normal subjects at different stages of ontogeny, and the appearance of these features in the history of art.     

Ontogenetic features of psychophysiological mechanisms of perception of speech emotional component in musically gifted children

Cerebral mechanisms of musical abilities were explored in musically gifted children. For this purpose, psychophysiological characteristics of perception of emotional speech information were experimentally studied in samples of gifted and ordinary children. Forty six schoolchildren and forty eight musicians of three age groups (7-10, 11-13 and 14-17 years old) participated in the study. In experimental session, a test sentence was presented to a subject through headphones with two emotional intonations (joy and anger) and without emotional expression. A subject had to recognize the type of emotion. His/her answers were recorded. The analysis of variance revealed age- and gender-related features of emotional recognition: boys musicians led the schoolchildren of the same age by 4-6 years in the development of mechanisms of emotional recognition, whereas girls musicians were 1-3 years ahead. Musical education in girls induced the shift of predominant activities for emotional perception in the left hemisphere; in boys, on the contrary, initial distinct dominance of the left hemisphere was not retained in the process of further education.