[Changes of Alpha Cortical Potentials Spatial Synchronization on Value Go/NoGo Stimuli].

At healthy people (n = 35) on model of the cognitive set on an angry face is shown: introduction of positive and negative coordinated stimuli Go/NoGo in the inter-stimuli interval can change considerably the top-down positive and negative influences of prefrontal cortex on the cortical areas participating in a visual perception and by that to influence plasticity of the set. The cortical topography of the top-down influences in response to NoGo is determined by local changes of power of fluctuations of potentials in alpha rhythm range. Changes of spatial synchronization of alpha potentials occurs only in their low-frequency range, depending on the level of plasticity of the set.

[Relationships between the Flexibility of Cognitive Performance and the Response of Alpha-Rhythm in the Go/NoGo Task].

During the experiments, healthy subjects (n = 35) completed Go/NoGo task with a set towards the recognition of negative face expression; the visual stimuli were set in the middle of a 16-second-long interval between target (face) and triggering stimuli. The local changes in low-frequency alpha-oscillations in response to stimuli (desynchronization after a positive Go stimulus and synchronization after an inhibitory NoGo stimulus) take place in posterior frontal and anterior temporal lobes of the left hemisphere, i.e.

[The role of the top-down inhibitory control in providing flexibility of cortical processes of recognition of emotional face expression].

On the ground of own and those found in literature it is argued that the neural mechanism of implicit estimation of time intervals between significant visual events should be considered in the framework of top-down cognitive control. Based on that view, putative mechanism of active inhibition are considered. Based on the set model on recognition of emotionally negative face expression it is shown that implicit estimation of time intervals between significant visual events plays an important role in providing flexibility of cognitive processes.

[The spatial synchronization and power of the alpha and theta rhythm after action of signals Go/NoGo].

At adult healthy subjects (n = 35) in pause between the target (facial expression) and triggering stimuli showed the conditioning signals of Go/NoGo defining significants of triggering stimulus. The low-frequency alpha rhythm reacts to stimuli Go/NoGo in the left hemisphere more strongly. The coherence of low-frequency alpha potentials on 5-7 second after positive and negative conditioning (Go/NoGo) stimuli increases.

[Induced synchronization of alpha rhythm in the time intervals between the visual stimuli at different degrees of set flexibility].

In healthy adults (n = 35) was used the model the set study of recognition angry facial expression. The load on working memory by extending the interstimuli time up to 16 sec between the target (facial image) and starting (spot light) stimuli does not lead to a significant slowdown of switching of the set. Differences in the magnitude of the induced synchronization of the alpha rhythm in interstimulus period obtained in the subjects with the change in recognition of emotional facial expressions and the subjects "without errors".

[Changes of the alpha-rhythm after introducing stimuli Go/NoGo in the context of experiments with a set to an angry face].

At healthy adults is (n = 35) in the middle of 16 second pauses between target (faces) and starting stimuli conditioning signals Go/NoGo. Lack of essential changes of flexibility of the set after introduction of an additional cognitive task is explained by enhansment of the induced synchronization of an alpha rhythm in time intervals between target, conditioning and starting stimuli. The increase of alpha potentials synchronization reflect the top-down inhibitory control suppressing effect of irrelevant factors, and that facilitating processing of significant information.

[Psychophysiological signs of high-flexible forms of set on the emotionally negative facial expression].

In a series of studies of influence of past experience on an recognition of emotionally negative facial expression where obtained experimental facts which we consider as the formation signs of under certain conditions high-plastic cognitive (flexible) sets ("not fixed sets", according to D.N. Uznadze) when there switching or updating was not accompanied by illusory distortion of recognition.

[Changes of the l and upper alpha frequency oscillating during time intervals between meaningful visual stimuli].

In healthy adults (n = 35) was used the model of the cognitive set to emotionally negative facial expression ("angry face"). In order to load the working memory was lengthened the time interval between target (face) and trigger stimuli. In cases of the flexible set (no errors in recognition of facial expression was accompanied switching or updating the set) the induced high frequency alpha oscillations (10.

[Changes in the spatial synchronization of neocortical potentials in interstimulus intervals during formation of a set to emotionally negative facial expression].

The model of cognitive set to emotionally negative facial expression was used in the study (35 young healthy subjects) of EEG events in a 8-second interval between the target and triggering stimuli. Coherence of brain potentials recorded from different cortical areas of the right and left brain hemispheres in the alpha and theta bands was analyzed in time segments within pre- and poststimulus intervals. A certain dynamics in the spatial synchronization in the alpha-band was revealed, which might reflect modulation of selective attention in time periods of the cognitive process providing its plasticity and set shift in response to a change in the situation.

[Development of function of the recognition of angry face expression in children of 5-11 years old].

At children 5-6, 7-8 and 10-11 years on model of cognitive set are revealed age features of influence of last experience on perception of a face expression. At children of 5-6 years rigid set on an angry face was experimentally formed: at a testing stage show set-shifting caused large number of erroneous recognition of face expression of perseverative type (assimilative illusions). Plasticity of the set raises in 7-8-year age and considerably the number of assimilative illusions decreases.

[Dynamics of induced EEG in the intervals between a target and trigger stimuli during formation of a set to emotionally negative facial expression].

A visual set was used as a model to study the influence of the increased memory load on the recognition of facial expression in 70 healthy adults. In order to additionally load the working memory, we lengthened the time gap between target (faces) and trigger stimuli. Such a lengthening from 1 to 8 s resulted in an increase of set plasticity (fewer mistakes in facial expression recognition).

[Induced cortical electrical activity during different time-spans between warning and target stimuli].

A certain alpha-band EEG dynamics was revealed in healthy adults (n = 16) at the interval between a warning and a target stimulus in a simple visuospatial task (subjects were instructed to locate a specific letter in the table of letters). Two series of experiment--either with a 2-sec or a 9-sec inter-stimulus interval were conducted, each consisting of 60 trials. In both series, we observed an induced desynchronization of low alpha (8-10 Hz) at the first second after the warning stimulus and its desynchronization just before the target stimulus.

[Theta and alpha-band EEG spatial synchronization under the conditions of visual set, formed to an angry face expression. A study of 5-11-year-old children].

EEG coherence in theta and alpha bands during set-forming and set-shifting was studied in 5-6-year-old (n=18) and 10-11-year-old (n=25) children. Set was formed to visual stimuli (facial photos with emotionally negative expression). Younger children displayed smaller coherence values, especially in the right hemisphere, than older ones.

[Cognitive control in recognition of emotionally negative face in 5-10-year-old children].

We used the experimental model of cognitive visual set, designed by D.N. Uznadze, to study the influence of previous experience on emotional face expression recognition in pre-school (6.

[Changes in face expression recognition caused by additional visual-spatial load].

Changes in face expression recognition and EEG synchronization arising from additional load on working memory were studied in healthy adults. Two types of additional task--semantic and visuospatial--were used to load working memory in an experiment with a visual set, formed to facial stimuli. During perception of new facial stimuli, both these types of additional task caused an increase of erroneous face expression recognitions in the form of assimilative illusions.

[Induced synchronization/desynchronization of the theta and alpha cortical electrical activity to a face stimuli with increasing visual working memory load].

Using a cognitive set to emotional facial expression as a model, induced synchronization/desynchronization of the cortical theta- and alpha-activities were studied in adult healthy people under conditions of increased load on the working memory (additional task of the verbal stimuli recognition). A correlation was found between behavioral (increase in the set rigidity) and electrophysiological (decrease of the induced theta-rhythm synchronization) data. A hypothesis is suggested that the earlier revealed increase in the tonic prestimulus theta-activity and suppression of the poststimulus phasic activation of the cortico-hippocampal system are one of the mechanisms of the decrease in plasticity of the cognitive function of the emotional facial expression recognition under conditions of the increased load on the working memory.

[Context effects recognition of the emotional facial expression].

Influence of additional working memory load on emotional face recognition was studied in healthy adults. Visual set to emotional face expression was experimentally formed, and two types of additional task--visual-spatial or semantic--were embedded in the experiment. Additional task caused less plastic set, i.

[Flexibility of cognitive activity depends on its context].

The main purpose of this survey is to explain the importance of set-shifting for a flexible cognitive activity. Working memory overload may result in set-shifting slowdown, i.e.

[Influence of the working memory load on the spatial synchronization of prestimulus cortical electrical activity during recognition of facial expression].

The effect of increased working memory load (introduction of additional cognitive task into the context) was studied in adult healthy subjects (n = 35, 16 men, 19 women) in experiments with cognitive set. The EEG coherence in the frequency bands theta (4-7 Hz) and alpha (8-13 Hz), as well as alphal (8-10 Hz) and alpha2 (11-13 Hz) was analyzed and compared to the control data obtained in the experiments without additional memory load. Additional memory load was accompanied by an increase in the rigidity of the set to facial expression and substantial change in the pattern of the spatial synchronization of cortical potentials: coherence of potentials in the theta bands increased between the left and right frontal areas and between the frontal and temporal areas.

[EEG spatial synchronization at different set stages in 8-year-old children with different levels of selective attention fronto-thalamic system maturity].

Visual cognitive set was studied in two groups of 8-year-old children: with normal development of fronto-thalamic system (FTS) (n = 21) and with functional immaturity of this system (n = 29). In most of the children with the FTS-immaturity a formed visual set was rigid. EEG was recorded from the frontal, central, temporal, parietal and occipital regions, and coherence function in theta-, alpha- and beta-bands was analyzed.

Evoked synchronization/desynchronization of cortical electrical activity in response to facial stimuli during formation of a set to an emotionally negative expression.

Evoked EEG theta and alpha rhythm synchronization/desynchronization responses to facial stimuli were studied in healthy subjects (n = 35) in an experiment involving formation of a set to an emotionally negative facial expression. The magnitude of the evoked theta activity synchronization response in the group of subjects with the plastic type of set was greater and the latent period was shorter than in the group with the rigid type of set. These differences were particularly clear in the temporal and parietal-occipital areas.

Synchronization of EEG theta and alpha rhythms in an unconscious set to the perception of an emotional facial expression.

Coherence functions in cortical electrical potentials in the theta (4-7 Hz) and alpha ranges (8-13 Hz) recorded during the formation and testing stages of a visual set to facial images bearing an emotional expression (an angry face) were studied in healthy adult subjects (n = 35). Differences in the spatial synchronization between theta and alpha potentials were seen, especially in rigid forms of the set, in which cases of erroneous perception of facial expressions were seen with contrast and assimilative illusions. This group of subjects (n = 23) showed increases in theta potentials between the dorsolateral areas of the frontal cortex (the orbitofrontal cortex) and the temporal area in the right hemisphere.

[Visual set and shifting of selective attention in 8-year-old children with EEG-signs of immaturity of fronto-thalamic and brainstem activating systems].

Visual set (by D.N.Uznadze) was studied in three groups of 8-year-old children: children with EEG-signs of immaturity of fronto-thalamic activation system; children with a deficit of non-specific activation from mesencephalic reticular formation; children with normal development of these systems (control group).

[Event-related synchronization/desynchronization of cortical theta- and alpha-electrical activity and cognitive set to emotionally negative face expression].

Alpha- and theta-band EEG synchronization/desynchronization, induced by the presentation of emotionally negative stimulus (angry faces), was studied in 35 healthy adults. In subjects with a plastic set induced theta-synchronization was greater, and its latency was shorter, than in subjects with a rigid set. This difference is particularly apparent in temporal and parieto-occipital brain regions.

Relationship between the plasticity of a set to an emotional facial expression and the load on working memory.

The effects of increasing the loading on working memory (by introduction of an additional cognitive task into the experimental context) on the recognition of an emotional facial expression using a visual set model were studied in healthy adult humans. A relationship was found between the plasticity of the cognitive set to an emotional facial expression and working memory: increases in the load on memory slowed set substitution when the situation changed. The set became more rigid, as indicated by an increase in the number of trials showing erroneous assessments of facial expressions, i.