[The Futures of Auditory Passive Perception While Listening to Sounds in Healthy Persons of Young or Advanced Age (ERP and Psychology Tests Analysis).]

The study analyzed ERPs in 37 healthy right handed subjects without neurological and psychiatric disorders. Young age group consisted of 18 persons aged 18 to 27; advanced age group included 19 persons aged 32 to 59. ERPs were recorded by 32 scalp electrodes according to 10-20% system. Two toned addball paradigm including standard and target tones was used for ERP-recording. The sound sequence was given to examinees without any preliminary instruction. Complex psychology testing included Stroop color and word test for the attention and interference assessment, and Wisconsin card sorting test. Significantly larger amplitude of N200 was detected in young persons in comparison to ones of advantage age. Wavelet-analysis revealed stronger wavelet-connections in frontal-central area on the time range of P300 in persons of advanced age vs. younger ones. The correlation of data of psychological tests examining executive functions was detected with latency of P300 in young examinees and with amplitude of P300 in advanced age ones. Obtained data suggests that switching from one activity to another is prevalence in young persons and focusing on a current activity in advanced age persons.

[The comparative analysis of changes of short pieces of EEG at perception of music on the basis of the event-related synchronization/desynchronization and wavelet-synchrony].

The going of present pilot study is an analysis of features changes of EEG short pieces registered from 32 sites, at perception of musical melodies healthy examinees depending on logic (cognizance) and emotional (it was pleasant it was not pleasant) melody estimations. For this purpose changes of event-related synchronization/desynchronization, and also wavelet-synchrony of EEG-responses at 31 healthy examinees at the age from 18 till 60 years were compared. It is shown that at a logic estimation of music the melody cognizance is accompanied the event-related desynchronization in the left fronto-parietal-temporal area. At an emotional estimation of a melody the event-related synchronization in left fronto - temporal area for the pleasant melodies, desynchronization in temporal area for not pleasant and desynchronization in occipital area for the melodies which are not causing the emotional response is typical. At the analysis of wavelet-synchrony of EEG characterizing jet changes of interaction of cortical zones, it is revealed that the most distinct topographical distinctions concern type of processing of the heard music: logic (has learned-hasn't learned) or emotional (it was pleasant-it was not pleasant). If at an emotional estimation changes interhemispheric communications between associative cortical zones (central, frontal, temporal), are more expressed at logic - between inter - and intrahemispheric communications of projective zones of the acoustic analyzer (temporal area). It is supposed that the revealed event-related synchronization/desynhronization reflects, most likely, an activation component of an estimation of musical fragments whereas the wavelet-analysis provides guidance on character of processing of musical stimulus.

[Higher mental functions and cognitive auditory event-related potentials impairment in liquidators of Chernobyl accident].

An integrated neuropsychological study and analysis of cognitive auditory event-related potentials (ERP) using the three-stimulus oddball paradigm was performed in ten subjects who participated in the liquidation of Chernobyl accident and ten healthy subjects. Impairment of higher mental functions, including aspontaneity, fatigability, a decrease in the auditory-verbal and visual memories, and higher motor function deficiency was shown in liquidators. A decrease of amplitude in all components of ERP (N1, N2 and P3) was found in liquidators for all stimuli in both experimental situations (audition of all stimuli and counting of deviant stimuli) compared to healthy subjects. The latent period (LP) of ERP in liquidators was decreased for N1 and N2 components and increased for P3. The largest between-group differences in the LP were revealed in the frontal areas for N1 and P3 in the left hemisphere and for N2 - in the right one. The correlation analysis between the ERP and a neuropsychological study had shown that changes in the LP of N1 are correlated to the impairment of short-term memory and pose praxis of the right hand while changes in the N2 were correlated to the impairment of long-term memory and pose praxis of the left hand. The changes in LP of P3 were correlated to complex cognitive processing disorders. Thus, the complex study identified the deceleration of perception, processing, and analysis of information combined with the weakened inhibition and "uneconomical" type of reactivity which led to the impairment of higher mental functions in liquidators compared to healthy subjects of the same age. The changes found in liquidators are similar to those observed in elderly people and support the hypotheses on accelerated brain ageing caused by low dose irradiation.

[Long-latency components (N100, N200 and P300) of acoustic evoked potentials in prediction of mental recovery in severe traumatic brain injury].

The authors analyzed correlations of amplitude and latency levels of N100, N200 and P300 components of acoustic evoked potentials (AEP) registered during sonic stimulation and counting of target-oriented stimuli in 22 patients in vegetative state and mutism as an outcome of traumatic brain injury. Results were analyzed with association of electrophysiological findings with data of diffusion-tensor MRI. 55 healthy volunteers were included into control group. It is described that patients in vegetative state with formal recovery to the level of clear consciousness develop all three components of AEP in response to target-oriented tone. The instruction "to counts" leads to their better development. Patients with restoration to minimal level of consciousness produce all components during audition of sounds and only N100 and N200 in response to standard tone after instruction "to count". It is discovered that levels of amplitude have bigger correlation according to Spearman's criterion with outcome in comparison to latency. There changes are more prominent in N100 and N200 components rather in P300. In addition, after instruction "to count sounds" the registered changes between stages of vegetative state and mutism are significant for leads of left hemisphere, and during audition of sounds--for sagittal leads. The study showed correspondence of acquired changes with MRI data. Chronic unconscious state is associated with changes in corpus callosum (degeneration fibers) and corticospinal tracts in the brainstem. The data are discussed in light of hypothesis of the role of morphofunctional disconnections (brainstem-thalamus and interhemispheric) in impairment of attention and in genesis of different forms of posttraumatic unconscious state.

[Possibilities of wavelet-syncronization method for estimation of the spatial distribution of components of auditory evoked potentials in healthy subjects].

Event-related potentials (ERP) are informative indicators of higher nervous activity of healthy people and patients in pathological states. Traditionally, methods of ERP processing include peak-time characteristics, topographical mapping and localization of equivalent dipole sources. At the same time, estimation of ERP synchronization is complicated by a short duration of the process. The wavelet analysis makes it possible to overcome the disadvantages of the traditional Furrier analysis and to calculate characteristics of ERP synchronization, in particular, phase synchronization. A new approach to estimation of the auditory ERP in healthy persons is proposed in the article. The method is based on the analysis of phase wavelet-synchronization of ERP individual components under conditions of differentiation of different degrees of attention concentration in healthy persons.

[Amplitude-time parameters of long-latency components (N1, N2 and P300) of acoustic evoked potential of healthy examinees of young and mature age].

The aim of study was to track a cumulative changes of amplitude-time parametres of components N1, N2 and P300 of acoustic evoked potential in experimental situations different in complexity (at the account and listening of sounds) and to compare the received distinctions at examinees of young and mature age. ERP were recorded at 12 healthy subjects from 18 to 22 ages and 12 subjects from 32 to 59 ages. The two-stimuli oddball paradigm was used. It is revealed that components N1, N2 and P300 recorded in the situation of the listenings of sounds without any preliminary instruction do not differ at persons of young and mature age. At examinees of younger age the biger amplitude of component N1 is noted at the account of sounds in comparison with listening whereas the latency of the one do not change depending on complexity of the task. It is shown that component N2 has stability of latency in relation to age and an experimental situation. The amplitude of component N2 is above at the account of sounds in both age groups. The amplitude-time parametres of component P300 do not differ at examinees of different age in a problem of listening of sounds. The revealed features of components N1, N2 and P300 at examinees of young and mature age in experimental situations different in complexity, allow to assume that with the years at the person adaptive mechanisms which allow carrying out successfully of the task.

[Features of cognitive audiory evoked potentials changes at participants of liquidation of chernobyl accident consequences the message II. the analysis of late component P300].

At 10 participants of liquidation of consequences of Chernobyl accident (middle age 50.5 +/- 4.0 years) and at 10 healthy persons (middle age 47.0 +/- 6.0 years) are performed complex neuropsychological examination and registration acoustical cognitive evoked potentials (EP) using odd-ball paradigms. Neuropsyhological research has revealed at liquidators disorders of the higher mental functions, such as aspontanity, decrease speech and a visual memory, and also deficit of higher motor functions. According to the analysis of amplitude-time characteristics of component P300 acoustical cognitive EP a decrease in amplitude of this component at liquidators in all areas of the brain, for both experimental situations for all stimulus in comparison with healthy persons the same age was revealed. At the analysis of latent period (LP) P300 at liquidators the most distinct increase was revealed in a situation of passive listening for all kinds of stimulus. The analysis of reactivity of LP in different experimental situations has shown that at healthy persons during passive listening had similar values for all kinds of stimulus, and an account situation the maximum values--for significant stimulus. For liquidators the type of reaction in the form of increase in LP values at the majority of stimulus in both experimental situations. The analysis of regional LP changes of component P300 has found out the maximum distinctions between groups in frontal area of the left hemisphere. Along with it at liquidators the type the reactions similar for all shown stimulus without dependence from their importance in comparison with norm is revealed "uneconomical, superfluous". It can testify about decreasing of attention and memory reserves and to promote disorder of the higher mental functions. The described of amplitude-time characteristics of component P300 of acoustical EP at liquidators EP can testify to delay of perception, processing and the information analysis in a combination to easing of inhibitory processes leading to the higher mental dysfunctions. The obtained data have similarity to people of old age, supporting a hypothesis about the accelerated ageing of a brain, and also about pathological development of processes of ageing as a result of influence of low doses of radiation.

[Specificity of auditory evoked potencials changes in participants of Chernobyl accident consequences: I. Analysis of early N1 component].

Amplitude-time characteristics analysis of the N1 component of auditory cognitive evoked potentials (EP) was made in 10 persons who had participated in the cleanup of the Chenobyl Accident - liquidators (mean age 50.5 +/- 4.0 years old) and in 10 healthy subjects (mean age 47 +/- 6.0 years old). Comparison of amplitude features of the N1 auditory EP component in liquidators of the Chernobyl Accident found a decrease in all areas of the cortex with the maximum decrease in the central and frontal leads, and also an inversion in reactive changes to stimuli of different significance in comparison to healthy subjects of the same age. The most distinct differences between the healthy subjects and liquidators of the Chernobyl Accident were found for time characteristics of the N1 component. They show a significantly smaller value of latent period (LP) for all stimuli and for all experimental tasks in comparison with healthy subjects and more distinct for a significant stimulus when persons counted these stimuli. Analysis of regional changes in LP of the N1 component found that liquidators, in comparison with healthy subjects, have maximal differences in the frontal area of the left hemisphere which were accompanied with inversion asymmetry of LP in this component. Less distinct changes were observed in the central area with relatively little damage in the parietal area. Detected changes in the amplitude-time characteristics of the N1 component of the auditory cognitive EP in liquidators of Chernobyl Accident can show an abnormality in primary attention and its reserves due to weakened inhibitory processes in comparison with healthy subjects, which has similarities of old age. The obtained data supports the hypothesis about the accelerated brain aging in liquidators of Chernobyl Accident as a result of low dosage radiation effects; however, it also allows the pathological development of the brain ageing due to the effects of radiation.

[Dynamics of P300 component of acoustic evoked potential in postraumatic unconsciousness].

In order to reveal features of the brain reactions to external stimuli in the course of consciousness recovery after a severe craniocerebral injury, component P300 of acoustic evoked potential was analyzed in 9 patients with chronic and 32 patients with reversible unconsciousness. In patients with chronic unconsciousness, P300 parameters displayed a linear correlation with the current functional state. However, this component remained significantly different from its normal shape and varied only in a narrow range. In patients with reversible unconsciousness, time course of changes in amplitude and latency between recovery stages was of linear character with a tendency to normalization. The findings suggest that, in reversible unconsciousness states, processing of sensory information at different recovery stages may be performed with various functional systems that determine varying quality of processing, whereas changes in chronic unconsciousness are caused by a decrease in the number of active elements within the same functional system.

Frontal and temporal sources of mismatch negativity in healthy controls, patients at onset of schizophrenia in adolescence and others at 15 years after onset.

Mismatch negativity (MMN) is an event-related potential measure of auditory change detection. It is widely reported to be smaller in patients with schizophrenia and may not improve along with otherwise successful clinical treatment. The main aim of this report is to explore ways of measuring and presenting four features of frequency-deviant MMN dipole sources (dipole moment, peak latency, brain location and orientation) and to relate these to the processes of psychopathology and illness progression. Data from early onset patients (EOS) at the start of the illness in adolescence, and others who had their first break in adolescence 15 years ago (S-15Y) were compared with two groups of age-matched healthy controls (C-EOS, C-15Y). A four-source model fitted the MMN waveform recorded from all four groups, whether MMN amplitude was more (EOS) or less (S-15Y) reduced. The locations were in the left superior temporal and anterior cingulate gyri, right superior temporal and inferior/mid frontal cortices. Dipole latencies confirmed a bottom-up sequence of processing and dipole moments were larger in the temporal lobes and on the left. Patients showed small dipole location changes that were more marked in the S-15Y than the EOS group (more rostral for the left anterior cingulate, more caudal for the right mid-frontal dipole) consistent with illness progression. The modelling of MMN dipole sources on brain atlas and anatomical images suggests that there is a degree of dissociation during illness between small progressive anatomical changes and some functional recovery indexed by scalp recordings from patients with an onset in adolescence 15 years before compared to adolescents in their first episode.

[Component P300 of acoustic evoked potential in patients with local brain lesion]. / Komponent P300 akusticheskogo vyzvannogo potentsiala u bol'nykh s ochagovym porazheniem golovnogo mozga.

The aim of the study was a comparative analysis of spatial-temporary organization of P300 acoustic evoked potential (AEP) in patients with local lesions of the brain stem, frontal and temporal structures in the situations of "passive" listening to sounds and their active recognition (a count). Specific changes of P300 parameters were distinguished in each group. The peak-temporary P300 parameters--latency increase, decrease of amplitude and tendency to the decrease of half-cycle--were similarly changed, irrespective of brain damage topography. A degree of the changes correlated with a level of functional acoustic evoked potential decompensation. In relation to pathologic process location, the topographical P300 AEP features were more specified, comparing to peak-temporary parameters. An existence of two systems for P300 generation at "active" counting and "passive" listening was suggested. In "passive" listening, a response is mostly determined by intact left frontal lobe and middle-stem structures but in "active" counting--by intact right frontal lobe or lobes and limbic system structures (hippocampus).

[Characteristics of the spatio-temporal organization of the P300 component of AEP during the "active" and "passive" stimulus perception in healthy subjects]. / Osobennosti prostranstvenno-vremennoi organizatsii komponenta P300 AVP pri "aktivnom" i "passivnom" vospriiatii stimula u zdorovykh ispytuemykh.

The concern of the work was in detection and analysis of P300 component of the acoustic evoked potential in healthy subjects in different experimental situations. During counting the rare sounds, P300 was most pronounced in the frontocentral and parietooccipital areas mainly of the left-hemisphere. The response shape was correlated with characteristics of the basic rhythm of the background EEG. Responses of simple and complex shapes were distinguished. The simplest responses were recorded in subjects with hypersynchronous alpha-rhythm. Analysis of three-dimensional dipole source localization showed that structures of the brainstem, limbic system, and frontal lobes participate in generation of the wave. In all the subjects, the decisive role in response generation was played by the brainstem structures. In persons with hypersynchronous alpha-rhythm, the contribution of the frontal lobes was less pronounced. During "passive" listening of sounds, P300 parameters significantly differed from those observed during counting only in 46% of cases (in persons having no hypersynchronous alpha-rhythm). A simplification of the response shape during "passive" listening was observed in these cases, the area of the maximal response expression was shifted to symmetrical areas of the right-hemisphere, the number of dipole sources reduced due to a decrease in the contribution of the frontal and limbic structures into the response generation.

[Visual evoked potentials and the P300 component in different courses of the posttraumatic vegetative state]. / Zritel'nye vyzvannye potentsialy i komponent P300 pri raznom techenii posttravmaticheskogo vegetativnogo sostoianiia.

The late latency components of visual evoked potentials (VEP) and the component P300 AEP were analyzed to evaluate their informative value in the process of mental function restoration in patient after long-term traumatic coma. VEP components with latencies of 70 to 320 msec were studied in 24 patients. Topographical mapping of the power of the study VEP components and components P300 was made by the peak amplitude. Long-term VEP components and component P300 were examined by the method of three-dimensional localization of equivalent dipole sources. In 16 patients with positive tendencies in the condition there was a stable localization of the maximum VEP power in the parietal, sagittal, and occipital regions, component P300 showed its maximum amplitude in the central and parietal regions in the left hemisphere. Eight patients with negative tendencies in the status had the maximum VEP and component P300 in the frontal and temporal regions, predominantly in the right hemisphere. The paper shows it important to evaluate not only time-amplitude parameters and analyzes the tomographic features of its formation in dynamics.

[The P300 component of the auditory evoked potential in the posttraumatic vegetative state]. / Komponent P300 akusticheskogo vyzvannogo potentsiala v posttravmaticheskom vegetativnom sostoianii.

The dynamic studies of P300 component of the acoustic evoked potential were conducted in 12 patients in posttraumatic state of the autonomic system. The amplitude and time parameters of P300 were analyzed, its spatial distribution over the cortex, and features of generation. The obtained results were compared with the normative data. Significant changes in P300 in comparison with the normal characteristics were revealed in patients with the absence of conscious mental activity. These changes were maximally expressed when the state of patients was irreversible. In case of patients' outcome from the studied state the amplitude-temporal and topographic response characteristics tended to normalization but did not reach it completely. The obtained results allow us to consider the P300 component as one of the most informative indices in consciousness recovery after severe brain injury.