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Biomedical subjects

A F Iznak

Publications and source records attributed to A F Iznak.

At least 19 recordsLinked to original sources
PubMed2001

[Quantitative EEG correlates of the human frontal lobe dysfunction].

Increased central-parietal EEG theta-2 activity (about 6.5 per sec) was found in children with cognitive disorders (in Rett's syndrome, fragile X-syndrome, infantile autism) and in elderly patients with Alzheimer-type dementia (with prevalence of neuropsychological "frontal" disorders) in the presence of suppressed alpha rhythm. This theta-activity was closely associated with cognitive deficits and possessed a specific functional topography, namely it focused in the parietal region and suppressed by both visual stimulation and motor tests. The similar EEG pattern was observed in some patients treated with neuroleptics and/or during hyperventilation. By taking into account the data available in the literature on motor, oculomotor, regional cerebral blood flow and the probability prediction in frontal lobar dysfunction, it is suggested that the theta-activity described appears in the visuomanual coordination system and is a physiological correlate of decreased functional status of frontal lobes.

Aged↗
PubMed1999

[Quantitative EEG in early and differential diagnosis of mild dementia of different genesis].

Quantitative EEG was used to reveal the specific features of its amplitude-frequency parameters and topography in patients with mild dementia of different genesis versus healthy elderly individuals. All four study groups of patients differ in EEC relative spectral density, they also differ from the healthy persons while alpharhythm was suppressed in Alzheimer's disease (AD) and vascular dementia (VD) and there was slower alpha-rhythm and higher theta-activity in senile AD (SAD). Patients with VD were characterized by desynchronized EEG. Factorial and stepwise discriminant analyses of EEG parameters showed that the control group greatly differed from patients with mild dementias. Patient groups mainly with atrophic atrophic AD and SAD or vascular (VD and mixed) dementia were also different whereas the mixed vascular-atrophic group is intermediate in EEC parameters between the VD group and the partially overlapped AD and SDA patient groups. Quantitative EEC data may be thus used for differential diagnosis to optimize therapy and prognosis even in mild dementia.

Aged↗
PubMed1996

Abnormal recognition of facial expression of emotions in depressed patients with major depression disorder and schizotypal personality disorder.

The aim of this paper is to study the recognition of facial expression of emotions in depressed patients with major depressive disorder (MD) and schizotypal personality disorder (STP). The pictures of sad, emotionally neutral, and happy faces followed by a masking stimulus were displayed for 80 msec on a computer screen randomly in the left or right hemifield of vision (LHF and RHF). The subjects had to respond by pressing a three position key. Multiple analysis of variance revealed that all depressed patients, relative to control subjects, made more errors in a task of recognition of facial affect. The characteristics of impairment of performance were found to be related to the nosology of depression. MD patients revealed significantly impaired recognition of negative (in LHF and in RHF) and positive (in LHF) facial emotions, as well as poorer recognition in the right hemisphere, and reduced hemispheric asymmetry. In remission, they showed statistically significant recovery of recognition function. STP patients were less impaired and showed slightly poorer recognition of sad (in RHF) and happy (in LHF) expressions. This group demonstrated significantly poor recognition of happy expressions, and more marked dysfunction of the left hemisphere. In remission, STP patients failed to improve in recognition of emotion. This suggests, that the features of emotion recognition in MD and STP groups reflect some differences in the neurophysiological mechanisms underlying the affect-related dysfunction in these groups of depressed patients.

Adult↗
PubMed1996

[Psychophysiological correlates of increasing the work ability of human operator owing to the programmable correction of the functional status].

There has been studied application of a complex approach to development of automated ways to gain contactless psychophysiological correction of functional status and improvement of performance of working up operators. The psychophysiological support of operator consisted in combined presentation of functional music, surf noise and pulsed dynamic green lighting under a special program built-up on the principle of biological feedback of heart and respiration rates. The individually adaptable audio and visual pulses on the programme showed a rather high efficiency as was confirmed by the change in the set of psychophysiological indices (heart rate, arterial pressure, cutaneogalvanic reaction, accommodation volume, critical rate of flicker fusion, electroencephalogram), and subjective SAM (self-feeling, activity, mood) estimates in the course of extended operator's activity.

Electroencephalography↗
PubMed1994

[The clinical, neurophysiological and differential diagnostic aspects in a study of severe forms of early childhood autism].

Clinical, pathopsychological and neurophysiological studies have been carried out in 85 children with infantile autistic psychosis and in 38 girls with Rett's syndrome. New improved differential diagnostic criteria between these two forms of early childhood autism have been suggested. EEG spectral density values in alpha-1, alpha-2, beta and theta subbands are established to be their neurophysiological markers. Special attention was paid to close relationship between ontogenetic neuromorphogenesis of the brain cortical structures (e.g. physiological lysis of cortical cell populations at the age 8-30 months of the child's life) and the defect severity in the onset of illness at the same age range in patients with the studied forms of early childhood autism. The data obtained are discussed in terms of new approaches to understanding pathogenesis of different forms of early childhood autism.

Autistic Disorder↗
PubMed1994

[The recognition of the facial expression of emotions by patients with endogenous depression (clinico-psychophysiological research)].

The recognition of facial emotional expression in depressed patients with major depressive disorder (MDD) and slow progressive schizophrenia (SPS) in acute state and in remission was studied in comparison with healthy persons. All the subjects were right-handed. The drawings of sad, neutral and happy faces followed by masking stimulus were displayed in the center field and in the left or right hemifield of vision on the computer screen for 80 ms. All the depressed patients revealed marked impairment of facial emotion recognition, especially for negative on, and disturbances of hemisphere asymmetry. There were some differences between MDD and SPS patients. The MDD patients showed more significant impairment of emotion recognition and right hemisphere disfunction. The SPS patients were less impaired and revealed mild worsening in the left hemisphere only. In remission MDD patients showed a significant improvement of emotion recognition contrary to SPS patients who failed to recover this function. The revealed emotion recognition disturbances in MDD patients are supposed to be dynamic, whereas in depressed patients with SPS it is considered to be a trait feature.

Adult↗
PubMed1992

[Longitudinal approaches to the problem of clinical heterogeneity of Alzheimer-type dementia].

A total of 160 patients with Alzheimer-type dementias (ATD), including 84 with Alzheimer's diseases (AD) and 76 with senile dementia (SD), were examined. The initial signs of the disease were analyzed by making a retrospective assessment of informative history data. The prospective follow-up involved clinical, neuropsychological and electrophysiological (EEC mapping, evoked potentials) studies by applying the standardized assessment of results. There was shown to be a set of clinical and paraclinical parameters for the status of ATD patients, indicating a distinct-quantitative and qualitative difference between patients with AD and those with SD and supporting the heterogeneity of ATD.

Aged↗
PubMed1992

[EEG-mapping in Alzheimer-type dementias].

EEG topographic correlates of the severity and type of Alzheimer-type dementias have been studied in 21 patients with senile dementia (SD) and 18 with Alzheimer's disease (AD) who were subdivided into smaller groups by MMSE grades for the severity of dementia, as well as in 15 mentally normal elderly persons. EEC maps in SD and AD patients differed from those in normal subjects in increased theta-delta EEG spectral power and suppressed alpha-band power that was more pronounced in the left hemisphere in AD than in SD patients. AD and SD patients had also different EEG topographical changes with intensified cognitive dysfunctions. The results suggest that there is a great cholinergic deficiency and cortical rather than subcortical impairments in patients with AD than in those with SD.

Alzheimer Disease↗
PubMed1983

[Functional interrelation of the brain structures of the cat during the generation of rhythmic activity. I. The frequency characteristics of the electroencephalogram].

The similarity of frequency parameters of electroencephalograms (EEG) recorded from visual, associative and sensorimotor cortical area, caudate nucleus and several thalamic nuclei have been analysed using the period analysis of EEG and cluster analysis of data obtained to clarify the functional interrelationships between these parts of the brain during generation of rhythmic activity of different types. Functional interrelationships between brain structures in freely moving cats during the states of drowsiness and slow-wave sleep have been shown to differ from "classical" thalamo-cortical pacemaker relations.

Animals↗