Functional Interhemispheric Asymmetry Research Articles

CLINICAL AND NEUROLOGICAL FEATURES DEPENDING ON THE SIDE OF LOCALIZATION IN PATIENTS WITH ISCHEMIC STROKE

In recent years, research into functional interhemispheric asymmetry has been intensively carried out in our country and abroad. An analysis of publications related to this topic shows that the problem of interhemispheric asymmetry is associated with some fundamental properties of living matter and is present at almost all stages of the evolutionary ladder. In the 30-40s of the 20th century, the study of functional asymmetry in healthy people began. The identified asymmetries were divided into three main types: mental, motor and sensory.

FUNCTIONAL ASYMMETRY AS ONE OF THE MECHANISMS OF FUNCTIONING OF THE NERVOUS SYSTEM IN NORMAL AND PATHOLOGICAL CONDITIONS

In recent years, research into functional interhemispheric asymmetry has been intensively carried out in our country and abroad. An analysis of publications related to this topic shows that the problem of interhemispheric asymmetry is associated with some fundamental properties of living matter and is present at almost all stages of the evolutionary ladder. In the 30-40s of the 20th century, the study of functional asymmetry in healthy people began. The identified asymmetries were divided into three main types: mental, motor and sensory.

АНАЛИЗ РЕОЭНЦЕФАЛОГРАФИЧЕСКОГО ИССЛЕДОВАНИЯ МЕЖПОЛУШАРНОЙ АСИММЕТРИИ МОЗГОВОГО КРОВОТОКА У ЗДОРОВЫХ И УМСТВЕННО ОТСТАЛЫХ ДЕТЕЙ 8-11 ЛЕТ

The features of functional organization of hemodynamic processes in brain basins of healthy children and children with mild mental retardation, depending on the nature of asymmetry and gradient of cerebral blood flow, were studied. The study involved 131 children aged from 8 to 11 years. Of them, 73 were healthy with normal physical and mental development, and 58 children - with mild mental retardation. The study was conducted to determine what kind of sports and physical activity allow children with mental retardation to engage in activities. To study the functional interhemispheric asymmetry of cerebral blood flow in the studied groups of children, the technique of rheoencephalography was used. The article presents the results of empirical studies of rheoencephalography parameters of the brain among healthy children and those with mild mental retardation. The parameters of cerebral blood circulation of healthy children and children with mental retardation aged 8-11 years, reflecting the state of different parts of the cerebral vascular system, were studied. We also analyzed and compared age-related changes in the functional organization of hemodynamic processes in healthy children aged 8-11 years and in children diagnosed with mental retardation.

Systemic analysis of eeg activation response in right and left handers

Most researchers in the study of the EEG activation response studied changes in alpha activity, while the dynamics of changes in other EEG rhythms and functional interhemispheric asymmetry (FMAA) was described and analyzed to an immeasurably lesser extent. Considering electrogenesis as a systemic category, it is advisable to study the relationships between the amplitudes of EEG rhythms using multiple regression and correlation methods of analysis. The EEG was studied on practically healthy people, students, in the state of PR and OR. Lateralization (right-handed-left-handed) was determined by EEG parameters. Activation coefficients (AC) were determined by dividing the beta-2 rhythm duration index by the alpha rhythm duration index. Relationships formed between the amplitudes of EEG rhythms were studied using calculations of multiple linear regression and correlation.
 In own research we was show: when opening the eyes, the amplitude of alpha and beta-1 rhythms in right-handers and left-handers decreased statistically signifiantly. Changes in the parameters of beta-2 EEG rhythms when opening the eyes in right-handers were determined to be increased in the left and right hemispheres, and in left-handers only in the forehead-temporal abduction of the left hemisphere - an increase in the duration index. Indicators of theta rhythm in right-handed people decreased in the left and right hemispheres when opening the eyes, and in left-handers, changes in theta rhythm were manifested only in the crown-occiput abduction of the right abduction. The amplitude and frequency of the EEG delta rhythm in right-handers decreased in the left and right hemispheres, and the duration indices were determined to be statistically significantly increased in all leads, with the exception of the forehead-temporal of the left hemisphere, while in left-handers, changes in the delta rhythm were observed mainly in the right hemisphere and were expressed in a decrease in amplitudes and rhythm frequencies. In the study of FIA, the alpha-rhythm index of right-handers under PR conditions was determined to be negative, and in left-handers it was positive. Under conditions of operational rest, this indicator was positive for both left-handers and right-handers. When opening the eyes, the AC in most leads increased statistically significantly in both right-handers and left-handers.
 The regression analysis revealed that the number of statistically significant regression coefficients increased significantly in the left hemisphere in right-handers under OP conditions, while in left-handers it decreased in the right hemisphere.

Evaluating interhemispheric synchronization and cortical activity in acute stroke patients using optical hemodynamic oscillations

Objective. An understanding of functional interhemispheric asymmetry in ischemic stroke patients is a crucial factor in the designs of efficient programs for post-stroke rehabilitation. This study evaluates interhemispheric synchronization and cortical activities in acute stroke patients with various degrees of severity and at different post-stroke stages. Approach. Twenty-three patients were recruited to participate in the experiments, including resting-state and speed finger-tapping tasks at week-1 and week-3 post-stroke. Multichannel near-infrared spectroscopy (NIRS) was used to measure the changes in hemodynamics in the bilateral prefrontal cortex (PFC), the supplementary motor area (SMA), and the sensorimotor cortex (SMC). The interhemispheric correlation coefficient (IHCC) measuring the synchronized activities in time and the wavelet phase coherence (WPCO) measuring the phasic activity in time-frequency were used to reflect the symmetry between the two hemispheres within a region. The changes in oxyhemoglobin during the finger-tapping tasks were used to present cortical activation. Main results. IHCC and WPCO values in the severe-stroke were significantly lower than those in the minor-stroke at low frequency bands during week-3 post-stroke. Cortical activation in all regions in the affected hemisphere was significantly lower than that in the unaffected hemisphere in the moderate-severe stroke measured in week-1, however, the SMC activation on the affected hemisphere was significantly enhanced in week-3 post-stroke. Significance. In this study, non-invasive NIRS was used to observe dynamic synchronization in the resting-state based on the IHCC and WPCO results as well as hemodynamic changes in a motor task in acute stroke patients. The findings suggest that NIRS could be used as a tool for early stroke assessment and evaluation of the efficacy of post-stroke rehabilitation.

Analysis of changes in electrogenesis in schizoprenia using computer electroencephalography

Rationale. Psychiatrists do not have objective methods for identifying the brain disorders responsible for mental illness, which prevents timely diagnosis. Therefore, the search for markers of this disease, primarily related to CNS activity, is very relevant.The purpose. A comparative study; by using periodometric analysis of EEG indicators, interhemispheric asymmetry of EEG rhythm amplitudes, and by using multiple regression analysis to identify connections-relations between EEG amplitude and frequency rhythms of different leads in healthy people and schizophrenic patients.Material and Methods. EEG recording was performed in a state of quiet wake with closed eyes on the Neuron-Spectrum-2 electroencephalograph. The analysis was performed using periodometric analysis.The differences of the indicators were monitored using the calculation of the coefficients of concordance (CCs). Connections-relations between indicators were investigated using multiple regression analysis.Own research. In patients with schizophrenia compared with healthy people, there was detected a decrease in the amplitudes of rhythms of EEG, an increase in the duration indices in the delta and theta ranges and a decrease in the duration indices of the alpha and beta rhythms. In patients with schizophrenia, there was a decrease in negativity and an inversion of functional interhemispheric asymmetry (FIHA) to positivity in the delta, theta, and alpha ranges and an increase of (FIHA) positivity in low-frequency and high-frequency EEG beta rhythms. Multiple regression and correlation analysis of the rhythm amplitudes interactions revealed that in the delta and theta ranges in the main group the number of regression coefficients was less than in the control group and in alpha, beta-LF and beta-HF – more than in control group.Conclusions. 1. The obtained results indicated the activation of the right hemisphere in comparison with the left in patients with schizophrenia, possibly due to a decrease in the activating effect of the reticular formation of the brain stem.2. It has been suggested that these changes in the aggregate are the neurophysiological basis of disorders of higher nervous (mental) activity in patients with schizophrenia

Functional Interhemispheric Asymmetry of Human Brain and Audition

The review presents the current understanding of interhemispheric asymmetry of the human brain activity, recorded by electrophysiological and hemodynamic methods using various sound features. Along with the anatomical differences which may exist between the auditory cortices of the left and right brain hemispheres, the authors consider how lateralization of auditory responses depends on the parameters of sound stimulation and what patterns of interhemispheric asymmetry can be found in auditory evoked potentials (AEP) elicited during spatial processing of sound stimuli.

Individual functional interhemispheric asymmetry profile and clinical and neurophysiological features in patients with Parkinson's disease

The authors determined the individual profile of functional interhemispheric asymmetry (IPFIA) in 70 patients (28 men and 42 women) with Parkinson's disease (PD), by using the examination protocol comprising 48 assignments, its association with clinical asymmetry and effect on electroencephalography (ECG) readings. Right-sided PD onset was significantly more frequently observed in patients with a right IPFIA than in those with mixed and left IPFIAs (p<0.05). Left-sided PD onset was significantly more common in patients with mixed and left IPFIAs than in those with a right IPFIA (p<0.05). EEG showed that the generator of pathological slow wave activity was on the side contralateral to that of the affected extremity and had a clearer lateralization in the initial involvement of the dominant hemisphere in the pathological process.

Reflection of the process of emotional perception of short musical fragments in the parameters of long-latency auditory evoked potentials

The amplitude–temporal parameters of long-latency components of evoked potentials (recorded in symmetrical leads of the parietal regions) were studied during listening to short fragments of classical musical works, which had different emotional expressiveness, presented to healthy subjects by different modes. In random order of presentation, the maximal markedness of the N1-P2 complex and the P3 wave was found to be observed for fragments causing predominantly negative emotional experiences, while the minimal amplitude values and the highest values of the latencies were observed in response to presentation of a musical fragment assessed as emotionally neutral. Significantly higher amplitude values of these oscillations were recorded in the right parietal lead as compared to the left. The data obtained are interpreted in the context of the specific features of perception of short musical fragments in a human with the use of data concerning functional interhemispheric asymmetry when opposite-sign emotional experiences occur.

Interhemispheric asymmetry of regional cerebral blood flow in prepubescent boys with attention deficit hyperactivity disorder.

The prefrontal cortex is asymmetric in both structure and function. In normal subjects, the right prefrontal cortex is activated more than the left during response inhibition. Patients with attention deficit hyperactivity disorder (ADHD) have impaired response inhibition and altered structural interhemispheric asymmetry. This study was conducted to examine the functional interhemispheric asymmetry during response inhibition in children with ADHD. Subjects were divided into three groups according to the level of motor hyperactivity. Blood flow tracer (99m)Tc-ethyl cysteinate dimer was injected while subjects were performing a response inhibition task (RIT), followed by single photon emission computerized tomography (SPECT). After three-dimensional reconstruction, filtering and smoothing, individual scans were morphed to a template. Three average group images were created from individual scans. Each average group image was subtracted voxel-by-voxel from its mirror image to compare the regional cerebral blood flow (rCBF) in the right and left cerebral hemispheres, yielding images of significant interhemispheric rCBF asymmetry. The severe hyperactivity group exhibited most prefrontal left>right rCBF asymmetry and left>right occipitoparietal asymmetry. Reversal of functional prefrontal asymmetry in boys with severe motor hyperactivity supports the hypothesis of right prefrontal cortex dysfunction in ADHD.

Interhemispheric regulation of dopaminergic ascending systems

There are previous evidences of biochemical and functional interhemispheric asymmetry for central dopaminergic systems. The purpose of the current study was to establish an evidence of the existence of mechanisms for interhemispheric regulation of dopaminergic systems. The initial hypothesis was that to compensate the spontaneous interhemispheric assmmetry, the brain side with lower dopamine (DA) concentration show a higher DA turnover. The ratio of metabolite/neurotransmitter was computed as an index of presynaptic turnover rate. Both striatum and hippocampus showed a DOPAC/DA index higher in the brain side with a lower DA concentration. In addition, we found an inverse relation between the interhemispheric index of DA and interhemispheric index of DA turnover. Taken together the present data provide evidence of an interhemispheric regulation for the DA-innervation of both striatum and hippocampus in normal unlesioned rats.

Interzonal transcallosal connections of the auditory and parietal cortex.

Transcallosal evoked potentials arising in the parietal region in response to stimulation of the auditory cortex of the opposite hemisphere were investigated in acute experiments on cats immobilized by tubocurarine. Interzonal transcallosal responses were recorded over the whole surface of the parietal cortex and were of two types: positive-negative and negative-positive. Positive-negative EP have a longer response latency and a greater total amplitude of both components. Negative-positive EP disappeared after division of the corpus callosum, whereas positive-negative responses were not significantly changed. Interzonal transcallosal potentials were characterized by the presence of functional interhemispheric asymmetry of individual shape. The right hemisphere was dominant with respect to average amplitude of the negative phase in negative-positive responses. The amplitude of the early positive component was greater in the right hemisphere in males and in the left hemisphere in females. The late negative wave in animals of both sexes was greater in the right hemisphere. Late components of the EP had a significantly shorter peak latency in the dominant hemisphere. Characteristics of generation and interhemispheric asymmetry of auditory-parietal transcallosal responses are discussed and compared with visual-parietal responses.

New evidence on the callosal system.

In the present paper experimental data on the principles of functional organization of the animal callosal system and the roles of symmetry and asymmetry in interhemispheric interaction are considered. A conclusion has been made that the cerebral hemispheres function not according to homotopicity principle but according to the principle of heterotopicity. A utilization of both homotopical callosal projections and intracortical pathways takes place. In interhemispheric relations the major role is played by the principle of the common pathway. Of great importance in asymmetry organization is the physiological dominant, which is formed and reinforced by excitation spreading through the corpus callosum and along intracortical pathways. Transcallosal excitation, interacting with thalamocortical and extracallosal ones, contributes to the creation and modulation of functional interhemispheric asymmetry.

Individual and species interhemispheric asymmetry in animals.

1. As a result of this investigation it was shown for the first time, contrary to the widely held opinion, that individual and species functional interhemispheric asymmetry can be found not only in man, but also in animals. This conclusion is supported also by data obtained by Nottebohm [23] who described dominance of the left hemisphere in vocalization control in some song birds, and by statements of Ettlinger and Moffett [17], that dominance of the left forelimb can arise inMacaca rhesus. 2. Individual and species asymmetry in animals may perhaps be based on similar physiological mechanisms. The further study of species and individual FIA in animals will be of great theoretical interest for the understanding of the principles governing cerebral lateralization of functions in man, and it will also be of practical importance for the creation of models of various pathological states.