Interhemispheric Interactions Research Articles

P346 Assessing Brain Morphology in Functional Gastrointestinal and Inflammatory Bowel Disorders Using Functional Magnetic Resonance Imaging (fMRI)

Abstract Background Functional gastrointestinal disorders (FGIDs) and non-specific inflammatory bowel diseases (IBD) are increasingly common in young adults. Studies have shown abnormal interhemispheric interactions in FGIDs and altered Default Mode Network (DMN) connectivity in brain regions linked to gastric sensations and emotional regulation. This study explores these neural mechanisms in FGIDs and IBDs, focusing on chronic visceral pain and its association with DMN reorganization. Methods The study included patients with functional dyspepsia (FD), N=18; irritable bowel syndrome (IBS), N=20 and IBD, N=18 alongside a control group of 18 healthy volunteers. Selection criteria included the Rome III Criteria for FGIDs and various diagnostic tests for IBDs. MRI scans were conducted using a 3T Achieva TX Scanner, applying standard T1 and T2 sequences without contrast agents. Functional imaging utilized T2 Gradient Echo-Planar Imaging. Results DMN analysis showed no anterior-posterior split. Significant differences were observed in the IBD group compared to controls, particularly in the left superior frontal gyrus. When comparing all patient groups with controls, increased DMN connectivity was noted in the left cingulum and supplementary motor area. These areas were also significant when comparing only FGIDs patients with controls, indicating altered DMN connectivity in these disorders. Please see: Figure 1 and Table 1. Conclusion The study highlights differences in DMNs between patient and control groups, especially in the left superior frontal gyrus, left cingulum, and left supplementary motor area. All disease groups showed variations from controls in the DMN pattern within the left cingulum. Significant differences in the DMN of the supplementary motor area were observed in functional gastric disease groups compared to controls. These findings suggest a link between brain areas involved in sensorimotor processes and symptoms of FD and IBS, providing insights into the neural basis of these conditions. Despite varied changes, common features differentiating the entire study group from healthy controls were identified. This condensed version focuses on the key aspects of your original text, ensuring that the main findings and methodology are clearly presented within the character limit.

Балансировочные комплекты и доски-балансиры Ф. Белгау как эффективное средство улучшения межполушарного взаимодействия у детей с задержкой психического развития

<p><em>The paper describes and analyzes effective means of improving the interhemispheric interaction of children with mental retardation. The method of cerebellar stimulation allows you to most effectively organize the correctional and developmental process in working with children to improve interhemispheric interaction, stabilize behavior, overcome disturbances in the vestibular apparatus (problems in coordination and coordination of movements), improve posture, a sense of balance, develop visual-motor and spatial coordination, correct violations in the development of speech, increase the overall level of intelligence. Children in this category often have behavioral and concentration difficulties. Purposeful development of interhemispheric interaction contributes to the correction, including behavioral disorders. For children with mental retardation, a work program “Neuro-fitness for the mind” was compiled. The article presents a study of the results of the program implementation. This practice shows positive results in working with children with mental retardation.</em></p>

Успешное обучение языкам в контексте учета межполушарной асимметрии головного мозга у учащихся подросткового возраста

The authors consider the problem of hemispheric asymmetry and its impact on the results of language acquisition. The age and type of nervous system are given as the main criteria determining the degree of manifestation of hemispheric asymmetry. Theoretical data on the importance of the work of the left and right hemispheres from the linguistic point of view are stated, as well as arguments in favor of using exercises aimed at involving both hemispheres in the learning process. The authors rely on theoretical works in order to identify age-related functional changes in the work of the hemispheres, partially correlate these changes with the stages of development of thinking. The results of experiments conducted with two groups of respondents belonging to different categories are analyzed. The first group of respondents are students studying Russian as a foreign language. The second group is English-Russian bilinguals. In order to eliminate errors related to gender and age, the sample was carried out according to the following principle: group 1 - a girl and a boy (18 years old), group 2 - a girl and a boy (17.5 years old). The results of girls and boys are compared separately based on data on the sex differences of the brain. The neuropsychological and linguistic methods used for the ascertaining experiment and the features of their use for testing each group of respondents are described.
 
 The article presents the results of a formative experiment conducted over two months, for which individual exercise systems were developed aimed at forming interhemispheric interaction between bilinguals and foreign students studying Russian.
 
 Based on the comparison of the obtained data, conclusions are drawn, as well as a theoretical justification of the experimental results is given.

Interhemispheric connectivity dynamics of brain activity indused by cortical spreading depolarization in rats

Growing experimental and clinical evidence indicates the crucial role of network dysfunction in neurological disorders’ pathogenesis, including migraine, one of the most prevalent chronic brain diseases. Episodic headache attacks, frequently unilateral, accompanied by an aura, are associated with migraine. Migraine aura is a neurological condition characterized by the temporary development of unilateral sensory, motor, and/or speech disturbances. The symptoms are thought to indicate transient cerebral dysfunction in the cerebral cortex resulting from cortical spreading depolarization (SD), a wave of strong cellular depolarization that gradually spreads through the cortex at a rate of 3–5 mm/min. Electrophysiologically, the cortical SD wave is revealed by a high-amplitude slow negative shift in the extracellular potential and temporary suppression of the electrical activity of the cortex (EEG depression). The change in extracellular potential is associated with strong neuroglial depolarization and disruption of local ion homeostasis, which lasts for 1–2 min in healthy neuronal tissue. The SD results in a momentary suppression of the spontaneous electrical activity within the cortex, which is preceded by a brief excitation of the neurons. The neurological symptoms of the aura suggest a unilateral impairment of interhemispheric interactions during the early phase of a migraine attack. Our study investigated the effect of unilateral SD (a probable pathophysiological mechanism of migraine aura) on interhemispheric functional communication in freely behaving rats using local field potentials of the visual and motor cortex. Two methods were used to examine connectivity: mutual information function, computed using the method proposed in [1], and phase synchronization, calculated through the method [2], for four frequency bands: delta (1–4 Hz), theta (4–10 Hz), beta (10–25 Hz), and gamma (25–50 Hz). This was done by performing calculations on non-overlapping twenty-second intervals. Functional connectivity evolution was analyzed using local field potential records collected from homotopic points of the motor and visual cortex of two hemispheres in freely moving rats after inducing a single unilateral cortical SD in the somatosensory cortex. Cortical SD caused a significant wide-band decline (3–4 times) in interhemispheric functional connectivity in both the visual and motor cortex areas. Following the depolarization wave, the functional decoupling of the hemispheres began and progressively intensified, concluding by 5 min after the induction of the cortical SD wave. The network impairment displayed region- and frequency-specific features, with greater prominence observed in the visual cortex than in the motor cortex. The decline in functional connectivity was concurrent with abnormal animal behavior and aberrant activity in the ipsilateral cortex that appeared after the SD wave had ended. The study indicated that unilateral SD leads to a reversible decline in the functional interhemispheric connectivity in the awake animal cortex. Given the crucial role of synchronizing cortical oscillations for processing sensory information and integrating sensorimotor functions, the intracortical functional interactions disruption resulting from a unilateral SD wave, which we discovered in our present study, could contribute to the neuropathological mechanisms of migraine aura and sensory processing dysfunction during a migraine attack.

Study of the role of evolutionary new enhancers in the development of the <i>corpus callosum</i>

One important aspect of the mammalian brain is the exchange of information between neurons located in different hemispheres. This process evolved during the development of mammals. In marsupial (Marsupialia) and monotreme (Monotremata) mammals, the communication between hemispheres is facilitated through an enlarged anterior commissure. In placental (Eutheria) mammals, a new brain structure, the corpus callosum, emerged during the evolutionary process. The corpus callosum, comprising 80% of the brain’s commissural axons, is the largest commissure in the human body. The corpus callosum is a major contributor to the efficiency of higher neural activities, including memory, decision making, social interaction, and language. A possible explanation for the emergence of a novel structure for interhemispheric interaction is a change in the growth direction of neocortical axons during development. Changes in gene expression levels can regulate this process, which involves controlling axon growth and cell migration in the neocortex. A full comprehension of this process will enable the creation of new animal models for studying cortical malformations and the navigation of axons in the cerebral cortex leading to the formation of interhemispheric connections. Several enhancers were identified for protein-coding genes with differing expression patterns in neocortical cells of placental and non-placental (marsupial) mammals. Throughout the genomes of the house opossum (Monodelphis domestica) and the house mouse (Mus musculus), the acetylation levels of histone H3 on lysine 27 (H3K27ac) were compared. H3K27ac is considered an epigenetic marker for active gene enhancers. Then, a screening of candidate genes was performed to evaluate their localization and expression levels in the cortex during embryonic development. Thus, the Tbr1 gene was identified. Incorrect expression of this gene may result in changes to cortical development. The CRISPR/Cas9 system was combined with in utero electroporation to completely delete the active Tbr1 gene enhancer in developing neocortical cells of mouse embryos at day 14 of embryonic development. The impact of this enhancer deletion was then analyzed on the expression of Tbr1 in the upper layers of the cortex, as well as the direction of axon growth and neuronal migration on the 18th day of embryonic development. A significant reduction in Tbr1 expression was observed in the upper layers of the cortex after deletion of the active enhancer. Only 30% of the electroporated neurons retained Tbr1 expression. Moreover, a considerable delay in neuronal migration was observed in the subventricular zone (41% versus 17% in the control group) and in the upper layers of the cortex (20% versus 35% in the control group). However, the direction of axonal growth remained unchanged: callosal axons effectively crossed the midline and created the corpus callosum. Thus, expression of the evolutionary novel Tbr1 enhancer is important for neuronal migration during corticogenesis. However, its contribution to the development of the corpus callosum is not fully understood. A detailed analysis of the corpus callosum morphology post-enhancer deletion will be the subsequent step.

MODERN METHODS FOR ASSESSING MOTOR AND SENSORY INTER-HEMISPHERIC ASYMMETRY OF THE BRAIN IN CHILDREN OF PRIMARY AND SECONDARY SCHOOL AGE (8-11 YEARS OLD)

Background: The neuropsychological study of some features of interhemispheric relationships in the motorsphere in children with various types of mental disorders is of undoubted interest. It can show a number of new aspects of the problem of the formation of inter-hemispheric asymmetry and inter-hemispheric interaction in ontogenesis. Methodology: Nowadays, two approaches are used in physiology to assess brain inter-hemispheric differences: the method of determining the "handiness" by means of a survey (Edinburgh test) and the method of actively detecting motor and sensory asymmetry by N.N. Bragina and T.A. Dobrokhotova methodology. Results: The neuropsychological study of some features of interhemispheric relationships in the motor sphere in children with various types of mental disorders is of undoubted interest. It can show a number of new aspects of the problem of the formation of inter-hemispheric asymmetry and inter-hemispheric interaction in ontogenesis. Both techniques are widely represented in modern scientific literature, but we have not found research that describes the relationship between the results of testing assessment of functional brain asymmetry using the Edinburgh test and tests for determining motor and sensory asymmetry. Normally, the formation of brain inter-hemispheric asymmetry and inter-hemispheric interaction is, of course, heterochronical in nature. Conclusion: Therefore, the examined schoolchildren may encounter an almost fully formed primary level of interhemispheric connections, while the second and third levels are still in their formation. At the same time, a comparison between the results of healthy children of 8–11 years of age shows that the functional organization of inter-hemispheric asymmetry and inter-hemispheric interaction in this age range is in a state of constant ongoing development.

Behavioral measurement of interhemispheric interactions during multiple episodes of falling asleep

Behavioral measurement of interhemispheric interactions during multiple episodes of falling asleep

MODERN ASPECTS OF BRAIN FUNCTIONAL INTERHEMISPHERIC ASYMMETRY STUDY

One of the basic principles of the functioning of the hemispheres of the brain is asymmetry. The unevenness of the left and right hemispheres of the human brain in combination with the phenomenon of dominance of one of them affects the features of the construction and perception of the picture of the world, the nature of reaction and behavior. The problems of functional insufficiency of interhemispheric interactions are highlighted, a comparative analysis of indicators of socio-psychological adaptation of persons with a predominance of one of the hemispheres, as well as features of lateralization of a healthy brain and pathology is presented. An attempt has been made to consider and study modern aspects of interhemispheric asymmetry, as well as to present issues of functional insufficiency of interhemispheric interactions. The results of studies of stationary and dynamic properties of the functional specialization of the hemispheres considered in the article showed that the issue of the organization of functional hemispheric asymmetry, starting with classical and modern ideas, is of great interest to various specialists.

Psychophysiological Characteristics of Athletes-Volleyball Players with Hearing Impairment

To reveal the features of the central nervous system and the severity of hemispheric asymmetry in volleyball athletes with hearing deprivation. Materials and methods: The study involved 14 athletes with hearing deprivation of varying degrees, aged 20 to 35 years (mean age 29.20 ± 1.3 years), with different sports qualifications. When evaluating the indicators of a simple visual-motor reaction, the reaction time, the degree of its stability, the level of functional capabilities of the nervous system of athletes were determined. To determine manual asymmetry, M. Annette's questionnaire, motor tests (dynamometry, tests for the interlacing of hands and applause) were used, and the coefficient of the right hand was calculated. When detecting visual asymmetry, the Rosenbach test and the spyglass test were used. The ratio of the right eye was also calculated. Results: It was revealed that a third of the examined athletes have a symmetrical distribution of signs both in the visual and manual spheres, a significant dependence of which on sports titles was not found. The time of a simple visual-motor reaction in volleyball athletes with hearing deprivation was reduced. The stability of the reaction and the level of functional capabilities were within the normal range and had a significant dependence on the sports title and category. Conclusion: It was revealed that volleyball players with hearing impair ment form a special type of interhemispheric interaction, characterized by a more even distribution of functional activity between the right and left hemispheres, and in connection with this, a low level of development of manual and visual asymmetry.

A table tennis serve versus rally hit elicits differential hemispheric electrocortical power fluctuations.

Human visuomotor control requires coordinated interhemispheric interactions to exploit the brain's functional lateralization. In right-handed individuals, the left hemisphere (right arm) is better for dynamic control and the right hemisphere (left arm) is better for impedance control. Table tennis is a game that requires precise movements of the paddle, whole body coordination, and cognitive engagement, providing an ecologically valid way to study visuomotor integration. The sport has many different types of strokes (e.g., serve, return, and rally shots), which should provide unique cortical dynamics given differences in the sensorimotor demands. The goal of this study was to determine the hemispheric specialization of table tennis serving - a sequential, self-paced, bimanual maneuver. We used time-frequency analysis, event-related potentials, and functional connectivity measures of source-localized electrocortical clusters and compared serves with other types of shots, which varied in the types of movement required, attentional focus, and other task demands. We found greater alpha (8-12 Hz) and beta (13-30 Hz) power in the right sensorimotor cortex than in the left sensorimotor cortex, and we found a greater magnitude of spectral power fluctuations in the right sensorimotor cortex for serve hits than return or rally hits, in all right-handed participants. Surprisingly, we did not find a difference in interhemispheric functional connectivity between a table tennis serve and return or rally hits, even though a serve could arguably be a more complex maneuver. Studying real-world brain dynamics of table tennis provides insight into bilateral sensorimotor integration.NEW & NOTEWORTHY We found different spectral power fluctuations in the left and right sensorimotor cortices during table tennis serves, returns, and rallies. Our findings contribute to the basic science understanding of hemispheric specialization in a real-world context.

Hemispheric specialization and interhemispheric interaction - From perception to consciousness: Introduction to a special issue in honor of Eran Zaidel (1944–2021)

Hemispheric specialization and interhemispheric interaction - From perception to consciousness: Introduction to a special issue in honor of Eran Zaidel (1944–2021)

Monitoring of asthenic disorders in patients with psychoneurological pathology

24 healthy adults as well as 69 patients with asthenic manifestations (43 patients with chronic ischemia of brain and 26 patients with different types of multiple sclerosis) were examined with using of an original computer modification of tapping. The results of the study showed that parameters of serial motor reactions and their relationship in healthy adults were indicated the stability of the brain functional state and significant influence of cortex regulatory systems on its dynamics according to tasks that are performed. Examination materials of patients indicated the significant reduction of ability of cortex regulatory influences on subcortical non-specific systems under load conditions, reduction of level of interhemispheric interaction as well as availability of non-adaptive changes with reduction of functional state of different types in dynamics of examination. These manifestations were correlated with clinical symptoms severity. The proposed option of tapping has shown its ability to determine of common features and differences of asthenic syndrome in patients with chronic ischemia and multiple sclerosis in connection with the development of pathological conditions and processes of its compensation. This is very important especially in the early stages of the disease and may be used for assessment of the effectiveness of therapy. Key words: chronic ischemia, multiple sclerosis, asthenic manifestations, functional state of brain, tapping

Seasonal Predictability of North American Surface Temperature Arises from SST Propagation over the Western Pacific

Abstract The predictability of temperatures in North America is of great importance for local agriculture and human health. In autumn (SON), the temperature in North America is correlated with ENSO, but its predictive skill is limited. Here, we show that spring (MAM) sea surface temperature (SST) anomalies in the southwest Pacific (SWP) exhibit a higher correlation with autumn temperature in North America (r = 0.73) than ENSO. This cross-seasonal and cross-hemispheric relationship is established via the western tropical Pacific (WTP) region. The spring SWP SST anomalies show a cross-hemispheric propagation embedded in the southerly monsoonal flow through the wind–evaporation–SST feedback, which sustains the progression of SST anomalies toward the WTP in autumn. The AGCM simulations from multimodels show that active convection in the WTP caused by SST warming stimulate a Rossby wave train propagating downward to North America, where it is governed by an anomalous high with increased atmospheric thickness and tropospheric temperature. Consequently, the longwave radiative heating over North America is enhanced, raising the surface air temperature. These results indicate that the SWP SST is a useful predictor of North American temperature 6 months in advance through the cross-hemispheric influence. A model based on the spring SWP SST and preceding winter ENSO (Niño-3.4) shows a high predictive skill for the autumn temperature anomalies in North America. Significance Statement Seasonal predictions of surface temperature are important for agricultural decision-making, disaster prevention, and mitigation. Over the western Pacific, associated with the seasonal evolution of ITCZ, there is a strong northward progression of SST anomaly signals generated in the southwest Pacific. This study finds that this cross-hemispheric SST propagation can significantly impact the autumn surface temperature over central North America through the atmospheric bridge. A statistical model incorporating southwest Pacific SST for spring is constructed to predict the North American autumn surface temperature and exhibits high consistency with observations. This improves our understanding of the interhemispheric interactions at seasonal time scales and the seasonal predictability of the North American climate.

Abnormal hemispheric specialization and inter-hemispheric functional cooperation in generalized anxiety disorder

Abnormal hemispheric specialization and inter-hemispheric interactions may contribute to the pathogenesis of general anxiety disorder (GAD). The current study investigated these abnormalities in GAD patients based on the two analytic approaches and examined whether such abnormalities are correlated with anxiety symptom severity. Seventy-three patients with GAD and 60 matched healthy controls were recruited. All participants completed anxiety symptoms assessment and resting-state functional magnetic resonance imaging (rs-fMRI). The autonomy index (AI) and Connectivity between Functionally Homotopic voxels (CFH) were applied to measure and compared between groups. Compared to controls, patients showed stronger AI in the right middle temporal gyrus (MTG). Seed-based analysis revealed stronger functional connectivity (FC) of the right MTG with both right precuneus and right dorsolateral prefrontal cortex (dlPFC) in patients. Patients also exhibited greater CFH in right anterior cingulate cortex (ACC) but decreased CFH in bilateral postcentral gyrus (PCG) and superior occipital gyrus (SOG). Further there were significant correlations between these regional CFH and anxiety symptoms severity. GAD patients demonstrate right hemispheric specialization and aberrant inter-hemispheric functional cooperation, and abnormal inter-hemispheric coordination is associated with anxiety symptom severity. These findings provide a clue to understanding the neuropathological mechanisms of GAD.

A frontal transcallosal inhibition loop mediates interhemispheric balance in visuospatial processing

Interhemispheric communication through the corpus callosum is required for both sensory and cognitive processes. Impaired transcallosal inhibition causing interhemispheric imbalance is believed to underlie visuospatial bias after frontoparietal cortical damage, but the synaptic circuits involved remain largely unknown. Here, we show that lesions in the mouse anterior cingulate area (ACA) cause severe visuospatial bias mediated by a transcallosal inhibition loop. In a visual-change-detection task, ACA callosal-projection neurons (CPNs) were more active with contralateral visual field changes than with ipsilateral changes. Unilateral CPN inactivation impaired contralateral change detection but improved ipsilateral detection by altering interhemispheric interaction through callosal projections. CPNs strongly activated contralateral parvalbumin-positive (PV+) neurons, and callosal-input-driven PV+ neurons preferentially inhibited ipsilateral CPNs, thus mediating transcallosal inhibition. Unilateral PV+ neuron activation caused a similar behavioral bias to contralateral CPN activation and ipsilateral CPN inactivation, and bilateral PV+ neuron activation eliminated this bias. Notably, restoring interhemispheric balance by activating contralesional PV+ neurons significantly improved contralesional detection in ACA-lesioned animals. Thus, a frontal transcallosal inhibition loop comprising CPNs and callosal-input-driven PV+ neurons mediates interhemispheric balance in visuospatial processing, and enhancing contralesional transcallosal inhibition restores interhemispheric balance while also reversing lesion-induced bias.

Different effects of I-wave periodicity repetitive TMS on motor cortex interhemispheric interaction.

Activity of the neural circuits in the human motor cortex can be probed using transcranial magnetic stimulation (TMS). Changing TMS-induced current direction recruits different cortical neural circuits. I-wave periodicity repetitive TMS (iTMS) substantially modulates motor cortex excitability through neural plasticity, yet its effect on interhemispheric interaction remains unclear. To explore the modulation of interhemispheric interaction by iTMS applied in different current directions. Twenty right-handed healthy young volunteers (aged 27.5 ± 5.0 years) participated in this study with three visits. On each visit, iTMS in posterior-anterior/anterior-posterior direction (PA-/AP-iTMS) or sham-iTMS was applied to the right hemisphere, with corticospinal excitability and intracortical facilitation of the non-stimulated left hemisphere evaluated at four timepoints. Ipsilateral silent period was also measured at each timepoint probing interhemispheric inhibition (IHI). PA- and AP-iTMS potentiated cortical excitability concurrently in the stimulated right hemisphere. Corticospinal excitability of the non-stimulated left hemisphere increased 10 min after both PA- and AP-iTMS intervention, with a decrease in short-interval intracortical facilitation (SICF) observed in AP-iTMS only. Immediately after the intervention, PA-iTMS tilted the IHI balance toward inhibiting the non-stimulated hemisphere, while AP-iTMS shifted the balance toward the opposite direction. Our findings provide systematic evidence on the plastic modulation of interhemispheric interaction by PA- and AP-iTMS. We show that iTMS induces an interhemispheric facilitatory effect, and that PA- and AP-iTMS differs in modulating interhemispheric inhibition.

Enhanced interhemispheric resting-state functional connectivity of the visual network is an early treatment response of paroxetine in patients with panic disorder.

This study aimed to detect alterations in interhemispheric interactions in patients with panic disorder (PD), determine whether such alterations could serve as biomarkers for the diagnosis and prediction of therapeutic outcomes, and map dynamic changes in interhemispheric interactions in patients with PD after treatment. Fifty-four patients with PD and 54 healthy controls (HCs) were enrolled in this study. All participants underwent clinical assessment and a resting-state functional magnetic resonance imaging scan at (i) baseline and (ii) after paroxetine treatment for 4weeks. A voxel-mirrored homotopic connectivity (VMHC) indicator, support vector machine (SVM), and support vector regression (SVR) were used in this study. Patients with PD showed reduced VMHC in the fusiform, middle temporal/occipital, and postcentral/precentral gyri, relative to those of HCs. After treatment, the patients exhibited enhanced VMHC in the lingual gyrus, relative to the baseline data. The VMHC of the fusiform and postcentral/precentral gyri contributed most to the classification (accuracy = 87.04%). The predicted changes were accessed from the SVR using the aberrant VMHC as features. Positive correlations (p < 0.001) were indicated between the actual and predicted changes in the severity of anxiety. These findings suggest that impaired interhemispheric coordination in the cognitive-sensory network characterized PD and that VMHC can serve as biomarkers and predictors of the efficiency of PD treatment. Enhanced VMHC in the lingual gyrus of patients with PD after treatment implied that pharmacotherapy recruited the visual network in the early stages.

Effect of Visual Feedback on Behavioral Control and Functional Activity During Bilateral Hand Movement.

Previous researches state vision as a vital source of information for movement control and more precisely for accurate hand movement. Further, fine bimanual motor activity may be associated with various oscillatory activities within distinct brain areas and inter-hemispheric interactions. However, neural coordination among the distinct brain areas responsible to enhance motor accuracy is still not adequate. In the current study, we investigated task-dependent modulation by simultaneously measuring high time resolution electroencephalogram (EEG), electromyogram (EMG) and force along with bi-manual and unimanual motor tasks. The errors were controlled using visual feedback. To complete the unimanual tasks, the participant was asked to grip the strain gauge using the index finger and thumb of the right hand thereby exerting force on the connected visual feedback system. Whereas the bi-manual task involved finger abduction of the left index finger in two contractions along with visual feedback system and at the same time the right hand gripped using definite force on two conditions that whether visual feedback existed or not for the right hand. Primarily, the existence of visual feedback for the right hand significantly decreased brain network global and local efficiency in theta and alpha bands when compared with the elimination of visual feedback using twenty participants. Brain network activity in theta and alpha bands coordinates to facilitate fine hand movement. The findings may provide new neurological insight on virtual reality auxiliary equipment and participants with neurological disorders that cause movement errors requiring accurate motor training. The current study investigates task-dependent modulation by simultaneously measuring high time resolution electroencephalogram, electromyogram and force along with bi-manual and unimanual motor tasks. The findings show that visual feedback for right hand decreases the force root mean square error of right hand. Visual feedback for right hand decreases local and global efficiency of brain network in theta and alpha bands.

Merging and modifying hypotheses on the emotional and cognitive effects of eye movements: The dopaminergic regulation hypothesis

The integration of hypotheses from Eye-Movement Desensitization and Reprocessing (EMDR) and Saccade Induced Retrieval Enhancement (SIRE), both of which have been met with considerable skepticism, may lead to significant gains in both domains. Cognitive accounts of EMDR, the orienting response (OR) and working memory (WM) hypotheses, and of SIRE, the interhemispheric interaction (IHI) and the top-down attentional control (TDAC) hypotheses, are discussed. The accounts show several blind spots and frictions, for instance, on re-imagining during EMs, on hemispheric lateralization, and on emotional influences of eye movements. The failure to consider these factors across and within domains may well explain the many disparate findings. This perspective aims to remove the artificial separation and seeks a theoretical integration of the domains. It combines elements of OR and TDAC into a new dopaminergic regulation hypothesis while replacing affective (i.e., positive vs. negative) by motivational mechanisms (i.e., fostering approach and recoding). EMs are posited to result in a short-latency, targeted release of dopamine, which is the central neuromodulator in approach tendencies. According to this hypothesis, the largest effects are obtained in individuals with collateralized eye dominance and dopamine dominance. Concrete suggestions are made to improve research conditions and therapeutic efficacy.

Functional and Structural Properties of Interhemispheric Interaction between Bilateral Precentral Hand Motor Regions in a Top Wheelchair Racing Paralympian.

Long-term motor training can cause functional and structural changes in the human brain. Assessing how the training of specific movements affects specific parts of the neural circuitry is essential to understand better the underlying mechanisms of motor training-induced plasticity in the human brain. We report a single-case neuroimaging study that investigated functional and structural properties in a professional athlete of wheelchair racing. As wheelchair racing requires bilateral synchronization of upper limb movements, we hypothesized that functional and structural properties of interhemispheric interactions in the central motor system might differ between the professional athlete and controls. Functional and diffusion magnetic resonance imaging (fMRI and dMRI) data were obtained from a top Paralympian (P1) in wheelchair racing. With 23 years of wheelchair racing training starting at age eight, she holds an exceptional competitive record. Furthermore, fMRI and dMRI data were collected from three other paraplegic participants (P2-P4) with long-term wheelchair sports training other than wheelchair racing and 37 able-bodied control volunteers. Based on the fMRI data analyses, P1 showed activation in the bilateral precentral hand sections and greater functional connectivity between these sections during a right-hand unimanual task. In contrast, other paraplegic participants and controls showed activation in the contralateral hemisphere and deactivation in the ipsilateral hemisphere. Moreover, dMRI data analysis revealed that P1 exhibited significantly lower mean diffusivity along the transcallosal pathway connecting the bilateral precentral motor regions than control participants, which was not observed in the other paraplegic participants. These results suggest that long-term training with bilaterally synchronized upper-limb movements may promote bilateral recruitment of the precentral hand sections. Such recruitment may affect the structural circuitry involved in the interhemispheric interaction between the bilateral precentral regions. This study provides valuable evidence of the extreme adaptability of the human brain.