Assessing Cerebral Dominance in the Geriatric Population: A Neuropsychological Perspective

Although the left and right human cerebral hemispheres differ both functionally and anatomically, little is known about the environmental or genetic factors that govern central nervous system asymmetry. Nevertheless, cerebral asymmetry is strongly correlated with handedness, and handedness does have a significant genetic component. To explore the relative contribution of environmental and genetic influences on cerebral asymmetry, we examined the volumes of left and right cerebral cortex in a large cohort of aging identical and fraternal twins and explored their relationship to handedness. Cerebral lobar volumes had a major genetic component, indicating that genes play a large role in changes in brain volume that occur with aging. Shared environment, which likely represents in utero events, had about twice the effect on the left hemisphere as on the right, consistent with less genetic control over the left hemisphere. To test the major genetic models of handedness and cerebral asymmetry, twin pairs were divided into those with two right handers and those with at least one left hander (nonright handers). Genetic factors contributed twice the influence to left and right cerebral hemispheric volumes in right-handed twin pairs, suggesting a large decrement in genetic control of cerebral volumes in the nonright-handed twin pairs. This loss of genetic determination of the left and right cerebral hemispheres in the nonright-handed twin pairs is consistent with models postulating a right-hand/left-hemisphere-biasing genetic influence, a "right-shift" genotype that is lost in nonright handers, resulting in decreased cerebral asymmetry.

Aging has important impacts on both the function and structure of the brain, yet the interplay between these changes remains unclear. Here, we present a unified framework including both single-modal and multimodal age predictions using a large UK Biobank dataset (27,793 healthy subjects, 49 to 76 years) to identify and validate brain functional network connectivity (FNC) and gray matter volume (GMV) changes associated with aging, then propose a novel analysis method to reveal various joint aging patterns, and finally investigate the association between joint function–structure changes and cognitive declines. Multimodality outperforms single modality in the age prediction, underscoring the significance of multimodal aging-related changes. Aging primarily induces synergistic changes, with both FNC and GMV decreased in the cerebellum, frontal pole, paracingulate gyrus, and precuneus cortex, indicating consistent degeneration in motor control, sensory processing, and emotional regulation, and contradictory changes with increased FNC magnitude but decreased GMV in the occipital pole, lateral occipital cortex, and frontal pole, acting as a compensatory mechanism as one ages to preserve visual acuity, cognitive ability, and behavioral modulation. Particularly, joint changes, with both FNC and GMV decreased in the crus I cerebellum and the paracingulate gyrus, show a strong Pearson correlation with the reaction time. In summary, our study unveils diverse joint function–structure changes, providing strong evidence for understanding distinct cognitive deteriorations during aging.

Electroencephalography can assess connectivity between brain hemispheres, potentially influencing cognitive functions. Much of the existing electroencephalography research primarily focuses on undirected connectivity, leaving uncertainties about directed connectivity alterations between left-right brain hemispheres or frontal-posterior lobes in mild cognitive impairment. We analyzed resting-state electroencephalography data from 34 mild cognitive impairment individuals and 23 normal controls using directed transfer function and graph theory for directed network analysis. Concerning the dominance within left-right hemispheres or frontal-posterior lobes, the mild cognitive impairment group exhibited decreased connectivity within the frontal compared with posterior brain regions in the delta and theta bands. Regarding the dominance between the brain hemispheres or lobes, the mild cognitive impairment group showed reduced connectivity from the posterior to the frontal regions versus the reverse direction in the same bands. Among all participants, the intra-lobe frontal-posterior dominance correlated positively with executive function in the delta and alpha bands. Inter-lobe dominance between frontal and posterior regions also positively correlated with executive function, attention, and language in the delta band. Additionally, interhemispheric dominance between the left and right hemispheres positively correlated with attention in delta and theta bands. These findings suggest altered cerebral dominance in mild cognitive impairment, potentially serving as electrophysiological markers for neurocognitive disorders.

Cerebral lateralization, the partitioning of functions into a certain hemisphere of the brain, is ubiquitous among vertebrates. Evidence suggests that the cognitive processing of a stimulus is performed with a specific hemisphere depending in part upon the emotional valence of the stimulus (i.e. whether it is appetitive or aversive). Recent work has implicated a predominance of right-hemisphere processing for aversive stimuli. In fish with laterally placed eyes, the preference to view an object with a specific eye has been used as a proxy for assessing cerebral lateralization. The habenula, one of the most well-known examples of an asymmetrical neural structure, has been linked to behavioural asymmetry in some fish species. Here, we exposed convict cichlid fish (Amatitlania nigrofasciata) to both a social and non-social lateralization task and assessed behavioural lateralization in either the presence or absence of an aversive stimulus, damage-induced alarm cues. We also assessed whether behavioural asymmetry in these tests was related to asymmetry of the habenular nuclei. We found that when alarm cues were present, fish showed increased left-eye (and by proxy, right hemisphere) preference for stimulus viewing. In addition, females, but not males, showed stronger eye preferences when alarm cues were present. We did not find a relationship between behavioural lateralization and habenular lateralization. Our results conflict with previous reports of concordance between behavioural and habenular lateralization in this fish species. However, our results do provide support for the hypothesis of increased right-hemisphere use when an organism is exposed to aversive stimuli.

John Hughlings Jackson

Current findings show some brain regions consistently related to performance of the Wisconsin Card Sorting Test (WCST). An increase of local cerebral blood flow or metabolic demands has been detected in those regions. Functional integration of the neuronal circuits that subserve the task performance, based upon the identification of the oscillations and their distributed cerebral sources, has not been accomplished previously. The event-related tonic oscillations within a period of 2,000 msec after the stimulus onset and the probable neural substrate were evaluated in healthy volunteers by variable-resolution brain electrical tomography (VARETA). The WCST induced a significant increase of delta, theta, beta-2, and gamma oscillations, but decrease of alpha. Areas such as the frontal subregions, temporal, cingulate, parahippocampal, parietal, occipitotemporal cortex, and occipital poles showed modified activity during the task, with EEG spectral band selectivity as well as some overlapping among them. Frontal and temporal regions generated the delta/theta oscillations. Additionally, the occipitotemporal and parietal regions were the source of the delta activity, lacking theta activation. The parietal region also showed tonic alpha, beta-2 and gamma changes. These data imply that different processes have been simultaneously mediated during task performance. Relationships among the individual bands, the neural substrata and the specific cognitive process that support the task were established. The selectively distributed delta, theta, alpha, beta-2 and gamma oscillations reflect communication networks through variable populations of neurons, with functional relations to the working memory functions and the information processing that subserve the WCST performance.

Event Abstract Back to Event Study of cerebral asymmetry in schizophrenia based on an novel automatic cerebral hemisphere segmentation method for MRI Lu Zhao1*, Ulla Ruotsalainen1, Jussi Hirvonen2, Jarmo Hietala3 and Jussi Tohka1 1 Tampere University of Technology, Finland 2 Turku PET Centre, Finland 3 University of Turku, Finland In this work, we statistically analyzed the cerebral volume asymmetry for schizophrenic and healthy populations by employing a novel and completely automatic cerebral hemisphere segmentation method for MRI. The segmentation method is based on the information of partial volume effect (PVE) and the partial differential equations based shape bottlenecks (PDE-SB) algorithm [1]. PVE is an inevitable problem of MRI, but it is rarely taken into account by the existing automatic MR brain image segmentation techniques. The PDE-SB algorithm can detect the bottlenecks connecting two parts of a complex object by simulating a steady state of the information transmission process between the two parts with partial differential equations. Our method consists of two major stages: compartmental brain decomposition [2] and cerebral hemisphere segmentation [3]. Firstly, a partial volume estimation approach [4] is used to obtain the partial volume voxel classification [into grey matter (GM), white matter (WM), cerebrospinal fluid (CSF), CSF/GM, GM/WM and CSF/background] and estimate the amount of each tissue type in each brain voxel. Then the WM+GM/WM region is split into compartmental seeds corresponding to cerebrum, cerebellum and brainstem utilizing the PDE-SB algorithm. The brain volume is compartmentally decomposed by reconstructing the original shapes of the three compartments from the compartmental seeds according to the compartmental boundary knowledge defined with partial volume information. The cerebrum portion is extracted from the decomposed brain volume, and the cerebral hemispheres are segmented with the PDE-SB algorithm and the partial volume estimation results. In this work, this method was applied to a set of clinical T1-weighted MR images of 18 schizophrenic (11 males, 7 females) and 19 healthy (12 males, 7 females) subjects. All subjects were right-handed, and the schizophrenic patients were never medicated. With the obtained PVE information and cerebral hemisphere segmentation, the asymmetry index (AI) was calculated for cerebrum, cerebral GM and cerebral WM. AI was defined as (VR-VL)/[1/2(VR+VL)]×100, where VR and VL were the volume sizes of the right and left hemispheres respectively. The permutation test was conducted to evaluate the statistical significance of the difference of acquired AIs between schizophrenic and healthy populations. Here, the null hypothesis was defined as that AIs of schizophrenic and healthy populations had identical probability distribution, and the significance level was selected as 0.05. According to the statistical analysis results, the cerebral GM volume asymmetry of female schizophrenic population had significantly different probability distribution from the female healthy population's (p=0.002). There were no significant difference between schizophrenic and healthy populations with regard to volume asymmetry in the other cases (p>0.05). Conference: Neuroinformatics 2008, Stockholm, Sweden, 7 Sep - 9 Sep, 2008. Presentation Type: Poster Presentation Topic: Neuroimaging Citation: Zhao L, Ruotsalainen U, Hirvonen J, Hietala J and Tohka J (2008). Study of cerebral asymmetry in schizophrenia based on an novel automatic cerebral hemisphere segmentation method for MRI. Front. Neuroinform. Conference Abstract: Neuroinformatics 2008. doi: 10.3389/conf.neuro.11.2008.01.069 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 28 Jul 2008; Published Online: 28 Jul 2008. * Correspondence: Lu Zhao, Tampere University of Technology, Tampere, Finland, lu.zhao@tut.fi Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Lu Zhao Ulla Ruotsalainen Jussi Hirvonen Jarmo Hietala Jussi Tohka Google Lu Zhao Ulla Ruotsalainen Jussi Hirvonen Jarmo Hietala Jussi Tohka Google Scholar Lu Zhao Ulla Ruotsalainen Jussi Hirvonen Jarmo Hietala Jussi Tohka PubMed Lu Zhao Ulla Ruotsalainen Jussi Hirvonen Jarmo Hietala Jussi Tohka Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Cerebral asymmetry in bipolar disorders: A scoping review

First Page

Optic ataxia (Garcin-Rondot) observed in four patients with cerebrovascular disease was evaluated clinically and radiologically (CAT), and its possible mechanism was proposed on the basis of the analysis of our cases and the cases in literature ( Table 1.). The optic ataxia of Garcin-Rondot is charactereized by the inability to grasp an object presented in the peripheral visual field, while retaining the ability to grasp an object the patient is looking at. This could be explained by the failure of retinal information to reach the PG area of Economo-Koskinas (angular gyrus or Brodmann's 39 area in man), which is shown by an arrow pointing upwards to the left in Fig. 1.. In other words, this means the disturbance of visuo-somatosensory coordination. On the other hand, in the optic ataxia of Bálint syndrome, grasping of an object is difficult even when the patient is looking at the object, This may be explained by the failure of extraretinal oculomotor information (the upward arrow in Fig. 1 .) to reach the PG area, although in addition retinal information may not reach it. Possible mechanism of the two types of optic ataxia explained above is summarized in Fig. 6.. The mechanism may be comparable with that of Parinaud syndrome which also has two types, absolute and dissociative. The mechanism of the optic ataxia of Garcin-Rondot can be mostly explained by the disconnexion theory as mentioned above except for the difference in the symptoms depending on the side of the lesion. In the left cerebral hemisphere lesion, the symptom appears in the right hand in the right homonymous hemivisual field, whereas in the right-sided lesion, it appears in both hands in the left homonymous hemivisual field (Fig∂.5., lower half). Thus, there seems to be right cerebral hemisphere dominance in the normal visuo-motor coordination (Fig. 5., upper half), as the right cerebral hemisphere is known to be dominant in space perception and body skill.

Objectives It is well established that the brainstem regulates the act of swallow. However, the role of cortex and its influence on swallowing are still a question. Hence, the present study aimed to investigate if cerebral hemispheric laterality controls swallow activity. Methods Thirty normal right handed participants were subjected to time test of swallow using 100 ml of water. Dual paradigm was used to investigate hemispheric laterality for swallowing which involved listening to the speech or music stimuli presented binaurally while swallowing. The clinician measured total time taken and hyolaryngeal movement simultaneously which was used to calculate volume/time, volume/swallow, and time/swallow on an offline basis. Results Results revealed that swallow performance decreased with the dual task paradigm compared to baseline swallow. These results are suggestive of cortex playing a role during swallowing in the dual task paradigm. Moreover, quantitative parameters like volume/swallow and volume/time were affected more when speech was competing with swallowing. However, music exerted greater interference over the speech for time/swallow. Conclusions These results suggests that there exists differential cue lateralization hypothesis which means volume related parameters are controlled by left hemisphere and time related swallowing parameters are controlled at the right hemisphere.

A DWI study of the contralateral hemisphere in cerebral hemiatrophy

Anatomical Asymmetries Versus Variability of Language Areas of the Brain

On the basis of electrophysiological and neuropsychological investigations the existence of cerebral hemispheric dominance has been established. Thus, a certain psycho-behavioural function may not be equally governed by either the left or the right hemisphere, a tendency towards lateralization coming into play (Sperri, 1974; Arseni, Golu, Dănăilă, 1983; Funnell, Carballis, Gazzanga, 2000). The functional asymmetry of the analysers is encountered both at the peripheral level, through the sensory-motor lateralization of paired receptors, and at the cortical level, through the asymmetrical functioning of the cerebral hemispheres. Consequently, tests for hemispheric dominance, as well as tests for lateralization must, respectively, be employed. When examining cerebral hemispheric dominance and lateralization, the characteristics of the organs under investigation are taken into account, and so is the age of the subjects. The examination of functional asymmetry in the case of analyzers with paired receptors has relied on an impressive number of trials, procedures, tests and questionnaires on lateralization, all suitable for the subjects’ age and for the psycho-physiological characteristics of the respective couple of paired organs. The combined use of lateralization tests specifically adapted for all paired organs (hand, eye, is essential in order to establish the degree of lateralization homogeneity. The examinations and the calculation of the laterality index are to be done periodically, the results being recorded in a chart that reflects the evolution of lateralization as a result of engaging the child in various activities meant for a specific type of lateralization.

We report the results of a cross-modal priming study investigating the processing of opaque compound words, when followed by figuratively and literally related primes, in L1 (Polish) and L2 (English). Additionally, the half-divided visual field paradigm was used to verify which cerebral hemisphere is responsible for semantic decomposition, and whether the language status will lead to different activation patterns. The left hemisphere is generally believed to process the more salient or conventional meanings of figurative expressions, and the right hemisphere their less salient or unconventional meanings. However, this assumption has not so far been verified for compounds. The results suggest that both the figurative and the literal meanings of opaque compounds were processed significantly faster by the left hemisphere in the case of L1 Polish. No statistically significant differences were obtained for L2 English. At the same time, English compounds were overall processed significantly faster than Polish compounds.