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Developmental Cognitive Neuroscience Oct 2014Many perceptual processes, such as language or face perception, are asymmetrically organised in the hemispheres already in childhood. These asymmetries induce... (Review)
Review
Many perceptual processes, such as language or face perception, are asymmetrically organised in the hemispheres already in childhood. These asymmetries induce behaviourally observable spatial biases in which the observer perceives stimuli in one of the hemispaces more efficiently or more frequently than in the other one. Another source for spatial biases is spatial attention which is also asymmetrically organised in the hemispheres. The bias induced by attention is directed towards the right side, which is clearly demonstrated by patients with neglect but also in lesser degree by healthy observers in cognitively loading situations. Recent findings indicate that children and older adults show stronger spatial biases than young adults. We discuss how the development of executive functions might contribute to the manifestation of spatial biases during the lifespan. We present a model in which the interaction between the asymmetrical perceptual processes, the age-related development of the lateralised spatial attention and the development of the executive functions influence spatial perceptual performance and in which the development and decline of the executive processes during the lifespan modify the spatial biases.
Topics: Aging; Attention; Executive Function; Functional Laterality; Humans; Perceptual Disorders; Space Perception
PubMed: 25279854
DOI: 10.1016/j.dcn.2014.09.004 -
Journal of Neuroscience Research Mar 2022The human brain functional lateralization has been widely studied over the past decades, and neuroimaging studies have shown how activation of motor areas during hand...
The human brain functional lateralization has been widely studied over the past decades, and neuroimaging studies have shown how activation of motor areas during hand movement execution (ME) is different according to hand dominance. Nevertheless, there is no research directly investigating the effects of the participant's handedness in a motor imagery (MI) and ME task in both right and left-handed individuals at the cortical and subcortical level. Twenty-six right-handed and 25 left-handed participants were studied using functional magnetic resonance imaging during the imagination and execution of repetitive self-paced movements of squeezing a ball with their dominant, non-dominant, and both hands. Results revealed significant statistical difference (p < 0.05) between groups during both the execution and the imagery task with the dominant, non-dominant, and both hands both at cortical and subcortical level. During ME, left-handers recruited a spread bilateral network, while in right-handers, activity was more lateralized. At the critical level, MI between-group analysis revealed a similar pattern in right and left-handers showing a bilateral activation for the dominant hand. Differentially at the subcortical level, during MI, only right-handers showed the involvement of the posterior cerebellum. No significant activity was found for left-handers. Overall, we showed a partial spatial overlap of neural correlates of MI and ME in motor, premotor, sensory cortices, and cerebellum. Our results highlight differences in the functional organization of motor areas in right and left-handed people, supporting the hypothesis that MI is influenced by the way people habitually perform motor actions.
Topics: Brain Mapping; Functional Laterality; Hand; Humans; Imagination; Magnetic Resonance Imaging; Movement
PubMed: 34981561
DOI: 10.1002/jnr.25003 -
Journal of Neurology, Neurosurgery, and... Aug 2016Several studies have suggested an asymmetry in Meyer's loop in individuals, with the left loop anterior to the right. In this study we test the hypothesis that there is...
OBJECTIVES
Several studies have suggested an asymmetry in Meyer's loop in individuals, with the left loop anterior to the right. In this study we test the hypothesis that there is an association between Meyer's loop asymmetry (MLA) and language lateralisation.
METHODS
57 patients with epilepsy were identified with language functional MRI (fMRI) and diffusion MRI acquisition. Language lateralisation indices from fMRI(LI) and optic radiation and arcuate fasciculus probabilistic tractography was performed for each subject. The subjects were divided into left language dominant (LI>0.4) and non-left language groups (LI<0.4) according to their LI.
RESULTS
A negative linear correlation was identified between language lateralisation and MLA, with greater left lateralised language associated with more anteriorly placed left Meyer's loops (R value -0.34, p=0.01). There was a significant difference in mean MLA between the two groups, with the left loop being anterior to the right loop in the LI>0.4 group and posterior to the right loop in the LI<0.4 group (p=0.003). No correlation was found between language lateralisation and arcuate fasciculus volume.
CONCLUSIONS
This study suggests an association between the extent of Meyer's loop asymmetry and the lateralisation of language determined by fMRI in patients with epilepsy. Further studies should be carried out to evaluate this association in control subjects and with other measures of language lateralisation.
Topics: Adult; Epilepsy, Temporal Lobe; Female; Functional Laterality; Functional Neuroimaging; Geniculate Bodies; Humans; Language; Magnetic Resonance Imaging; Male; Middle Aged; Neural Pathways; Visual Cortex; Young Adult
PubMed: 26384513
DOI: 10.1136/jnnp-2015-311161 -
NeuroImage. Clinical 2018To diagnose and lateralise temporal lobe epilepsy (TLE) by building a classification system that uses directed functional connectivity patterns estimated during EEG...
OBJECTIVE
To diagnose and lateralise temporal lobe epilepsy (TLE) by building a classification system that uses directed functional connectivity patterns estimated during EEG periods without visible pathological activity.
METHODS
Resting-state high-density EEG recording data from 20 left TLE patients, 20 right TLE patients and 35 healthy controls was used. Epochs without interictal spikes were selected. The cortical source activity was obtained for 82 regions of interest and whole-brain directed functional connectivity was estimated in the theta, alpha and beta frequency bands. These connectivity values were then used to build a classification system based on two two-class Random Forests classifiers: TLE vs healthy controls and left vs right TLE. Feature selection and classifier training were done in a leave-one-out procedure to compute the mean classification accuracy.
RESULTS
The diagnosis and lateralization classifiers achieved a high accuracy (90.7% and 90.0% respectively), sensitivity (95.0% and 90.0% respectively) and specificity (85.7% and 90.0% respectively). The most important features for diagnosis were the outflows from left and right medial temporal lobe, and for lateralization the right anterior cingulate cortex. The interaction between features was important to achieve correct classification.
SIGNIFICANCE
This is the first study to automatically diagnose and lateralise TLE based on EEG. The high accuracy achieved demonstrates the potential of directed functional connectivity estimated from EEG periods without visible pathological activity for helping in the diagnosis and lateralization of TLE.
Topics: Area Under Curve; Brain Waves; Electroencephalography; Electronic Data Processing; Epilepsy, Temporal Lobe; Female; Follow-Up Studies; Functional Laterality; Humans; Machine Learning; Male; Retrospective Studies
PubMed: 29527470
DOI: 10.1016/j.nicl.2017.09.021 -
Psychoneuroendocrinology Feb 2018After decades of research, the influence of prenatal testosterone on brain lateralization is still elusive, whereas the influence of pubertal testosterone on functional...
After decades of research, the influence of prenatal testosterone on brain lateralization is still elusive, whereas the influence of pubertal testosterone on functional brain lateralization has not been investigated, although there is increasing evidence that testosterone affects the brain in puberty. We performed a longitudinal study, investigating the relationship between prenatal testosterone concentrations in amniotic fluid, pubertal testosterone concentrations in saliva, and brain lateralization (measured with functional Transcranial Doppler ultrasonography (fTCD)) of the Mental Rotation, Chimeric Faces and Word Generation tasks. Thirty boys and 30 girls participated in this study at the age of 15 years. For boys, we found a significant interaction effect between prenatal and pubertal testosterone on lateralization of Mental Rotation and Chimeric Faces. In the boys with low prenatal testosterone levels, pubertal testosterone was positively related to the strength of lateralization in the right hemisphere, while in the boys with high prenatal testosterone levels, pubertal testosterone was negatively related to the strength of lateralization. For Word Generation, pubertal testosterone was negatively related to the strength of lateralization in the left hemisphere in boys. For girls, we did not find any significant effects, possibly because their pubertal testosterone levels were in many cases below quantification limit. To conclude, prenatal and pubertal testosterone affect lateralization in a task-specific way. Our findings cannot be explained by simple models of prenatal testosterone affecting brain lateralization in a similar way for all tasks. We discuss alternative models involving age dependent effects of testosterone, with a role for androgen receptor distribution and efficiency.
Topics: Adolescent; Brain; Cognition; Female; Functional Laterality; Humans; Longitudinal Studies; Male; Pregnancy; Prenatal Exposure Delayed Effects; Puberty; Receptors, Androgen; Sex Characteristics; Sexual Maturation; Testosterone; Ultrasonography, Doppler, Transcranial
PubMed: 29195161
DOI: 10.1016/j.psyneuen.2017.10.027 -
Brain Research Sep 2021Functional lateralization relates to a natural asymmetry in the dominance right or left body side, and is a fundamental principle of the brain. The hemispheres of the...
Functional lateralization relates to a natural asymmetry in the dominance right or left body side, and is a fundamental principle of the brain. The hemispheres of the brain control the contralateral body side, and show subtle, yet striking, anatomical asymmetries and functional lateralization. Innovative technologies, including Virtual Reality (VR), are entering the areas of experimental research, modeling and simulation related to the study of lateralization, with new perspectives of different applications in modern medical practice. Researchers/clinicians note that there are fewer VR studies with healthy participants, and which are important in evaluating/interpreting clinical outcomes, and testing the usefulness, limitations, and sensitivity of VR. The presented influence of the domination of upper/lower limbs on the performance of VR exercises was studied in healthy right-handed adults. Virtual testing sessions were performed independently with both/ dominant/ non-dominant hands, and the similar VR sessions were conduced on a Wii Balance Board (WBB) with the choice of body side, at different levels of the difficulty. The obtained results are consistent with other studies which show that cognitive-motor training in VR with the WBB platform is a very sensitive and promising tool for recognizing/assessing functional asymmetries of the right-left body side not only in disturbed lateralization, but also in the test training of healthy subjects.
Topics: Adolescent; Adult; Female; Functional Laterality; Healthy Volunteers; Humans; Male; Postural Balance; Video Games; Virtual Reality; Young Adult
PubMed: 34052260
DOI: 10.1016/j.brainres.2021.147537 -
Communications Biology Jul 2022Evolution of the direct, monosynaptic connection from the primary motor cortex to the spinal cord parallels acquisition of hand dexterity and lateralization of hand...
Evolution of the direct, monosynaptic connection from the primary motor cortex to the spinal cord parallels acquisition of hand dexterity and lateralization of hand preference. In non-human mammals, the indirect, multi-synaptic connections between the bilateral primary motor cortices and the spinal cord also participates in controlling dexterous hand movement. However, it remains unknown how the direct and indirect corticospinal pathways work in concert to control unilateral hand movement with lateralized preference in humans. Here we demonstrated the asymmetric functional organization of the two corticospinal networks, by combining network modelling and simultaneous functional magnetic resonance imaging techniques of the brain and the spinal cord. Moreover, we also found that the degree of the involvement of the two corticospinal networks paralleled lateralization of hand preference. The present results pointed to the functionally lateralized motor nervous system that underlies the behavioral asymmetry of handedness in humans.
Topics: Animals; Brain; Functional Laterality; Hand; Humans; Magnetic Resonance Imaging; Mammals; Spinal Cord
PubMed: 35790815
DOI: 10.1038/s42003-022-03615-2 -
Behavioural Neurology 2004Recent research indicates that (a) the perception and expression of facial emotion are lateralized to a great extent in the right hemisphere, and, (b) whereas facial... (Review)
Review
Recent research indicates that (a) the perception and expression of facial emotion are lateralized to a great extent in the right hemisphere, and, (b) whereas facial expressions of emotion embody universal signals, culture-specific learning moderates the expression and interpretation of these emotions. In the present article, we review the literature on laterality and universality, and propose that, although some components of facial expressions of emotion are governed biologically, others are culturally influenced. We suggest that the left side of the face is more expressive of emotions, is more uninhibited, and displays culture-specific emotional norms. The right side of face, on the other hand, is less susceptible to cultural display norms and exhibits more universal emotional signals.
Topics: Cross-Cultural Comparison; Cultural Characteristics; Emotions; Facial Expression; Functional Laterality; Humans; Pattern Recognition, Visual; Social Values
PubMed: 15201491
DOI: 10.1155/2004/786529 -
Seizure Oct 2018Ictal nausea/vomiting has been linked to the non-dominant hemisphere and has been considered a lateralizing sign. However, small case series and single cases have...
PURPOSE
Ictal nausea/vomiting has been linked to the non-dominant hemisphere and has been considered a lateralizing sign. However, small case series and single cases have reported seizure localisation in the dominant hemisphere. Here we aimed to determine the seizure localisation and lateralization in cases with ictal nausea/retching/vomiting to test the hypothesis that these signs are of lateralizing value.
METHODS
We searched two large tertiary epilepsy-center video-EEG databases (period: 1980-2017) for reports on ictal nausea/retching/vomiting and retrieved ictal EEG seizure location, lateralization and clinical symptoms.
RESULTS
We identified 13 patients with focal epilepsy and video-EEG-documented ictal nausea (n = 2), nausea and retching (n = 3), retching followed by vomiting (n = 5) or only vomiting (n = 3). Aetiology was genetic (n = 1), structural/metabolic (n = 7) or of unclear origin (n = 5). While in 12/13 patients epileptic discharges were temporal, a single case was parietal. A left-sided seizure origin was more frequent than a right-sided origin (62 vs. 38%). Assuming a left-sided language dominance in the single left-handed patient and in those two patients with unclear handedness (based on the known distribution of hemispheric speech-dominance), the distribution of ictal nausea/retching/vomiting to the dominant vs. non-dominant hemisphere was not significantly different from a random distribution (8 vs. 5, p = 0.581).
CONCLUSION
Ictal nausea/retching/vomiting are most frequently of temporal origin. In contrast to previous studies, our ictal video-EEG data suggests that these signs have no lateralizing value. Thus, video-EEG should be performed and while this clinical sign points to a temporal seizure origin, it does not determine its lateralization.
Topics: Adolescent; Adult; Brain Waves; Child; Electroencephalography; Epilepsy; Female; Functional Laterality; Humans; Magnetic Resonance Imaging; Male; Nausea; Retrospective Studies; Vomiting; Young Adult
PubMed: 30118929
DOI: 10.1016/j.seizure.2018.08.011 -
The American Journal of Occupational... Mar 2024Handedness and motor asymmetry are important features of occupational performance. With an increased understanding of the basic neural mechanisms surrounding handedness,... (Review)
Review
IMPORTANCE
Handedness and motor asymmetry are important features of occupational performance. With an increased understanding of the basic neural mechanisms surrounding handedness, clinicians will be better able to implement targeted, evidence-based neurorehabilitation interventions to promote functional independence.
OBJECTIVE
To review the basic neural mechanisms behind handedness and their implications for central and peripheral nervous system injury.
DATA SOURCES
Relevant published literature obtained via MEDLINE.
FINDINGS
Handedness, along with performance asymmetries observed between the dominant and nondominant hands, may be due to hemispheric specializations for motor control. These specializations contribute to predictable motor control deficits that are dependent on which hemisphere or limb has been affected. Clinical practice recommendations for occupational therapists and other rehabilitation specialists are presented.
CONCLUSIONS AND RELEVANCE
It is vital that occupational therapists and other rehabilitation specialists consider handedness and hemispheric lateralization during evaluation and treatment. With an increased understanding of the basic neural mechanisms surrounding handedness, clinicians will be better able to implement targeted, evidence-based neurorehabilitation interventions to promote functional independence. Plain-Language Summary: The goal of this narrative review is to increase clinicians' understanding of the basic neural mechanisms related to handedness (the tendency to select one hand over the other for specific tasks) and their implications for central and peripheral nervous system injury and rehabilitation. An enhanced understanding of these mechanisms may allow clinicians to better tailor neurorehabilitation interventions to address motor deficits and promote functional independence.
Topics: Humans; Functional Laterality; Hand; Peripheral Nervous System; Language
PubMed: 38305818
DOI: 10.5014/ajot.2024.050398