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Human Brain Mapping Sep 2016The importance of relationships between handedness, language lateralization and localization, and white matter tracts for language performance is unclear. The goal of...
The importance of relationships between handedness, language lateralization and localization, and white matter tracts for language performance is unclear. The goal of the study was to investigate these relationships by examining arcuate fasciculus (AF) structural asymmetry (DTI) and functional asymmetry (fMRI) in language circuits, handedness, and linguistic performance. A large sample of right-handed (n = 158) and atypical-handed (n = 82) healthy adults underwent DTI at 3 T to assess number of streamlines and fractional anisotropy (FA) of the AF, and language fMRI. Language functions were assessed using standard tests of vocabulary, naming, verbal fluency, and complex ideation. Laterality indices (LIs) illustrated degree of asymmetry and lateralization patterns for the AF (streamlines and FA) and verb generation fMRI. Both handedness groups showed leftward lateralization bias for streamline and fMRI LIs and symmetry for FA LI. The proportion of subjects with left, right, or symmetric lateralization were similar between groups if based on AF LIs, but differed if based on fMRI LIs (p = 0.0016). Degree of right-handedness was not associated with AF lateralization, but was associated with fMRI language lateralization (p = 0.0014). FA LI was not associated with performance on language assessments, but streamline LI was associated with better vocabulary and complex ideation performance in atypical-handed subjects (p = 0.022 and p = 0.0098, respectively), and better semantic fluency in right-handed subjects (p = 0.047); however, these did not survive multiple comparisons correction. We provide evidence that AF asymmetry is independent of hand preference, and while degree of right-handedness is associated with hemispheric language lateralization, the majority of atypical-handed individuals are left-lateralized for language. Hum Brain Mapp 37:3297-3309, 2016. © 2016 Wiley Periodicals, Inc.
Topics: Adolescent; Adult; Aged; Arcuate Nucleus of Hypothalamus; Brain Mapping; Diffusion Tensor Imaging; Female; Functional Laterality; Humans; Image Processing, Computer-Assisted; Language; Magnetic Resonance Imaging; Male; Middle Aged; Young Adult
PubMed: 27144738
DOI: 10.1002/hbm.23241 -
Brain and Cognition Apr 2016After decades of research, it remains unclear whether emotion lateralization occurs because one hemisphere is dominant for processing the emotional content of the...
After decades of research, it remains unclear whether emotion lateralization occurs because one hemisphere is dominant for processing the emotional content of the stimuli, or whether emotional stimuli activate lateralised networks associated with the subjective emotional experience. By using emotion-induction procedures, we investigated the effect of listening to happy and sad music on three well-established lateralization tasks. In a prestudy, Mozart's piano sonata (K. 448) and Beethoven's Moonlight Sonata were rated as the most happy and sad excerpts, respectively. Participants listened to either one emotional excerpt, or sat in silence before completing an emotional chimeric faces task (Experiment 1), visual line bisection task (Experiment 2) and a dichotic listening task (Experiment 3 and 4). Listening to happy music resulted in a reduced right hemispheric bias in facial emotion recognition (Experiment 1) and visuospatial attention (Experiment 2) and increased left hemispheric bias in language lateralization (Experiments 3 and 4). Although Experiments 1-3 revealed an increased positive emotional state after listening to happy music, mediation analyses revealed that the effect on hemispheric asymmetries was not mediated by music-induced emotional changes. The direct effect of music listening on lateralization was investigated in Experiment 4 in which tempo of the happy excerpt was manipulated by controlling for other acoustic features. However, the results of Experiment 4 made it rather unlikely that tempo is the critical cue accounting for the effects. We conclude that listening to music can affect functional cerebral asymmetries in well-established emotional and cognitive laterality tasks, independent of music-induced changes in the emotion state.
Topics: Adolescent; Attention; Auditory Perception; Brain; Dichotic Listening Tests; Emotions; Facial Recognition; Female; Functional Laterality; Happiness; Humans; Male; Music; Task Performance and Analysis; Young Adult
PubMed: 26970942
DOI: 10.1016/j.bandc.2016.03.001 -
Cerebral Cortex (New York, N.Y. : 1991) Jun 2012Lateralization of brain connectivity may be essential for normal brain function and may be sexually dimorphic. Here, we study the laterality patterns of short-range...
Lateralization of brain connectivity may be essential for normal brain function and may be sexually dimorphic. Here, we study the laterality patterns of short-range (implicated in functional specialization) and long-range (implicated in functional integration) connectivity and the gender effects on these laterality patterns. Parallel computing was used to quantify short- and long-range functional connectivity densities in 913 healthy subjects. Short-range connectivity was rightward lateralized and most asymmetrical in areas around the lateral sulcus, whereas long-range connectivity was rightward lateralized in lateral sulcus and leftward lateralizated in inferior prefrontal cortex and angular gyrus. The posterior inferior occipital cortex was leftward lateralized (short- and long-range connectivity). Males had greater rightward lateralization of brain connectivity in superior temporal (short- and long-range), inferior frontal, and inferior occipital cortices (short-range), whereas females had greater leftward lateralization of long-range connectivity in the inferior frontal cortex. The greater lateralization of the male's brain (rightward and predominantly short-range) may underlie their greater vulnerability to disorders with disrupted brain asymmetries (schizophrenia, autism).
Topics: Adolescent; Adult; Aged; Aged, 80 and over; Brain Mapping; Female; Functional Laterality; Humans; Male; Middle Aged; Nerve Net; Neural Pathways; Sex Characteristics; Young Adult
PubMed: 21878483
DOI: 10.1093/cercor/bhr230 -
Philosophical Transactions of the Royal... Apr 2009Brain asymmetries are a widespread phenomenon among vertebrates and show a common behavioural pattern. The right hemisphere mediates more emotional and instinctive... (Review)
Review
Brain asymmetries are a widespread phenomenon among vertebrates and show a common behavioural pattern. The right hemisphere mediates more emotional and instinctive reactions, while the left hemisphere deals with elaborated experience-based behaviours. In order to achieve a lateralized behaviour, each hemisphere needs different information and therefore different representations of the world. However, how these representations are accomplished within the brain is still unknown. Based on the pigeon's visual system, we present experimental evidence that lateralized behaviour is the result of the interaction between the subtelencephalic ascending input directing more bilateral visual information towards the left hemisphere and the asymmetrically organized descending telencephalic influence on the tecto-tectal balance. Both the bilateral representation and the forebrain-modulated information processing might explain the left hemispheric dominance for complex learning and discrimination tasks.
Topics: Animals; Behavior, Animal; Brain; Columbidae; Emotions; Functional Laterality; Models, Animal; Prosencephalon; Visual Pathways; Visual Perception
PubMed: 19064354
DOI: 10.1098/rstb.2008.0240 -
PloS One 2017Laterality is a well described phenomenon in domestic dogs. It was shown that dogs, under calm Earth's magnetic field conditions, when marking their home ranges, tend to...
Laterality is a well described phenomenon in domestic dogs. It was shown that dogs, under calm Earth's magnetic field conditions, when marking their home ranges, tend to head about north- or southwards and display thus magnetic alignment. The question arises whether magnetic alignment might be affected or even compromised by laterality and vice versa. We tested the preference of dogs to choose between two dishes with snacks that were placed left and right, in different compass directions (north and east, east and south, south and west or west and north) in front of them. Some dogs were right-lateral, some left-lateral but most of them were ambilateral. There was a preference for the dish placed north compared to the one placed east of the dog ("pull of the north"). This effect was highly significant in small and medium-sized breeds but not in larger breeds, highly significant in females, in older dogs, in lateralized dogs but less significant or not significant in males, younger dogs, or ambilateral dogs. Laterality and "pull of the north" are phenomena which should be considered in diverse tasks and behavioral tests with which dogs or other animals might be confronted. The interaction and possible conflict between lateralization and "pull of the north" might be also considered as a reason for shifted magnetic alignment observed in different animal species in different contexts.
Topics: Animals; Behavior, Animal; Dogs; Female; Functional Laterality; Magnetic Fields; Male; Orientation, Spatial
PubMed: 28945773
DOI: 10.1371/journal.pone.0185243 -
Srpski Arhiv Za Celokupno Lekarstvo 2005Lateralisation associates the extremities and senses of one side of the body, which are connected by afferent and efferent pathways, with the primary motor and sensory... (Review)
Review
Lateralisation associates the extremities and senses of one side of the body, which are connected by afferent and efferent pathways, with the primary motor and sensory areas of the hemisphere on the opposite side. Dominant laterality denotes the appearance of a dominant extremity or sense in the performance of complex psychomotor activities. Laterality is manifested both as right-handedness or left-handedness, which are functionally equivalent and symmetrical in the performance of activities. Right-handedness is significantly more common than left-handedness. Genetic theory is most widely accepted in explaining the onset of lateralisation. According to this theory, the models of brain organisation asymmetry (anatomical, functional, and biochemical) are strongly, genetically determined. However, the inability to clearly demonstrate the association between genetic factors and left-handedness has led researchers to investigate the effects of the environment on left-handedness. Of particular interest are the intrauterine environment and the factors influencing foetal development, of which hormones and ultrasound exposure are the most significant. It has been estimated that an extra five cases of nonright-handed lateralisation can be expected in every 100 males who were exposed to ultrasound in utero compared to those who were not. Socio-cultural pressure on left-handed individuals was much more severe in the past, which is confirmed by scientific findings that left-handedness is present in 13% of individuals in their twenties, while in less than 1% of individuals in their eighties.
Topics: Functional Laterality; Humans
PubMed: 16758857
DOI: 10.2298/sarh0512532m -
Archives of Sexual Behavior Jul 2019Non-right-handedness appears to be more common among bisexuals and homosexuals than among heterosexuals, which might be indirect evidence of effects of prenatal androgen...
Non-right-handedness appears to be more common among bisexuals and homosexuals than among heterosexuals, which might be indirect evidence of effects of prenatal androgen exposure. Current data suggest higher prenatal testosterone levels among bisexual and homosexual women, but are inconclusive for men. This study examined the association between sexual orientation and non-right-handedness for sex differences and whether higher rates of mixed-handedness, rather than left-handedness, might be the driving factor. This allowed for more specific tests regarding the predictions of two competing theories of prenatal androgen exposure, the Geschwind-Galaburda theory and the callosal hypothesis, than in previous research. Being a potentially better indicator of cerebral lateralization than handedness, associations with footedness were also explored. To counter inconsistencies and shortcomings of previous research, we utilized two large discovery and replication datasets (ns = 2368 and 1565) and applied latent variable analysis to reliably classify lateral preferences (i.e., handedness, footedness). This maximized the statistical conclusion validity and allowed for direct tests of replicability. Sexual orientation was differentially associated with lateral preferences among men and women. Associations among women were consistent with predictions of the Geschwind-Galaburda theory, whereas among men they were consistent with predictions of the callosal hypothesis. The results were further consistent with models of homosexuality that suggest a role of parental epigenetic marks on sexually dimorphic fetal development. Research efforts should be increased with regard to footedness and epigenetic theories of homosexuality.
Topics: Adolescent; Adult; Aged; Aged, 80 and over; Bisexuality; Female; Functional Laterality; Homosexuality; Humans; Male; Middle Aged; Sexual Behavior; Young Adult
PubMed: 30498915
DOI: 10.1007/s10508-018-1346-9 -
Psychologie & Neuropsychiatrie Du... Mar 2008Cerebral hemispheric lateralization is an old concept, particularly concerning language. In children, numerous arguments favour a left hemispheric predisposition for... (Review)
Review
Cerebral hemispheric lateralization is an old concept, particularly concerning language. In children, numerous arguments favour a left hemispheric predisposition for language, but do not exclude its strengthening during childhood. In the elderly, changes in the lateralization have been described. Two models were proposed to explain these changes. The right hemi-aging model is supported by behavioral studies and the age-related asymmetry reduction model is documented by brain imaging studies. We review the data supporting the two models. The significance of this age-related asymmetry reduction is questionable. The dedifferentiation view suggests that bilateral activation in older adults reflects difficulty in recruiting specialized neural mechanisms. Age-related asymmetry reduction may also be evidence of compensatory mechanisms and plasticity of the aging brain. It is useful for understanding physiopathology of cognitive decline and rehabilitation potential of the aging brain.
Topics: Aged; Aging; Functional Laterality; Humans; Speech
PubMed: 18364296
DOI: 10.1684/pnv.2008.0114 -
Biology Letters Feb 2019Lateralized behaviour in social insects is of biological significance, as certain lateral biases appear to have emerged in tandem with eusociality, and thus can provide...
Lateralized behaviour in social insects is of biological significance, as certain lateral biases appear to have emerged in tandem with eusociality, and thus can provide insights into its functioning. Here, I investigate behavioural asymmetry in an ecologically important social insect, the honeybee Apis mellifera. Experiments show that foraging bees exhibit a strong rightward turning bias, accompanied by reduced decision latency when entering open cavities, yet demonstrate no directional preference in sequential choice-mazes. A rightward exploration preference within unknown cavities is consistent with current information relating to the physiology of this species, with workers being better equipped for sensory investigation and threat response using their right antenna and eye. Furthermore, when applied to collective nest-choice scenarios, a similar bias would promote the uniform assessment of nest cavities, and consistency in quorum attainment. Conversely, such laterality appears to provide no immediate advantage in enclosed decision-maze systems, where thigmotaxis instead predominates. As such, my results show that directional biases in A. mellifera are extent, yet context-dependent, thus providing a simple and optimized response to varied social challenges.
Topics: Animals; Bees; Bias; Decision Making; Functional Laterality; Humans
PubMed: 30958134
DOI: 10.1098/rsbl.2018.0877 -
International Journal of Environmental... Sep 2020The behavioral preference for the use of one side of the body starts from pre-natal life and prompt humans to develop motor asymmetries. The type of motor task completed...
The behavioral preference for the use of one side of the body starts from pre-natal life and prompt humans to develop motor asymmetries. The type of motor task completed influences those functional asymmetries. However, there is no real consensus on the occurrence of handedness during developmental ages. Therefore, we aimed to determine which motor asymmetries emerged differently during childhood. A total sample of 381 children in grades 1 to 5 (6-11 years old) of primary school were recruited and tested for two fine coordination tasks (, led by dexterity, and , led by speed-dominated skills) and handgrip strength (). Data about their handedness, footedness and sports participation were also collected. Children performed better with their dominant side, especially for the and tests. The asymmetries were more marked in right-handed children and did not differ by age, gender or type of sport. Our findings support the thesis of a functional lateralization in complex coordinative tasks and in maximal strength during developmental ages. Furthermore, our findings extend the evidence of a stronger lateralization in right-handed individuals, demonstrating it at a functional level in primary school children performing motor tasks. Fine motor skills allow a "fine" understanding of developmental trajectories of lateralized behavior.
Topics: Child; Foot; Functional Laterality; Hand; Hand Strength; Humans; Motor Skills
PubMed: 32942557
DOI: 10.3390/ijerph17186705