scholarly journals Human Handedness: Genetics, Microtubules, Neuropsychiatric Diseases and Brain Language Areas

2018 ◽  
Author(s):  
A. Wiberg ◽  
G. Douaud ◽  
M. Ng ◽  
Y. Al Omran ◽  
F. Alfaro-Almagro ◽  
...  

AbstractBackgroundThe skew in distribution of handedness is a uniquely human trait, and has fascinated researchers for centuries. The heritability of handedness is estimated at 25%, but defining genetic variants contributing to this trait has so far proved elusive.MethodsWe performed GWAS of self-reported handedness in UK Biobank, a prospective cohort study of ∼500,000 individuals. Furthermore, we investigated correlations between our associated SNPs and brain imaging-derived phenotypes (IDPs) from >9,000 individuals in UK Biobank, as well as between self-reported handedness and IDPs.ResultsOur association study of 38,322 left-handers vs 356,567 right-handers (excluding ambidextrous participants) revealed three genome-wide significant loci (rs199512, 17q21.31, p=4.1x10−9; rs45608532, 22q11.22, p=1.4x10−8; rs13017199, 2q34, p=3.3x10−8). In the imaging study, we found strong associations between rs199512 and diffusion MRI measures mainly in white matter tracts connecting language-related brain regions (p<2.0x10−6). Direct investigation between handedness and IDPs revealed numerous associations with functional connectivity between the same language-related areas of the brain. A second GWAS of non-right handers (n=44,631) vs right-handers (n=356,567) revealed an additional locus: rs3094128, 6p21.33, p=2.9x10−8. Three of the four associated loci (2q34, 17q21.31, 6p21.33) contain genes that encode microtubule-related proteins that are highly expressed in the brain: MAP2, MAPT and TUBB. These genes are strongly implicated in the pathogenesis of diseases that are known to affect an excess of left-handed people, including schizophrenia.ConclusionsThis is the first GWAS to identify genome-wide significant loci for human handedness in the general population, and the genes at these loci have biological plausibility in contributing to neurodevelopmental lateralization of brain organisation, which appears to predispose both to left-handedness and to certain neurodegenerative and psychiatric diseases.

Brain ◽  
2019 ◽  
Vol 142 (10) ◽  
pp. 2938-2947 ◽  
Author(s):  
Akira Wiberg ◽  
Michael Ng ◽  
Yasser Al Omran ◽  
Fidel Alfaro-Almagro ◽  
Paul McCarthy ◽  
...  

The brain signature and genetic basis of handedness are unclear. Wiberg et al. show that left-handers have higher functional connectivity between language networks, and identify four genomic regions associated with handedness. Variants within these regions appear, by influencing brain architecture, to predispose both to left-handedness and to certain neuropsychiatric diseases.


2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Nicole M. Wanner ◽  
Mathia Colwell ◽  
Chelsea Drown ◽  
Christopher Faulk

Abstract Background Use of cannabidiol (CBD), the primary non-psychoactive compound found in cannabis, has recently risen dramatically, while relatively little is known about the underlying molecular mechanisms of its effects. Previous work indicates that direct CBD exposure strongly impacts the brain, with anxiolytic, antidepressant, antipsychotic, and other effects being observed in animal and human studies. The epigenome, particularly DNA methylation, is responsive to environmental input and can direct persistent patterns of gene regulation impacting phenotype. Epigenetic perturbation is particularly impactful during embryogenesis, when exogenous exposures can disrupt critical resetting of epigenetic marks and impart phenotypic effects lasting into adulthood. The impact of prenatal CBD exposure has not been evaluated; however, studies using the psychomimetic cannabinoid Δ9-tetrahydrocannabinol (THC) have identified detrimental effects on psychological outcomes in developmentally exposed adult offspring. We hypothesized that developmental CBD exposure would have similar negative effects on behavior mediated in part by the epigenome. Nulliparous female wild-type Agouti viable yellow (Avy) mice were exposed to 20 mg/kg CBD or vehicle daily from two weeks prior to mating through gestation and lactation. Coat color shifts, a readout of DNA methylation at the Agouti locus in this strain, were measured in F1 Avy/a offspring. Young adult F1 a/a offspring were then subjected to tests of working spatial memory and anxiety/compulsive behavior. Reduced-representation bisulfite sequencing was performed on both F0 and F1 cerebral cortex and F1 hippocampus to identify genome-wide changes in DNA methylation for direct and developmental exposure, respectively. Results F1 offspring exposed to CBD during development exhibited increased anxiety and improved memory behavior in a sex-specific manner. Further, while no significant coat color shift was observed in Avy/a offspring, thousands of differentially methylated loci (DMLs) were identified in both brain regions with functional enrichment for neurogenesis, substance use phenotypes, and other psychologically relevant terms. Conclusions These findings demonstrate for the first time that despite positive effects of direct exposure, developmental CBD is associated with mixed behavioral outcomes and perturbation of the brain epigenome.


2021 ◽  
Vol 118 (47) ◽  
pp. e2113095118
Author(s):  
Zhiqiang Sha ◽  
Antonietta Pepe ◽  
Dick Schijven ◽  
Amaia Carrión-Castillo ◽  
James M. Roe ◽  
...  

Roughly 10% of the human population is left-handed, and this rate is increased in some brain-related disorders. The neuroanatomical correlates of hand preference have remained equivocal. We resampled structural brain image data from 28,802 right-handers and 3,062 left-handers (UK Biobank population dataset) to a symmetrical surface template, and mapped asymmetries for each of 8,681 vertices across the cerebral cortex in each individual. Left-handers compared to right-handers showed average differences of surface area asymmetry within the fusiform cortex, the anterior insula, the anterior middle cingulate cortex, and the precentral cortex. Meta-analyzed functional imaging data implicated these regions in executive functions and language. Polygenic disposition to left-handedness was associated with two of these regional asymmetries, and 18 loci previously linked with left-handedness by genome-wide screening showed associations with one or more of these asymmetries. Implicated genes included six encoding microtubule-related proteins: TUBB, TUBA1B, TUBB3, TUBB4A, MAP2, and NME7—mutations in the latter can cause left to right reversal of the visceral organs. There were also two cortical regions where average thickness asymmetry was altered in left-handedness: on the postcentral gyrus and the inferior occipital cortex, functionally annotated with hand sensorimotor and visual roles. These cortical thickness asymmetries were not heritable. Heritable surface area asymmetries of language-related regions may link the etiologies of hand preference and language, whereas nonheritable asymmetries of sensorimotor cortex may manifest as consequences of hand preference.


2021 ◽  
Vol 15 ◽  
Author(s):  
Daniel Golkowski ◽  
Rebecca Willnecker ◽  
Jennifer Rösler ◽  
Andreas Ranft ◽  
Gerhard Schneider ◽  
...  

The neurophysiology of the subjective sensation of being conscious is elusive; therefore, it remains controversial how consciousness can be recognized in patients who are not responsive but seemingly awake. During general anesthesia, a model for the transition between consciousness and unconsciousness, specific covariance matrices between the activity of brain regions that we call patterns of global brain communication reliably disappear when people lose consciousness. This functional magnetic imaging study investigates how patterns of global brain communication relate to consciousness and unconsciousness in a heterogeneous sample during general anesthesia and after brain injury. First, we describe specific patterns of global brain communication during wakefulness that disappear during propofol (n = 11) and sevoflurane (n = 14) general anesthesia. Second, we search for these patterns in a cohort of unresponsive wakeful patients (n = 18) and unmatched healthy controls (n = 20) in order to evaluate their potential use in clinical practice. We found that patterns of global brain communication characterized by high covariance in sensory and motor areas or low overall covariance and their dynamic change were strictly associated with intact consciousness in this cohort. In addition, we show that the occurrence of these two patterns is significantly related to activity within the frontoparietal network of the brain, a network known to play a crucial role in conscious perception. We propose that this approach potentially recognizes consciousness in the clinical routine setting.


2008 ◽  
Vol 20 (12) ◽  
pp. 2153-2166 ◽  
Author(s):  
Anna Mestres-Missé ◽  
Estela Càmara ◽  
Antoni Rodriguez-Fornells ◽  
Michael Rotte ◽  
Thomas F. Münte

An important issue in language learning is how new words are integrated in the brain representations that sustain language processing. To identify the brain regions involved in meaning acquisition and word learning, we conducted a functional magnetic resonance imaging study. Young participants were required to deduce the meaning of a novel word presented within increasingly constrained sentence contexts that were read silently during the scanning session. Inconsistent contexts were also presented in which no meaning could be assigned to the novel word. Participants showed meaning acquisition in the consistent but not in the inconsistent condition. A distributed brain network was identified comprising the left anterior inferior frontal gyrus (BA 45), the middle temporal gyrus (BA 21), the parahippocampal gyrus, and several subcortical structures (the thalamus and the striatum). Drawing on previous neuroimaging evidence, we tentatively identify the roles of these brain areas in the retrieval, selection, and encoding of the meaning.


2016 ◽  
Vol 113 (10) ◽  
pp. 2738-2743 ◽  
Author(s):  
Ahmed Mahfouz ◽  
Boudewijn P. F. Lelieveldt ◽  
Aldo Grefhorst ◽  
Lisa T. C. M. van Weert ◽  
Isabel M. Mol ◽  
...  

Steroid receptors are pleiotropic transcription factors that coordinate adaptation to different physiological states. An important target organ is the brain, but even though their effects are well studied in specific regions, brain-wide steroid receptor targets and mediators remain largely unknown due to the complexity of the brain. Here, we tested the idea that novel aspects of steroid action can be identified through spatial correlation of steroid receptors with genome-wide mRNA expression across different regions in the mouse brain. First, we observed significant coexpression of six nuclear receptors (NRs) [androgen receptor (Ar), estrogen receptor alpha (Esr1), estrogen receptor beta (Esr2), glucocorticoid receptor (Gr), mineralocorticoid receptor (Mr), and progesterone receptor (Pgr)] with sets of steroid target genes that were identified in single brain regions. These coexpression relationships were also present in distinct other brain regions, suggestive of as yet unidentified coordinate regulation of brain regions by, for example, glucocorticoids and estrogens. Second, coexpression of a set of 62 known NR coregulators and the six steroid receptors in 12 nonoverlapping mouse brain regions revealed selective downstream pathways, such as Pak6 as a mediator for the effects of Ar and Gr on dopaminergic transmission. Third, Magel2 and Irs4 were identified and validated as strongly responsive targets to the estrogen diethylstilbestrol in the mouse hypothalamus. The brain- and genome-wide correlations of mRNA expression levels of six steroid receptors that we provide constitute a rich resource for further predictions and understanding of brain modulation by steroid hormones.


2020 ◽  
Author(s):  
Danni A. Gadd ◽  
Anna J. Stevenson ◽  
Robert F. Hillary ◽  
Daniel L. McCartney ◽  
Nicola Wrobel ◽  
...  

AbstractModifiable lifestyle factors influence the risk of developing many neurological diseases. These factors have been extensively linked with blood-based genome-wide DNA methylation (DNAm), but it is unclear if the signatures from blood translate to the target tissue of interest - the brain. To investigate this, we apply blood-derived epigenetic predictors of four lifestyle traits to genome-wide DNAm from five post-mortem brain regions and the last blood sample prior to death in 14 individuals in the Lothian Birth Cohort 1936 (LBC1936). Using these matched samples, we found that correlations between blood and brain DNAm scores for smoking, high density lipoprotein (HDL) cholesterol, alcohol and body mass index (BMI) were highly variable across brain regions. Smoking scores in the dorsolateral prefrontal cortex had the strongest correlations with smoking scores in blood (r=0.5, n=14) and smoking behaviour (r=0.56, n=9). This was also the brain region which exhibited the strongest correlations for DNAm at site cg05575921 - the single strongest correlate of smoking in blood - in relation to blood (r=0.61, n=14) and smoking behaviour (r=-0.65, n=9). This suggested a particular vulnerability to smoking-related differential methylation in this region. Our work contributes to understanding how lifestyle factors affect the brain and suggests that lifestyle-related DNAm is likely to be both brain region dependent and in many cases poorly proxied for by blood. Though these pilot data provide a rarely-available opportunity for the comparison of methylation patterns across multiple brain regions and the blood, due to the limited sample size available our results must be considered as preliminary and should therefore be used as a basis for further investigation.Abstract FigureGraphical abstract 203mm x 127mm (DPI 300)Abbreviated summary [50 words]: We apply blood-derived epigenetic signatures of lifestyle traits to matched blood and brain samples, uncovering variability in how well blood translates across brain regions and a relationship between smoking and the prefrontal cortex. Our preliminary results contribute to understanding how lifestyle-related DNA methylation affects the brain in health and disease.


2021 ◽  
Author(s):  
Joan Fitzgerald ◽  
Laura Fahey ◽  
Laurena Holleran ◽  
Pilib Ó Broin ◽  
Gary Donohoe ◽  
...  

AbstractCognitive resilience is the ability to withstand the negative effects of stress on cognitive functioning and is important for maintaining quality of life while aging. Here we employed a proxy phenotype approach to create a longitudinal cognitive resilience phenotype using past education years and current processing speed, reflecting an average time span of 40 years, in 330,097 individuals from the UK Biobank. A genome-wide association study identified 13 independent genome-wide significant loci that implicate 33 genes. A portion of resilience’s genetic signal is distinct from the genetics of intelligence. Functional analyses showed enrichment in several brain regions and involvement of specific cell types, including GABAergic neurons (P=6.59×10−8) and glutamatergic neurons (P=6.98×10−6) in the cortex. Gene-set analyses implicated the biological process “neuron differentiation” (P=9.7×10−7) and the cellular component “synaptic part” (P=2.14×10−6). Mendelian randomization analysis showed a causative effect of white matter volume on cognitive resilience. These results enhance neurobiological understanding of resilience.


2021 ◽  
Vol 12 ◽  
Author(s):  
Zhixin Chai ◽  
Zhijuan Wu ◽  
Qiumei Ji ◽  
Jikun Wang ◽  
Jiabo Wang ◽  
...  

Both 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) are important epigenetic modifications in neurodevelopment. However, there is little research examining the genome-wide patterns of 5mC and 5hmC in brain regions of animals under natural high-altitude conditions. We used oxidative reduced representation bisulfite sequencing (oxRRBS) to determine the 5mC and 5hmC sites in the brain, brainstem, cerebellum, and hypothalamus of yak and cattle. We reported the first map of genome-wide DNA methylation and hydroxymethylation in the brain, brainstem, cerebellum, and hypothalamus of yak (living at high altitudes) and cattle. Overall, we found striking differences in 5mC and 5hmC between the hypothalamus and other brain regions in both yak and cattle. Genome-wide profiling revealed that 5mC level decreased and 5hmC level increased in the hypothalamus than in other regions. Furthermore, we identified differentially methylated regions (DMRs) and differentially hydroxymethylated regions (DhMRs), most of which overlapped with each other. Interestingly, transcriptome results for these brain regions also showed distinctive gene levels in the hypothalamus. Finally, differentially expressed genes (DEGs) regulated by DMRs and DhMRs may play important roles in neuromodulation and myelination. Overall, our results suggested that mediation of 5mC and 5hmC on epigenetic regulation may broadly impact the development of hypothalamus and its biological functions.


2021 ◽  
Author(s):  
Zhiqiang Sha ◽  
Antonietta Pepe ◽  
Dick Schijven ◽  
Amaia Carrion Castillo ◽  
James M. Roe ◽  
...  

Roughly 10% of the human population is left-handed, and this rate is increased in some brain-related disorders. The neuroanatomical correlates of hand preference have remained equivocal. We re-sampled structural brain image data from 28,802 right-handers and 3,062 left-handers (UK Biobank population dataset) to a symmetrical surface template, and mapped asymmetries for each of 8,681 vertices across the cerebral cortex in each individual. Left-handers and right-handers showed average differences of surface area asymmetry within fusiform, anterior insular, anterior-middle-cingulate and precentral cortex. Meta-analyzed functional imaging data implicated these regions in executive functions and language. Polygenic disposition to left-handedness was associated with two of these regional asymmetries, and 18 loci previously linked with left-handedness by genome-wide screening showed associations with one or more of these asymmetries. Implicated genes included six encoding microtubule-related proteins: TUBB, TUBA1B, TUBB3, TUBB4A, MAP2 and NME7 - the latter is mutated in left-right reversal of the visceral organs. There were also two cortical regions where average thickness asymmetry was altered in left-handedness: on the postcentral gyrus and inferior occipital cortex, functionally annotated with hand sensorimotor and visual roles. These cortical thickness asymmetries were not heritable. Heritable surface area asymmetries of language-related regions may link the etiologies of hand preference and language, whereas non-heritable asymmetries of sensorimotor cortex may manifest as consequences of hand preference.


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