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PubMed2026

Causal relationships between somatic movement, brain structures, and mental well-being: A multi-stage Mendelian randomization study.

BACKGROUND: While the relationships between somatic movement, mental well-being, and brain health have been well established, the causal nature and underlying mechanisms of such associations remain incompletely understood. METHODS: By applying multi-stage Mendelian randomization to multi-source summary data derived from genome-wide association studies, we examined the causal effects of 4 somatic movement measures on 2 mental well-being indices and 13 types of brain structures, followed by testing the mediating roles of brain structures in accounting for the causal associations between somatic movement and mental well-being. RESULTS: Two-sample Mendelian randomization revealed that more physical activity was causally associated with greater mental well-being (life satisfaction and positive affect), while more sedentary behavior (longer leisure screen time and more sedentary behavior at work) with lower mental well-being. With respect to brain structures, sedentary behavior was causally linked to decreased volume, surface area, and local gyrification index in distributed cortical regions. Remarkably, decreased surface area of the piriform cortex was found to mediate the causal associations between sedentary behavior and lower mental well-being. CONCLUSIONS: Our findings not only complement and extend earlier reports on the associations of somatic movement with mental well-being and brain health by further resolving the causality but also help elucidate the neural mechanisms by which sedentary behavior adversely affects mental well-being.

Humans↗
PubMed2006

Effects of antipsychotics on brain structure.

PURPOSE OF REVIEW: This review highlights the recent findings of different effects of typical and atypical antipsychotics on brain structure. RECENT FINDINGS: Studies examining the effect of treatment with typical antipsychotics on brain structure revealed a significant increase in basal ganglia volumes and decreased grey matter volume in different cortical regions. These volume changes were detectable even after a 12-week treatment. In contrast to these results, treatment with atypical antipsychotics does not seem to change basal ganglia volumes in neuroleptic-naïve patients. Moreover, switching from typical to atypical antipsychotic treatment reduces the increased basal ganglia volume to normal values compared with healthy controls. Only the volumes of thalamus and cortical grey matter increased after atypical antipsychotic treatment. SUMMARY: Currently, there is growing evidence that atypical antipsychotics might ameliorate structural changes caused by the disease process underlying schizophrenia and effects of typical antipsychotics. Further studies have to investigate the mechanism leading to these varying effects on brain structure.

Antipsychotic Agents↗
PubMed2004

Sensitivity to pain and c-Fos expression in brain structures in rats.

The induction of c-Fos protein--a product of the c-fos gene, a marker of changes in neuronal activity, was studied in brain structures of animals differing in their sensitivity to the acute painful stimulation, a foot-shock (MS--more sensitive rats; LS--less sensitive rats, according to the arbitrary criterion in the flinch-jump pretest). After the pretest the animals were dived into the control group, exposed on retest 10 days later to the testing cage only (C1 group), and aversively stimulated animals (MS and LS groups, given five mild footshocks 1.5 h before immunocytochemical part of the experiment). Additional control group of naive, intact animals, was studied in parallel (C group). It was shown that animals subjected to the flinch-jump test retained a strong emotional reaction on re-exposure to the shock cage on retest (a conditioned fear) 10 days later, as revealed by the widespread expression of c-Fos protein in the examined brain structures, as compared with the control, naive rats not exposed to the testing cage. In the lateral habenular nucleus (LHAB) a similar effect has been found in the control animals re-exposed to the testing cage only (C1 group), and in the MS group, suggesting that this brain area participates predominantly in processing of emotional-cognitive component of a painful stimulation. In the periaqueductal gray and basolateral nucleus of amygdala the most pronounced, but significantly higher in comparison with C group only, expression of c-Fos was detected in MS rats. Interestingly, a strong and uniform enhancement of c-Fos expression appeared in all other brain structures examined, including cortical areas, indicating their sensitivity to non-direct (conditioned) aversive stimuli. The only significant difference in c-Fos expression between LS and MS rats found in LHAB points to this brain structure as selectively engaged in processing of the emotional-cognitive component of a painful stimulation. The reactivity of LHAB may be responsible for the genetically determined differences in sensitivity to pain.

Analysis of Variance↗
PubMedDate not supplied

[Functional status of brain structures during exposure to anticipatory and trigger signals for feeding behavior].

The difference index of functional states of brain structures (the hippocampus, amygdala, frontal cortex) was estimated in dogs under the action of anticipating and triggering signals of a complex conditioned stimulus consisting of two similar tones, divided by a pause. It was found that during both signals the functional states of the brain structures were equivalent, though food-procuring behaviour of the animals under the action of the anticipating stimulus was inhibited. This fact corroborates the assumption that reactions of inhibitory type are determined by a high level of the brain structures functional state.

Amygdala↗
PubMed2026

Understanding specificity in immune-brain pathways: A systematic review of differential associations between individual cytokines and brain structure and function measured through magnetic resonance imaging in humans.

Research shows that cytokines are associated with psychiatric disorders, including major depression, and multiple aspects of brain structure and function. Accumulating data suggest that different cytokines may have unique profiles of biological activity, particularly in their neuromodulatory roles, but it is currently unclear whether they have unique associations with specific neural circuits in humans. In this paper, we systematically review magnetic resonance imaging studies conducted with depressed or healthy control human participants under age 65 that examine associations between peripheral cytokines and brain structure and function, with the goal of evaluating evidence for the specificity of these cytokine-brain associations. We find that across multiple measures of brain structure and function, the majority of studies reviewed reported unique associations between individual cytokines and brain outcomes. A synthesis of findings across studies also suggests a preliminary hypothesis of specific associations of interleukin-6 levels in circulation with the default mode network and tumor necrosis factor-alpha with the salience network, which could be tested in future research. We conclude the review with future directions for research that can strengthen understanding of these associations.

Humans↗
PubMed2003

Fos-like immunoreactivity in auditory and nonauditory brain structures of hamsters previously exposed to intense sound.

Fos-like immunoreactivity (FLI) was evaluated in auditory and nonauditory brain structures in hamsters that had been exposed previously to intense sound and tested behaviorally for tinnitus. The immunocytochemical results demonstrated a significant increase in exposed animals of FLI in auditory brain structures such as the lateral lemniscus, central nucleus of inferior colliculus, and auditory cortex, as well as in some nonauditory brain structures such as the locus coeruleus, lateral parabrachial nucleus, certain subregions of the hypothalamus, and amygdala. The behavioral scores suggest that animals that had been exposed to intense sound developed tinnitus. This is consistent with the hypothesis that FLI induced by intense sound exposure might represent a neural correlate of tinnitus or of plasticity associated with tinnitus. The possibility and the mechanisms underlying the increased FLI are discussed.

Acoustic Stimulation↗
PubMed2025

Human development, inequality, and their associations with brain structure across 29 countries.

BACKGROUND: The macro-social and environmental conditions in which people live, such as the level of a country's development or inequality, are associated with brain-related disorders. However, the relationship between these systemic environmental factors and the brain remains unclear. We aimed to determine the association between the level of development and inequality of a country and the brain structure of healthy adults. METHODS: We conducted a cross-sectional study pooling brain imaging (T1-based) data from 145 magnetic resonance imaging (MRI) studies in 7,962 healthy adults (4,110 women) in 29 different countries. We used a meta-regression approach to relate the brain structure to the country's level of development and inequality. RESULTS: Higher human development was consistently associated with larger hippocampi and more expanded global cortical surface area, particularly in frontal areas. Increased inequality was most consistently associated with smaller hippocampal volume and thinner cortical thickness across the brain. CONCLUSIONS: Our results suggest that the macro-economic conditions of a country are reflected in its inhabitants' brains and may explain the different incidence of brain disorders across the world. The observed variability of brain structure in health across countries should be considered when developing tools in the field of personalized or precision medicine that are intended to be used across the world.

Humans↗
PubMed2006

Relationship of catechol-O-methyltransferase variants to brain structure and function in a population at high risk of psychosis.

BACKGROUND: There is growing evidence that the gene catechol-O-methyltransferase (COMT) is involved in the etiopathogenesis of schizophrenia. This study sought to clarify the effects of the COMT Val158Met polymorphism on brain structure, function, and risk of developing schizophrenia in a well-characterized cohort of individuals at high risk of schizophrenia for familial reasons. METHODS: In a sample of 78 people at high genetic risk of schizophrenia, the risk of progression to schizophrenia associated with the COMT Val allele was estimated. The relationship of the Val allele to brain structure and function was investigated using structural magnetic resonance imaging (sMRI) and functional magnetic resonance imaging (fMRI) data collected on the high-risk subjects before their disease outcome was known. RESULTS: The COMT Val allele increased the risk of schizophrenia in this cohort in a dose-dependent manner. Subjects with the COMT Val allele had reduced gray matter density in anterior cingulate cortex. In addition, there was evidence of increased activation in lateral prefrontal cortex and anterior and posterior cingulated, with increasing sentence difficulty in those with the COMT Val allele despite a similar level of performance. CONCLUSIONS: The COMT Val allele is associated with an increased risk of schizophrenia in subjects at increased familial risk, in whom it has demonstrable effects on prefrontal brain structure and function. These patterns of altered brain structure and function have previously been associated with schizophrenia in this and other samples.

Adolescent↗
PubMed1999

Measurement of brain structures with artificial neural networks: two- and three-dimensional applications.

PURPOSE: To evaluate the ability of an artificial neural network (ANN) to identify brain structures. This ANN was applied to postprocessed magnetic resonance (MR) images to segment various brain structures in both two- and three-dimensional applications. MATERIALS AND METHODS: An ANN was designed that learned from experience to define the corpus callosum, whole brain, caudate, and putamen. Manual segmentation was used as a training set for the ANN. The ANN was trained on two-thirds of the manually segmented images and was tested on the remaining one-third. The reliability of the ANN was compared against manual segmentations by two technicians. RESULTS: The ANN was able to identify the brain structures as readily and as well as did the two technicians. Reliability of the ANN compared with the technicians was 0.96 for the corpus callosum, 0.95 for the whole brain, 0.86 (right) and 0.93 (left) for the caudate, and 0.71 (right) and 0.88 (left) for the putamen. CONCLUSION: The ANN was able to identify the structures used in this study as well as did the two technicians. The ANN could do this much more rapidly and without rater drift. Several other cortical and subcortical structures could also be readily identified with this method.

Adult↗
PubMedDate not supplied

Concentrations of cAMP and activity of pertinent enzymes in certain brain structures of the rabbit.

The concentrations of cAMP and the activity of adenyl cyclase and specific cAMP-phosphodiesterase were determined in certain structures of rabbit brain. Statistically significant differences were found in the concentrations of cAMP; and enzyme activity between certain structures of the brain, particularly in the structures of the brain stem: mesencephalon, diencephalon and the pontine structures.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed2006

[Pathophysiological aspects of brain structural disturbances in patients with Fabry disease: literature review].

Fabry Disease (FD) is a rare X-linked lysosomal storage disorder caused by deficiency of alpha-galactosidase A (alpha-GAL) enzyme activity. Neutral glycosphingolipides (esp. Gb3) accumulate in lysosomes of several tissues, particularly in vascular endothelium and smooth muscle cells. Cerebral manifestations that might be mainly due to progressive cerebrovascular dysfunction, are one major and often life-threatening burden of the disease. We reviewed the present literature concerning brain structural alterations in FD and discuss the possibly relevant underlying pathophysiological aspects of these disturbances. Cerebrovascular events (TIA, stroke) occur in FD at a rather early age. In female FD patients who were considered to be less affected "carriers" for a long time, the prevalence of cerebrovascular events seems to be at last as high as in male patients. In structural imaging white matter lesions (WML) can be found frequently even in young FD patients. In a recent study clinically equally affected men and women with FD showed a comparable severity of WML load. Different pathophysiological aspects of cerebral angiopathy and WML development are discussed against the background of current concepts (e. g. accumulation of Gb3 in vascular endothelium with consecutive cell proliferation and luminal stenosis, acceleration of focal intravasal pressure and disturbances of vascular auto-regulation). Pathological increase of pulvinar signal in T1-weighted MRI has also been described in FD. This finding was assumed to be caused by calcification as a consequence of disturbed local circulation. To enhance our knowledge about the relevant neurobiological processes the authors propose a more sensitive and early detection of brain structural changes in FD. New brain structural MRI methods such as diffusion-tensor imaging could provide a pattern of ultrastructural changes even in young patients without visible WML. This strategy could be as well useful for quantification of possible effects of the enzyme replacement therapy on brain structural alterations in FD. Based on recent data a systematic FD-screening by measuring Gb3 in urine of young patients with cryptogenic stroke should be discussed. Basically in such cases FD should be clinically considered.

Brain↗
PubMed2001

Genetic influences on brain structure.

Here we report on detailed three-dimensional maps revealing how brain structure is influenced by individual genetic differences. A genetic continuum was detected in which brain structure was increasingly similar in subjects with increasing genetic affinity. Genetic factors significantly influenced cortical structure in Broca's and Wernicke's language areas, as well as frontal brain regions (r2(MZ) > 0.8, p < 0.05). Preliminary correlations were performed suggesting that frontal gray matter differences may be linked to Spearman's g, which measures successful test performance across multiple cognitive domains (p < 0.05). These genetic brain maps reveal how genes determine individual differences, and may shed light on the heritability of cognitive and linguistic skills, as well as genetic liability for diseases that affect the human cortex.

Adult↗
PubMedDate not supplied

Brain structure in men remains highly heritable in the seventh and eighth decades of life.

The midsagittal cross-sectional dimensions of the corpus callosum, the coronal cross-sectional area of the lateral ventricles at the level of the pons, and a three-dimensional estimate of intracranial volume were derived from magnetic resonance brain images obtained from 45 monozygotic and 40 dizygotic male twin pairs aged 68 to 78. Univariate genetic analyses indicated strong genetic influences contributing significantly to the variability of each brain structure. The estimated proportion of genetic variance (i.e. heritability) was 81% for intracranial volume, 79% for the midline cross-sectional area of the corpus callosum, and 79% for lateral ventricle size. There was no evidence that shared environmental influences contributed significantly to twin-pair similarities. We further used bivariate genetic modeling to estimate the genetic and environmental correlation between correlated brain structures. Intracranial volume and corpus callosum area was highly correlated, and this relationship was entirely due to shared genetic effects between these two brain structures. By contrast, the relationship between the height of the corpus callosum and the size of the lateral ventricles was due to both genetic and environmental influences in common. Corresponding genetic and environmental correlations were 0.68 and 0.58, respectively, indicating that more than half of the genetic and environmental influences on these two brain structures were shared. The manner in which the brain responds to the environment with advancing age is highly genetically determined, both for the lateral ventricles, which dilate with aging and disease, and for the corpus callosum, which is deformed in shape by age-related ventricular enlargement, whereas its midline cross-sectional area remains unchanged.

Aged↗
PubMed2003

Brain structure and function in adolescents with anorexia nervosa.

Anorexia nervosa (AN) commonly arises during adolescence and is associated with significant medical morbidity. Abnormalities in brain structure and function are among the most common, early, and concerning physical consequences. Advances in neuroimaging technology have played an important role in delineating the structural and functional changes found in patients with AN. Studies using computed tomography and magnetic resonance imaging have demonstrated changes in brain structure in the low-weight stages of AN. In addition, functional neuroimaging techniques have demonstrated altered brain metabolism. Debate continues as to whether these brain abnormalities are fully reversible with weight restoration. Neuropsychological research has demonstrated that cognitive dysfunction is also a common feature of AN. Multiple studies have indicated deficits in various neuropsychological domains. Whether the reported cognitive deficits are reversible with weight gain remains unknown. To date, some preliminary evidence suggests that reported cognitive deficits in patients with AN may be associated with structural brain abnormalities. This chapter reviews the current literature about neuroimaging studies and cognitive function in adolescents with AN, discusses the possible underlying mechanisms causing these changes, and explores the possible association between them.

Adolescent↗
PubMed1988

[Effect of adenosine on cyclic nucleotide levels in brain structures].

Adenosine influence on cAMP and cGMP levels in cortex, hypothalamus, hippocampus and cerebellum was studied. It was established that adenosine and inhibitor of its reuptake--dipyridamole change cyclic nucleotide levels in some structures of brain (intraperitoneal injection). It was shown that cAMP and cGMP were in reciprocal relations in cortex, but not in hypothalamus, hippocampus and cerebellum.

Adenosine↗
PubMed1998

[Morphometric characterization of median brain structures using intravital magnetic resonance tomography].

Linear parameters of corpus callosum and submucosal structures (transparent septum, cupula, thalamus, pineal body and the third ventricle choroid plexus) were measured using 80 MR tomograms and 40 craniograms of 20 patients aged 20-50. Linear parameters were compared with the cranium shape and statistically processed. The dependence of linear parameters of the structures mentioned upon the shape of the cranium was demonstrated. They were characterized morphometrically in dolychomeso- and brachiocephals. The data obtained are of interest in assessment of MR tomograms with pathological changes and individualization of surgical interventions in median structures of brain.

Adult↗
PubMed2003

Cognitive ability and brain structure in type 1 diabetes: relation to microangiopathy and preceding severe hypoglycemia.

Type 1 diabetes is associated with chronic hyperglycemia and exposure to intermittent severe hypoglycemia. The long-term cerebral effects of these consequences of diabetes are ill defined. In this study, the history of preceding severe hypoglycemia and the presence of background retinopathy were examined in relation to cognitive ability (neuropsychological test battery) and brain structure (magnetic resonance imaging) in a cross-sectional evaluation of 74 young people with type 1 diabetes. Participants differed by their severe hypoglycemia exposure and degree of diabetic retinopathy and none had previous neuropsychological pathology. Severe hypoglycemia did not influence cognitive ability or brain structure. Background diabetic retinopathy was associated with small focal white-matter hyperintensities in the basal ganglia (33.3 vs. 4.7%, after correction for age, P = 0.005) and significant cognitive disadvantage, affecting fluid intelligence (P = 0.008, Eta(2) = 0.14), information processing (P = 0.001, Eta(2) = 0.22), and attention and concentration ability (P = 0.03, Eta(2) = 0.09). In conclusion, recurrent exposure to severe hypoglycemia alone in young people with type 1 diabetes had no detrimental impact on brain structure or function over the duration of diabetes examined. Chronic hyperglycemia (inferred by the presence of background diabetic retinopathy) may affect brain structure and function.

Adult↗
PubMed1980

[Formation of functional synaptic connections between heterogeneous brain structures in an organotypic nerve tissue culture].

A directed growth of nervous fibres and formation of functional synaptic connections between heterogeneous brain structures (spinal cord and olfactory bulb of mouse embryos) were studied in organotypic nervous tissue culture by means of neuromorphological and neurophysiological methods. Within the first week in vitro fibre connections between the spinal cord and olfactory bulb explants were formed as glioneuritic bridges. In the formation of these connections glial cells play an active role and organize an oriented substrate upon which there occur growth and fasciation of axons developing later. Silver impregnation showed that connections between the explants were formed by bundles of axons or by separate nerve fibres. An electrophysiological study of the co-cultured heterogeneous brain structures revealed that functional synaptic connections were developed between the spinal cord and olfactory bulb explants by the second week of cultivation. Electrical stimuli applied to the spinal cord explants evoked short- and long-latency responses of neurons in the olfactory bulb explants. The described formation of nonspecific for the given brain structures functional synaptic connections in vitro showed a high degree of morphogenetic plasticity of growing or regenerating axons and an active role of neuroglial cells in a directed growth of nervous fibres.

Animals↗