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Results for “cortical structure”

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At least 19 recordsLinked to original sources
PubMed2025

Asthma causally affects the brain cortical structure: a Mendelian randomization study.

OBJECTIVE: The potential causal relationship between asthma and brain structures remains uncertain. We performed a two-sample Mendelian randomization to investigate the causal effects of various asthma phenotypes - unspecified asthma, moderate-to-severe asthma, childhood-onset asthma, and adult-onset asthma (AOA) - on cerebral cortex structure. METHODS: We utilized phenotype data derived from genome-wide association studies (GWASs). The ENIGMA Consortium GWAS provided outcome variables for surface area (SA) and thickness across the whole brain and 34 region-specific areas of the cerebral cortex. Using the inverse variance-weighted method as our primary estimation approach, we employed several techniques, including Cochran's Q statistic, the MR-PRESSO global test, MR-Egger, and weighted median, to assess heterogeneity and pleiotropy, thereby ensuring the robustness of our findings. Additionally, we conducted enrichment analyses of gene sets with causal effects on cortical structure and applied bioinformatics techniques to construct interaction networks and identify hub nodes. RESULTS: At the global level, AOA was associated with a significant reduction in full cortical SA (β = -58.49 mm2, p = 0.017). In regional analyses, moderate-to-severe asthma exhibited a more pronounced impact on the cerebral cortex compared to other phenotypes. Enrichment analysis revealed that pathways implicated in brain morphology among asthma patients were primarily linked to immune and inflammation-driven pathways. CONCLUSIONS: Our findings provide new evidence supporting a causal relationship between asthma and alterations in cortical structure, offering potential explanations for cognitive and psychiatric impairments observed in individual post-asthma.

Humans↗
PubMed2026

Linking cortical structure and delirium in the elderly: insights from cohort study and shared genetic risk analysis.

BACKGROUND: This study aimed to assess the association between regional cortical changes measured via baseline magnetic resonance imaging (MRI) and the incidence of delirium. METHODS: Observational associations were assessed using a prospective cohort from the UK Biobank and an independent clinical cohort. The population-based study included participants aged 60 years or older who had undergone structural brain MRI since 2014. Regional cortical volume, mean thickness, and surface area were extracted based on the Desikan-Killiany cortical atlas. Delirium was defined using ICD-10 diagnostic codes. Additionally, preoperative brain MRI images from participants in another cohort were collected and automatically segmented using deep learning algorithms to obtain cortical measurements. Logistic analysis was performed to investigate the associations between cerebral cortical structure and delirium risk. Lastly, genome-wide association study data derived from the ENIGMA Consortium and FinnGen Biobank were utilized to conduct conditional/conjunctional false discovery rate (cond/conjFDR) analyses to identify shared genetic loci associated with cortical structures and delirium. RESULTS: This observational analysis included 31,890 participants from the UK Biobank and 152 participants from an independent cohort. In the UK Biobank cohort, decreased cortical thickness in the 17 regions was associated with a significantly increased risk of delirium. Similarly, a preoperative reduction in cortical volume in 7 regions was associated with an increased risk of delirium in the independent cohort. Besides, 100 single-nucleotide polymorphisms (SNPs) were identified as significantly associated with cortical structures when conditioned on delirium. Finally, colocalization analysis demonstrated that these pleiotropic risk loci modulated the expression of NT5C2, RGP1, CCDC25, TPM2, EEF1AKMT2, IQANK1 and LHPP in blood and brain tissues. CONCLUSION: Regional cortical atrophy is associated with an increased risk of delirium in the elderly. Brain MRI examinations may be beneficial for preoperative delirium risk assessment in elderly individuals undergoing elective surgery.

Humans↗
PubMed2026

Cerebral Cortical Structural Variation and General Cognitive Ability: Evidence From Mendelian Randomization.

Understanding the cortical architecture underlying individual differences in general cognitive ability (GCA) remains a central question in cognitive neuroscience. Prior work has established associations between global brain size and GCA, yet the regional effects and directionality of these relationships remain debated. Using a genetically informed cortical parcellation in 11,289 UK Biobank participants, we examined associations between cortical surface area (SA), cortical thickness (CT), and GCA measured via verbal-numerical reasoning. Total SA showed a robust positive association with GCA. At the regional level, dorsolateral prefrontal and superior temporal SA exhibited the strongest positive associations, which persisted after adjustment for global SA. In contrast, CT showed comparatively modest associations. Using Mendelian randomization (MR) with genome-wide significant genetic instruments, we observed evidence consistent with a bidirectional relationship between total SA and GCA. At the regional level, dorsolateral prefrontal and temporal SA demonstrated evidence of MR-inferred directional effects on GCA, while GCA showed evidence of MR-inferred directional effects on total SA and perisylvian thickness. These findings support a polyregional SA architecture underlying GCA, with prominent contributions from prefrontal and temporal association cortices. Our results refine global brain-GCA models and highlight the value of genetically informed parcellation for identifying regional cortical contributions.

Humans↗
PubMed1976

[A method of assessing the degree of vertical organization of cerebral cortical structures].

A method of obtaining a comparative quantitative evaluation of the vertical order of neurons in the cerebral cortex structures with the help ofinformational indices of the entropy and organization is proposed. The presence of the vertical column order of neurons is considered as a manifestation of a certain general regularly in the building of neural complexes. The morphological preparation (section) of the definitive process. The scheme of operations with the given record (morphological preparation) in the uork permits obtaining the values of the entropy and organization. In the example of the middle of layer III field 17 and sublayer III2 of layer 18 of the human new cortex it has been shown that the proposed method contributes to revealing the difference in the degree of the vertical order of neurons in these structures.

Cerebral Cortex↗
PubMedDate not supplied

[Dynamics of evoked potentials in cortical projection structures during a retarded instrumental defense reflex in dogs].

Evoked potentials (EP) in the somatosensory and auditory cortical areas were studied in four dogs against the background of a retarded defensive instrumental conditioned reflex to clicks. Four phases of the reflex were singled out by the changes in the structure of EP late components (LC) in the two projection zones. The most complex LC changes in the form of intensified negative components and the appearance of additional negative LC are recorded in response to the first click of the series and to the one followed by the conditioned motor reaction (CMR). Against the background of CMR delay, the EPs increased, while during the CMR, they decreased, owing to the diminished negative components, while the positive components were preserved and sometimes intensified. An assumption has been made that cortical projection structures of paired stimuli function in one and the same regime.

Animals↗
PubMed1977

[Topography and cytoarchitectonics of the main cortical zones of the turtle forebrain].

The description of cytoarchitectonics and topography of the three principle cortical zones of the forebrain of Emys orbicularis reveals that the cortical structures in the species are precisely distinguished with respect to their neuronal characteristics, density and the situation of cellular elements. Emys orbicularis occupies an intermediate position among the species of the order Chelonia described in the literature as regards the level of development of the forebrain cellular structures. Emys orbicularis is less progressive in respect to the structure of telencephalic cortical formations than Testudo carolina and has a number of progressive properties as compared with Testudo geometrica. Testudo graeca seems to be close to Emys orbicularis in the development of forebrain cellular structures.

Animals↗
PubMed1979

The origin of the hind limb vasodilatation evoked by stimulation of the motor cortex in the cat.

In cats under Althesin anaesthesia, the hind limb area of the motor cortex has been stimulated by means of monopolar, semi-micro-electrodes with careful experimental control so as to avoid reflex effects evoked through stimulation of meningeal afferent fibres or stimulus spread to non-cortical structures. 2. Localized cortical stimulation which elicited muscle contractions in the contralateral hind limb also elicited vasodilation in the same limb: the stimulus threshold was the same for both effects, and the magnitude of the dilatation was related to the strength of contraction. 3. Reduction of the somatic motor response, caused by lesions in the medullary pyramidal tract, was accompanied by a parallel reduction of the vascular response. 4. Prevention of the motor response by gallamine or by spinal cord section at L4--L5 (which leaves the sympathetic outflow to the hind limbs intact) led to abolition of the vascular response. During recovery from gallamine, contraction and vasodilatation returned in parallel. 5. The muscle vasodilatation was insensitive to atropine or guanethidine. 6. It is concluded that the hind limb vasodilatation observed on stimulation of the motor cortex is simply a post-contraction hyperaemia, and that it is independent of the sympathic nervous system. Previous conclusions of a sympathetically mediated vasodilatation probably resulted from inadequate control of the stimulus or a failure to recognize weak muscle contractions.

Animals↗
PubMedDate not supplied

[Interrelationship between the auditory, parietal and sensomotor regions of the dog cerebral cortex during a defensive conditioned reflex].

Interrelations between projection (auditory), associative (parietal) and integrative-triggering (sensorimotor) cortical areas were studied in dogs by EP parameters and localization during formation of defensive conditioned reflex to clicks. These interrelations were studied in intact animals and after ablation of either T3 areas or PI2 area of the auditory cortex. It was found that in intact animals auditory cortical areas are constantly involved in brain integrations whereas parietal ones show periodical participation (EPs in the parietal cortical area accompany some pairings of signal stimulus with reinforcement). Integrative-triggering cortical structures are involved in the systemic processes in the period of stabilisation of defensive reaction. After ablation of T3 area integrative-triggering cortical structures are turned on within a large exitation system from the beginning of the defensive reaction formation. After ablation of PI2 area parietal areas constantly participate in brain integrations. The nature of their participation in the forming of a given functional system is determined by the state of the auditory system or location of its injury.

Animals↗
PubMed1977

Measurements of the microscopic structure of cortical bone.

A technique is described in which the microstructure of cortical bone is analysed in terms of distributions of possible paths which ionizing particles take as they transverse the soft-tissue cavities and mineralized component. Measurements are restricted to transverse planes in the long bones, but a method is suggested for generating approximate omnidirectional path-length distributions from the measured transverse distributions. Results are presented for some long bones of a 50 year old man, a 9 year old boy and a young adult beagle, and these suggest that considerable structural differences occur between the two species. Values of some commonly quoted structural parameters are also given. For example, mean transverse cavity path lengths range between 67 and 99 micron in the long bones of the adult man compared with 29 micron in the beagle femur; the corresponding mean path lengths through the mineralized component are 830-1040 and 1500 micron. Finally, the total cavity plus periosteal surface for cortical bone in adult man is estimated to be about 6 m2.

Animals↗
PubMed1978

Structure of cortical microtubule arrays in plant cells.

Serial sectioning was used to track the position and measure the lengths of cortical microtubules in glutaraldehyde-osmium tetroxide-fixed root tip cells. Microtubules lying against the longitudinal walls during interphase, those overlying developing xylem thickenings, and those in pre-prophase bands are oriented circumferentially but on average are only about one-eighth of the cell circumference in length, i.e., 2-4 micrometer. The arrays consist of overlapping component microtubules, interconnected by cross bridges where they are grouped and also connected to the plasma membrane. Microtubule lengths vary greatly in any given array, but the probability that any pass right around the cell is extremely low. The majority of the microtubule terminations lie in statistically random positions in the arrays, but nonrandomness in the form of groups of terminations and terminations in short lines parallel to the axis of cell elongation has been observed. Low temperature induces microtubule shortening and increases the frequency of C-shaped terminations over the 1.7% found under normal conditions; colchicine and high pressures produce abnormally large proportions of very short microtubules amongst those that survive the treatments. Deuterium oxide (D2O) treatment probably induces the formation of additional microtubules as distinct from increasing the length of those already present. The distribution of C-shaped terminations provides evidence for at least local polarity in the arrays. The validity of the findings is discussed, along with implications for the development, maintenance, and orientation of the arrays and their possible relationship to the orientation of cellulose deposition.

Cell Membrane↗