Regional Differences In Thickness Research Articles

Social Responsiveness Scale (SRS) in Relation to Longitudinal Cortical Thickness Changes in Autism Spectrum Disorder.

The relationship between brain development and clinical heterogeneity in autism (ASD) is unknown. This study examines the Social Responsiveness Scale (SRS) in relation to the longitudinal development of cortical thickness. Participants (N = 91 ASD, N = 56 TDC; 3-39years at first scan) were scanned up to three times over a 7-year period. Mixed-effects models examined cortical thickness in relation to SRS score. ASD participants with higher SRS scores showed regionally increased age-related cortical thinning. Regional thickness differences and reduced age-related cortical thinning were found in predominantly right lateralized regions in ASD with decreasing SRS scores over time. Our findings emphasize the importance of examining clinical phenotypes in brain-based studies of ASD.

Size and Shape of the Corpus Callosum in Adult Niemann-Pick Type C Reflects State and Trait Illness Variables

Variable alterations to the structure of the corpus callosum have been described in adults with NPC, a neurometabolic disorder known to result in both white and gray matter pathology. This study sought to examine the structure of the callosum in a group of adult patients with NPC and compared callosal structure with a group of matched controls, and to relate callosal structure with state and trait illness variables. Nine adult patients with NPC were matched to control subjects (n = 26) on age and sex. The corpus callosum was segmented from the midsagittal section of T1-weighted images on all subjects, and total area, length, bending angle, and mean thickness were calculated. In addition, 39 regional thickness measures were derived by using a previously published method. All measures were compared between groups, and analyzed alongside symptom measures, biochemical parameters, and ocular-motor measures. The callosal area and mean thickness were significantly reduced in the patient group, and regional thickness differences were greatest in the genu, posterior body, isthmus, and anterior splenium. Global callosal measures correlated significantly with duration of illness and symptom score, and at trend level with degree of filipin staining. Measures of reflexive saccadic peak velocity and gain, and self-paced saccades, correlated strongly with total callosal area. Callosal structure and size reflect both state and trait markers in adult NPC, and they may be useful biomarkers to index both white and gray matter changes that reflect illness severity and progression.

Correlation of Plio–Pleistocene Tephra in Ethiopian and Kenyan rift basins: Temporal calibration of geological features and hominid fossil records

The 200-m-thick fossiliferous Konso Formation and overlying terrace deposits, which crop out at the end of the southern sector of the Main Ethiopian Rift (MER), contain more than 30 distal tephra layers. Local and regional tephra correlations of more than 20 tephra units were established using major and trace element data of discrete and purified bulk glass samples within the Konso study area. Eleven correlative marker tuffs were recognized in stratigraphic sections of both the Konso Formation and the Omo-Turkana Basin sediments in southern Ethiopia and northern Kenya. The Turoha, Hope, Ivory, Bright White, and Boleshe Tuffs in the Konso Formation, and the Upper White Tuff in the overlying terrace deposits are securely correlated with the KBS, Akait, Lokapetamoi, Chari, Lower Nariokotome, and Silbo Tuffs of the Omo-Turkana Basin, using least mobile major elements (CaO, Fe 2O 3*, and TiO 2) and geochronology. Preliminary correlations are also suggested between the Konso Formation distal tephra and proximal units of the Quaternary caldera-forming silicic centers in the central sector of the MER. The strongly peralkaline tuffs of the Konso Formation are compositionally similar to proximal eruptions mostly located along the Quaternary axial rift zone of the southern, central, and northern sectors of the MER. The tephra correlation provides information about the temporal and spatial features of the volcanic and tectonic processes recorded in the evolving basins. Thickness and sedimentation rate were determined for both the Konso Formation and the Omo-Turkana Basin sections, measured between the Turoha (=KBS; 1.91 ± 0.03 Ma) and the Bright White (=Chari; 1.40 ± 0.02 Ma) Tuffs. Although the lithostratigraphic sequence at the Konso study area is younger, sedimentation rate within the Konso Formation was comparable to that of the Koobi Fora Formation, higher in the Nachukui Formation, and lower in the Shungura Formation. Local and regional differences in thickness and sedimentation rates within the Plio–Pleistocene deposits of the Konso, Shungura, Nachukui, and Koobi Fora Formations may be attributed to erosion associated with increased topographic gradients maintained by continued subsidence mostly along axial fault zones of basins and uplift along the margins of the broadly rifted zone of the Omo-Turkana Basin and the southern sector of the MER.

Regional variation in canine diaphragm thickness

To quantify the relationship between both regional and overall diaphragm morphometry and body weight in the dog, diaphragm thickness was measured in five regions of the costal diaphragm and three regions of the crural diaphragm in 40 healthy dogs (8-40 kg). Surface area of the diaphragm, diaphragm weight, and body weight were also determined. Diaphragm surface area and weight varied linearly with body weight, but there was no significant correlation between overall diaphragm thickness and body weight. Diaphragm thickness varied significantly between regions, and three regions had systematic left-to-right differences as well. Because diaphragm geometry influences the diaphragm's function as a pressure generator, regional differences in thickness may alter the relationship between the force developed by the activation of a particular region of the diaphragm and its action on the respiratory system.

A morphometric analysis of the development of the rat lens capsule.

This study analysed patterns of growth of the lens capsule by measuring capsule thickness at 13, 16 and 19 days of embryonic development and 2, 21, 140 and 600 days of post-natal development. The major findings were that, at early stages of embryonic development, the posterior capsule was thicker than the anterior capsule. However, at later stages, the posterior capsule did not increase in thickness whereas the anterior capsule continued to thicken so that, by 2 days of post-natal development, the situation was reversed and the anterior capsule was significantly thicker than the posterior capsule. This trend continued and by 600 days post-natal development, the anterior capsule was 7.5 times thicker than the posterior capsule. In these older lenses the capsule tapered sharply in thickness from the anterior to the posterior equatorial region. These regional differences in thickness of the lens capsule, and the changes reported during development, may reflect changes in capsule production by epithelial and fibre cells as they differentiate.

Intraoperative assessment of left ventricular heterogeneity

To evaluate regional differences in thickness and systolic function of human myocardium perfused by angiographically normal coronary arteries in valvular and ischemic heart disease, we performed intraoperative epicardial M-mode mapping of ventriculographically normal wall regions (perfused by normal coronary arteries) in 22 subjects undergoing either coronary bypass surgery for stenoses in other vessels (n = 15) or mitral (n = 5) and/or aortic valve replacement (n = 4). In patients in whom both anterior and inferior walls were ventriculographically normal and normally perfused (n = 6), comparison of the two walls showed the anterior wall to be thicker at both end diastole and end systole, but there was no difference in the percentage of systolic thickening. Analysis of myocardium along the long axis revealed apical sites to be thinner than basal sites at both end diastole and end systole. Percentage of systolic thickening was also increased at apical sites. In patients in whom only the anterior wall was normal, a similar decrease in anterior wall thickness was noted at the apex. Thus systematic regional heterogeneity along both the left ventricular major and minor axes is found in the chronically diseased human heart as it is in the normal heart. Assessment of myocardial structure and function and of the effects of therapeutic interventions must take this heterogeneity into account.

Regional differences in thickness and metabolism of the myelin sheath along the optic nerve and tract of rabbit

Myelin content and metabolism were analysed along the optic nerve and tract of adult rabbit using biochemical and morphological methods. The yield of purified myelin increased with distance from the eye. Morphometric analyses using electron microscopy revealed the same trend. In transverse section, the mean values of myelin area, myelin thickness and axon area increased from the eye to the chiasma, but subsequently decreased in the tract. However, the degree of ensheathment of axons (myelin area/axon area) increased along both nerve and tract. Information on myelin metabolism was obtained from [ 3H]leucine incorporation into proteins of optic nerve and tract incubated in vitro. Regions near the eye were more active in amino acid incorporation. Myelin specific activity decreased with distance from the eye, while the percentage of tissue protein radioactivity associated with myelin increased. The results show that in adult rabbit the degree of myelin ensheathment of optic axons increases from the eye to the brain. The thicker myelin sheaths of regions near the brain probably have a slower turnover. Possible regional differences in the distribution and/or metabolism of oligodendrocytes are discussed.