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PubMed2004

A magnetic resonance imaging study of cortical thickness in animal phobia.

BACKGROUND: Despite the high prevalence of specific phobia (SP), its neural substrates remain undetermined. Although an initial series of functional neuroimaging studies have implicated paralimbic and sensory cortical regions in the pathophysiology of SP, to date contemporary morphometric neuroimaging methods have not been applied to test specific hypotheses regarding structural abnormalities. METHODS: Morphometric magnetic resonance imaging (MRI) methods were used to measure regional cortical thickness in 10 subjects with SP (animal type) and 20 healthy comparison (HC) subjects. RESULTS: Consistent with a priori hypotheses, between-group differences in cortical thickness were found within paralimbic and sensory cortical regions. Specifically, in comparison with the HC group, the SP group exhibited increased cortical thickness in bilateral insular, bilateral pregenual anterior cingulate, and bilateral posterior cingulate cortex as well as left visual cortical regions. CONCLUSIONS: Taken together, these structural findings parallel results from initial functional imaging studies that implicate paralimbic and sensory cortical regions in the mediating anatomy of SP symptoms. Further research will be necessary to replicate these findings and to determine their specificity as well as their pathophysiologic significance.

Adult↗
PubMed2006

Differential cortical thickness across the central sulcus: a method for identifying the central sulcus in the presence of mass effect and vasogenic edema.

BACKGROUND AND PURPOSE: Identification of the motor strip on MR imaging studies is difficult in the presence of mass effect and vasogenic edema because sulcal landmarks are obscured. We hypothesize that a difference in cortical thickness between the motor and sensory strips is readily apparent on T2-weighted images in the presence of vasogenic edema and reliably identifies the central sulcus. METHODS: Thirteen patients with brain tumors resulting in vasogenic edema near the central sulcus were identified. The cortical thickness of the anterior and posterior banks of the central sulcus as well as the neighboring sulci in the frontal and parietal lobes were measured from T2-weighted images. Similar measures were obtained from neighboring sulci in the frontal and parietal lobes. Location of the central sulcus was confirmed with standard anatomic landmarks in all patients and by intraoperative cortical mapping in 2 patients. RESULTS: A twofold difference in cortical thickness between the anterior and posterior banks of the central sulcus uniquely identified the central sulcus on T2-weighted images in the presence of vasogenic edema, despite the marked distortion of sulcal anatomy as a result of mass effect. This relationship was not present in neighboring sulci. CONCLUSION: Cytoarchitectonic differences in the motor and sensory cortices result in a markedly thicker posterior than anterior bank of the central sulcus that is readily visible on routine T2-weighted images in the presence of vasogenic edema. Therefore, the cortical thickness can serve as a complementary method in identification of the motor strip in patients with mass effect.

Brain Edema↗
PubMed2006

Fractal dimension in human cortical surface: multiple regression analysis with cortical thickness, sulcal depth, and folding area.

Fractal dimension (FD) has been widely used to provide a quantitative description of structural complexity in the cerebral cortex. FD is an extremely compact measure of shape complexity, condensing all details into a single numeric value. We interpreted the variation of the FD in the cortical surface of normal controls through multiple regression analysis with cortical thickness, sulcal depth, and folding area related to cortical complexity. We used a cortical surface showing a reliable representation of folded gyri and manually parcellated it into frontal, parietal, temporal, and occipital regions for regional analysis. In both hemispheres the mean cortical thickness and folding area showed significant combination effects on cortical complexity and accounted for about 50% of its variance. The folding area was significant in accounting for the FD of the cortical surface, with positive coefficients in both hemispheres and several lobe regions, while sulcal depth was significant only in the left temporal region. The results may suggest that human cortex develops a complex structure through the thinning of cortical thickness and by increasing the frequency of folds and the convolution of gyral shape rather than by deepening sulcal regions. Through correlation analysis of FD with IQ and the number of years of education, the results showed that a complex shape of the cortical surface has a significant relationship with intelligence and education. Our findings may indicate the structural characteristics that are revealed in the cerebral cortex when the FD in human brain is increased, and provide important information about brain development.

Adult↗
PubMed2004

Auditory sensory gating deficit and cortical thickness in schizophrenia.

Both an EEG P50 sensory gating deficit and abnormalities of the temporal lobe structure are considered characteristic of schizophrenia. The standard P50 sensory gating measure does not foster differential assessment of left- and right-hemisphere contributions, but its analogous MEG M50 component may be used to measure gating of distinct auditory source dipoles localizing to left- and right-hemisphere primary auditory cortex. The present study sought to determine how sensory gating ratio may relate to cortical thickness at the site of the auditory dipole localization. A standard auditory paired-click paradigm was used during MEG for patients (n=22) and normal controls (n=11). Sensory gating ratios were determined by measuring the strength of the 50 ms response to the second click divided by that of the first click (S2/S1). Cortical thickness was assessed by two reliable raters using 3D sMRI. Results showed that: (1) patients had a P50 and left M50 sensory gating deficit relative to controls; (2) cortex in both hemispheres was thicker in the control group; (3) in schizophrenia, poorer left-hemisphere M50 sensory gating correlated with thinner left-hemisphere auditory cortical thickness; and (4) poorer right-hemisphere M50 auditory sensory gating ratio correlated with thinner right-hemisphere auditory cortical thickness in patients. The MEG-assessed hemisphere-specific auditory sensory gating ratio may be driven by this structural abnormality in auditory cortex.

Acoustic Stimulation↗
PubMed1991

Apical membrane ionic channels in the rabbit cortical thick ascending limb in primary culture.

Cortical thick ascending limbs of Henle's loop (cTAL) were microdissected from rabbit kidneys and cultured in a hormonally-defined medium. The cultured cells grew as a monolayer and retained the morphological and biochemical characteristics of the original tubule. Cyclic AMP production of the cultured cells was increased by human calcitonin (x13) and parathyroid hormone (x2). The cultured epithelial developed a transepithelial potential of 4.1 +/- 1.3 mV that was orientated positively towards the apical compartment. The basolateral membrane of the cells exhibited a chloride conductance sensitive to diphenylamine 2-carboxylate (DPC) and the apical membrane a barium-sensitive K+ permeability. Patch clamp analysis conducted on the apical membrane of the cells revealed the presence of three types of ionic channel. The first is a large conductance Ca(2+)-activated K+ channel (95 pS). The second K+ channel has a much smaller conductance (18.3 pS) and is insensitive to Ca2+. It may represent the conductive pathway for K+ recycling into the lumen in the original tubule. The last channel is cation selective, does not discriminate between Na+ and K+ and was found to have a conductance of 20.5 pS. Channel activity required a high cytoplasmic calcium concentration (1 mM), and was blocked by ATP (10 microM) applied on its cytoplasmic face.

Alkaline Phosphatase↗
PubMed2004

Correlation of gonial angle size with cortical thickness, height of the mandibular residual body, and duration of edentulism.

STATEMENT OF PROBLEM: Previous reports on widening of the gonial angle in edentulous patients are conflicting. Aside from age and loss of teeth, other factors may influence change in gonial angle. PURPOSE: This study evaluated gonial angles from panoramic radiographs of young and older dentate subjects and elderly edentulous subjects and investigated the relationship of gonial angle size to gender, age group, cortical thickness at the gonial angle, height of the mandibular residual body, and edentulous period in elderly edentulous subjects. MATERIAL AND METHODS: A total of 356 panoramic radiographs of 3 groups of subjects were evaluated: the young dentate group, 131 subjects (mean age 27 years); the older dentate group, 97 subjects older than age 52 (mean age 64 years); and the elderly edentulous group, 128 subjects aged 76, 81, or 86 (mean age 80 years). The gonial angle, cortical thickness at gonial angle, and height of mandibular residual body were measured from panoramic radiographs made with the same radiographic equipment and selected according to criteria. A structured questionnaire was used to determine the history of edentulism. Paired and unpaired 2-tailed t tests served to test the difference in gonial angle measurements, and a linear regression was performed to study correlations (alpha=.05). RESULTS: Difference in size of the gonial angle was found between dentate men and women (P<.05 in the young and P<.001 in the older dentate group), but not between elderly edentulous men and women. The elderly edentulous subjects had significantly larger gonial angles (128.4 degrees +/- 6.6) than did the young (122.4 degrees +/- 6.6, P<.001) and older dentate subjects (122.8 degrees +/- 6.6, P<.001). The angle size was negatively related to cortical thickness at the gonial angle only among 76-year-old edentulous women (P<.01), and was associated with average height of the mandibular residual body in the edentulous men and women (P<.01). No association existed between angle size and duration of edentulism. No differences were significant in any test of intraexaminer error. CONCLUSION: In this study, elderly edentulous subjects had larger gonial angles than did dentate subjects. The angle size was correlated with low height of the mandibular residual body and with its cortical thickness in edentulous women.

Adult↗
PubMed2005

Cortical thickness analysis in autism with heat kernel smoothing.

We present a novel data smoothing and analysis framework for cortical thickness data defined on the brain cortical manifold. Gaussian kernel smoothing, which weights neighboring observations according to their 3D Euclidean distance, has been widely used in 3D brain images to increase the signal-to-noise ratio. When the observations lie on a convoluted brain surface, however, it is more natural to assign the weights based on the geodesic distance along the surface. We therefore develop a framework for geodesic distance-based kernel smoothing and statistical analysis on the cortical manifolds. As an illustration, we apply our methods in detecting the regions of abnormal cortical thickness in 16 high functioning autistic children via random field based multiple comparison correction that utilizes the new smoothing technique.

Adolescent↗
PubMed2001

Comparative radiologic study of bone density and cortical thickness of donor bone used in mandibular reconstruction.

OBJECTIVE: The aim of this study was to compare the total cancellous bone density, bone-implant interface density, and cortical thickness of 6 donor bone types commonly used in oral and maxillofacial reconstruction. METHODS: A total of 120 bones from 20 Korean adults-including iliac bones, fibulas, cranial bones, scapulas, ribs, and clavicles-were selected. The implant recipient site was determined by the shape, contour, and anatomical limitations of the bones. The serial cross-sectional images of each bone were then acquired through computed tomography. Total cancellous bone density, bone-implant interface density around the imaginary implant fixture, and the cortical thickness along both sides of the imaginary fixture on each cross-sectional image were evaluated and compared. RESULTS: The cancellous bone density of each donor bone type had a statistically significant difference. The cranial bone showed the highest cancellous bone density, followed by the iliac bone, clavicle, scapula, rib, and fibula (P <.05). The bone-implant interface density of the cranial bone, clavicle, fibula, and scapula each belonged to the same Duncan's group, whereas the rib and iliac bone showed lower bone-implant interface density. In average cortical thickness, the scapula and fibula had a thicker cortex surrounding the imaginary implant than the other bones, and the rib had the thinnest cortex. CONCLUSION: Although more extensive testing is needed to explain the clinical implications of these results, the findings of this study may help clinicians choose the most appropriate donor bone.

Adult↗
PubMed2007

Small-world anatomical networks in the human brain revealed by cortical thickness from MRI.

An important issue in neuroscience is the characterization for the underlying architectures of complex brain networks. However, little is known about the network of anatomical connections in the human brain. Here, we investigated large-scale anatomical connection patterns of the human cerebral cortex using cortical thickness measurements from magnetic resonance images. Two areas were considered anatomically connected if they showed statistically significant correlations in cortical thickness and we constructed the network of such connections using 124 brains from the International Consortium for Brain Mapping database. Significant short- and long-range connections were found in both intra- and interhemispheric regions, many of which were consistent with known neuroanatomical pathways measured by human diffusion imaging. More importantly, we showed that the human brain anatomical network had robust small-world properties with cohesive neighborhoods and short mean distances between regions that were insensitive to the selection of correlation thresholds. Additionally, we also found that this network and the probability of finding a connection between 2 regions for a given anatomical distance had both exponentially truncated power-law distributions. Our results demonstrated the basic organizational principles for the anatomical network in the human brain compatible with previous functional networks studies, which provides important implications of how functional brain states originate from their structural underpinnings. To our knowledge, this study provides the first report of small-world properties and degree distribution of anatomical networks in the human brain using cortical thickness measurements.

Brain↗
PubMed2006

An MRI study of increased cortical thickness in autism.

OBJECTIVE: The purpose of this study was to examine cortical thickness in autism in light of the postmortem evidence of cortical abnormalities of the disorder. METHOD: Magnetic resonance imaging (MRI) scans were acquired from 17 children with autism and 14 healthy comparison subjects, and sulcal and gyral thickness were measured for the total brain and for all lobes. RESULTS: Increases in total cerebral sulcal and gyral thickness were observed in children with autism relative to comparison subjects. Similar findings were noted in the temporal and parietal lobes but not in the frontal and occipital lobes. CONCLUSIONS: These preliminary findings indicate that increased cortical thickness may contribute to the increased gray matter volume and total brain size that have been observed in autism and may also be related to anomalies in cortical connectivity.

Autistic Disorder↗
PubMed1982

Humeral cortical thickness in female Bantu--its relationship to the incidence of femoral neck fracture.

Measurements of the humeral cortical thickness demonstrate that generalised osteoporosis in female Bantu commences in the fifth decade and gradually increases until, in the ninth decade, all subjects are osteoporotic. The combined cortical thickness (CCT) of the humerus in young adults is very similar to that found previously in a white London population and the loss of cortex with age is very similar. It is concluded that the known low incidence of femoral neck fracture in Bantu is not due to a lower incidence of generalised osteoporosis but to environmental factors. The chief environmental factor postulated is the greater amount of physical work performed by the Bantu. A more careful mode of walking is suggested as a subsidiary cause.

Adolescent↗
PubMed1983

Chloride activity in cells of isolated perfused cortical thick ascending limbs of rabbit kidney.

Rabbit cortical thick ascending limb segments were perfused in vitro, and intracellular Cl- activity was estimated in three types of experiments using conventional and chloride selective microelectrodes. In series 1 Ringer like solutions were present on the two epithelial sides. In series 2 limen Cl- was replaced by gluconate, and in series 3 furosemide, 10-20 . 10(-6) mol . 1-1, was added to the lumen perfusate. It was found that under control conditions intracellular Cl- activity, as estimated from the difference of the reading of the conventional (n = 53) and ion selective electrodes (n = 118) was 26 +/- 1 mmol . 1-1. Thi value is approximately three times higher than expected for passive distribution of Cl-. After removal of lumen Cl- (series 2) intracellular Cl- activity fell to 9 mmol . 1(-1) which is only some 4 mmol . 1(-1) above passive distribution. We argue that these 4 mmol . 1(-1) reflect mainly the interference with the Cl- electrode by other anions, such as phosphate. The above estimates for intracellular Cl- activity, have to be diminished by these 4 mmol . 1(-1), and, thus, are close to 22 mmol . 1(-1). In series 3 a rapid and reversible fall in intracellular Cl- from 23 to 7 mmol . 1(-1) was observed. We conclude that the Cl- activity in cTAL cells is clearly above equilibrium under control conditions and that it falls rapidly to values close to equilibrium when Cl- reabsorption is blocked by either removing lumen Cl- or by blocking the Cl- entry via the Na+-2 Cl--K+-carrier with furosemide.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2002

Potentiation of [Ca2+]i response to angiotensin III by cAMP in cortical thick ascending limb.

BACKGROUND: In the rat cortical thick ascending limb (CTAL), intracellular Ca2+ ([Ca2+]i) responses to angiotensin II (Ang II) and angiotensin III (Ang III) were mediated by the Ang II subtype 1A receptor (AT1A-R), whereas the arginine vasopressin (AVP)-dependent cAMP accumulation involved the vasopressin receptor type 2 (V2-R). This work was performed in CTAL to investigate the crosstalk between these two receptors by studying their transduction pathways. METHODS: The cAMP-dependent pathway was activated by 10 minutes of prestimulation with either forskolin, CTP-cAMP or AVP, and Ang II/Ang III-induced [Ca2+]i responses were assessed. RESULTS: Pretreatment with 5 micromol/L forskolin significantly enhanced the [Ca2+]i response induced by 10-7 mol/L either Ang II or Ang III. Analysis of dose-response curves to Ang III in forskolin-treated CTAL demonstrated that the maximal [Ca2+]i response was significantly increased without altering the EC50. In Ca2+-free medium, the forskolin-induced potentiation of the [Ca2+]i response to Ang III was weaker but always present, suggesting that this effect was not only due to intracellular Ca2+ release but also to extracellular Ca2+ influx. Furthermore, the fact that the forskolin-induced potentiation of the [Ca2+]i response to Ang III was blocked by 10 micromol/L H-89, a specific protein kinase A (PKA) inhibitor, indicated that this effect occurred via activation of PKA. Finally, the potentiation of the [Ca2+]i response to Ang III also was observed following pretreatment with 100 micromol/L CTP-cAMP or 10-7 mol/L AVP. CONCLUSIONS: In CTAL, there is a positive crosstalk between the adenylyl cyclase and phosphoinositide pathways mediated by V2- and AT1A-R, respectively, through activation of PKA.

Angiotensin II↗
PubMed1986

Bone mineral content, cortical thickness and fracture rate in osteoporotic women after withdrawal of treatment with nandrolone decanoate, 1-alpha hydroxyvitamin D3, or intermittent calcium infusions.

Twenty-six post-menopausal osteoporosis patients were studied prospectively over a 2-yr period after the cessation of 2 yr of treatment with either nandrolone decanoate (anabolic steroid), 1 alpha hydroxyvitamin D3 or intermittent calcium infusions, the total observation period being 4 yr. Serial evaluations of bone mineral content in the radius, cortical thickness of the metacarpals and spinal roentgenograms were obtained. Nine patients who had been treated with 50 mg nandrolone decanoate every three weeks did not lose bone from the radius or the metacarpals during the 2 yrs following withdrawal of therapy. Eight patients who had received 1 microgram/day of oral 1 alpha hydroxyvitamin D3 retained a positive bone mineral content in the radius but lost cortical thickness from the metacarpals after withdrawal of therapy. Nine patients who had been treated with intermittent calcium infusions over 12 consecutive days annually did not lose further bone mineral content from the radius, but did lose cortical thickness at the expected rate during the 2-yr post-treatment period. The fracture rate at the end of the 4-yr observation period was 40% lower in the nandrolone decanoate group than in the 1-alpha-hydroxyvitamin D3 and calcium infusion groups. The results of this study indicate that, in contrast to oestrogen and calcium therapy, nandrolone decanoate and 1-alpha-hydroxyvitamin D3 have lasting beneficial effects, and that data obtained by photon absorptiometry do not always coincide with those obtained by radiogrammetry. These findings are highly relevant to the design of future therapeutic trials.

Aged↗
PubMed2002

Circumferential variation in human second metacarpal cortical thickness: sex, age, and mechanical factors.

Variation in cortical thickness (CT) in four quadrants of the human second metacarpal was investigated in a sample (100 males and 72 females, skeletal age 20 to 50+ years) from a 19th-century cemetery. Both left and right elements were studied (total N = 344). Multivariate analysis of covariance (MANCOVA) (for age, sex, and side, controlling for absolute size) was used to test the hypothesis of equality of thickness in the dorsal, palmar, medial, and lateral quadrants. Differences in regional CT posits localized regulation of resorption and formation adapting bone shape to functional loads, with implications for activity-modulation of skeletal senescence. The palmar cortex was found to be uniformly thicker in both sexes and both sides, and at all ages (young, middle, and old adult); the medial, lateral, and dorsal cortices did not differ significantly. Patterns of age-related loss occurring preferentially at the endocortical surface differed between men and women, with women showing significant declines across all age groups for all quadrants, and males only small decrements after middle age. The greater CT in the palmar quadrant corresponds to the region of maximum compressive strain in the second metacarpal for functions involving full flexion (grasping). Although the palmar cortex is thicker at all ages, women lose mass in that quadrant at the same rate as in other quadrants, suggesting that function does not offer protection against endocrinologically-mediated depletion of bone mass (postmenopausal osteopenia).

Adult↗
PubMed2006

Automated cortical thickness measurements from MRI can accurately separate Alzheimer's patients from normal elderly controls.

We investigated the potential of fully automated measurements of cortical thickness to reproduce the clinical diagnosis in Alzheimer's Disease (AD) using 19 patients and 17 healthy controls. Thickness maps were analyzed using three different discriminant techniques to separate patients from controls. All analyses were performed using leave-one-out cross-validation to avoid overtraining of the discriminants. The results show regionally variant patterns of discrimination ability, with over 90% accuracy obtained in the medial temporal lobes and other limbic structures. Multivariate discriminant analysis produced 100% accuracy with six different combinations, all involving the parahippocampal gyrus. We therefore propose automated measurements of cortical thickness as a tool to improve the clinical diagnosis of probable AD, as well as a research method to gain unique insight into the etiology of cortical pathology in the disease.

Aged↗
PubMed1985

Sodium-dependent bicarbonate absorption by cortical thick ascending limb of rat kidney.

In vitro microperfusion experiments were performed to investigate the mechanism of bicarbonate absorption in the cortical thick ascending limb of the rat. Tubules were perfused at 1.0-1.5 nl X min-1 X mm-1 and bicarbonate concentration was 25 mM in the perfusate and bath. Bicarbonate absorption rates were determined by microcalorimetry. Control tubules absorbed bicarbonate at a mean rate of 9.5 +/- 0.6 pmol X min-1 X mm-1. The limiting luminal bicarbonate concentration was approximately 5 mM for tubules perfused at slow rates with 25 mM bicarbonate in the bath. Acetazolamide (10(-4)M) in the bath reduced bicarbonate absorption by 76% without significant effect on transepithelial voltage. Removing sodium from the perfusate and bath or removing potassium from the bath reduced bicarbonate absorption and transepithelial voltage to near zero. Adding amiloride (5 X 10(-4) or 10(-3) M) to the perfusate reduced bicarbonate absorption by 60-75% without detectable effect on transepithelial voltage. Adding furosemide (10(-4)M) to the perfusate increased bicarbonate absorption significantly by 40-50% while decreasing transepithelial voltage from 17 to 1.8 mV. Thus, bicarbonate absorption by cortical thick ascending limbs requires carbonic anhydrase activity and sodium transport but is not dependent on transepithelial voltage. When considered together, the results are consistent with mediation of the bicarbonate absorption by apical membrane sodium-hydrogen exchange.

Absorption↗
PubMed1991

Antidiuretic hormone acts via V1 receptors on intracellular calcium in the isolated perfused rabbit cortical thick ascending limb.

The effect of antidiuretic hormone [( Arg]vasopressin, ADH) on intracellular calcium activity [Ca2+]i of isolated perfused rabbit cortical thick ascending limb (cTAL) segments was investigated with the calcium fluorescent dye fura-2. The fluorescence emission ratio at 500-530 nm (R) was monitored as a measure of [Ca2+]i after excitation at 335 nm and 380 nm. In addition the transepithelial potential difference (PDte) and transepithelial resistance (Rte) of the tubule were measured simultaneously. After addition of ADH (1-4 nmol/l) to the basolateral side of the cTAL R increased rapidly, but transiently, from 0.84 +/- 0.05 to 1.36 +/- 0.08 (n = 46). Subsequently, within 7-12 min R fell to control values even in the continued presence of ADH. The increase in R evoked by the ADH application corresponded to a rise of [Ca2+]i from a basal level of 155 +/- 23 nmol/l [Ca2+]i up to 429 +/- 53 nmol/l [Ca2+]i at the peak of the transient, as estimated by intra- or extracellular calibration procedures. The electrical parameters (PDte and Rte) of the tubules were not changed by ADH. The ADH-induced Ca2+ transient was dependent on the presence of Ca2+ on the basolateral side, whereas luminal Ca2+ had no effect. d(CH2)5[Tyr(Me)2]2,Arg8vasopressin, a V1 antagonist (Manning compound, 10 nmol/l), blocked the ADH effect on [Ca2+]i completely (n = 5). The V2 agonist 1-desamino-[D-Arg8]vasopressin (10 nmol/l, n = 4), and the cAMP analogues, dibutyryl-cAMP (400 mumol/l, n = 4), 8-(4-chlorophenylthio)-cAMP (100 mumol/l, n = 1) or 8-bromo-cAMP (200 mumol/l, n = 4) had no influence on [Ca2+]i. The ADH-induced [Ca2+]i increase was not sensitive to the calcium-channel blockers nifedipine and verapamil (100 mumol/l, n = 4). We conclude that ADH acts via V1 receptors to increase cytosolic calcium activity transiently in rabbit cortical thick ascending limb segments, possibly by an initial Ca2+ release from intracellular stores and by further Ca2+ influx through Ca2+ channels in the basolateral membrane. These channels are insensitive to L-type Ca2+ channel blockers, e.g. nifedipine and verapamil.

8-Bromo Cyclic Adenosine Monophosphate↗