Shape Of Corpus Callosum Research Articles

Neuronal Fiber Composition of the Corpus Callosum Within Some Odontocetes

Odontocetes (toothed whales) evolved from terrestrial mammals approximately 55 million years ago and have since remained on a unique evolutionary trajectory. This study used formalin-fixed tissue and light microscopy to quantify the size and number of fibers along the corpus callosum of the bottlenose dolphin (n = 8). Two other species, the Amazon River dolphin (n = 1) and the killer whale (n = 1), were included for comparison. A large amount of variation in the shape and area of the corpus callosum was observed. The odontocete corpus callosum is a heterogeneous structure with variation in fiber size and density along the length of the corpus callosum in all specimens examined. Using the species with the largest sample size, the bottlenose dolphin, comparisons by sex and age (sexually mature verses immature) were made for the area of the corpus callosum, five subregions, and fiber densities. Although no sex differences were detected, age appeared to affect the size, shape, and fiber composition of the bottlenose dolphin corpus callosum.

Functional anatomy of interhemispheric cortical connections in the human brain

Interhemsipheric interaction between the human cerebral hemispheres is served by abundant white-matter fibres in the human corpus callosum (CC). Damage to these fibres has notable behavioural and cognitive sequelae that depend on the exact location of the fibre loss. Until now, correlations between fibre loss and neurological disorders have been limited to post-mortem studies. Here we used probabilistic diffusion magnetic resonance imaging tractography to produce a two-dimensional map of the CC in the mid-sagittal plane. We observed an antero-posterior topography of interhemispheric tracts within the CC, consistent with our current neuroanatomical understanding of post-mortem studies in human. Callosal tract to the left and right hemispheres had comparable volume. Gender, a factor that is often reported to affect CC shape and geometry, also had no effect on the volume of the tracts. Our map showed high consistency across individuals. We propose that this map might be useful in the study of the effects of damage to human CC in neurodegenerative and cognitive disorders.

Correlation of corpus callosal morphometry with cognitive and motor function in periventricular leukomalacia.

We aim to correlate size and shape of corpus callosum with severity of motor and cognitive impairments in children with periventricular leukomalacia (PVL). Children with PVL were stratified based on the severity of their motor and cognitive impairments. An age-matched control group was established. The corpus callosum was identified on mid-sagittal T (1)-weighted spin-echo (TR/TE: 550/15) MR images. The shape characteristics of the corpus callosum were measured with respect to a template via a shape transformation. The degree of callosal-shape transformation was quantified by a deformation function, which in turn was compared, using point-wise T-tests, for controls versus patients, diplegic versus quadriplegic patients, and patients with mild versus severe cognitive impairment. 29 children with spastic cerebral palsy and PVL and 32 age-matched controls were identified. In the PVL group, the entire corpus callosum was significantly smaller than in the control group (p value = 0.001). Significant differences existed in the shape of the corpus callosum between patients with diplegic versus quadriplegic and between patients with severe versus mild cognitive impairment. Global and regional corpus callosal morphology can be quantified using deformation functions.

Gender- and age-related differences in the morphology of the corpus callosum.

The size and shape of the adult corpus callosum may vary with gender and age. There is, however, little data on the morphology of the corpus callosum in the Indian population. The purpose of this study was to measure the size of the corpus callosum in normal adult Indian males and females, and to identify gender- and age-related differences. The size of the corpus callosum on midsagittal section was measured in 100 (50 males, 50 females) normal adult Indians using magnetic resonance imaging. The length of the corpus callosum, the width of the genu, trunk, and splenium, the area of the splenium, and the total area of the corpus callosum were measured. The length of the brain also was measured. Means were compared for significant difference by gender using the Student's unpaired t-test and by age using ANOVA followed by Duncan's multiple range test. Gender was estimated by discriminant function analysis and age was estimated by regression analysis from significant parameters. The corpus callosum was longer in males and the discriminant score to differentiate gender was determined with an accuracy of 66%. The length of the corpus callosum increased with age and regression equations for predicting age was derived from the length of the corpus callosum. The width of the trunk and genu decreased with age in males but not in females.

Shape Differences in the Corpus Callosum in First-Episode Schizophrenia and First-Episode Psychotic Affective Disorder

The corpus callosum, the largest white matter tract in the brain, is a midline structure associated with the formation of the hippocampus, septum pellucidum, and cingulate cortex, which have been implicated in the pathogenesis of schizophrenia. Corpus callosum shape deformation, therefore, may reflect a midline neurodevelopmental abnormality. Corpus callosum area and shape were analyzed in 14 first-episode psychotic patients with schizophrenia, 19 first-episode psychotic patients with affective disorder, and 18 normal comparison subjects. No statistically significant corpus callosum area differences between groups were found, but there were differences in the structure's shape between the patients with schizophrenia and the comparison subjects. A correlation between width and angle of the corpus callosum was found in patients with affective disorder. Corpus callosum shape abnormalities in first-episode psychotic patients with schizophrenia may reflect a midline neurodevelopmental abnormality.

Corpus Callosum Shape and Neuropsychological Deficits in Adult Males with Heavy Fetal Alcohol Exposure

Persons with brain damage consequent to prenatal alcohol exposure have typically been diagnosed with either fetal alcohol syndrome (FAS) or fetal alcohol effects (FAE), depending on facial features. There is great variability of behavioral deficits within these groups. We sought to combine neuroanatomical measures with neurocognitive and neuromotor measures in criteria of greater sensitivity over the variety of consequences of alcohol exposure. To this end, midline curves of the corpus callosum were carefully digitized in three dimensions from T1-weighted MR scans of 15 adult males diagnosed with FAS, 15 with FAE, and 15 who were unexposed and clinically normal. From 5 h of neuropsychological testing we extracted 260 scores and ratings pertaining to attention, memory, executive function, fine and gross motor performance, and intelligence. Callosal midline shape was analyzed by new morphometric methods, and the relation of shape to behavior by partial least squares. The FAS and FAE subgroups have strikingly more variability of callosal shape than our normal subjects. With the excess shape variation are associated two different profiles of behavioral deficit unrelated to full-scale IQ or to the FAS/FAE distinction within the exposed subgroup. A relatively thick callosum is associated with a pattern of deficit in executive function; one that is relatively thin, with a deficit in motor function. The two combine in a very promising bipolar discrimination of the exposed from the unexposed in this sample. Thus there is considerable information in callosal form for prognosis of neuropsychological deficits in this frequently encountered birth defect.

Less developed corpus callosum in dyslexic subjects—a structural MRI study

Background: Based on previous studies and due to the characteristics of dyslexia as an auditory phonological decoding disorder, we predicted that the shape of the posterior corpus callosum (CC) would differ between dyslexic and control subjects. Method: Twenty right-handed boys with developmental dyslexia were selected from a carefully screened general population sample (mean age 11 years) and compared to a matched control group. The CC contour was manually traced on the aligned midsagittal MR slice and total callosal area and its subregions were compared between the groups. A statistical shape analysis and subsequent CC classification was performed using a recently developed shape model method. Results: The shape analysis revealed shorter CC shape in the dyslexic group, localised in the posterior midbody/isthmus region. This region contains interhemispheric fibers from primary and secondary auditory cortices. A shape length difference larger than a fixed threshold in the posterior midbody region could correctly discriminate between control and dyslexic subject in 78% of the cases, where a dyslexic CC was shorter in this region than a control CC. However, there were no significant group differences with respect to overall CC area or subregions. Conclusion: A clear shape difference in the posterior midbody of the CC was found between dyslexic and control subjects. This fits with recent other studies that have reported a strong growth factor in this CC region during the late childhood years, coinciding with literacy acquisition. Our results show that the dyslexic group has not undergone the same growth pattern as the normal reading group.

A Study of Corpus Callosum Shape, Executive Function Deficits, and Trouble with the Law among Patients with Fetal Alcohol Spectrum Defects

A Study of Corpus Callosum Shape, Executive Function Deficits, and Trouble with the Law among Patients with Fetal Alcohol Spectrum Defects

Corpus callosum shape and size in male patients with schizophrenia

Background: Corpus callosum (CC) morphology has recently been investigated in schizophrenia using refined imaging and analytic techniques; however, methodological problems and small sample sizes have led to inconsistent findings. Methods: This study used a large sample of male schizophrenics ( n = 79) and male controls ( n = 65) to investigate size and shape of the CC on midsagittal magnetic resonance images. Size was determined by tracing the area of the CC, and shape was determined using a landmark-based analysis. In addition, the relationship between CC morphology and phenomenologic variables such as age of onset, length of illness, exposure to medications, and symptom severity was explored. Results: After controlling for age, height, and parental socioeconomic status, there was a main effect of diagnosis on CC size ( F = 5.05, df = 1,139, p < .03), with patients’ CCs being significantly smaller. No difference was found between patients and controls in CC shape ( F = 1.07, df = 18,125, p > .38) or orientation ( F = 0.79, df = 18,125, p > .70), using a landmark-based technique. Finally, there was a significant inverse correlation between size of CC and severity of negative symptoms. Conclusions: These findings support previous studies that have found a decrease in size of the CC in patients with schizophrenia. Moreover, the decrement in volume is generalized, not regional, and is related to the severity of negative symptoms.

Morphology of the corpus callosum in human fetuses

Shape and size of the human fetal corpus callosum of a relatively racially homogeneous southern Indian sample population were studied in midsagittal sections of formalin fixed brains. Length of corpus callosum and width of its genu, body, and splenium were measured and the data statistically analyzed. Presence of an isthmus between the body and splenium did not correlate with the measured variables. There was no significant gender difference. The variables correlated significantly among each other but only callosal length and genu width correlated with gestation age. Significant absolute increase occurred in callosal length and genu width, whereas body and splenium widths remained the same. Simple regression equations to estimate the callosal length and genu width for a given age are derived. Clin. Anat. 10:22–26 © 1997 Wiley-Liss, Inc.

Morphology of the corpus callosum in human fetuses.

Shape and size of the human fetal corpus callosum of a relatively racially homogeneous southern Indian sample population were studied in midsagittal sections of formalin fixed brains. Length of corpus callosum and width of its genu, body, and splenium were measured and the data statistically analyzed. Presence of an isthmus between the body and splenium did not correlate with the measured variables. There was no significant gender difference. The variables correlated significantly among each other but only callosal length and genu width correlated with gestation age. Significant absolute increase occurred in callosal length and genu width, whereas body and splenium widths remained the same. Simple regression equations to estimate the callosal length and genu width for a given age are derived.

Corpus callosum shape analysis in first-episode schizophrenia

Corpus callosum shape analysis in first-episode schizophrenia

Shape of the human corpus callosum in childhood. Elliptic Fourier analysis on midsagittal magnetic resonance scans.

The authors previously investigated the midsagittal magnetic resonance images of neurologically intact adults, and analyzed the shape of corpus callosum from a mathematic standpoint. Significant effects of age were demonstrated, without significant sex differences. In the current study, the same mathematic method was applied to analyze the sex and age shape differences of the human corpus callosum in childhood. On the midsagittal magnetic resonance images of 84 neurologically intact children (39 boys, 45 girls, aged 4 months to 15 years) the outline of the corpus callosum was identified. Its shape was quantified using elliptic Fourier analysis, which allows for global evaluation of the shape of organs identified by their outlines independently from size, spatial orientation, and relationship to reference planes. Subjects were grouped by sex and age. The shape of the corpus callosum within age and sex classes in childhood was more homogeneous than in adulthood. A significant effect of age was demonstrated by the analysis of variance; however, no significant sex differences were found. Corpus callosum shape in midsagittal magnetic resonance images was strongly influenced by central nervous system development and aging, but the influence of sex was not sufficient to be detected by current standard magnetic resonance imaging technology, and by the available sample sizes. The current investigation supplies data on the normal callosal shape in the first two decades of life, thus completing previous analysis.

Shape of the Human Corpus Callosum

Sex, age, or functional-asymmetry-related variations in the size and shape characteristics of the midsagittal magnetic resonance (MR) image of the human corpus callosum (CC) have been widely investigated in the last 10 years, with conflicting results. In the current study, the authors attempted to analyze the sex- and age-related shape differences of the human CC in a large sample of adult subjects from a mathematical standpoint. On the midsagittal MR images of 143 neurologically intact adults (75 women, 68 men, 21 to 81 years of age) the outline of the CC was identified. The shape of the CC was quantified using elliptic Fourier analysis, which allows for a global evaluation of the shape of organs identified by their outlines independent of their size, spatial orientation, and relation to reference planes. Subjects were grouped by sex and age. The shape of the human CC within age and sex class was highly variable. The analysis of variance showed a significant effect of age; however no significant sex differences could be demonstrated. Larger sample sizes are required to definitively assess the normal shape variations in human CC. The method developed also could be applied to the comparison of healthy and diseased individuals.

Morphometry of the corpus callosum in monozygotic twins discordant for schizophrenia: a magnetic resonance imaging study.

The corpus callosum (CC) has been the focus of several morphometric studies of patients with schizophrenia, but the results of these studies have been contradictory. In an attempt to improve the reliability of morphometric measurements of the corpus callosum, a computerised image analysis system was used to measure the shape, area, thickness and length of the CC on magnetic resonance imaging (MRI) in 12 pairs of monozygotic twins discordant for schizophrenia (SC). No differences in CC area (anterior, middle, posterior thirds and total), length or vertical thickness of the CC body (at three levels) were demonstrated by t test comparisons of the affected SC and unaffected twins. Statistical analysis of a Fourier expansion series suggested differences in shape between normal and SC cotwins in the second harmonic of the anterior and middle segments and effects of gender on posterior CC shape. These results fail to replicate previous findings of altered length, thickness and area in the schizophrenic CC, but implicate disease-related shape differences in the anterior and middle segment of the corpus callosum and gender-related differences in splenium shape. The disease-related shape distortion suggest ventriculomegaly rather than an intrinsic abnormality of the corpus callosum.

Magnetic resonance imaging morphology of the corpus callosum in monozygotic twins.

Recent reports describe wide variations in the size and shape of the human corpus callosum. To investigate genetic influences on this variability, magnetic resonance images from 5 pairs of monozygotic twins and 10 unrelated control subjects were analyzed. Measurements of size and shape revealed greater similarity in twin pairs than in randomly paired controls. The results are consistent with the view that the anatomy of the corpus callosum, while clearly influenced by nongenetic factors, is under considerable genetic control.

Forms and measures of adult and developing human corpus callosum: is there sexual dimorphism?

The sexual dimorphism of the human corpus callosum (CC) is currently controversial, possibly because of difficulties in morphometric analysis. We have reinvestigated the issue by using morphometric techniques specially designed to yield objective measurements of CC size and shape. The development of the CC was studied with similar techniques in order to investigate whether its final shape and size might be influenced by axonal elimination, as could be expected from previous animal studies. We have measured the CCs of 32 men and 26 women; 27 male and 19 female CCs were from brain tissue, the others were from magnetic resonance imaging graphs. Women tended to have 1) a smaller cross-sectional callosal area (CCA); 2) a larger fraction of CCA in the posterior fifth of the CC; 3) more slender CCs; and 4) more bulbous splenia. These differences could not be detected by simple inspection but were demonstrated by measurement and statistical analysis. However, CCA was correlated with the other sexually dimorphic parameters, and the sex-related differences in the latter became nonsignificant when variations in CCA were factored out or when male and female populations with similar CCA were compared. In addition, we analyzed CCs of 16 male and 16 female fetuses and of 13 male and 15 female infants and children. This sample ranged in age between 20 weeks of gestation and 14 years but covered in detail the period up to 14 months after birth. CCA increased throughout the latter period but decreased slightly between about 33 weeks of gestation and the beginning of the second postnatal mouth. This decrease coincided with thinning of the CC and a marked increase in bulbosity of the splenium. No sexual dimorphism could be demonstrated until the beginning of the postnatal period. In the age group between birth (at term) and the 14th month, CCA was, as in the adult, larger in males. Unlike in the adults, the CC was longer in males and the bulbosity index was the same in the two sexes. Axonal elimination may play a role in the perinatal pause in CCA growth and in the concomitant changes in callosal shape.

Sexual dimorphism in the human corpus callosum.

Preliminary observations suggest a sex difference in the shape and surface area of the human corpus callosum. The sexual dimorphism is striking in the splenium, the caudal or posterior portion of the corpus callosum. The female splenium is both more bulbous and larger than the male counterpart. Since peristriate, parietal, and superior temporal fibers course through the splenium, this finding could be related to possible gender differences in the degree of lateralization for visuospatial functions.