[Combined cerebral dysplasia: azygous a. cerebri anterior in corpus callosum insufficiency with a corpus callosum lipoma and an aneurysm of the a. cerebri media].
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Adult↗
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The corpus callosum, its role in memory: a presentation of a patient with an arteriovenous malformation of the corpus callosum.
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Adult↗
The visual map in the corpus callosum of the cat.
The corpus callosum conveys all the fibers that connect areas 17 and 18 in the 2 cerebral hemispheres of the cat. The purpose of the present study was to ascertain the organization of the visual field map described by these fibers in the corpus callosum. This was achieved by injecting anterograde and retrograde pathway tracers at known locations in the callosally connected zones of areas 17 and 18. The positions of the injection sites were varied systematically to include all visual field elevations represented along the marginal and posterolateral gyri. Overall, the results show (1) that callosal fibers projecting between the 2 marginal gyri, where the lower visual fields are represented, pass through the body of the corpus callosum; (2) that fibers connecting the junction of the marginal and posterolateral gyri in the 2 hemispheres, where central fields are represented, pass through the dorsal splenium of the corpus callosum; and (3) that fibers passing between the ventral portions of the 2 posterolateral gyri, where upper fields are represented, pass through posterior and ventral splenium. In addition, the density of visual fibers in the splenium is greater than in the body of the corpus callosum. Within the overall pattern, a finer arrangement exists, and it was possible, by comparison with the cortical visual field maps, to describe a map of visual field elevations in the corpus callosum. In this map, the representations of the different visual field elevations are not a simple reflection of the map in the cortex. The map of the lower fields contained in the body is spread out, whereas the map of the central and upper fields in the splenium is highly compressed. The high degree with which observations can be reproduced in different cats indicates that the map is stereotyped from one animal to another.
Animals↗
Lipoma of the corpus callosum.
A case of corpus callosum lipoma with presumptive diagnosis is presented. Review of the literature disclosed 84 cases with such diagnoses. Lipoma of the corpus callosum is a rare intracranial lesion, perhaps congenital and often asymptomatic, but can present with seizure disorder, headache, mental changes, paresis or paralysis. Twenty-one patients had been operated upon. Surgical treatment seems to be of no value in this disease.
Adolescent↗
Spatial frequency thresholds of single striate cortical cells in neonatal corpus callosum sectioned cats.
Following section of the corpus callosum at 1-6 postnatal weeks in cats, behavioral visual acuity was measured binocularly and monocularly from 6-29 postnatal weeks; physiological determination of spatial frequency thresholds of single striate cortical cells was performed when the cats were at least 8 months old. Results were compared between cats with callosum section at each postnatal week, as well as with normal cats. Cats with callosotomy at 1-3 postnatal weeks had deficits in behavioral visual acuity, and the deficits were greatest in the youngest operated cats. Cats with callosotomy at 1-2 postnatal weeks failed to resolve as high spatial frequencies as did normal cats, and the resolution of the 1 week operated cats was lower than the resolution of the 2 week operated cats. Cats with callosotomy at 3-6 postnatal weeks had spatial frequency thresholds that were equivalent to those of normal cats. To determine what kinds of striate cells had reduced spatial resolution following neonatal corpus callosum section, cells were categorized according to class (Simple, Complex), receptive field location (Central, Peripheral), and monocular behavioral acuity eye performance (Better Eye, Worse Eye). Cats with corpus callosum section during postnatal week 1 had the lowest spatial resolution for all cell categories compared to all groups tested. However, cats with callosum section during postnatal week 2 had normal spatial frequency thresholds for Simple, Central and Better Eye categories. The cats with callosum section in postnatal weeks 3-6 had normal spatial frequency thresholds for all cell categories. For corpus callosum sectioned cats with and without visual deficits, and for normal cats, visual acuity measured behaviorally is significantly related to visual acuity measured physiologically. The results show that neonatal corpus callosum section in cats can affect behavioral visual acuity, as well as the spatial frequency thresholds of many categories of striate cortical cells. However, callosum section at different ages affects different populations of cortical cells. Furthermore, the results suggest that neonatal corpus callosum section may directly affect a single fundamental property of cells in primary visual cortex with a resulting disruption of many visual functions.
Aging↗
Bilateral receptive fields in cortical area SII: contribution of the corpus callosum and other interhemispheric commissures.
The corpus callosum contributes to the interhemispheric transfer of somatosensory information. Since the somatosensory pathways are essentially crossed, a number of studies have postulated that the corpus callosum may be responsible for the presence of bilateral receptive fields (RFs) in cortical area SII. Moreover, subcortical structures, as well as some of the other commissures, may also contribute to the bilateral nature of these cells. In order to assess the relative importance of the corpus callosum, this study compared the RF properties of cells in area SII of callosum-sectioned cats to normal cats, using single-cell recordings. Results showed that the corpus callosum makes an important contribution to the bilateral activation of cells in SII, since the proportion of cells with bilateral RFs found in callosum-sectioned cats was less than half that obtained in normal cats. The decrease in the proportion of bilateral RFs was found for all body regions with the exception of the face. However, the substantial number of bilateral RFs remaining in callosotomized cats indicates that this structure is not the sole contributor to the bilateral activation of cells in SII. In order to determine whether this residual bilateral activation might be mediated by the other interhemispheric commissures, a group of cats was subjected, besides the callosotomy, to the additional transection of their subcortical commissures, including the anterior, posterior, habenular, and intertectal commissures, as well as the massa intermedia. When this group of deep-split cats was compared to the callosotomized group, the results indicated that the contribution of the other commissures to bilateral activation is negligible, since approximately the same proportion of bilateral RFs was encountered in the two groups. The relative importance of the callosal contribution to bilateral RFs of different body regions is discussed with respect to the roles commonly attributed to this structure.
Animals↗
[The MR findings on the corpus callosum of normal young volunteers].
The size and shape of the corpus callosum of twenty-seven normal young volunteers (age 18-31 years, 17 men and 10 women) were investigated using a superconducting high field (1.5 T) MRI unit. The length of the corpus callosum was 71.1 +/- 5.1 mm (mean +/- S.D.) and the height was 24.9 +/- 2.1 mm. The length ratio of the corpus callosum to the brain was 43.9 +/- 2.3% with the ratio of the height 25.0 +/- 2.3%. The callosal index (height/length) was 35.4 +/- 2.9%. The area of the corpus callosum in the midsagittal plane was 681.4 +/- 93.6 mm2 (min. 563 mm2 to max. 902 mm2). We divided the corpus callosum into three segments: rostrum and genu; anterior and posterior trunks; splenium. Each part accounts for one third of the total area of the corpus callosum. The genu and splenium were generally equal in thickness. The minimal thickness of the trunk was 3 mm with the maximal one 9 mm. The posterior trunk was never thicker than the anterior one. The posterior part of the posterior trunk showed thinning and concavity in almost all cases. So-called impressio corporis callosi was observed in 12 cases (44.4%). Thirteen cases (48.1%) showed a shallow concave configuration at the anterior dorsal surface of the corpus callosum. Six cases of these were thought to be due to compression by the pericallosal artery. This finding was not detected in the posterior portion of the corpus callosum. This concavity was also seen in infants. The thinning of the posterior part of the posterior trunk was seen after the development of the splenium, but the concave configuration at the anterior dorsal surface of the corpus callosum may be encountered before the full development of the genu and splenium.
Adult↗
Sex differences in the corpus callosum of the living human being.
The sexual dimorphism of the corpus callosum has remained controversial since the original report by de Lacoste-Utamsing and Holloway in 1982, for several reasons: (1) measurements have been performed in a variety of ways in different laboratories, in part because published reports frequently do not describe the methodology in detail; (2) despite known age-related changes during both childhood and adulthood, no investigators have explicitly age-matched subjects; and (3) the size and shape of corpora callosa vary considerably among individuals, requiring large sample sizes to demonstrate significant sex differences. Therefore, we have examined magnetic resonance images for 24 age-matched children and 122 age-matched adults for possible sex differences in the corpus callosum. While we observed a dramatic sex difference in the shape of the corpus callosum, there was no conclusive evidence of sexual dimorphism in the area of the corpus callosum or its subdivisions. Utilizing several criteria, there were significant sex differences in shape: subjective evaluation indicated that the posterior region of the corpus callosum, the splenium, was more bulbous shaped in females as a group and in women, and more tubular-shaped in males as a group and in men; mathematical evaluation confirmed this observation in that the maximum width of the splenium was significantly greater in women than in men, and that the percentage by which the average width of the splenium was greater than that of the adjacent corpus callosum was significantly greater in females than in males. However, sex differences in bulbosity did not reach significance in children (aged 2-16 yr). In contrast, among the area measurements of the corpus callosum and 22 subdivisions, only 1 exhibited a significant sex difference, which would be expected by chance. The area of the corpora callosa increased significantly with age in children and decreased significantly with age in adults. In adults, the midsagittal surface area of the cerebral cortex decreased significantly with age in women but not in men. These anatomical sex differences could, in part, underlie gender-related differences in behavior and neuropsychological function.
Adolescent↗
Tests of genetic allelism between four inbred mouse strains with absent corpus callosum.
Inbred mouse strains that lack the corpus callosum connecting the cerebral hemispheres in the adult differ from the C57BL/6J strain at several relevant but unknown loci. To identify at least one major locus that influences axon guidance, different strains showing phenotypically similar defects were crossed to test for allelism. If the F1 hybrid between two strains with the same brain defect is phenotypically normal, it is much more likely that the two strains will differ at fewer loci than will an acallosal strain and C57BL/6J. This approach proved to be very informative. Five reasonable models of inheritance involving two or three loci were assessed, and the data justified rejection of all but one hypothesis. A total of 479 mice were obtained from four inbred strains prone to absence of the corpus callosum (BALB/cWah1, BALB/cWah2, I/LnJ, and 129/ReJ), one normal strain (C57BL/6J), and 11 F1 hybrids among them. Because the size of forebrain axon bundles is generally greater in mice with larger brains, and because whole brain size is certainly polygenic, the phenotypically normal groups were used to derive a standard index of the degree of corpus callosum deficiency relative to brain size. Results demonstrated clearly that the hybrid between BALB/cWah1 and 129/ReJ is normal, whereas the crosses among the BALB/c substrains and I/LnJ yielded many mice with deficient corpus callosum. I/LnJ crossed with 129/ReJ also produced some animals with callosal defects. The data were consistent with a model in which the difference between BALB/c and 129/ReJ involves two loci, whereas the defect in I/LnJ involves homozygosity at three loci, which impairs development more severely.(ABSTRACT TRUNCATED AT 250 WORDS)
Alleles↗
[Vascularization of the corpus callosum in humans].
The blood supply of the corpus callosum is studied in 20 brains by injecting the vascular system with gelatinous Indian ink. The arterial vascularization derives mainly from the anterior cerebral arteries, accessed from the median artery of the corpus callosum or from the terminal and choroidal branches of the posterior cerebral arteries. The various arteries give off perforating branches which are direct or indirect, short, of middle length or long. All these arteries concentrate on the peripheral wall of the corpus callosum. Inside of it these various arteries give off numerous terminal and collateral branches running between the nervous fibres and forming a characteristic vascular network which nourishes the capillary network. The venous vascularization of the corpus callosum is tributary to the deep venous system of the brain and concentrates on the central wall of the commissure.
Arterioles↗
Agenesis of corpus callosum in calves.
Agenesis of the corpus callosum is a rare brain defect in cattle, and was described in two calves. It was characterized by the total absence of the corpus callosum, septum pellucidum and hippocampal commissure. Fornices were present but separated. Both calves also had moderate internal hydrocephalus, micrencephaly and a CSF-filled cyst in the longitudinal fissure dorsal to the thalamus. Clinical signs were not specific. Etiology and pathogenesis are unknown. No evidence of inflammation or inheritance was found as cause of the defect.
Agenesis of Corpus Callosum↗
Interhemispheric transfer of visuomotor conditional learning via the anterior corpus callosum of monkeys.
Two experiments examined interhemispheric transfer of learning across the anterior corpus callosum in monkeys (Macaca fascicularis). The animals learned a series of visuomotor conditional discrimination problems for food reward. Within each problem the animals were first trained using one hand to make the motor responses, and were then required to use the opposite hand in order to test for intermanual transfer of the initial learning. In Exp. 1, a group of animals with surgical section of the entire corpus callosum and anterior commissure showed a complete absence of intermanual transfer of learning. A second group, in which only the anterior commissure and the posterior part of the corpus callosum were sectioned, leaving the anterior corpus callosum intact, showed good intermanual transfer. Thus, intermanual transfer in the second group represented interhemispheric information transfer via the anterior portions of the corpus callosum. However, in Expt. 2, normal intermanual transfer was seen in a group of animals in which the anterior corpus callosum alone had been sectioned. We conclude that the anterior corpus callosum can mediate interhemispheric transfer of visuomotor conditional learning, but is not the only available route for such transfer in the present task.
Animals↗
The venous vascularization of the corpus callosum in man.
The vascularization of the corpus callosum in Man is studied in 20 brains. Their vascular system is injected with Indian ink and gelatin. The corpus callosum is drained by callosal veins and callosocingulate veins towards the deep venous system of the brain. Most of these veins run downwards and join together at the central level of the corpus callosum. They then form the subependymal veins, which form the septal veins and the medial atrial vein. All these vessels are tributaries of the internal cerebral veins.
Adult↗
Lipoma of the corpus callosum.
Lipoma of the corpus callosum is a rare congenital condition, often asymptomatic, but which may present as epilepsy, hemiplegia, dementia, or headaches. This paper reviews the condition and reports the only two cases which are known to the Hospital for Sick Children, Great Ormond Street, London. The second case demonstrated the value of computerised axial tomography (EMI scan) in making the diagnosis and showing associated anomalies.
Brain↗
Marchiafava-Bignami disease: serial changes in corpus callosum on MRI.
Serial MRI findings of changes in corpus callosum lesions in two cases of Marchiafava-Bignami disease are presented. In both, MRI displayed diffuse swelling of the corpus callosum in the acute stage, thought to represent oedema and demyelination. In the chronic stage, in addition to atrophy of the corpus callosum with presumed focal necrosis, previously undescribed focal hypointensity on T2-weighted images, of unknown cause, was observed in the corpus callosum.
Alcoholism↗
[Behavioral asymmetry in BALB/cCF mice with corpus callosum abnormalities].
The possible homology between anomalies of the corpus callosum in mice and in humans remains questionable. The small number of existing behavioural studies in mice have not shown effects, at the behavioural level, of the absence or reduction in size of the corpus callosum. We therefore examined the development, during the first 3 weeks of postnatal life, of a number of simple reflex and integrative responses in the members of a sample of 101 BALB/cCF mice; at autopsy carried out at 50 days of age, 29 mice showed anomalies of the corpus callosum (total absence or an area less than 0.75 mm2). Asymmetry of the development of these responses was measured either as the proportion of animals showing asymmetrical appearance of responses on the left and right sides, and as the delay between appearances on the left and right sides in "asymmetrical" mice. Both measures decreased over the first 15 postnatal days, at the same rate in normal and abnormal mice; in each case the decrease is better described by a second-order, quadratic, function than by a simple linear function. We therefore conclude that the integrity of the corpus callosum is not necessary for the normal maturation of sensorimotor behaviour in mice, and suggest that this conclusion may possibly be explained by the relatively recent appearance of mice in the mammalian radiation.
Agenesis of Corpus Callosum↗
Fiber composition of the human corpus callosum.
The densities of fibers of different sizes were calculated in ten regions of the corpus callosum of twenty human brains (ten females, ten males). Light microscopic examination revealed a consistent pattern of regional differentiation of fiber types in the corpus callosum. Thin fibers are most dense in the anterior corpus callosum (genu), and decrease in density posteriorly towards the posterior midbody, where they reach a minimum. Towards the posterior corpus callosum (splenium), the density of thin fibers increases again, but in the posterior pole of the callosum the density decreases locally. Large-diameter fibers show a pattern complementary to that of thin fibers, having a peak of density in the posterior midbody and a local increase of density in the posterior pole of the corpus callosum. Across subjects, the overall density of callosal fibers had no significant correlation with callosal area and an increased callosal area indicated an increased total number of fibers crossing through. Considering different fiber sizes, this was only true for small diameter fibers, whose large majority is believed to interconnect association cortex. No sex differences in fiber composition of the corpus callosum were found.
Adult↗
Lipoma of the corpus callosum associated with frontal and facial anomalies.
Seven patients with a corpus callosum lipoma associated with a frontal cranial defect with or without a superficial lipoma or a fronto-nasal dysplasia, were encountered over a period of 12 years. This group of patients is reported as these associated lesions may provide a lead to the cause of lipomas of the corpus callosum as well as of the different lesions in the fronto-facial region. From our experience and that of others, the frontal lesion may be an extracranial lipoma, a frontal bone defect, with or without an external lipoma, a lipomeningocele connecting the extracranial lipoma through a frontal defect with the corpus callosum lipoma, a frontal encephalocele. Fronto-nasal dysplasia associated with a corpus callosum lipoma, seems to form an independent group although some of these patients may have other extracranial lesions as well. It is suggested by the authors that as the primitive mesenchyme gives rise to the meninx primitiva as well as to the fronto-facial skeleton a disturbance of the neural crest may give rise to these combined lesions. Further analysis of similar cases may indicate the timing of these events, and perhaps reveal a common causative factor.
Adult↗