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PubMed1993

Sexual dimorphism in linear measures of the corpus callosum in cats.

The sexual dimorphism in the linear measures of the corpus callosum was studied in adult cats. In absolute measures, males had significantly larger genu, isthmus, and splenium than females; the mean absolute lengths were not significantly different in males and females. There were significant positive linear correlations between callosal measures and brain weight in the male and female cats, (no significant correlation between isthmus width and brain weight in females). The mean callosal measures predicted from brain weights in regression equations were found to be significantly greater in males than in females. This sexual dimorphism in callosal measures of cats showed similarities with rats, but not with humans. It was suggested that this may be due to cognitive differences between animal and human brains as well as brain development under relatively simple environmental factors such as gonadal hormones (testosterone) in animals compared to human brains.

Animals↗
PubMed2000

Microanatomy of the pericallosal arterial complex.

OBJECT: The pericallosal arterial complex supplies the callosal and pericallosal regions, as well as the anterior two thirds of the medial and superomedial aspects of both hemispheres. It is composed of the pericallosal artery (that is, the segment of the anterior cerebral artery located distal to the anterior communicating artery [ACoA]) and the median callosal artery (or third pericallosal artery), which originates from the ACoA. This system was studied in 46 specimens (23 human cadaver heads) injected with colored latex. METHODS: After being injected with colored latex, embalmed, and bleached, the specimens were studied with the aid of optic magnification. The pericallosal artery was found to be divided into four segments (A2-A5 in the proximodistal direction). After giving rise to central, callosal, and cortical branches, it terminated near the splenium of the corpus callosum as the posterior pericallosal artery, or on the precuneus as the inferomedial parietal artery. CONCLUSIONS: The authors propose a logical classification of the different variations in the pericallosal arterial complex based on embryological development. This complex can be considered a hemodynamic solution to an abnormal regression of one of its parts, which is balanced by the development of supplemental channels from other parts.

Anterior Cerebral Artery↗
PubMed1999

Immunocytochemical localization of pectins in the maturing anther of Allium cepa L.

Distribution of pectins in cell walls of maturing anther of Allium cepa L. was investigated. The monoclonal antibodies against defined epitopes of pectin were used: JIM5 recognizing unesterified pectin and JIM7 recognizing esterified pectin. It has been found that the cell walls of all anther tissues mainly contain esterified pectins. In the somatic tissues only small amounts of unesterified pectins are present in the cell wall junctions and adjacent middle lamellae and in the cell walls of the connective tissue. Thickening of the epiderm cell walls and growth of trabeculae in endothecium are completed through deposition of esterified pectins. In the cell walls of the middle layer and tapetum, unesterified pectins have been found only prior to their disintegration. The primary wall of microsporocytes is made up mainly of esterified pectins. Unesterified pectins occur outside microsporocytes only prior to the callose isolation stage. The presence of esterified pectins has also been detected on the surface of the callose wall surrounding dividing microsporocytes. Lysis of those pectins takes place after microsporogenesis, simultaneously with the lysis of the callosic walls. Before these processes pectins are unesterified. In the sporoderm of pollen grains mainly esterified pectins occur. They have been localized in the intine and aperture. The level of unesterified pectins in the intine is markedly lower.

Animals↗
PubMed1999

[Four "alien" hands for two hands after a lesion in corpus callosum].

Callosal lesions, associated or not to internal frontal lesions, may produce different types of complex gestural behaviors. Four signs can be identified, each of which has been generally reported separately: the "alien hand" sign, the "diagnostic apraxia", the "wayward hand" and the "callosal apraxia". Some authors justify considering these signs as different entities, while others propose regrouping them either in an unique syndrome--the "alien hand"--or as two syndromes--the "frontal alien hand" and the "callosal alien hand". We present the observation of a patient who presented with the four mentioned syndromes in association. In this context, we review the clinical features of each of the four signs and the arguments supporting their individualization.

Agnosia↗
PubMed2000

Marchiafava-Bignami disease: literature review and case report.

OBJECTIVE: We postulated that disruption of callosal pathways as occurs in Marchiafava-Bignami disease (MBD) is associated with marked impairment in brain functioning as measured by cognitive assessment and neuroimaging. BACKGROUND: MBD is considered to be a rare and severe complication of chronic alcoholism. It is characterized by necrosis and subsequent atrophy of the corpus callosum, which is the major brain structure connecting corresponding areas of both hemispheres. METHODS: We review the existing literature on MBD with respect to conceptualization, theories of pathogenesis, forms of the disease, and neuroimaging and neuropsychological findings. We then present the case of a middle-aged man with MBD who underwent extensive clinical, neuropsychological, and neuroimaging studies. RESULTS: Neuropsychological evaluation revealed a pattern of severe global dementia. Magnetic resonance imaging showed moderate atrophy of anterior callosal regions and severe atrophy of posterior callosal regions in the setting of cortical and subcortical atrophy. Resting metabolism positron emission tomography revealed decreased glucose metabolism most pronounced in subcortical and mesial frontal regions. The differential diagnosis, function of the corpus callosum, and potential limitations of our case study are discussed. CONCLUSIONS: On account of the history, clinical presentation, and results of magnetic resonance imaging of the brain, we diagnosed our patient with chronic MBD.

Alcohol-Related Disorders↗
PubMed2001

Morphometric study of the midsagittal MR imaging plane in cases of hydrocephalus and atrophy and in normal brains.

BACKGROUND AND PURPOSE: Midsagittal morphologic changes often aid in the diagnosis of hydrocephalus. Stretching and upward displacement of the corpus callosum, widening of third ventricular recesses, and decreased mammillopontine distance have been described as indicating the possibility of hydrocephalus. Quantitative studies are scarce. We performed retrospective, quantitative analysis to verify and quantify changes in midline morphology that might differentiate hydrocephalus and ventriculomegaly due to atrophy. METHODS: Sagittal MR imaging studies of 22 patients with hydrocephalus and 32 patients with atrophy were analyzed, as were 42 studies with normal findings. The studied parameters included mammillopontine and mammillocommissural distances, callosal height at two points, and the distances between the lines passing through the chiasm (chiasmal line) and the edge of the callosal splenium. Various angles between the chiasmal line and surrounding structures were measured. Similar measurements were done with the line passing through the third ventricular floor segment anterior to the mammillary bodies (third ventricular line). RESULTS: In hydrocephalus, mammillopontine distance decreased, mammillocommissural distance increased, the third ventricular floor segment was concave in most cases, and the chiasmal line rotated clockwise. These changes were not seen in atrophy. Callosal height was increased in hydrocephalus significantly more than in atrophy. CONCLUSION: Specific changes of the midsagittal plane in hydrocephalus, some of which have not been described previously, can be observed and quantified, which might aid in differentiating this condition from atrophy.

Adolescent↗
PubMed1975

[Interhemispheric relations of the cat visual cortex following unilateral polarization of the secondary visual area].

In 40 anesthetized cats, evoked potentials following light flashes during unilateral polarization of the secondary cortical visual area with DC anode (2-10 mcA) were studied in symmetrical centers of the 17th and 18th fields. Four phases of interhemisphere interrelationships between the 18th field's symmetrical centers were shown: 1 -- extracallosal phase of synergic depression; 2 -- callosal phase of dominant interrelationships; 3 -- callosal phase of synergic depression; 4 -- callosal-extracallosal phase of dominant interrelationships. In symmetrical centers of the 17th field, the only 1 extracallosal phase of synergic depression was observed during which the transcallosal modulation of nervous processes occurred. The data obtained are interpreted from the standpoint of the role of dominanta in interhemisphere interrelationships.

Animals↗
PubMed2004

[Interhemispheric connections of areas 17 and 18 in the cortical columns of cats with unilateral strabismus].

The interhemispheric connections of areas 17 and 18 of the cerebral cortex were investigated in cats with experimental unilateral strabismus. Single cortical columns were microiontophoretically injected with horseradish peroxidase, and retrogradelly labeled cells were demonstrated in the opposite brain hemisphere. After tracer injection in area 18 columns, the labeled callosal cells were located in area 17/18 transitional zone, similar to what was found in normal cats. However, in some cases the expansion of the region of callosally labeled cells distribution, was found. It is proposed that the extent of the region of callosally-connected cells may vary depending on whether the cells receive their input from intact or strabismic eye.

Animals↗
PubMed2006

[Influence of mandibular fracture upon intensity and prevailing direction of carbonate and citrate transport between blood and bones].

Using new coefficient of the difference relative radioactivity (CD(RRA)) bone/blood there was studied [(14)C]-carbonate and [3-(14)C]-citrate in 1-month and 6-months rats after right-side fracture of the mandible in prevailing direction between blood and bone. Animals were taken out from the experiment 20 min after intraperitoneal injection of [(14)C]-carbonate and [3-(14)C]-citrate on 7th day after (stage of cell-fibrous callosity), on 14th day after (stage of chondroid callosity) and on 28th day after (stage of the primary bone callosity) the experiment start. Changes after injections of marked citrate and carbonate were similar. Input % (ratio pulse/min in bone and blood serum) and RRA in 1 week increased sharply, decreased in 2 weeks and less changing in 4 weeks. After fracture CD(RRA) in traumatized mandible and non traumatized femur in rats were changing in the opposite directions that testifies to the different prevailing directions of marked substances transport between blood and bones.

Animals↗
PubMedDate not supplied

Clinical manifestations of hydrocephalus caused by impingement of the corpus callosum on the falx: an MR study in 40 patients.

The clinical features of patients with hydrocephalus include generalized reductions in coordinated motor and cognitive functions. Although some group similarities have been noted, the outward manifestations of this dysfunction vary in degree and character, with some subjects revealing no overt signs of the underlying hydrocephalus. A retrospective review of subjects with MR criteria of hydrocephalus was undertaken to reevaluate the specific imaging correlates of the signs and symptoms associated with this pathologic process. Forty adults with hydrocephalus on MR evaluation were carefully scrutinized in an effort to elucidate specific clinicoradiologic patterns of abnormality. Spin-echo MR techniques were used with T1 and/or T2 weighting in three orthogonal planes. MR criteria of hydrocephalus encompassed dilated lateral ventricles to include the temporal horns, a pronounced upward elevation of the corpus callosum, and an outward expansion of the cerebral hemispheres at the expense of the subarachnoid space overlying the convexities. The significant related morphologic change on MR that has not been previously described in hydrocephalus was a localized dorsal flattening and thinning of the posterior body of the corpus callosum. Importantly, all but three of the 24 patients with this phenomenon manifested varying combinations of imbalance, gait disturbance, incontinence, short-term memory deficits, and global dementia. In the presence of hydrocephalus, but in the absence of this specific callosal configuration, only one of the remaining 16 subjects revealed symptoms that might suggest the presence of hydrocephalus (i.e., profound dementia). The structure responsible for this focal callosal flattening and thinning in hydrocephalus is the rigid free surface of the falx cerebri as it impinges on the caudal extent of the upwardly expanding corpus callosum and supracallosal hippocampal formation. This mechanical insult hypothetically causes variable axonal dysfunction, ranging from decreased to increased neurophysiologic activity. In summary, it is postulated that callosal impingement represents a dynamic partial hemispheric disconnection and accounts, in part, for the complex clinical state associated with hydrocephalus.

Adult↗
PubMedDate not supplied

[Development of action potentials spreading antidromally from an acute epileptogenic focus through the corpus callosum].

The activity of callosal neurones located in the sensorimotor cortical area was studied in unanaesthetized rabbits. An epileptogenic focus was produced by application of penicillin or strychnine in the homotopic region of the contralateral hemisphere. During hyperpolarization of the membrane, corresponding to the appearance of paraxysmal discharges in the homotopic area, some of the neurones exhibited a group of antidromic action potentials (APs) in their soma with a 70-80 msec latency. Analysis of the APs form and of interspike intervals between the tested APs and antidromic APs evoked by stimulation, allowed to identify spontaneous antidromic APs in the extracellular records of callosal neurones as well. The data obtained show that under the influence of epileptogenic agents in the axon terminals located in the focus of the epileptic activity APs may appear, spreading antidromally through the corpus callosum to the soma of the callosal neurones.

Action Potentials↗
PubMed1990

[Dissymmetry in the interhemispheric transfer between visual areas in the adult cat, induced by chiasmotomy and monocular occlusion].

In the adult cat, a midsagittal section of the optic chiasm, which deprives each hemisphere of about half of its visual afferences, is followed after 6 weeks by a change in the callosal interhemispheric transfer, if one eye was occluded during the whole postoperative recovery period, thus depriving one hemisphere of direct visual messages related to patterned vision: with respect to controls only chiasmotomized, with binocular visual experience during an identical postoperative period, the deprived hemisphere displayed a significantly larger callosal afferent traffic while its own callosal efferences were on the contrary significantly reduced. This dissymmetry reveals that important postoperative changes can thus take place even in the adult animal.

Animals↗
PubMed1989

Patterns of connections in rat visual cortex.

The definition of visual areas is one of the central problems in visual cortex research. Rodent extrastriate cortex offers a striking example of the complexity of this issue, in that different parcelation schemes identify within it from 2 to as many as 13 separate visual areas. In the experiments reported here, patterns of connections within rat visual cortex were studied in an effort to better define its organizational layout. The experimental paradigm used consisted of the following steps: first, the pattern of callosal connections was revealed in vivo with the fluorescent tracer bisbenzimide. Then, using the callosal pattern as a landmark, single injections of WGA-HRP were placed at various sites in striate and extrastriate cortex. Subsequently, the relation between the tangential distribution of ipsilateral corticocortical connections, the callosal connections, and the borders of striate cortex were examined in the flattened cortex preparation. The experiments revealed widespread, patchy connections within rat visual cortex. These connections appeared to reflect 3 organizational trends. First, neighboring sites were more extensively connected than distant ones. Second, extrastriate sites receiving common striate cortex inputs tended to be interconnected. Finally, projections from opposite poles in striate cortex tended to form interdigitating patterns of connections in regions of overlap. Altogether these trends suggest that the extrastriate band adjoining striate cortex has a single, global map organization. However, within the global map, a clear modular organization was evident, which appeared to correspond to the multiple visuotopic representations reported for this region. Based on its location, and some organizational similarities. it is suggested that the global map may constitute the rat homolog of area V2 in cat and monkey.

Animals↗
PubMed1986

Interhemispheric transmission delays in human strabismics.

Experimentally induced strabismus in cats and monkeys leads to a variety of anatomical, physiological, and perceptual deficits. Given the similarities between the perceptual deficits of human strabismics and those of animal models, it is reasonable to suggest similarities in the underlying anatomical and physiological deficits. In cat, one anatomic anomaly associated with strabismus is a disruption of the normal development of the posterior corpus callosum. The present study provides evidence that interhemispheric transmission in human strabismics may be disrupted also. Simple unimanual reaction times were used to examine the transmission of information through callosal fibres. Estimates of cross-callosal transmission time for strabismics were consistently longer than for individuals with no history of strabismus. This difference was found only when targets were presented within 5 degrees of the fixation point. The results suggest that human strabismics may have abnormalities in those callosal fibres which are involved in the interhemispheric transmission of visual information.

Adolescent↗
PubMed1987

[A case of interhemispheric glio-ependymal cyst in a newborn infant].

An interhemispheric glio-ependymal cyst in a male neonate is reported. Neuroradiologically, the cyst, which had a septum like component within it, was located in the right frontoparietal interhemispheric and displaced the third and lateral ventricles. It had no communication with the ventricular system. As for anomalies associated with it, the total callosal agenesis and congenital hydrocephalus were revealed in CT scan. Angiogram suggested that polymicroglia accompanied with the cyst. It was confirmed that the cyst was divided into two parts by the septum during surgery. Microscopic examination showed that the cyst wall was composed of ependyma, connective tissue and glial cells. Choroid plexus component was also found in the septum. On the basis of the fact above, it was diagnosed interhemispheric glio-ependymal cyst. We believe that this interhemispheric cyst described above is a true cyst and differs morphologically and embryologically from the midline cyst which is produced with callosal agenesis and due to increased intraventricular pressure. In fact, the latter is an encystic third ventricle but not a true cyst. Both of them are, however, usually called interhemispheric cyst in the literature. We conclude that this case is appeared to be a true cyst because we can differentiate it from third ventricle by neuroradiological findings. We discussed nature of different interhemispheric cysts with callosal agenesis and suggested that recognition of the morphological relationship between the interhemispheric cysts and third ventricle was utmost important to make a correct diagnosis.

Agenesis of Corpus Callosum↗
PubMed1985

[The degenerative process during development of the corpus callosum].

The ontogenesis of the corpus callosum is inextricably linked with the various processes controlling prosencephalic development. Our study is based on series of frontal and sagittal sections through the prosencephalon of 16 and 17 day mouse embryos and on ultrathin sections of the septum, particularly of the zone where the callosal fibres cross. The septum, which contains the first callosal fibres, does not undergo the fusional process described by other authors. The passage of pioneer fibres from one hemisphere to the other is preceded by the degeneration and death of the atrocytes of the cortical plate in the fundus of the interhemispheric issure, and by proliferation of the subependymal cells. The proliferation and migration of the subependymal cells from the medial angles of the lateral ventricles may well assist the passage of pioneering callosal fibres.

Animals↗
PubMedDate not supplied

[Resistance of visual recognition to interference in the intact and callosotomized rat].

Recognition of structured visual stimuli under the action of light interference was studied by means of conditioning in rats with intact and dissected callosal body. Addition of noise to conditioned signals was achieved by insertion of additional element into their image. It was found that as more noise was added the number of correct responses decreased and latencies of conditioned food-procuring reactions became longer. The number of individuals in the sample, which possessed a differentiation level higher than the random one decreased. Noise immunity of males in the range of weak and average noises proved to be higher than in females, and, as a rule, equal at high noises. Section of the callosal body produced changes in noise immunity of visual recognition; the nature and degree of the changes depended on the intensity of noise and on the animal's sex. The existence of modulating callosal influences on noise immunity of visual recognition is suggested.

Animals↗
PubMedDate not supplied

[Interhemispheric interrelationships in the visual cortex of cats following unilateral polarization and photic stimulation of different intensity].

Anodic polarization of the parastriate area in the right hemisphere causes in symmetric regions of cat's visual cortex dynamic changes in EPs, interhemispheric functional asymmetry and interhemispheric relations, depending on the intensity of photic stimulation. The sequence of phases of interhemispheric callosal relations and characteristics of interaction between callosal and extracallosal influences were traced in different periods of polarization excitation. It was found that interhemispheric callosal and extracallosal influences lead either to stabilization of initial EP levels and interhemispheric asymmetry or to their change depending on conditions of photostimulation and on the stage in the formation of polarization site.

Animals↗