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PubMed2003

Pathway-specific differences in subunit composition of synaptic NMDA receptors on pyramidal neurons in neocortex.

Heterogeneity of synaptic inputs onto neocortical layer 5 pyramidal neurons could result from differences in the underlying receptors, yet previous work has shown that functional attributes of AMPA receptors are uniform among synaptic connections onto these neurons. To determine whether NMDA receptors (NMDARs) would be similarly uniform, we compared in the same pyramidal neurons pharmacologically isolated NMDAR-mediated EPSCs evoked by stimulation of two anatomically distinguishable pathways, callosal or intracortical. Based on differences in voltage dependence, decay kinetics, apparent Mg2+sensitivity, and subunit-specific (NR2A, NR2B, and NR2C/D) pharmacology, we found NMDARs at these inputs to be distinct. Furthermore, NMDARs activated by the intracortical pathway were more efficient at integrating EPSPs and bringing the neuron closer to the spike-firing threshold than the callosal pathway. These results suggest that pyramidal neurons encode information differentially depending on the origin of their neocortical inputs and that NMDAR-dependent synaptic plasticity may be pathway specific.

Action Potentials↗
PubMed1992

[Interhemispheric choroidal epithelial cyst associated with partial agenesis of the corpus callosum: case report and review of the literature].

A case of interhemispheric choroidal epithelial cyst is reported. The patient is a 9-month-old female who was transadmitted to our hospital for further examination because of the enlargement of her head. She had no neurological deficits nor symptoms of increased intracranial pressure. CT scanning performed on admission showed multiple cystic lesions in the right frontoparietal interhemispheric space, whose circumference was partially enhanced with contrast medium. Metrizamide CT cisternography demonstrated no communication between the lesions and the ventricular system. The signal intensity of the cysts was higher than that of cerebrospinal fluid on both T1-weighted and T2-weighted MR images. Sagittal T1-weighted images showed partial agenesis of the corpus callosum. The surgical exploration was performed via interhemispheric approach. The cyst wall was found to be white, relatively rich in vascular components, and was removed as much as possible. The examination of the cyst fluid showed total protein levels of 1250 to 3440 mg/dl, and sugar contents of 43 to 99mg/dl. Callosal agenesis was confirmed at operation. The light microscopic examination revealed that the cyst wall was composed of a single layer of columnar or cuboidal epithelium with occasional papillary configuration and thick collagenous connective tissue. The epithelial cells contained PAS-positive granules in the cytoplasm. Electron microscopy showed numerous club-shaped microvilli with no coating materials, continuous basement membrane, tight junction, interdigitation, and multiple fenestrations of endothelium of stromal vessels. On the basis of these findings, the lesion was diagnosed as choroidal epithelial cyst. In the literature, interhemispheric choroidal epithelial cyst associated with partial callosal agenesis, confirmed ultrastructurally, has not, to out knowledge, been reported.

Agenesis of Corpus Callosum↗
PubMed1992

[MR imaging of pericallosal lipomas].

Eight cases of pericallosal lipomas were studied by MR imaging at 1.5 Tesla. All were located around the splenium of the corpus callosum, and were classified as the curvilinear type. Corpus callosal abnormalities were detected in the six of these eight cases, and included two cases of short corpus callosum and four of thin splenium. The larger lipomas tended to have greater abnormalities of the corpus callosum. T1-weighted sagittal images were the most useful pulse sequences for diagnosing pericallosal lipomas and corpus callosal abnormalities. On review of the literature we found that the curvilinear type of pericallosal lipoma is more frequently observed by MR imaging than the tubulonodular type.

Adolescent↗
PubMed2003

Testosterone and free thyroxin blood in congenitally acallosal male BALB/cCF mice.

OBJECTIVES: Approximately 20% of BALB/cCF mice are born with partial or total absence of the corpus callosum. Here, we analyzed testosterone and free thyroxin blood levels in adult male mice of this strain in order to see if these hormones are related to the incidence of callosal defects. METHODS: Blood collected from the axillary blood vessels of 12 normal and 10 acallosal deeply anesthetized adult male mice was used in order to determine testosterone and free thyroxin levels through chemiluminescence (IMMULITE, Diagnostics Products Corporation, USA). RESULTS: No significant difference (one-way ANOVA: F = 0.11, df = 1, p > 0.10) was found between normal ((-)X= 1.95, SD = 0.62) and acallosal ((-)X= 1.86, SD = 0.62) mice for free thyroxin level. On the other hand, in those mice that had detectable testosterone levels (above 0.2 ng/ml), a significant difference was found (t = 2.8, df = 6.06, p = 0.03): normal mice (n = 7, (-)X= 8.73, SD = 7.64) had a higher level than acallosal mice (n = 4, (-)X= 0.62, SD = 0.41). CONCLUSIONS: The present results indicate that the incidence of callosal agenesis is not related to free thyroxin levels in the blood of adult BALB/cCF mice. On the other hand, in spite of the fact that low testosterone levels seems to be frequent in male mice of this strain, acallosal mice tend to have lower levels of this hormone than normal mice.

Agenesis of Corpus Callosum↗
PubMed2004

[Cellular responses of rice to Magnaporthe grisea at the early stages of disease development].

This paper presents a detailed investigation of the cytological and cytochemical events in rice cells infected by Magnaporthe grisea during the early stages of disease development. It was demonstrated that the spatial and temporal development of cytoplasmic aggregation, host cell autofluorescence, callose deposition and phospholipase D (PLD) accumulation were some of the earliest responses of host cells to M. grisea attacking and showed different patterns between the compatible and incompatible interaction. In the cv. IR64 and strain BN111 interaction (resistant), the earliest cellular response observed in the inner epidermis of rice leaf sheath was aggregation of the cytoplasm. Then, the attacked host cells turned brown and the cell cytoplasm collapsed (HR). In the moderately resistant reactions of cv. IR64 to strain PO66, the granule formation was delayed, and no apposition was observed in host cells. In the compatible reactions of cv. IR64 to strain Ca89, no visible cellular response was detected until 40 h after inoculation. As to auto-fluorescence of host cells, some penetration sites showed faint fluorescence under blue light as early as 12 h after inoculation in the cv. IR64-strain BN111 interaction. As the disease developed, the percentage of attacked epidermal cells showing autofluorescence increased quickly from 20 to 24 h after inoculation and the penetrated host cells showed strong autofluorescence. In the moderately resistant interaction, autofluorescence had been detected until 24 h after inoculation. In the compatible interaction, little autofluorescent cell was detected during the disease development. Patterns of callose deposition and phospholipase Dgamma (PLDgamma) showed the similar dynamic characteristics as did the phenolic compounds.

Cytoplasm↗
PubMed2005

[Interhemispheric connections in the visual cortex of cats reared with bilateral strabismus].

We have determined the spatial distribution of retrograde labelled callosal cells after microiontophoretic horseradish peroxidase injections into the single cortical columns of area 17, 18 in cats reared with bilateral convergent strabismus. The obtained strabismus angle was in the range 10-35 degrees. The zone of labelled cells was located asymmetrically in respect to location of injected column in opposite hemisphere. Some cells were revealed in the transition zone 17/18 and their retinotopic coordinates corresponded to the injected column, as was shown in intact cats. Other labelled cells were located in areas 17, 18, in clusters approximately in 1000 mkm from marginal clusters of transition zone. Analysis of labeling in lateral geniculate nucleus has shown that most of the injected columns were driven by ipsilateral eye. The data obtained may be interpreted as evidence of eye-specificity of monosynaptic callosal connections. The functional role in such connections changes in cats with bilateral strabismus is discussed.

Animals↗
PubMed2005

The alien hand syndrome: report of a case and review of the literature.

The term "alien hand syndrome (AHS)" comprises many clinical signs of which the common features are the involuntary motor movement of the affected limb and the denial of limb ownership. It can result from several diseases involving corpus callosum or medial frontal cortex. Two major types of AHS were previously classified, callosal and frontal types. Moreover posterior subtype of which the lesions do not involve corpus callosum have been reported. In the present report, the authors describe a 57-year-old man with AHS, aggressive behavior and hemispatial neglect which are the rare manifestations of callosal damage. Neuroimaging demonstrated subacute infarction of entire corpus callosum from the rostrum to splenium. A review of the literature on these abnormalities is included in the present paper.

Apraxia, Ideomotor↗
PubMed2007

[Neuropsychological approach to visual attention].

Visual experience depends critically on visual attention, which selects a particular aspect of a visual display. Recent clinical, neuroimaging, and animal studies revealed that visual attention was divided into active and passive or top-down and bottom-up attention. Although these dichotomies are clear-cut in definition, visual attention could be modulated by many factors. Detailed observation of brain-injured patients provides with evidence for dynamic and fine control of visual attention. We observed patients with dorsal simultanagnosia and that with callosal disconnection syndrome. Patients with dorsal simultanagnosia demonstrated that extent of visual attention was dynamically changed depending on the level of visual processing. Despite the ability to read a kanji character and to describe its components correctly, a patient could not notice a component that he had just written and could not assemble individual components to make up a correct kanji character. He could point to an overlapping area of two figures. But once he started to color the overlapping area, he missed the margin of the area and colored much larger area. Another patient with dorsal simultanagnosia missed borderlines between columns of a newspaper and read letters continuously across columns. In contrast, he could point to lines between figures or meaningless patterns easily. These findings indicated that visual attention was directed automatically to meaningful characters. A patients with callosal disconnection syndrome demonstrated left unilateral spatial neglect only when he used his right hand to draw figures. Right hand movement, controlled by the left hemisphere, elicited visual attention to the right hemispace, resulting in the left unilateral spatial neglect. Thus visual attention is not simply top-down or bottom up, but is implicitly affected by the visual recognition as well as motor component of the task.

Aged↗
PubMed1991

[Dislocated neurons and neural network: hodological study of the motor cortex of the reeler mutant mouse].

Reeler, an autosomal recessive mutation in mice, causes cytoarchitectonic abnormalities of cerebral cortex, which are characterized by malposition of neurons. We examined hodological systems of the reeler motor cortex. The results are described as follows. (1) In normal controls, corticospinal tract neurons retrogradely labeled after the injection of HRP ioto the lumbar cord were situated only in layer V (layer of large pyramids: LP). In the reeler, by contrast, the labeled corticospinal tract neurons were scattered diffusely throughout all levels of the corresponding area. (2) In the normal controls, callosal commissural neurons retrogradely labeled after the HRP injection into the motor cortex were distributed in a bilaminar pattern such that the largest number of cells were located in the supragranular layers II (layer of small pyramids; SP) and III (layer of medium pyramids; MP), and in the infragranular layer V (LP). In the reeler mutant mice, callosal commissural neurons were found in all cortical layers, but two-thirds were situated in the lower half of the cortex. (3) In the normal controls, most of the thalamocortical neurons labeled after HRP injection into the motor cortex were located in the ventrolateral nucleus, the lateral division of the ventrobasal nucleus, the central lateral, paracentral and central intralaminar nuclei, and the medial division of the posterior complex. In the reeler mutant mice, retrogradely labeled neurons were again found in the nuclei referred to above, and the distribution pattern and morphology of HRP-filled neurons were also similar to those of normal controls. In the reeler, thalamocortical fibers took an abnormal course within the motor cortex: they ascended obliquely from the white matter to the pial surface and then descended obliquely to the deeper layers. These results strongly suggest that dislocated neurons project correctly to normally-situated and/or abnormally situated target(s).

Animals↗
PubMed1977

The histoenzymic activity of gyrus cinguli in the course of postnatal ontogeny of the rat.

Histochemical investigations concerning the activity of several dehydrogenases and hydrolases in the area cinguli during postnatal ontogenic development of the rat were performed. Brain sections corresponding to the region of area cinguli, obtained from rats aged 1, 3, 8, 17, 40 and 60 days postnatal, were subjected to histochemical assays for various dehydrogenases, phosphatases and esterases. The developmental changes concerning histoenzymic reactivity of the callosal gyrus with regard to several respiratory and hydrolytic enzymes were assessed and described. Considerable differences in enzymic reactivity, appertaining particularly to the phosphatases and esterases, between the anterior and posterior parts of the callosal gyrus were found. The unusual enzymic reactivity of glial cells in the individual regions of the area cinguli has been pointed out.

Animals↗
PubMed1990

The organization and connections of somatosensory cortex in marmosets.

Microelectrode mapping methods were used to define and describe 3 representations of the body surface in somatosensory cortex of marmosets: S-I proper or area 3b of anterior parietal cortex, S-II, and the parietal ventral area (PV) of the upper bank of the lateral sulcus. In the same animals, injections of anatomical tracers were placed into electrophysiologically determined sites in area 3b or S-II. Mapping results and patterns of connections were later related to architectonic fields that were delimited in sections cut parallel to the surface of manually flattened cortex and stained for myelin. There were several major results. (1) Recordings from area 3b revealed a characteristic somatotopic organization of foot to face in a mediolateral sequence as previously reported in other members of the marmoset family (Carlson et al., 1986). (2) Multiple injections of WGA-HRP in area 3b demonstrated dense, patchy interconnections with ipsilateral S-II, PV, area 3a, and area 1, less dense interconnections with primary motor cortex (M-I), the supplementary motor area (SMA), limbic cortex of the medial wall (L), and rostrolateral parietal cortex of the lateral sulcus (PR), and callosal connections with areas 3b, S-II, and PV. Injections of 3 different tracers into the representation of 3 body regions in area 3b indicated that the connections with areas 3a, 3b, 1, S-II, and PV are topographically organized. (3) Recordings from cortex on the upper bank of the lateral sulcus demonstrated a somatotopic representation of the body surface that matches that of S-II of other mammals. S-II immediately adjoined areas 3b along the dorsal lip of the lateral sulcus. The face representation in S-II was adjacent to the face representation in 3b while the trunk, hindlimb, and forelimb were represented in a caudorostral sequence deeper in the sulcus. (4) Injections in S-II revealed ipsilateral connections with areas 3a, 3b, 1, a presumptive area 2, PV, PR, M-I, SMA, limbic cortex, the frontal eye fields, and the frontal ventral visual area. Dense callosal connections were with S-II and PV. (5) The recordings also revealed a systematic representation just rostral to S-II that has not been previously described in primates.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMedDate not supplied

MR imaging of corpus callosotomy.

MR findings in 13 patients who underwent corpus callosotomy for medically intractable seizures were reviewed. Preoperative MR studies were available in nine patients: five showed at least one morphological and/or MR signal abnormality including corpus callosal thinning (four cases), cerebellar atrophy (two cases), cortical atrophy (two cases), and periventricular hyperintensity on T2-weighted images (one case). Four patients had normal MR studies. Postoperative MR studies were obtained in 11 patients with subtotal callosotomy and two with total callosotomy. Of all pulse sequences, sagittal T1-weighted images best showed the surgical division, although two cases displayed a coaptation artifact, which was misleading. A surgical clip placed at the posterior extent of the callosotomy was best visualized with sagittal T1-weighted imaging. Two patients (15%) had MR findings consistent with subacute blood in the callosum, and three patients (23%) demonstrated parafalcial hyperintensity on T2-weighted images 1 week after callosotomy. Motion artifact was a significant problem with coronal imaging and T2-weighted pulse sequences in postoperative patients. Patients selected for corpus callosotomy may have a normal baseline MR or show nonspecific abnormalities. MR imaging is an effective method for evaluating callosal division, and in some cases, may demonstrate signal changes consistent with surgically related edema and/or blood.

Adolescent↗
PubMed1989

[Dormancy in Vicia loiseleurii seeds. Observations of the seminal tegument].

Seed coat structure has been examined in Vicia loiseleurii (M. Bieb.) Litw. on sections and phytoglyphs. The structure is the typical one of the Papilionaceae, with malpighian (= palisade) layer, hour-glass cell layer and hypodermis. An apparently non-cellular thick strip separates the seed coat from the cotyledons of the embryo. The malpighian cell of V. loiseleurii, with its cone-shaped cap or dome, is very similar to the well studied one of the Melilotus alba seed. Histochemical tests reveal the hydrophobic nature of the cap, which is stained by Sudan Blck B, Nile Blue and rendered highly fluorescent in its basal part by Auramine O. Aniline blue evidentiates callose in the wall below the cap. It is suggested that the impermeability of the coat, cause of the dormancy of the V. loiseleurii seed, is dependent on both the hydrophobic caps and the callose-containing radial walls of its malpighian cells.

Fabaceae↗
PubMedDate not supplied

Complications of the Grice-Green operation.

A case presentation involving complications resulting from errors in surgical technique with the Grice-Green procedure is discussed in this report. The patient was treated 18 years after bilateral tendo achillis lengthenings and Grice-Green extra-articular subtalar arthrodeses with autogenous tibial bone grafts. The complications encountered were severe adductovarus deformity of the feet with multiple painful plantar callosities, in-toed gait with weightbearing on the lateral aspect of the feet, inversion ankle instability, and tripping over the feet. Deformity and symptoms were worse on the right foot. The patient required further surgery, consisting of bilateral calcaneal osteotomy, metatarsal neck osteotomies, excision of callosities and ostectomies for painful plantar metatarsal base lesions, tenotomy of the abductor hallucis and digital fusions. The original surgery was performed for idiopathic flatfeet. Despite the many different causes of flatfoot for which the Grice-Green procedure has been employed, most authors believe it should not be used for idiopathic flatfeet, and restrict its use to the original indication, that of paralytic pes valgus secondary to poliomyelitis. The reader should also realize that there are very long-term consequences to surgery on the pediatric patient.

Adult↗
PubMed1988

The deafferented visual cortex and interhemispheric relationships: a physiological approach.

A condition of asymmetrical activation in the visual system, induced by unilateral optic tract section (OTX) was examined in nine adult cats, four of which had been reared after early onset of monocular deprivation (MD-OTX) during the critical developmental period. Their results were compared to those of monocularly deprived (MD) and normal control cats. Extracellular single-unit recordings from areas 17, 18 and their border were performed at various intervals after OTX to study the effects of this isolation of one hemisphere from direct geniculo-cortical input. Electrophysiological results from the isolated hemispheres of both OTX and MD-OTX cats revealed that contralateral input via the corpus callosum was virtually undetectable in the majority of cats. Only in the cats in which the deprivation was ipsilateral to the OTX, 3.5% of the cells exhibited visual activity in the isolated hemisphere. In the intact hemisphere of the OTX group, binocularity was unaffected overall in comparison to the normal control animals, except for a slight decrease within the 0-4 degrees region from the vertical meridian. In the MD-OTX group, the cats with onset of deprivation prior to natural eye opening possessed an increase in deprived eye responsiveness compared to the control MD cats. No such an increase was seen in later onset of deprivation (3-4 weeks following natural eye opening) in the MD-OTX cats. Overall, visual responsiveness was reduced in all of the OTX and MD-OTX cats, with a return towards normal control values seen only in one animal with extended recovery (6 months). Orientation and direction selectivity were dramatically decreased in the OTX and MD-OTX cats. As the majority of receptive fields mapped from the OTX cats were in the ipsilateral visual field to the section, the remaining small number of receptive fields in the contralateral "blind" visual fields adds further support for a nasotemporal overlap in the retina of the cat. The conclusion from these results is that an asymmetrical level of direct geniculo-cortical input in the visual system of the adult cat yields a physiological bidirectional inactivation of the callosal pathway for the transfer of visual information. Thus, activation of the callosal pathway connecting the cortical visual areas has been postulated to be dependent upon simultaneous, reciprocal interaction between the two hemispheres.

Animals↗
PubMed1988

MR imaging of pericallosal lipoma.

Early pathologic reports of corpus callosal lipoma described a consistent relationship between the lipoma and the dorsal surface of the corpus callosum, particularly when the lipoma is not associated with corpus callosal agenesis. MR imaging, especially T1-weighted sagittal acquisitions, exquisitely demonstrated this anatomic relationship in three relatively asymptomatic patients. Therefore, in most cases, a lipoma of the corpus callosum is more accurately described as a pericallosal lipoma. In one individual, common associated findings (partial agenesis of the corpus callosum and choroid plexus lipoma) were also noted. Surgical therapy is usually not indicated because symptoms are generally not related and the anterior cerebral artery is often encased by the lipoma.

Adult↗
PubMed1988

Split brain acutely and chronically induced in cats causes ipsilateral eye dominance and reduced excitability of cells in the visual cortex.

The ocular dominance distribution and the excitability level of single cells in the callosal projection zone of the visual cortex (area 17-18 boundary), were electrophysiologically studied in acute and in chronic cats following simultaneous (OCX-CCX) and separate transections of the optic chiasm (OCX) and corpus callosum (CCX). Except for a few cells (3.4%) in the acute OCX-CCX cats showing an interhemispheric transfer, as expressed by their contralateral eye response, all other cells had a monocular response to the ipsilateral eye. An ipsilateral monocular response was found in the chronic OCX-CCX cats, even for long survival periods (17.0 months). The result for the OCX cats was similar, as indicated by the major ipsilateral response and the small proportion of cells showing an interhemispheric transfer. No improvement was found with postoperative time; acute OCX cats had 5.0% cells with contralateral input and 1-7 months chronic cats had 1.7-6.5% of these cells. These animals have thus split brain from point of view of the visual cortex; each hemisphere is therefore independent of the other one as far as neuronal functions are concerned. A remarkable reduction in binocularity was found following callosal transection (CCX) both in acute (41.4% binocularly driven cells) and in 3-39 months chronic cats (45.5% cells), in comparison to the control cats (74.2%). This indicates that elimination of the corpus callosum as itself enhances the binocularity diminution in split brain cats. The reduction found in visual responsiveness in our split brain cats (total: 63.2% unresponsive cells), is attributed to the summation of the individual effects of the optic chiasm and corpus callosum transections. A consistent tendency was found in the long chronic in comparison to the acute OCX-CCX, OCX, and CCX cats for a decrease in the responsiveness level with survival time; however, the short chronic OCX-CCX and CCX cats had the maximal proportion of unresponsive cells. It was concluded that the split brain induced in adult cats has a permanent effect on interhemispheric transfer to visual cortex cells. The absence of interhemispheric interaction under these conditions is not compensated by either transfer through anterior parts of the corpus callosum or through other commissures.

Animals↗
PubMed1988

The changes of enzymatic activity in blood vessel walls of rat brain during extrauterine development. Histophotometric studies.

The investigations of acylohydrolase acylocholine (cholinesterase) enzymatic activity in the brain vessels walls were performed during extrauterine ontogenic development on 3rd, 7th, 14th, 21st, 28th, 40th and 60th days of life and in the 18 months old rats using Koelle method. Objective evaluation of histoenzymatic reaction intensity is rather difficult because of subjective factors and technical problems. Therefore, our estimations were performed by the use of microscopic unit "Morphoquant" produced by CARL ZEISS Jena factory and coupled with a KSR 4100 ROBOTRON computer. The measurements on 50 fields from parietal cortex or callosal corpus were executed using white light. The area of a single measuring field was 4,200 micron2. The results of measurements were expressed as the percentage of the measured field area occupated by blood vessels with positive ChE reaction in their walls. The results indicate that the amount of blood vessels with positive ChE reaction during the whole postnatal development is increasing. In particular, a very intense increase in the amount of vessels with ChE reaction take place between 7th to 14th days of extrauterine life. In the white matter of callosal corpus a very strong increase in the blood vessels amount with positive ChE reaction is visible between 21st and 28th days of life. In the brains of 18 months old rats a decrease in the positive blood vessels amount was noted. When compared to the parietal cortex, this decrease was higher in corpus callosum. From 40th day of life the amount of blood vessels with positive histoenzymatic reaction for ChE was higher in the grey matter than in the white matter.

Animals↗