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PubMed2000

Adult ovary transfer counteracts the callosal enlargement resulting from prepubertal ovariectomy.

The rat corpus callosum (CC) is larger in males than females, and is sensitive to hormone manipulations during development. Previous research found that, in rats, CC sensitivity to testosterone ended by postnatal day 8 (P8). In contrast, more recent findings demonstrated that CC responsivity to ovarian hormones continued at least through P70. The current experiment extends these findings by showing that the female callosum is still sensitive to ovarian hormones as late as P130, well into adulthood.

Analysis of Variance↗
PubMed1990

Right hand agraphia and left hand apraxia following callosal damage in a right-hander.

A right-handed Japanese man showed agraphia more marked with the right hand, apraxia confined to the left hand, and right ear extinction on dichotic listening, following damage to the anterior two-thirds of the corpus callosum, the rostral and lower parts of the right medial frontal lobe and a small portion of the left medial frontal lobe. The symptoms were attributed to hemispheric disconnection, on the assumption that the right hemisphere was dominant for language and the left for limb praxis. This case provides good evidence for dissociated lateralization of language and limb praxis in some right-handed individuals. The study of writing performance suggested the following hypotheses: (1) motor engrams for limb praxis and writing may be dissociated, and (2) motor engrams for writing Kana (phonogram) and Kanji (ideogram) letters are represented on both hemispheres, although the hemisphere nondominant for language seems unable to combine graphemes into a correct meaningful sequence.

Agraphia↗
PubMed1985

Apraxia of the left limbs in a case of callosal disconnection: the contribution of medial frontal lobe damage.

A 40 year old right-handed woman suffered hemorrhage from an anterior cerebral artery aneurysm. CT scan showed destruction of the anterior two thirds of the corpus callosum, both cingulate gyri, and the white matter underlying the medial frontal lobes. The left limbs displayed apraxia on verbal command, in imitation, and in actual object use. There were antagonistic actions of both hands, and the patient accused her left hand of disobeying her. We interpret the leftsided apraxia as resulting from a lack of interhemispheric transfer combined with a deficit in ipsilateral motor control stemming from damage to the left supplementary motor area. Right frontal lobe damage may have impaired the motor learning capacity of the right hemisphere and thus its ability to compensate for the lack of left hemisphere motor control.

Adult↗
PubMed2000

Neonatal estrogen blockade prevents normal callosal responsiveness to estradiol in adulthood.

The rat corpus callosum (CC) is larger in males than females, and is responsive to hormone manipulations during development. We previously demonstrated that P25 ovariectomy (Ovx) enlarged (defeminized) adult CC, while P70 ovary transfer (OvT) counteracted this enlarging effect, resulting in smaller (feminized) CC. Since OvT females were not Ovx'd until P25, they received some neonatal estrogen (E) exposure. Behavioral data suggest that adult responsiveness to ovarian hormones depends upon prior organization by neonatal E. It has not been determined whether a similar phenomenon occurs for the feminization of brain morphology. The current experiment examined whether our previous finding of adult CC responsiveness to ovarian hormones depended upon neonatal E exposure. We investigated this by assessing the effects of P70 ovarian hormone replacement (via ovary transfer or E pellet) in females that received either (1) normal ovarian hormone exposure until P25 Ovx, or (2) the E receptor blocker tamoxifen from birth to P25 Ovx. Females receiving normal neonatal hormone exposure responded to P70 E in the female-typical manner: E reduced CC size. In contrast, females receiving neonatal E blockade responded to adult E in the opposite manner: E increased CC size. As far as we are aware, this is the first report suggesting that neonatal E exposure organizes the female brain so that it responds normally to the organizing actions of E when later exposure occurs. These findings further challenge the traditional model of female brain development, which asserts that normal female brain organization occurs by default, in the absence of gonadal hormone exposure.

Aging↗
PubMed2003

Corpus callosum and visual cortex of mice with deletion of the NMDA-NR1 receptor: I. Accelerated development of callosal projection neurons.

Many pharmacological experiments show that the ionotropic receptor NMDA has both neurotrophic and neuroexcitotoxic effects. The neurotrophic function is manifested in many ways including acceleration of neuronal development, enhancement of neuronal migration, neuroprotection, blockage of apoptosis, prevention of aging and prematurity, as well as effects on synaptic plasticity and synaptogenesis. On the other hand, the neuroexcitotoxic function is manifested in its role in neurological and psychiatric diseases such as epilepsy, Parkinson's disease and schizophrenia. The present study explores the consequences of complete and partial absence of NMDA-NR1 receptors throughout development. Using DiI tracing in vitro, the development of corpus callosum projection neurons in transgenic mice with deletion of the NMDA-NR1 receptor was observed in visual cortex. Compared to littermate controls, the histogenesis and neuronal development of corpus callosum cells of origin was found to be accelerated in NR1-/- mice. That is, the corpus callosum projection neurons in NR1 knockout mice developed earlier and faster than in littermate heterozygous and wild-type mice. However, the corpus callosum projection neurons in NR1 heterozygous mice developed earlier and faster than in littermate wild-type mice. This suggests that NMDA-NR1 receptors are involved in sequencing and/or temporal regulation of neuronal development, and that there is a gene-dose effect. Studies from other laboratories suggest that the observed phenomenon of prematurity or accelerated development is a direct effect of altered expression of genes found in mice with deletion of the NMDA-NR1 receptor.

Animals↗
PubMed1992

The effects of early experience on callosal development and functional lateralization in pigmented BALB/c mice.

A proportion of animals of the BALB/c inbred mouse strain have an unusually small (sometimes absent) midsagittal area of the corpus callosum (CC). In this study, we used a large sample of both males and females (total n = 198) from a pigmented congenic BALB/c line to investigate the relations among preweaning handling, area of CC, and direction and degree of lateralization as measured by Collins' paw preference task. Twenty litters were handled daily from the day after birth until day 25 (weaning) according to Denenberg's procedure and 18 litters were left undisturbed until weaning. All animals were tested for degree and direction of paw preference in a modification of Collins' apparatus at about 60 days and measures taken on CNS structures at 100 days of age. There were no handling or sex effects on degree or direction of paw preference or on the extent of CC defects, but for animals in the normal range (CC > or = 0.7 mm2), those which had been handled had significantly smaller callosa. No significant differences were detected between right and left hemisphere weights, and these measures did not appear to be related to the behavioural measures. There was no significant correlation between CC area and degree of paw preference nor was there any relationship between total agenesis and degree of handedness. This last result is particularly interesting in light of recent evidence that ILn/J mice, all acallosal, are exclusively ambilateral.

Animals↗
PubMed2003

Reproducibility of callosal effects of transcranial magnetic stimulation (TMS) with interhemispheric paired pulses.

Transcranial magnetic stimulation (TMS) of the motor cortex of one hemisphere (conditioning stimulus (CS)) inhibits EMG responses evoked in distal hand muscles by a later magnetic stimulus given at an appropriate interval, over the opposite hemisphere (test stimulus (TS)). This effect is commonly attributed to an inhibition produced at cortical level via a transcallosal route. The present study assessed the reproducibility of the transcallosal inhibition effects in different sessions in healthy subjects. Within- and between-subject variability, relating to interhemispheric differences was also evaluated. A magnetic CS on one hemisphere effectively inhibited EMG responses of the abductor digiti minimi stimulated by a TS delivered over the opposite hemisphere in a range of intervals centered at 12 ms. Even though group effects were reproduced in separate sessions, the high between- and within-subject variability yielded low test-retest correlations. This differentiation forces the definition of reproducibility (or repeatability), as the replication of the same mean curves of EMG reduction, and of reliability, as the between- or within-subject correlations between values of specific EMG measures.

Adult↗
PubMed1983

Keratosis palmoplantaris nummularis ("hereditary painful callosities"). Clinical and histopathologic aspects.

Three families are described. A number of the members of these families showed nummular keratoses on the plantar pressure points. The lesions usually appeared when the children began to walk. They progressed slowly and were often accompanied by pain. The hands showed only minor lesions, which frequently followed manual labor. Extrapalmoplantar lesions were rare. The histopathologic findings in our patients were those of focal epidermolytic hyperkeratosis. The classification of this type of dominant hereditary focal palmoplantar keratosis, for which the name keratosis palmoplantaris nummularis is suggested, is discussed.

Aged↗
PubMed1997

Corpus callosal morphology in treatment-naive pediatric obsessive compulsive disorder.

1. Abnormalities in association circuits have been described in Obsessive Compulsive Disorder (OCD) and may reflect neurodevelopmental abnormalities. Primary and association cortices are topographically mapped in the corpus callosum (CC). The authors hypothesized alterations in CC subdivisions that connect association, but not primary cortices in pediatric OCD. The authors predicted that normal age-related increases in CC area would be absent in OCD. 2. The authors compared the midsagittal magnetic resonance images of 21 psychotropic-naive, nondepressed OCD patients, 7.2-17.7 years, and 21 case-matched healthy controls. Total CC area as well as that of the anterior, middle and posterior genu, anterior and posterior bodies, isthmus, and the anterior, middle and the posterior splenii were measured. 3. All of the CC regions except the isthmus were significantly larger in OCD patients than in controls. CC area correlated significantly with OCD symptom severity but not illness duration. The age-related increase in CC size seen in normal subjects was absent in OCD patients. 4. These findings support theories of abnormal association cortex development in OCD but also suggest possible abnormalities of other primary cortical regions as well.

Adolescent↗
PubMed1999

Corpus callosal signal intensity in treatment-naive pediatric obsessive compulsive disorders.

1. Obsessive compulsive disorder (OCD) is increasingly recognized as a severe, highly prevalent and chronically disabling disorder, emerging during childhood in as many as 80% of cases. The authors previously found significant abnormalities in the region of the corpus callosum (CC) connecting ventral prefrontal cortex and striatum in pediatric OCD patients compared to controls that correlated significantly with OCD symptom severity. We speculated that this abnormality might reflect aberrant myelinization in OCD patients. 2. In order to better characterize the abnormality, the authors examined CC signal intensity (SI), believed to be a reliable index of myelinization of the CC. Lower numbers would indicate a greater concentration of white matter, while higher numbers indicate higher concentrations of gray matter. We compared the SI from midsagittal magnetic resonance images of 21 treatment-naive OCD patients, 7.2-17.7 years, and 21 case-matched healthy controls to examine regional CC signal intensity of the anterior, middle and posterior genu, body, isthmus, and the anterior, middle and the posterior splenii. 3. Mean total genu SI for the patient group (.993 + .006) was significantly less than the total genu SI of controls (.994 + .006) at F(1,37) = 4.73; p = .036. This abnormality in SI was localized to the CC region connecting ventral PFC and striatum, the anterior genu for the OCD group (.991 + .007) which was also less than control (.995 + .007) at F(1,37) = 5.47; p = .025., with no abnormality observed in middle or posterior genu regions. Genu SI was also inversely correlated with OCD symptom severity (r = -.55, p = .013) but not illness duration. Genu SI also correlated positively with genu area (r = .52, p = .020) in OCD patients but not controls. 4. Developmental abnormalities in genu size may arise from abnormalities in myelination in early onset OCD patients. The increased genu myelination observed in OCD patients may alter signal transduction and function of VPFC-striatal association circuits.

Adolescent↗
PubMed2001

Congenital CMV with callosal lipoma and agenesis.

An infant with symptomatic congenital Cytomegalovirus infection is reported. After the detection of abnormalities on cranial ultrasound scanning, magnetic resonance imaging of the brain revealed a complete absence of corpus callosum with a midline anterior tubulonodular lipoma. A proposed causative link between early in utero Cytomegalovirus infection and lipoma with agenesis of corpus callosum is discussed.

Agenesis of Corpus Callosum↗
PubMed2001

IFAP syndrome "plus" seizures, mental retardation, and callosal hypoplasia.

Ichthyosis follicularis, congenital alopecia, and photophobia are typical features of a rare X-linked recessive disorder termed ichthyosis follicularis with atrichia and photophobia syndrome. A 3-year-old male with these findings and severe growth failure, mental retardation, generalized seizures, vascularizing keratitis, nail anomalies, inguinal hernia, and a normal chromosome constitution is presented. Two maternal male relatives were affected by the same condition. Magnetic resonance imaging revealed corpus callosum hypoplasia not described at present. Syndromes with alopecia, seizures, and mental retardation are analyzed on the basis of genetic and clinical results.

Agenesis of Corpus Callosum↗
PubMed2000

Interhemispheric cooperation during word processing: evidence for callosal transfer dysfunction in schizophrenic patients.

Functional lateralization and interhemispheric interaction during word processing were investigated in schizophrenic patients (n=12) and matched healthy controls (n=18). Words and phonologically regular pseudowords were presented tachistoscopically either in the left or right visual field (unilateral conditions), or simultaneously in both visual hemifields (bilateral condition). Consistent with earlier findings, healthy controls showed a right visual field advantage (RVFA), indicating left-hemispheric dominance for language. The patients showed a RVFA similar to that of controls, consistent with normal left-hemispheric language dominance. Importantly, controls performed much better on words presented in the bilateral condition, when two copies of the same word appeared twice, compared to stimulation in only one of the visual hemifields. This bilateral advantage, which has been interpreted as evidence for cooperation between the hemispheres, was absent in schizophrenics. These data show that schizophrenic patients can exhibit similar lateralization patterns as healthy controls. Their specific functional deficit may be a lack of cooperation between the hemispheres.

Adult↗
PubMed2005

Callosal agenesis, chorioretinal lacunae, absence of infantile spasms, and normal development: Aicardi syndrome without epilepsy?

Aicardi syndrome is defined by the clinical triad of infantile spasms, agenesis of the corpus callosum, and pathognomonic chorioretinal lacunae. Almost all patients are females with severe cognitive and physical disabilities. All of the cases reported in the literature have had early-onset seizures. Most cases of Aicardi syndrome exhibit very slow development, even when seizures are eventually controlled, and the cases with a relatively favourable outcome are associated with low intelligence quotient levels. A relationship between chorioretinal changes or severity of the agenesis of the corpus callosum and prognosis of Aicardi syndrome has been claimed, but few data are available about the clinical features that can predict clinical outcome. We describe a case of Aicardi syndrome in a female aged 24 months. Magnetic resonance imaging showed complete agenesis of the corpus callosum and ophthalmoscopy revealed chorioretinal lacunae in the left eye. She had never had seizures and her psychomotor and language development were normal for age.

Corpus Callosum↗
PubMed2003

Biochemical evidence linking a putative callose synthase gene with (1 --> 3)-beta-D-glucan biosynthesis in barley.

A putative barley (1 --> 3)-beta-D-glucan synthase cDNA of 6.1 kb, which is homologous to the yeast FKS gene, was assembled from DNA fragments obtained through screening of barley cDNA and BAC libraries, and by PCR amplification. The corresponding gene, designated HvGSL1, is a member of a family of at least six genes in barley. Gene transcripts are detected at relatively high levels in early developing grain, florets, coleoptiles and roots, but not in leaves infected with a fungal pathogen. A (1 --> 3)-beta-D-glucan synthase has been purified more than 60-fold from barley suspension-cultured cells by detergent extraction, CaCl2 treatment, sucrose density gradient centrifugation and non-denaturing gel electrophoresis. The enzyme synthesizes (1 --> 3)-beta-D-glucan in vitro and is recognized by antibodies raised against a 17 kDa protein generated by heterologous expression of a fragment of the HvGSL1 cDNA. Furthermore, mass spectrometric analyses show that tryptic peptides produced by in-gel digestion of the active enzyme match peptides predicted from the gene sequence. Thus, the amino acid sequence predicted from the HvGSL1 gene has been linked with the actual amino acid sequence of an active (1 --> 3)-beta-D-glucan synthase fraction from barley.

Amino Acid Sequence↗