Reduced interhemispheric inhibition in musicians

In vivo magnetic resonance imaging has revealed that the anterior half of the corpus callosum is larger in musicians trained intensively from an early age than in untrained subjects. The corpus callosum is crucial for the coordination of bimanual motor activity, but neurophysiological correlates of morphological differences in the corpus callosum of musicians are not known. In the present study we have used transcranial magnetic stimulation (TMS) to assess interhemispheric inhibition in six adult professional musicians who began musical training at an early age. Conditioning TMS was applied to the hand area of the motor cortex of one hemisphere, followed 4-16 ms later by a test stimulus applied to the other hemisphere. Tests were performed at rest, and with the first dorsal interosseous muscle contralateral to the conditioning hemisphere voluntarily active. Conditioning TMS in musicians was 29% less effective at reducing the size of the test MEP at rest, and 63% less effective in the active condition, compared with control subjects. We conclude that transcallosal interhemispheric inhibitory circuits activated by TMS are less effective in musicians than in controls.     

胎儿胼胝体发育的超声监测

目的:探讨胎儿胼胝体生长发育规律。方法:对622例孕16～39周胎儿进行胼胝体超声检查,测量胼胝体前后径,并分析其与孕周的关系。结果:胎儿胼胝体前后径与孕周呈正相关(r=0.932,P<0.001),回归方程为:胼胝体前后径(mm)=-9.567+1.495×胎龄(周)。结论:胼胝体随孕周发育的变化规律及其正常测量数据为进一步判断病变提供了参照标准。     

Amiloride Relaxes Rat Corpus Cavernosum Relaxation In Vitro and Increases Intracavernous Pressure In Vivo

Introduction

The antihypertensive effects of thiazide diuretics such as hydrochlorothiazide are commonly associated with erectile dysfunction. The association of hydrochlorothiazide/amiloride is not associated with erectile dysfunction. The hypothesis is that amiloride has beneficial effect in penile erection and, therefore, counterbalances the hydrochlorothiazide-induced disruptive effect.

川芎嗪对离体兔阴茎海绵体平滑肌条收缩的影响

目的 初步探讨川芎嗪(Ligustrazine)对离体兔阴茎海绵体平滑肌条的舒张作用及其机制。方法 离体家兔阴茎海绵体平滑肌实验方法,观察川芎嗪对阴茎海绵体平滑肌的舒张效应,测定去氧肾上腺素(PE)和氯化钾(Ka)的浓度-效应曲线。结果 川芎嗪浓度依赖性地舒张PE诱发的阴茎海绵体平滑肌收缩作用,最大舒张效应为(74.1±6.2)％[对照组为(21.9±5.6)％,P<0.01]。不同浓度的川芎嗪可使PE和KCL的浓度-效应曲线右移,最大收缩反应降低,高浓度(0.8g/L)时抑制收缩作用更显著。结论 川芎嗪有明显的舒张阴茎海绵体平滑肌作用,并呈剂量依赖性。川芎嗪舒张阴茎海绵体平滑肌机制可能与抑制细胞外钙内流有关。     

CT appearances of haematomas in the corpus callosum in patients with subarachnoid haemorrhage

Corpus callosum heamatoma is a rare feature in subarachnoid haemorrhage (SAH), which may result from aneurysms of the anterior communicating artery (ACoA) or pericallosal artery (PCA). In 348 patients with aneurysmal SAH, bleeding from ACoA aneurysms in 88 cases produced no abnormality on CT in 7. Blood in the cistern of the lamina terminalis was the most frequent abnormality (76/88); haematomas of the septum pellucidum, confined to patients with ACoA aneurysms, were seen in 26 (30%). Rupture of PCA aneurysms in 12 patients gave rise to blood in the pericallosal cistern, anterior interhemispheric fissure and cistern of the lamina terminalis in 11. There was no blood in the septum pellucidum or the ventricular system in any case, but haematomas in the corpus callosum occurred in 8 (67%). In all of these, blood extended into the anterodorsal aspect of the callosum and spread posteriorly along its dorsal border. An identical, supracallosal pattern was seen in 2 patients (2.5%) with ACoA aneurysms, in whom haemorrhage was more extensive, with a large frontal lobe haematoma extending up from the cistern of the lamina terminalis in 1 and a haematoma of the septum pellucidum, with intraventricular extension in the other. In 8 patients (9%) with ACoA aneurysms a corpus callosum haematoma appeared to result from passage of blood up through the cistern of the lamina terminalis into the septum pellucidum and thence into the ventral aspect of the anterior corpus callosum; blood was present within the cistern, the septum and the ventricles.     

Disulfiram alters dopamine metabolism at sites in rat's forebrain as detected by push-pull perfusions

WEINER, H., C. W. SIMPSON, J. A. THURMAN AND R. D. MYERS. Disulfiram alters dopamine metabolism atsites in rat's forebrain as detected by push-pull perfusions. BRAIN RES. BULL. 3(5) 541–548, 1978.—The effect of tetraethylthiuramdisulfide (disulfiram) on the catabolism of dopamine within discrete regions of the brain was investigated in the unrestrained rat. After a guide cannula had been implanted stereotaxically, a given subcortical site was radiolabeled with ¹⁴C-dopamine (DA) by microinjecting 2.0 μCi in 2.0 μl. Successive push-pull perfusates collected from each tissue were assayed by paper electrophoresis for the separation of DA metabolites. When disulfiram, a potent aldehyde dehydrogenase (ALDH) inhibitor, was given intragastrically in a clinically efficacious dose of 200 mg, the formation of the acids DOPAC and HVA was inhibited within perfusates of the caudate nucleus and nucleus accumbens. However, following disulfiram treatment, the proportion of alcohol metabolites did not differ from the control level in the untreated rat. The level of ALDH decreased by approximately 50% in these subcortical nuclei following the inhibition of the enzyme by disulfiram. Conversely, in samples of perfusate obtained from ¹⁴C-labeled sites within inferofrontal cortex, periform cortex, diagonal band of Broca, lateral-posterior caudate nucleus, tuberculum olfactorium, lateral olfactory tract or the olfactory nuclear complex, the proportion of DA metabolites remained stable. Generally, a low rate of deamination of the exogenously injected DA occurred within perfusion sites in the ventrobasal forebrain, whereas an intermediate rate of deamination was noted in samples collected at more dorsal loci. Thus, clearcut regional differences in DA catabolism occur in the brain of the living animal, which may depend upon the characteristics of the dopaminergicrich area of the rat's brain.     

Callosal anomalies with interhemispheric cyst: expanding the phenotype

AIM: To determine the frequency and clinical features of corpus callosum hypoagenesis, dysgenesis or hypoplasia in conjunction with extraparenchymal interhemispheric cyst. METHODS: A retrospective study of clinical files and imaging records of all 2500 children referred to the University Department of Paediatrics, Catania, Italy, who underwent neuroimaging by ultrasound, computerized tomography or magnetic resonance imaging in 1992-2003. Five children (all girls, aged 2-18 y) were found to have abnormalities of the corpus callosum associated with interhemispheric cyst. RESULTS: Three cases were type 2b, one type 2c and one mixed type 2b and 2c according to the classification proposed by Barkovich et al. The onset of clinical symptoms was very early, with severe neurological involvement, seizures that were difficult to treat and profound psychomotor retardation. CONCLUSIONS: In callosal anomalies with cysts, a prevalence in females is not confined to type 2b cysts, the spectrum of abnormalities of the corpus callosum is more varied than previously recorded, and the natural history and outcome of the condition are poor with profound developmental delay and drug-resistant seizures. The finding that all the cases were of type 2 suggests that the overall phenotype is more widespread than previously thought and may present in association with other complex syndromes.     

Stereological analysis of microvascular parameters in a double transgenic model of Alzheimer's disease

Morphological alterations in microvasculature occur as a common finding in the brains of non-demented aged persons and patients with Alzheimer's disease. Quantifying the extent of this vascular pathology, however, has been complicated by systematic error (bias) associated with the applications of assumption- and model-based morphometric techniques to human and animal tissues. The current study used novel assumption- and model-free stereological approaches to quantify capillary parameters in the corpus callosum of a double amyloid precursor protein/presenilin-1 transgenic murine model of Alzheimer's disease. The results revealed significant reductions in the total number of capillary segments in white matter of transgenic mice compared to non-transgenic littermates, with no differences in total capillary length. These findings support the view that the expression of mutant human genes for beta-amyloid peptides alters the normal architecture of cerebral capillary vessels in the white matter of mouse brain, which may model microvasculature changes reported in Alzheimer's disease.     

Reversible cytotoxic edema in the splenium of the corpus callosum related to antiepileptic treatment: report of two cases and literature review

PURPOSE: Clinically silent lesions localized in the splenium of the corpus callosum (SCC) are a rare finding in the magnetic resonance imaging (MRI) of patients receiving antiepileptic drugs (AEDs). They are usually of benign character but may induce unnecessary complementary examinations if their nature is unrecognized. So far, 22 cases have been described in the literature, for which different etiologies have been proposed. We describe two further cases and discuss the probable lesion etiology. METHODS: We report two cases including a 25-year-old male patient and a 12-year-old female patient with a transient SCC lesion discovered in the context of a presurgical epilepsy evaluation. RESULTS: Comprehensive MRIs, including diffusion tensor imaging-based fiber tracking of the lesion, revealed a cytotoxic edema not disrupting neuronal fibers. Serum arginine vasopressin (AVP) measurements revealed an altered secretion during the acute phase in one patient. CONCLUSIONS: On the basis of our results, we hypothesize that the lesion consists of a cytotoxic edema, possibly induced by abrupt AED concentration changes and associated to alterations of AVP secretion.     

Comprehension of humor in primary agenesis of the corpus callosum

Individuals with agenesis of the corpus callosum (ACC) can, in some cases, perform normally on standardized intelligence tests. Nevertheless, recent studies suggest that individuals with ACC and normal IQ scores have deficits in domains of fluid and social intelligence. Anecdotal reports from families suggest diminished appreciation of the subtleties of social interactions, and deficits in the comprehension of jokes and stories. In this research, both the cartoon and narrative joke subtests of a humor test (developed by Brownell et al. [Brownell, H., Michel, D., Powelson, J., & Gardner, H. (1983). Surprise but not coherence: sensitivity to verbal humor in right-hemisphere patients. Brain and language, 18(1), 20-27] and Bihrle et al. [Bihrle, A. M., Brownell, H. H., Powelson, J. A., & Gardner, H. (1986). Comprehension of humorous and non-humorous materials by left and right brain-damaged patients. Brain and Cognition, 5(4), 399-411]) were given to 16 adults with complete ACC (all with IQs>80) and 31 controls of similar age and IQ. Individuals with ACC performed worse than controls on the narrative joke subtest (p<.025) when VIQ was controlled. However, on the cartoon subtest the two groups were not significantly different. Covarying age, forms of IQ, narrative memory, set-switching, and literal language comprehension did not substantially alter the group difference. However, covarying comprehension of nonliteral language and proverbs eliminated the difference, suggesting a common origin for the comprehension of jokes, nonliteral language, and proverbs, most likely related to capacity for understanding second-order meanings.