摘要:

WE investigated the spatio-temporal brain activity on the time scale of several milliseconds related to the mental rotation task requiring judgements of hand orientation, using a whole-cortex MEG (magnetoencephalography) system. Neuronal activity in the visual cortex was observed ∼100–200 ms from stimulus onset, and that in inferior parietal lobe followed (after 200 ms). Both of these activities showed a contralateral dominance to visual stimulus hemifield. Premotor activity started later than the inferior parietal lobe activity, and these activities partially overlapped. Activity in primary motor and/or motosensory areas was observed in some subjects. The whole-cortex neuromagnetic measurements provided the time course of activity in the human brain associated with the implicit motor imagery: visual cortex ← inferior parietal lobe ↔ premotor cortex. This process is considered to be the transformation process of retinotopic locations into a body-centered reference frame necessary for the mental rotation task.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

THE role of neuronal damage in the radiation-induced CNS injury resulting from brain tumor therapy remains poorly understood. To begin to define the radioresponse of neurons, the survival of rat cortical neuron cultures was investigated. Neuronal survival was reduced by ∼40% 24–48 h after irradiation with 3.5 Gy. The addition of the free radical scavenger NAC after irradiation increased neuronal survival. Neurons were also significantly less sensitive to radiation in co-cultures with astrocytes or in the presence of astrocyte-conditioned medium. Medium conditioned on astrocytes was found to acquire significant free radical scavenging capability. However, this antioxidant property does not appear to be responsible for neuronal radioprotection. The ability of astrocytes to reduce radiation-induced neuronal toxicity appears to be mediated by a soluble protein(s) of mol. wt > 10 kDa.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

A-HT2Areceptor promoter polymorphism, −1438G/A, was reported to be significantly increased in patients with anorexia nervosa when compared with controls. In practice, many patients with anorexia nervosa suffer from mood disorders. Furthermore, 5-HT2Areceptors are thought to play a role in the etiologies of mood disorders. Thus, we studied the polymorphism in 95 Japanese patients with mood disorders and 106 healthy Japanese controls. The allele frequency for the −1438G/A polymorphism did not differ between the patients and controls. In addition, the genotype frequencies did not differ according to the subdiagnosis, age of onset, family history of psychiatric illness or suicide attempts.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

HUMAN motor neuron (MN) isolation provides a critical tool to study neurophysiological properties and the effects of molecules of clinical relevance on isolated neurons. We developed an immunomagnetic separation technique based on specific MN antigen recognition for nerve growth factor receptor (p75-NGFR). We cultured an average of 250 000 cells from the anterior horns of a single cord (four specimens at postconception Weeks 6.0, 7.2, 8.0, and 8.3). At day 7in vitro(DIV), choline acetyltransferase (ChAT) and/or p75-NGFR-expressing cells (MNs) represented 72 ± 2% of the total growing cells. MNs survived for at least 4 weeks in biochemically defined medium. The immunomagnetic separation method has been demonstrated to be effective, reproducible, and quantitative for separation of MNs.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

INTERACTIONS of L-triiodothyronine (T3) in adult rat cerebrocortical synaptosomes were studiedin vitro.Scatchard plot analysis revealed two sets of T3binding sites. The degree of saturation of T3binding sites (putative receptor) correlated well with the dose-dependent inhibition of Na+-K+-ATPase activity in synaptosomes. The relative binding affinities and relative inhibition of enzyme activities for different TH analogues were L-T3> T3-amine > TRIAC = L-T4> r-T3> T2and L-T3> T3-amine > TRIAC > L-T4> r-T3> T2, respectively. The present study demonstrates the nature of inhibition of synaptosomal Na+-K+-ATPase activity may be as a function of T3occupancy of synaptosomal receptor sites in adult mammalian brain.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

PATIENTS with chronic fatigue syndrome (CFS) report cognitive difficulties (impaired attention, memory and reasoning). Neuropsychological tests have failed to consistently find cognitive impairments to the degree reported by CFS patients. We tested patients with CFS and sedentary controls in protocols designed to measure sensory reactivity and acquisition of the classically conditioned eyeblink response. Patients with CFS exhibited normal sensitivity and responsivity to acoustic stimuli. However, CFS patients displayed impaired acquisition of the eyeblink response using a delayed-type conditioning paradigm. Sensitivity and responsivity to the airpuff stimulus were normal. In the absence of sensory/motor abnormalities, impaired acquisition of the classically conditioned eyeblink response indicates an associative deficit. These data suggest organic brain dysfunction within a defined neural substrate in CFS patients.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

WE used a digoxigenin-UTP-labeled cRNA probe within situhybridization and Northern blot analysis to investigate the localization of brain derived neurotrophic factor (BDNF) mRNA and expression of its different transcripts in adult rat hypothalamus. As the BDNF gene is under the control of alternative multiple promoters, which provide tissue-specific gene expression, we studied whether these transcripts were expressed in adult hypothalamus. Our data revealed two novel sources of hypothalamic BDNF mRNA: the supraoptic and periventricular nuclei. In addition, we observed the expression of transcripts from exons I, II and III as well as the presence of 1.6 and 4.2 kb BDNF mRNAs. Finally, our findings confirmed expression of mRNA encoding neurotrophins receptors in the hypothalamus.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

To investigate the role of Group I mGluRs in allodynia and hyperalgesia, we examined the behavioural responses of rats to noxious and non-noxious mechanical and thermal stimuli following intrathecal (i.t.) treatment (25 nmol) with the selective mGluR1/5agonist, (RS)-dihydroxyphenylglycine ((RS)-DHPG). (RS)-DHPG administration produced a persistent decrease in response latency on a 48°C hotplate, a reduction in the 50% response threshold to von Frey hairs, and an increase in responses to a tail pinch. These data suggest that activation of spinal mGluR1/5receptors plays a role in the development of persistent allodynia and hyperalgesia associated with tissue or nerve injury.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

APOPTOSIS is a programmed cell death that occurs during the development of the nervous system and in neurodegenerative disorders. Tau protein is a microtubule-associated protein which promotes microtubule polymerization and stabilization. Apoptosis was induced in primary neuronal cultures by glutamate exposure (200 μM, 15 min) or by serum deprivation, and tau mRNA levels were studied by quantitative in situ hybridization in apoptotic and non apoptotic neurons. Compared to controls, tau mRNA expression was decreased in apoptotic neurons produced by excitotoxicity or trophic support withdrawal. Under these conditions, resistant neurons to apoptosis display either increased tau mRNA levels after glutamate exposure or a stable tau mRNA expression after serum deprivation. In conclusion, in thisin vitromodel, neurons which are resistant and sensitive to apoptosis can be differentiated according to tau mRNA expression.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

CELL death by apoptosis occurs in mature neurones of adult rat dentate gyrus following adrenalectomy. In these studies, apoptosis in the dentate gyrus was induced 3 days after adrenalectomy in male Fischer 344 rats ranging in age from 2–3 to 24–26 months. Glial fibrillary acidic protein and transforming growth factor-β1 mRNAs were increased in dentate gyrus of all age groups after adrenalectomy, but there was no effect of age on these responses. Furthermore, corticosterone treatment in the drinking water of adrenalectomized rats prevented both cell death and increases in glial mRNAs in all age groups that were tested (up to 16–18 months). Therefore, adrenalectomy-induced apoptosis can be used to study mechanisms of cell death and survival in aged brain.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID