摘要:

The hypothesis that sleep participates in the consolidation of recent memory traces has been investigated using four main paradigms: (1) effects of post-training sleep deprivation on memory consolidation, (2) effects of learning on post-training sleep, (3) effects of within sleep stimulation on the sleep pattern and on overnight memories, and (4) re-expression of behavior-specific neural patterns during post-training sleep. These studies convincingly support the idea that sleep is deeply involved in memory functions in humans and animals. However, the available data still remain too scarce to confirm or reject unequivocally the recently upheld hypothesis that consolidations of non-declarative and declarative memories are respectively dependent upon REM and NREM sleep processes.

ISSN:0959-4965    

出版商:OVID    

年代:2001

数据来源: OVID

ISSN:0959-4965    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

We investigated the effect of manganese on the morphology of cultured rat cortical astrocytes. Astrocytes exhibited flattened, polygonal morphology in the absence of stimulation, and differentiated into process-bearing stellate cells following exposure to MnCl2. MnCl2-induced stellation was a reversible process, which depended on the presence of extracellular free manganese. MnCl2-induced stellation did not stop with the introduction of pertussis toxin, PD98059, SB203580, phorbol 12-myristat 13-acetate, SQ22536, or LY83583. Alternatively, MnCl2-induced stellation did stop when exposed to colchicine and sodium orthovanadate, suggesting the involvement of the cytoskeletal elements and orthovanadate-sensitive protein tyrosine phosphatase. MnCl2might function as a factor regulating astrocyte morphology.

ISSN:0959-4965    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

We prospectively studied 5 patients while they were recovering from left-sided subcortical stroke affecting the cortico-spinal tract, and examined them twice with H215O-PET over several months while performing an identical task with the affected hand. Concomitant motor recovery was assessed by measuring the number of thumb-to-index tappings performed in 15 s at each PET session. Across patients, the hemispheric activation balance tended to shift over time toward the unaffected hemisphere, but the magnitude of this shift was highly variable from patient to patient and significantly correlated with recovery. Thus, in subcortical stroke, a shift of activation balance towards the unaffected hemisphere appears associated with lesser initial recovery and, conversely, the more this physiological balance is maintained over time the better the recovery.

ISSN:0959-4965    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Diffuse neurofibrillary tangles with calcification (DNTC) is a form of presenile dementia, characterized pathologically by fronto-temporal atrophy with neurofibrillary tangles (NFTs), neuropil threads and Fahr-type calcification, in which no senile plaques are observed. As already noted, chronic exposure to lead (Pb) might be one of the etiological factors of Fahr-type calcification. Until now, there have been no reports in which Pb concentration has been quantified in DNTC brains. We examined the concentration of Pb in fresh-frozen brain tissue and in 10% formalin-fixed brain tissue from six cases of DNTC, four cases of Alzheimer's disease, and in nine non-demented elderly controls by flameless atomic absorption spectrometry, and demonstrated a high concentration of Pb in DNTC brains. Although it remains unclear how these findings are related to the formation of NFTs, they suggest that Pb neurotoxicity may be involved in the pathogenesis of DNTC.

ISSN:0959-4965    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

To detect retinotopic activation in the human V5/MT, we obtained fMRI signals during optokinetic responses (OKR). We used two types of patterns, consisting of random dots plotted in either the central or peripheral regions, to stimulate the central and peripheral visual fields, respectively. These patterns moved at a constant speed of 20°/s rightward and leftward alternately. Subjects were required to track the patterns with their eyes. The two types of visual stimuli elicited different patterns of brain activation; the area with the most significant response to central visual field stimuli was located posteriorly to that responding to peripheral visual field stimuli.

ISSN:0959-4965    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

During development, astrocytes in the ventrobasal thalamus display spontaneous intracellular calcium [Ca2+]ioscillations, that can lead to the excitation of adjacent thalamocortical neurons via an NMDA receptor-mediated mechanism. In this study, we show that while astrocytes usually exhibit oscillations of irregular amplitude and frequency, a subset of spontaneously active thalamic astrocytes exhibits rhythmic, i.e. pacemaker, [Ca2+]ioscillations with an average frequency of 0.019 Hz. This frequency of the pacemaker oscillations is close to the modal frequency of the irregularly oscillating astrocytes, suggesting that there is a preferred frequency for astrocytic [Ca2+]ioscillations. If pacemaker [Ca2+]ioscillations underlie excitatory signaling to neurons, the result would be rhythmic activation of thalamocortical neurons and astrocyte-driven synchronized oscillations within neurons of the thalamocortical loop.

ISSN:0959-4965    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Patients with parkinsonism–dementia complex (PDC) of Guam showed moderate loss of choline acetyl transferase activity in the midfrontal and inferior parietal cortex, and severe loss in the superior temporal cortex. This deficit was similar to that seen in Alzheimer's disease and less severe than Lewy body disease. Thus, cholinergic deficits in the neocortex might contribute to some of the cognitive alterations in PDC of Guam.

ISSN:0959-4965    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Adjuvant-induced arthritis (AIA) is a widely used animal model of human rheumatoid arthritis (RA). We have previously shown that increased neuropeptide expression is observed in the spinal cord of AIA rats. To study the potential role of cytokines in the spinal cord of AIA, we wanted to determine whether there are changes of glial and cytokine expression (IL-1β, IL-6, TNF-α and IFN-γ) in the spinal cord of AIA rats. Our data indicated that macroglia and MHC class II immunostaining were enhanced, astrocytes expressing GFAP were increased in number and immunostaining intensity. Usingin situhybridization and immunohistochemical methods, both mRNA and protein levels of IL-1β, IL-6 and TNF-α were significantly increased in the spinal cord of arthritic rats. Increased cytokine expression was presented in the reactive astrocytes and microglia.

ISSN:0959-4965    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Serotonin reuptake inhibitors used for the treatment of depression act by increasing serotonin levels at the synaptic cleft and thereby activating 5-HT1Aserotonin receptors. However, the effect of increased levels of serotonin on postsynaptic 5-HT1Areceptor density is unknown. The purpose of this study was to investigate, in a culture model, how postsynaptic 5-HT1Areceptors are influenced by serotonin. Different concentrations of serotonin (0.5, 1, 10, 50 and 100 μM) were added to organotypic hippocampal cultures and incubated for 1 week. The cultures were immunostained for the 5-HT1Areceptor and the staining analyzed densitometrically. 5-HT1Alevels decreased with increasing serotonin concentrations, being significant at 10, 50 and 100 μM. These results indicate that at increasing serotonin levels the density of postsynaptic 5-HT1Areceptors is down-regulated.

ISSN:0959-4965    

出版商:OVID    

年代:2001

数据来源: OVID