摘要:

On 27 December 2001 the neuroscience community lost one of its most influential and enthusiastic emissaries. The many tributes that we have received atNeuroReportare testimony to the deep regard and affection in which David was held. In this issue, we publish an appreciation of David's contribution to science by Professor Tomas Hökfelt and a personal recollection by Dr Ivan Klimeš, the publisher who worked with David to foundNeuroReport12 years ago.

ISSN:0959-4965    

出版商:OVID    

年代:2002

数据来源: OVID

ISSN:0959-4965    

出版商:OVID    

年代:2002

数据来源: OVID

ISSN:0959-4965    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

We examined the role of main and external cuneate nuclei neurons in processing sensory information during forelimb passive movement. We recorded activity of neurons using circular and figure-eight trajectories, at different speeds, in anaesthetized rats. A multivariate regression analysis was performed to correlate neural discharge to movement direction and speed, the two components of the velocity vector. We found that the activity of the majority of cuneate neurons related to passive movement velocity and that the directional component of the velocity vector accounted for a larger fraction of the variability in the firing rate than the scalar component (speed). These results indicate that cuneate cells can process whole limb afferent information to elaborate a representation of the movement velocity vector.

ISSN:0959-4965    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Maternal hypothyroidism in the rat compromises&agr;-internexin (&agr;-IN) expression in early fetal brain. We have therefore examined whether 3,5,3′-triiodothyronine (T3) regulates&agr;-IN expression in fetal brain neurons in culture. Cells expressed transcripts encoding T3 nuclear receptor isoforms in a T3-independent manner.&agr;-IN protein abundance was increased in cultures treated with 0.1 and 1 nM T3 for 20 h (177 and 185% control, respectively) and in cultures treated with 1 nM T3 for 40 h (131% control).&agr;-IN transcript abundance was unaffected by T3 treatment. In conclusion, T3 at a physiological level, stimulates&agr;-IN protein, but not mRNA, levels in early differentiating neurons in culture. This supports the hypothesis that maternal thyroid hormone directly regulates early neuronal differentiation.

ISSN:0959-4965    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Inflammation and neuronal degeneration of the substantia nigra (SN) occur in Parkinson's disease (PD). We studied the effects of intranigral lipopolysaccharide (LPS) injection on adult Sprague–Dawley rats. Locomotor activity measurement, neurotransmitter determination and perfusion fixation for immunohistochemistry were done on the 7th day. Bilateral LPS injection increased locomotor activity 2- to 3-fold. In the SN, dopamine (DA) and serotonin (5-HT) decreased but the ratios dihydroxyphenylacetic acid (DOPAC)/DA, homovanillic acid (HVA)/DA and 5-hydroxyindole-acetic acid (5-HIAA)/5-HT increased. In the striatum, DA, DOPAC, HVA, 3-methoxytyramine and epinephrine decreased but HVA/DA and 5-HIAA/5HT ratios increased. Unilateral LPS decreased dopamineric neurons ipsilaterally but increased contralaterally. This study provides the first evidence of behavioral hyperactivity, epinephrine suppression and neuronal plasticity in the LPS model of PD.

ISSN:0959-4965    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Evidence from multiple paradigms has converged on the finding that stimulus repetition most often results in decreases in neural activity. The mechanisms of these decreases, however, are not yet well understood. The current study attempted to determine, through the use of masked word repetition priming, whether decreases in activity levels occur in response to pre- or post-prime identification processes. fMRI was performed while participants engaged in a lexical decision task where words were primed with a briefly presented and masked word. Masked word priming resulted in increased fMRI signal in regions of cortex associated with the perceptual identification of the target words. This finding provides evidence suggesting that the impact of repetition priming on the fMRI signal may depend upon whether or not the prime is identified.

ISSN:0959-4965    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

We sought to identify genes affected by the aging process in the rat hippocampus using cDNA expression array analysis. RNA samples were extracted from the hippocampus of 2-month-old and 20-month-old rats and reverse-transcribed in the presence of [32P]dCTP. Membrane sets of Rat Atlas array 2 (Clontech) were hybridized with cDNA probe sets. Among a total of 1176 cDNAs, 23 showed significant (more than 2-fold) changes between groups. Eight genes were increased in the old group, while the remaining fifteen genes were decreased. Reverse transcription-polymerase chain reaction (RT-PCR) was used to validate the relative expression pattern obtained by the cDNA array. The results were consistent for 20 of the 23 genes tested. Most interesting findings were the decrease in expression of proteins for energy metabolism, proteins involved in secretion, and ribosomal proteins. The possible physiological significance of these changes are discussed.

ISSN:0959-4965    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Binocular cells in area 19 are tuned to positional disparities. In effect, up to one-third of the cells respond preferentially to small incongruities between the optimal bar stimuli presented within the receptive fields of each eye. The aim of the present study was to determine whether cells in area 19 are also sensitive to phase disparities. Both types of disparities have been proposed as mechanisms through which stereoperception is achieved. Results indicate that phase disparities produced coherent interactions in 38% of the binocular cells, resulting in facilitation or summation. The remaining cells were phase insensitive. The overall results suggest that cells in area 19 code phase disparities in a proportion comparable to stimulus disparities, confirming that this area is implicated in binocular integration, albeit in a relatively smaller proportion than some of the other visual areas.

ISSN:0959-4965    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Proliferation, cell death and differentiation occur simultaneously in developing retina and are precisely orchestrated. We have studied the effects of biotin (vitamin H) on early retinal development.In vivoadministration of biotin to early embryonic chick eyes at moderately elevated levels induced malformations, affecting retina and lens structures. The effects were strictly age dependent and were only found in embryos treated between Hamburger and Hamilton stage 14–17. Biocytin, a biotin analogue, mimicked biotin effects, while avidin could block the effects. At the cellular level, biotin did not affect proliferation but reduced apoptosis. These results suggest that an adequate content of biotin and a precise regulation of retinal cell death are required for the correct morphogenesis of the eye.

ISSN:0959-4965    

出版商:OVID    

年代:2002

数据来源: OVID