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531.
In rapid streams of visual stimuli, identification of a first target interferes with identification of a second target presented within the next half second (the attentional blink or AB). It has been suggested that rapid perceptual decisions under masking interference involve interactions between frontal and posterior cortex. We investigated the neural correlates of the AB using functional magnetic resonance imaging (fMRI). Twelve subjects viewed rapid streams of black letters in which were embedded two white target letters (T1 and T2) separated by either 300 or 700 ms. As expected, fewer correct T2 identifications were observed in the short-delay condition. Corresponding fMRI statistical images showed increased activation in inferotemporal and posterior parietal cortex, but also in lateral frontal cortex and cerebellum in the short-delay condition suggesting that these brain regions are associated with perceptual decisions under masking interference. 相似文献
532.
Spatial learning in the 5-HT1B receptor knockout mouse: selective facilitation/impairment depending on the cognitive demand 下载免费PDF全文
Buhot MC Wolff M Benhassine N Costet P Hen R Segu L 《Learning & memory (Cold Spring Harbor, N.Y.)》2003,10(6):466-477
Age-related memory decline is associated with a combined dysfunction of the cholinergic and serotonergic systems in the hippocampus and frontal cortex, in particular. The 5-HT1B receptor occupies strategic cellular and subcellular locations in these structures, where it plays a role in the modulation of ACh release. In an attempt to characterize the contribution of this receptor to memory functions, 5-HT1B receptor knockout (KO) mice were submitted to various behavioral paradigms carried out in the same experimental context (water maze), which were aimed at exposing mice to various levels of memory demand. 5-HT1BKO mice exhibited a facilitation in the acquisition of a hippocampal-dependent spatial reference memory task in the Morris water maze. This facilitation was selective of task difficulty, showing thus that the genetic inactivation of the 5-HT1B receptor is associated with facilitation when the complexity of the task is increased, and reveals a protective effect on age-related hippocampal-dependent memory decline. Young-adult and aged KO and wild-type (WT) mice were equally able to learn a delayed spatial matching-to-sample working memory task in a radial-arm water maze with short (0 or 5 min) delays. However, 5-HT1BKO mice, only, exhibited a selective memory impairment at intermediate and long (15, 30, and 60 min) delays. Treatment by scopolamine induced the same pattern of performance in wild type as did the mutation for short (5 min, no impairment) and long (60 min, impairment) delays. Taken together, these studies revealed a beneficial effect of the mutation on the acquisition of a spatial reference memory task, but a deleterious effect on a working memory task for long delays. This 5-HT1BKO mouse story highlights the problem of the potential existence of "global memory enhancers." 相似文献
533.
Lostao L Joiner TE Lester D Regidor E Atach P Sandín B 《Suicide & life-threatening behavior》2006,36(1):113-119
In this study we analyzed the socioeconomic differences in mortality from suicide in the economically active male population aged 25-64 years in Spain and France in 1980-1982 and 1988-1990; in the case of Spain the data came from the Eight Provinces Study (Regidor, Gutierrez-Fisac, & Rodríguez, 1995). Individuals were grouped into four categories: professional/managerial, clerical/sales/ service, agricultural, and manual workers. For 1980-1982, among those aged 25-44, professionals and managers had the lowest risk of mortality in Spain, and clerical/sales/service workers in France. These socioeconomic differences in mortality increased in 1988-1990. In 1980-1982, among those aged 45-64, clerical/ sales/service workers had the lowest risk of mortality from suicide relative to the other occupational groups in both countries, but this difference was not maintained in 1988-1990. Thus, differences in suicide mortality for men by occupational status depended in the present study upon both the nation studied and the time period chosen for study. 相似文献
534.
Effects of sleep deprivation on Color-Word, Emotional, and Specific Stroop interference and on self-reported anxiety 总被引:5,自引:0,他引:5
Sagaspe P Sanchez-Ortuno M Charles A Taillard J Valtat C Bioulac B Philip P 《Brain and cognition》2006,60(1):76-87
The aim of this study was principally to assess the impact of sleep deprivation on interference performance in short Stroop tasks (Color-Word, Emotional, and Specific) and on subjective anxiety. Subjective sleepiness and performance on a psychomotor sustained attention task were also investigated to validate our protocol of sleep deprivation. Twelve healthy young subjects were tested at four-hourly intervals through a 36-h period of wakefulness under a constant routine protocol. Analyses of variance for repeated measurements revealed that self-assessment of sleepiness on a visual analogue scale as well as mean reaction time performance on the sustained attention task, both for the first minute and for 10 min of testing, were worsened by sleep deprivation. Analyses revealed an increase in self-reported anxiety scores on the STAI questionnaire but did not reveal any significant effect after sleep deprivation either on indexes of interference or on accuracy in Stroop tasks. However, analyses showed sensitivity to circadian effect on verbal reaction times in the threat-related (Emotional) and sleep-related (Specific) Stroop tasks. We concluded that 36 h of prolonged wakefulness affect self-reported anxiety and Emotional Stroop task resulting in a cognitive slowing. Moreover, total sleep deprivation does not affect interference control in any of the three short Stroop tasks. 相似文献
535.
We used electrophysiological methods to track the deployment of visual spatial attention while observers were engaged in concurrent central attentional processing, using a variant of the attentional blink paradigm. Two visual targets (T1, T2) were presented at a stimulus onset asynchrony of either 200 ms or 800 ms. T1 was a white digit among white letters presented on a dark background using rapid serial visual presentation at fixation. T2 was another digit that was presented to the left or right of fixation simultaneously with a distractor digit in the opposite visual field, each followed by a pattern mask. In each T2 display, one digit was red and one was green. Half of the subjects reported the red digit and ignored the green one, whereas the other half reported the green digit and ignored the red one. T1 and T2 were reported in one block of trials, and only T2 in another block (order counterbalanced across subjects). Accuracy of report of T2 was lower at short SOA than at long SOA when both T1 and T2 were reported, but was similar across SOA when only T2 was reported. The electrophysiological results focused on the N2pc component, which was used as an index of the locus of spatial attention. N2pc was reduced in amplitude when subjects reported T1, and particularly so at the short SOA. The results suggest that attention to T1 interfered with the deployment of visual spatial attention to T2. 相似文献
536.
Hotermans C Peigneux P Maertens de Noordhout A Moonen G Maquet P 《Learning & memory (Cold Spring Harbor, N.Y.)》2006,13(5):580-583
Motorskill learning is a dynamic process that continues covertly after training has ended and eventually leads to delayed increments in performance. Current theories suggest that this off-line improvement takes time and appears only after several hours. Here we show an early transient and short-lived boost in performance, emerging as early as 5-30 min after training but no longer observed 4 h later. This early boost is predictive of the performance achieved 48 h later, suggesting its functional relevance for memory processes. 相似文献
537.
Nguyen L Borgs L Vandenbosch R Mangin JM Beukelaers P Moonen G Gallo V Malgrange B Belachew S 《Mental retardation and developmental disabilities research reviews》2006,12(2):85-96
In white matter disorders such as leukodystrophies (LD), periventricular leucomalacia (PVL), or multiple sclerosis (MS), the hypomyelination or the remyelination failure by oligodendrocyte progenitor cells involves errors in the sequence of events that normally occur during development when progenitors proliferate, migrate through the white matter, contact the axon, and differentiate into myelin-forming oligodendrocytes. Multiple mechanisms underlie the eventual progressive deterioration that typifies the natural history of developmental demyelination in LD and PVL and of adult-onset demyelination in MS. Over the past few years, pathophysiological studies have mostly focused on seeking abnormalities that impede oligodendroglial maturation at the level of migration, myelination, and survival. In contrast, there has been a strikingly lower interest for early proliferative and differentiation events that are likely to be equally critical for white matter development and myelin repair. This review highlights the Yin and Yang principles of interactions between intrinsic factors that coordinately regulate progenitor cell division and the onset of differentiation, i.e. the initial steps of oligodendrocyte lineage progression that are obviously crucial in health and diseases. 相似文献
538.
Does the mastery of center-embedded linguistic structures distinguish humans from nonhuman primates?
In a recentScience article, Fitch and Hauser (2004; hereafter, F&H) claimed to have demonstrated that cotton-top tamarins fail to learn an artificial
language produced by a phrase structure grammar (Chomsky, 1957) generating center-embedded sentences, whereas adult humans
easily learn such a language. We report an experiment replicating the results of F&H in humans but also showing that subjects
learned the language without exploiting in any way the center-embedded structure. When the procedure was modified to make
the processing of this structure mandatory, the subjects no longer showed evidence of learning. We propose a simple interpretation
for the difference in performance observed in F&H’s task between humans and tamarins and argue that, beyond the specific drawbacks
inherent in F&H’s study, researching the source of the inability of nonhuman primates to master language within a framework
built around Chomsky’s hierarchy of grammars is a conceptual dead end. 相似文献
539.
Wietrzych M Meziane H Sutter A Ghyselinck N Chapman PF Chambon P Krezel W 《Learning & memory (Cold Spring Harbor, N.Y.)》2005,12(3):318-326
Retinoid signaling has been recently shown to be required for mnemonic functions in rodents. To dissect the behavioral and molecular mechanisms involved in this requirement, we have analyzed the spatial and recognition working memory in mice carrying null mutations of retinoid receptors RARbeta and RXRgamma. Double mutants appeared deficient in spatial working memory as tested in spontaneous alternation in the Y-maze and delayed nonmatch to place (DNMTP) test in the T-maze. These mutant mice did acquire, however, spatial place reference or right/left discrimination tasks in the T-maze set-up, indicating that basic sensorimotor functions, spatial orientation, and motivational factors are unlikely to account for deficits in working memory-sensitive tasks. Double-mutant mice were also deficient in novel object recognition at intermediate, but not short delays. RXRgamma appeared to be the functionally predominant receptor in modulation of the working memory, as RXRgamma, but not RARbeta single null mutant mice exhibited deficits similar to those observed in the double mutants. The mechanism of this modulation is potentially related to functions of RXRgamma in frontal and perirhinal cortex, structures in which we detected RXRgamma expression and which are functionally implicated in working memory processes. 相似文献
540.
Working memory (WM) span tasks involving a complex activity performed concurrently with item retention have proven to be good
predictors of high-level cognitive performance. The present study demonstrates that replacing these complex self-paced activities
with simpler but computer-paced processes, such as reading successive letters, yields more predictive WM span measures. This
finding suggests that strategic factors do not contribute to be relationship between WM spans and high-level cognition. 相似文献