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The authors assessed immediate repetition effects on event-related potentials (ERPs) while participants performed familiarity decisions for written personal names. For immediately repeated familiar names, the authors observed 3 distinct ERP modulations. At 180-220 ms, a posterior N200 effect occurred for names preceded by same-font primes only. In addition, an increased left temporal negativity (N250r, 220-300 ms) and a reduced central-parietal negativity (N400, 300-400 ms) were seen both for same-font and different-font repetitions. In a 2nd experiment, when names were preceded by either their corresponding face or the face of a different celebrity, only the N400 effect was preserved. These findings suggest that the N200, N250r, and N400 effects reflect facilitated processing at font-specific featural, lexical, and semantic levels of processing, respectively.  相似文献   

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This paper reviews and discusses basic knowledge of biochemical mechanisms of action of ethanol upon the central nervous system, the emphasis being on effects upon cerebral membrane structures and processes as well as mechanisms of chemical synaptic transmission. Results of detailed studies into material and steric changes in membranes, ion-dependent adenosine triphosphatases, variations in ion balance, effects upon cyclic nucleotides, influences on special transmitter systems, and mechanisms of formation of morphine-analogous condensation products are presented. In addition, open questions are derived and formulated in problem complexes.  相似文献   

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The effect of hypothermia on the retention of the water tank navigation task has been examined in 21 male hooded rats. After a 3-min swimming test on Day 1 the animals were trained on Days 2 and 3 (2 X 12 trials) to find a small submerged platform 1 cm below the surface of a large pool (120 cm in diameter) of opaque water. On Day 4, the rats were divided into three groups (n = 7) which were cooled to colonic temperatures of 22-24 degrees C (H1), 25-27 degrees C (H2), and 28-31 degrees C (H3), respectively, and given 12 retrieval trials in the water tank. Average escape latencies increased from 6 s in normothermic rats on Day 3 to 33, 19, and 12 s on Day 4 in the H1, H2, and H3 groups, respectively. Under the same testing conditions the performance of groups H1, H2, and H3 improved on Day 5 to 20, 8 and 6 s, respectively. It is concluded that spatial memory retrieval is resistant to mild hypothermia (30 degrees C), but that it is severely impaired at body temperatures below 25 degrees C. Reacquisition of the task is slowed down but not fully prevented in deep hypothermia.  相似文献   

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Critics of the moral panic dismiss this extremely useful, often-cited, and durable concept on the basis of inapplicable criteria. Drawing on the example of LSD use in the sixties, these critics mistakenly assume that the disaster analogy is apt, insisting that the threat to society, and society's responses, be very much like victims trapped in a burning building. In addition to the fact that the introduction of a new and potentially harmful drug into a society does not entail an on-the-spot threat or reaction, the natural disaster does not typically involve a folk devil or deviant. But the supposed threat of LSD use did entail sensitization, stereotyping, exaggeration, the rush to judgment, sensational anecdotes, and bogus claims. The moral panic notion continues to illuminate social processes and deserves to remain in the sociologist's conceptual tool-box.  相似文献   

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The methodical procedure for the determination of the F-wave conductivity in the ulnar nerve (in total - conductivity, afferent, conduction frequency forearm, afferent-efferent in the proximal segment of the peripheral motor neuron) and the results of a hundred examinations are presented. The results are compared with the motor nerve conduction velocity. No influences of sex, age or the site of lead could be discovered.  相似文献   

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Although the N400 ERP component has been extensively studied in younger adults, the underlying mechanisms are still unclear. In older adults, N400 ERP studies have shown less efficient use of context compared to younger adults. Here, we asked whether the mechanisms underlying the N400 effect are the same in terms of predictiveness and congruency in younger and older adults. We used a simple picture-word matching task in which we crossed predictiveness and congruency. Our results indicate a three-way interaction between predictiveness, congruency, and age, in that, younger adults showed an N400 effect only in strongly constrained conditions; whereas, older adults showed an effect in both strongly- and weakly constrained conditions. This interaction was not modulated by language experience or cognitive decline. Our results support either two separate mechanisms (lexical access and integration) that run in parallel and are modulated by age or a common prediction error mechanism that changes with age.  相似文献   

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Previously it has been shown that single episode of 2 h restraint produced behavioral deficits in rats which were not observed following daily restraint period of 2h/day for 5 days. It was suggested that adaptation to a stress schedule develops when the similar stress is administered repeatedly. In view of a role of 5-hydroxytryptamine (5-HT) in adaptation to stress the present study concerns effects of a 5-HT-1A agonist 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT) on the synthesis of 5-HT in brain regions of rats adapted to a repeated restraint stress schedule of 2h/day for 5 days. The drug injected systemically at a dose of 1 mg/kg decreased 5-HT synthesis in the hypothalamus, cortex, hippocampus, striatum and raphe regions of previously unrestrained rats. These decreases were either smaller (raphe) or not observed (hypothalamus, cortex and hippocampus) in most brain regions of rats adapted to the repeated restraint stress schedule of 2h/day for 5 days. These results suggest that a subsensitive negative feedback effect on the synthesis of 5-HT leading to an increase in synaptic 5-HT concentration might help coping with stress demand to produce adaptation to stress.  相似文献   

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The methods of nuclear medicine and electro-encephalography allow, in combination, in almost every case the answer to the question of the cerebral tumour relapse. Our evaluation confirms the discovery of the greater sensitivity of the isotopic methods with relapses of glioblastomas, while relapses of meningiomas, astrocytomas, oligodendrogliomas and spongioblastomas can be recognized more frequently only by electro-encephalographic methods. The value of angiography is limited in cases of cerebral tumour relapses without pathological vascularisation, since the swelling can spread in the resection cavity without retroaction on the surrounding areas. For this reason vascular displacement (an only be observed very late on. Clinical judgement is furthermore complicated by the fact that after the removal of the primary tumour, often no reposition of the arteries ensues. After our exainations, a negative angiographic condition can be rule out a diagnosis of a relapse which has been established by electro-encephaolographic and isotopic methods.  相似文献   

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以往对咸卦的解读多不能切近其本义。事实上,咸卦的主题是讲交往处事的道理或原则。关于卦辞,传统解读多基于男女相感来理解,其实卦辞着重强调的是屈身虚己、礼贤下士。关于初爻,诸家均未着眼于足拇趾与其他足趾的不同去体会“拇”的本质特征。依此角度理解,初爻讲的是要重视与外界的交往。解卦九四亦取“拇”象,且与“朋”象相合,比喻能力再强者遇到险难时往往也需要他人的配合支持。关于二爻,诸家多以腓体躁动取象,认为二爻“感物以躁”乃“凶之道”,实则二爻取象腿肚抽筋,喻勿与坏人、恶人相交。艮卦六二亦与腿肚抽筋有关,喻本当止而不得止之,是以有憾。关于三爻,诸家多以股随足或随身而动,不能自处,喻人无主见而听任摆布,基本得其正解。艮卦九三不取股象而取腰限之象,体现了取象的唯变所适之理,喻本不当止而强止之,将会导致严重后果。关于四爻,诸家皆以九四为有心之感而未及无心之感,其实四爻讲的是交往处事要心思端正、以心交心。关于五爻,诸家皆未抓住脢的本质特征。该爻实则是讲交往处事要有奉献精神,甘于做配角。关于上爻,诸家解读大致能得其正解,讲的是交往处事不能夸夸其谈,务必言实相符。  相似文献   

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Six experiments with rat subjects investigated the role of conditioning in morphine tolerance. Concurrent assessments of body temperature and pain sensitivity were conducted. Experience with morphine produced tolerance to its analgesic effects but enhancement of its hyperthermic effects. Environmental novelty enhanced analgesia but not body temperature (Experiments 1 and 4). Under conditions in which a discriminated hyperthermic CR provided clear evidence that morphine-environment learning had developed, discriminated analgesic tolerance was not obtained (Experiments 2 and 3). Similarly, whereas placebo administrations extinguished the hyperthermic CR (Experiments 4 and 6), analgesic tolerance remained unaffected (Experiments 4, 5, and 6). These experiments suggest that the pyretic and analgesic systems are differentially sensitive to conditioning and the effects of novelty.  相似文献   

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5-hydroxytryptamine (5HT)-depleted rats were subjected to behavioral experiments in which the response to activation of 5HT1A, 5HT1c, and 5HT2 receptor subtypes was measured. Depletion of 5HT was produced by unilateral intracerebroventricular injection of 5,7-dihydroxytryptamine (100 micrograms/rat) or by systemic injection of p-chlorophenylalanine (150 mg/kg injected intraperitoneally 72, 48, and 24 h before the test). The dose-response curve of the 5HT1A-mediated, 8-hydroxy-2-(di-n-propylamino)tetralin (0.022-0.46 mg/kg)-induced lower lip retraction was not changed after depletion, nor was the dose-response curve of the 5HT2 receptor-mediated (+-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (0.046-1.0 mg/kg)-induced head shake response. The dose-response curve for penile erections, a 5HT1c receptor-mediated response after mCPP (0.1-1.0 mg/kg), a direct 5HT1c agonist, is shifted to the left after 5HT depletion, whereas the response to indirect activation of the 5HT1c receptor with the 5HT reuptake inhibitors citalopram (2.2-4.6 mg/kg) and paroxetine (0.22-2.2 mg/kg) was inhibited after 5HT depletion. These results suggest that 5HT1c receptors are more subject to denervation supersensitivity than 5HT1A and 5HT2 receptors. This lesion model may be useful to discriminate behaviorally between direct and indirect activation of the 5HT1c receptor.  相似文献   

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14 persons were examined electro-neurographically before and after cooling with an ice bag. The following results were found. A slight decrease of the motor conductivity is verified. This decrease in function is shown most markedly in the slowly-conducting motor neurons. At the cooling borderlines reactions with increased function are discernible. For the clarification of the relevance of changes of the nerve conductivity, further investigations with methodic variants are necessary.  相似文献   

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