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排序方式: 共有640条查询结果,搜索用时 8 毫秒
631.
632.
Chilling injury: a plea for uniform terminology 总被引:1,自引:1,他引:0
Abstract This article proposes definitions for the terms now commonly applied to studies of both the molecular and cellular aspects of chilling injury. They are proposed with the intent of increasing the precision and clarity of communications on the subject and arc based on the present understanding and current hypotheses regarding the molecular events underlying the development of the visible symptoms of chilling injury. 相似文献
633.
Gang-caged adult male vervet monkeys were trained to urinate on demand into a plastic beaker by positive reinforcement (peanut rewards). The animals were not separated from their social group during training or sampling. 相似文献
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635.
The hippocampus is needed for at least one kind of trace classical conditioning, the air-puff eye-blink paradigm. A simple
model of region CA3 predicts three basic, quantitative observations of the learning behavior of rabbits. One particular quantified
prediction is the learnable trace interval. The boundary region of the reliably learnable trace interval represents a phase
transition. Within this transition, three behaviorally distinguishable modes are expressed: failure to blink; blink too soon;
and occasionally, appropriate predictive blinking. In the region of the phase transition, there is a small sub-interval where
the behavioral modes fluctuate rapidly from trial to trial for individual simulations. Such observed fluctuations are an experimental
prediction by the model. The discussion also includes a brief conjecture concerning the underlying cause of the phase transition
and the fluctuations. 相似文献
636.
Catherine A. Schaeffer Douglas C. Nathanson Craig F. Cegavske Richard A. Roemer 《Peptides》1982,3(5):715-719
Subjects were conditioned/extinguished under four experimental conditions using either MSH/ACTH 4–10 (A) or diluent (D): D/D, D/A, A/D, and A/A. The major question investigated was whether or not the peptide has an effect on this classically-conditioned behavior similar to that reported for instrumental conditioning paradigms. The results indicated that it does not. An effect was seen on performance, not on learning or attentional processes. Animals treated with the peptide performed more poorly (i.e., displayed fewer conditioned responses) during both acquisition and extinction. In addition, there was an apparent residual effect of the peptide that lasted 24 but not 48 hours. 相似文献
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639.
Y. S. Mineur D. H. Brunzell S. R. Grady J. M. Lindstrom J. M. McIntosh M. J. Marks S. L. King and M. R. Picciotto 《Genes, Brain & Behavior》2009,8(3):257-266
High-affinity, β2-subunit-containing (β2*) nicotinic acetylcholine receptors (nAChRs) are essential for nicotine reinforcement; however, these nAChRs are found on both gamma-aminobutyric acid (GABA) and dopaminergic (DA) neurons in the ventral tegmental area (VTA) and also on terminals of glutamatergic and cholinergic neurons projecting from the pedunculopontine tegmental area and the laterodorsal tegmental nucleus. Thus, systemic nicotine administration stimulates many different neuronal subtypes in various brain nuclei. To identify neurons in which nAChRs must be expressed to mediate effects of systemic nicotine, we investigated responses in mice with low-level, localized expression of β2* nAChRs in the midbrain/VTA. Nicotine-induced GABA and DA release were partially rescued in striatal synaptosomes from transgenic mice compared with tissue from β2 knockout mice. Nicotine-induced locomotor activation, but not place preference, was rescued in mice with low-level VTA expression, suggesting that low-level expression of β2* nAChRs in DA neurons is not sufficient to support nicotine reward. In contrast to control mice, transgenic mice with low-level β2* nAChR expression in the VTA showed no increase in overall levels of cyclic AMP response element-binding protein (CREB) but did show an increase in CREB phosphorylation in response to exposure to a nicotine-paired chamber. Thus, CREB activation in the absence of regulation of total CREB levels during place preference testing was not sufficient to support nicotine place preference in β2 trangenic mice. This suggests that partial activation of high-affinity nAChRs in VTA might block the rewarding effects of nicotine, providing a potential mechanism for the ability of nicotinic partial agonists to aid in smoking cessation. 相似文献
640.
作为一种高级认知活动,视觉功能减弱是否影响听觉恐惧条件化学习目前还不清楚.本文以突变体rd/rd、cl/cl小鼠为视觉功能减弱组,研究视觉功能减弱是否对听觉巴甫洛夫条件化恐惧反应有影响.在恐惧条件化、恐惧消退和消除记忆再现阶段记录了僵直行为.研究结果表明,视觉功能的减弱更有利于小鼠听觉恐惧条件化的建立.文中讨论了出现此... 相似文献