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An enduring controversy in neuroscience concerns how the brain "binds" together separately coded stimulus features to form unitary representations of objects. Recent evidence has indicated a close link between this binding process and 40-hertz (gamma-band) oscillations generated by localized neural circuits. In a separate line of research, the ability of young infants to perceive objects as unitary and bounded has become a central focus for debates about the mechanisms of perceptual development. Here we demonstrate that binding-related 40-hertz oscillations are evident in the infant brain around 8 months of age, which is the same age at which behavioral and event-related potential evidence indicates the onset of perceptual binding of spatially separated static visual features. 相似文献
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Edelman GM 《Science (New York, N.Y.)》2007,318(5853):1103-1105
Biologically based mobile devices have been constructed that differ from robots based on artificial intelligence. These brain-based devices (BBDs) contain simulated brains that autonomously categorize signals from the environment without a priori instruction. Two such BBDs, Darwin VII and Darwin X, are described here. Darwin VII recognizes objects and links categories to behavior through instrumental conditioning. Darwin X puts together the "what,"when," and "where" from cues in the environment into an episodic memory that allows it to find a desired target. Although these BBDs are designed to provide insights into how the brain works, their principles may find uses in building hybrid machines. These machines would combine the learning ability of BBDs with explicitly programmed control systems. 相似文献
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英语作为全球使用范围最广泛的语言之一,其重要作用已渗透到各行各业,高职院校学生掌握好英语技能既是时代发展的要求,也是提升就业本领的要求。学习动机是直接推动学生学习的动力,激发学生英语学习动机是学生积极主动学习英语的关键。本文从主观因素学习目的、态度、期值以及客观因素授课质量、教材、成绩等方面调查了影响云南省高职学生英语学习动机的问题,并从教师和学校两个维度提出相应的对策,以期激发学生英语学习动机。 相似文献
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大学语文是普通高校面向非中文专业学生开设的一门文化素质必修课,但其目前的教学现状是过多注重知识传授,且教学方法落后,不利于培养全面发展的综合性人才。结合自身实践,对大学语文的三级教学目标和实现方法进行研究,主要包括专题教学法与知识目标、任务教学法与能力目标、情境拓展教学法与境界目标3个方面,这将有助于提高教学质量,真正做到＂教书育人＂。 相似文献
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李玉梅 《大连水产学院学报》1988,(1)
为了避免对产品验收的误判,不同精度要求的测量对象,应选择相应能力的测量设备。本文对光栅式齿轮单啮仪进行了测量设备能力及系数的分析和计算,依此定量评定其测量设备能力的高低。这样的数量特征对测量设备(最仪)之间的实际效果对比等,都很有适用价值。 相似文献
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Cognitive capacity of very young children 总被引：1，自引：0，他引：1
Children between 2 years, 6 months old and 3 years, 2 months old correctly discriminate the relative number of objects in two rows; between 3 years, 2 months and 4 years, 6 months they indicate a longer row with fewer objects to have "more"; after 4 years, 6 months they again discriminate correctly. The discriminative ability of the younger children shows that the logical capacity for cognitive operations exists earlier than previously acknowledged. 相似文献
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提高大学生创新实践能力具有积极意义。探讨第二课堂对电气专业教学内容和课程体系改革的促进作用,同时结合教学工作,探索以典型工程对象为载体的“实践-理论-实践-理论”大学生创新精神与实践能力的培养模式。 相似文献
9.
Controlling electromagnetic fields 总被引：1，自引：0，他引：1
Using the freedom of design that metamaterials provide, we show how electromagnetic fields can be redirected at will and propose a design strategy. The conserved fields-electric displacement field D, magnetic induction field B, and Poynting vector B-are all displaced in a consistent manner. A simple illustration is given of the cloaking of a proscribed volume of space to exclude completely all electromagnetic fields. Our work has relevance to exotic lens design and to the cloaking of objects from electromagnetic fields. 相似文献
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种苗学是一门由实践能力或经验而得来的特殊技术技巧组成的学科,要求学生在实验过程中必须加强各种实践环节的学习。以培养学生创新能力为目标,研究以2个林学班级为对象,针对种苗学的特殊性,从实验教学内容、教学方法和考核评价体系等几个方面进行了改革,并对开放式教学模式下实验室的管理和运行模式进行了探讨。 相似文献
11.
The ability of mink, fer rets, skunks, and cats to learn to dis criminate between objects was com pared. Performance of mink and fer rets was similar to that reported for primates. This observation suggests that there is considerable overlap among mammals in ability to form learning sets. 相似文献
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Host-bacterial mutualism in the human intestine 总被引：2，自引：0，他引：2
Bäckhed F Ley RE Sonnenburg JL Peterson DA Gordon JI 《Science (New York, N.Y.)》2005,307(5717):1915-1920
The distal human intestine represents an anaerobic bioreactor programmed with an enormous population of bacteria, dominated by relatively few divisions that are highly diverse at the strain/subspecies level. This microbiota and its collective genomes (microbiome) provide us with genetic and metabolic attributes we have not been required to evolve on our own, including the ability to harvest otherwise inaccessible nutrients. New studies are revealing how the gut microbiota has coevolved with us and how it manipulates and complements our biology in ways that are mutually beneficial. We are also starting to understand how certain keystone members of the microbiota operate to maintain the stability and functional adaptability of this microbial organ. 相似文献
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The primate hippocampal formation: evidence for a time-limited role in memory storage 总被引：30，自引：0，他引：30
Clinical and experimental studies have shown that the hippocampal formation and related structures in the medial temporal lobe are important for learning and memory. Retrograde amnesia was studied prospectively in monkeys to understand the contribution of the hippocampal formation to memory function. Monkeys learned to discriminate 100 pairs of objects beginning 16, 12, 8, 4, and 2 weeks before the hippocampal formation was removed (20 different pairs at each time period). Two weeks after surgery, memory was assessed by presenting each of the 100 object pairs again for a single-choice trial. Normal monkeys exhibited forgetting; that is, they remembered recently learned objects better than objects learned many weeks earlier. Monkeys with hippocampal damage were severely impaired at remembering recently learned objects. In addition, they remembered objects learned long ago as well as normal monkeys did and significantly better than they remembered objects learned recently. These results show that the hippocampal formation is required for memory storage for only a limited period of time after learning. As time passes, its role in memory diminishes, and a more permanent memory gradually develops independently of the hippocampal formation, probably in neocortex. 相似文献
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Apparent motion was used to explore humans' ability to perceive the direction of motion in the visual field. A marked qualitative difference in this ability was found between short- and long-range motion. For short-range motion, the detection of the direction of motion is characterized by parallel operation over a wide visual field (that is, detection performance is independent of the number of objects in an array). When the positional displacement is large relative to an object's size, the direction of motion is detected in a serial manner. The process of detection is limited in this case by the ability to detect other events, such as appearance and disappearance of an object, and the ability to compute their spatio-temporal relations. The results are consistent with a previously suggested division of the motion detection system into short- and long-range processes. The direction of short-range motion can be perceived in parallel (preattentively), whereas long-range motion is attentive and requires more complicated computations. It seems that the detection of long-range motion is a conjunction task, combining the detection of disappearance and appearance. 相似文献
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How do we decide if the people we meet and the things we see are familiar or new? If something is new, we need to encode it as a memory distinct from already stored episodes, using a process known as pattern separation. If familiar, it can be used to reactivate a previously stored memory, by a process known as pattern completion. To orchestrate these conflicting processes, current models propose that the episodic memory system uses environmental cues to establish processing biases that favor either pattern separation during encoding or pattern completion during retrieval. To assess this theory, we measured how people's memory formation and decisions are influenced by their recent engagement in episodic encoding and retrieval. We found that the recent encoding of novel objects improved subsequent identification of subtle changes, a task thought to rely on pattern separation. Conversely, recent retrieval of old objects increased the subsequent integration of stored information into new memories, a process thought to rely on pattern completion. These experiments provide behavioral evidence that episodic encoding and retrieval evoke lingering biases that influence subsequent mnemonic processing. 相似文献
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Our ability to remember what we have seen is very limited. Most current views characterize this limit as a fixed number of items-only four objects-that can be held in visual working memory. We show that visual memory capacity is not fixed by the number of objects, but rather is a limited resource that is shared out dynamically between all items in the visual scene. This resource can be shifted flexibly between objects, with allocation biased by selective attention and toward targets of upcoming eye movements. The proportion of resources allocated to each item determines the precision with which it is remembered, a relation that we show is governed by a simple power law, allowing quantitative estimates of resource distribution in a scene. 相似文献
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理论力学教学改革的几点探讨 总被引：2，自引：0，他引：2
理论力学是高等工科院校重要的技术基础课之一，如何合理进行理论力学教学改革及提高理论力学教学质量是高校教学中不断探讨的主题。结合目前教学形式，从理论力学课程建设与改革、学生主动思维能力培养和学生自学能力培养几个方面对理论力学教学质量的影响展开探讨，介绍一些有利于提高理论力学教学质量的方法。 相似文献
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本文探讨了如何进行中小型农产品动态网站设计与推广，提出了如何帮助农民利用网络这一现代化的完美工具，去增强他们的竞争能力，提高劳动生产效率，进行农产品的宣传与销售，最终实现农民收入的绝对增长。 相似文献
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陈德军 《吉林农业科技学院学报》2011,(1):98-100,108
从三个方面说明如何分析隐喻含义,即说明一系列词类含义的词汇规则,在不同的语用语境中分析隐喻含义的逻辑技巧以及语篇的理论.从这三个方面分析了相关的材料：表位置变化的动词;有形物体作为人的表语时的隐喻含义转换;借助于语篇结构的隐喻含义。 相似文献