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Sparse coding presents practical advantages for sensory representations and memory storage. In the insect olfactory system, the representation of general odors is dense in the antennal lobes but sparse in the mushroom bodies, only one synapse downstream. In locusts, this transformation relies on the oscillatory structure of antennal lobe output, feed-forward inhibitory circuits, intrinsic properties of mushroom body neurons, and connectivity between antennal lobe and mushroom bodies. Here we show the existence of a normalizing negative-feedback loop within the mushroom body to maintain sparse output over a wide range of input conditions. This loop consists of an identifiable "giant" nonspiking inhibitory interneuron with ubiquitous connectivity and graded release properties. 相似文献
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In the brain, fast oscillations of local field potentials, which are thought to arise from the coherent and rhythmic activity of large numbers of neurons, were observed first in the olfactory system and have since been described in many neocortical areas. The importance of these oscillations in information coding, however, is controversial. Here, local field potential and intracellular recordings were obtained from the antennal lobe and mushroom body of the locust Schistocerca americana. Different odors evoked coherent oscillations in different, but usually overlapping, ensembles of neurons. The phase of firing of individual neurons relative to the population was not dependent on the odor. The components of a coherently oscillating ensemble of neurons changed over the duration of a single exposure to an odor. It is thus proposed that odors are encoded by specific but dynamic assemblies of coherently oscillating neurons. Such distributed and temporal representation of complex sensory signals may facilitate combinatorial coding and associative learning in these, and possibly other, sensory networks. 相似文献
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Molecular genetics has revealed a precise stereotypy in the projection of primary olfactory sensory neurons onto secondary neurons. A major challenge is to understand how this mapping translates into odor responses in these second-order neurons. We investigated this question in Drosophila using whole-cell recordings in vivo. We observe that monomolecular odors generally elicit responses in large ensembles of antennal lobe neurons. Comparison of odor-evoked activity from afferents and postsynaptic neurons in the same glomerulus revealed that second-order neurons display broader tuning and more complex responses than their primary afferents. This indicates a major transformation of odor representations, implicating lateral interactions within the antennal lobe. 相似文献
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The mushroom bodies of the Drosophila brain are important for olfactory learning and memory. To investigate the requirement for mushroom body signaling during the different phases of memory processing, we transiently inactivated neurotransmission through this region of the brain by expressing a temperature-sensitive allele of the shibire dynamin guanosine triphosphatase, which is required for synaptic transmission. Inactivation of mushroom body signaling through alpha/beta neurons during different phases of memory processing revealed a requirement for mushroom body signaling during memory retrieval, but not during acquisition or consolidation. 相似文献
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昆虫嗅觉机制的研究进展 总被引：1，自引：0，他引：1
嗅觉机制对于昆虫选择栖息地、获得食物、趋利避害、传递讯息、群集以及繁殖等许多行为起到重要作用。因此,通过研究昆虫嗅觉系统,可以阐释嗅觉发生过程中的普遍机理,还有助于理解昆虫嗅觉活动与其整个生命活动之间的联系,进而为高等动物特别是人的嗅觉研究提供科学依据。并且通过对昆虫嗅觉机理的研究,发展出了一系列新的害虫治理方法,为害虫防治提供了新的思路。近年来,随着生物化学、分子生物学、昆虫行为学和昆虫电生理学的深入研究,科技人员发现了许多相关的嗅觉活性分子和嗅觉相关基因,从分子层面对昆虫嗅觉机制进行解释。本文综述了气味信号通过嗅感器转变为电信号,并由昆虫触角叶编码整合,最终传递到前脑整个过程中所涉及的分子组件及昆虫体内生理生化等方面有关进展。 相似文献
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中国食用菌产业现状及前瞻 总被引：15，自引：0，他引：15
李玉 《吉林农业大学学报》2008,30(4)
目前中国食用菌产业的发展状况是产量高、栽培品种较多、栽培模式多样、从业人员众多,日益重视品种开发、审定,同时存在产品质量问题,其发展呈现出对循环经济模式达成共识、南菇北移之势强劲、品种审定和保护制度相继出台、深加工多样化起步的态势和特点.文中就中国食用菌产业现状进行阐析与探讨,并指出我国食用菌未来发展的关键所在. 相似文献
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Neurons with oscillatory properties are a common feature of the nervous system, but little is known about how neural oscillators shape the behavior of neuronal networks or how network interactions influence the properties of neural oscillators. Mathematical models are used to examine the effect of electrically coupling an oscillatory neuron to a second neuron that is either silent or tonically firing. Models of oscillatory neurons with varying degrees of complexity show that this coupling can either increase or decrease the frequency of an oscillator, depending on its membrane potential wave form, the state of the neuron to which it is coupled, and the strength of the coupling. Thus, electrical coupling provides a flexible mechanism for modifying the behavior of an oscillatory neural network. 相似文献
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Interhemispheric synchronization of oscillatory neuronal responses in cat visual cortex 总被引：32，自引：0，他引：32
Neurons in area 17 of cat visual cortex display oscillatory responses that can synchronize across spatially separate columns in a stimulus-specific way. Response synchronization has now been shown to occur also between neurons in area 17 of the right and left cerebral hemispheres. This synchronization was abolished by section of the corpus callosum. Thus, the response synchronization is mediated by corticocortical connections. These data are compatible with the hypothesis that temporal synchrony of neuronal discharges serves to bind features within and between the visual hemifields. 相似文献
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为筛选出适宜北京地区高温季节栽培平菇品种,选取10个耐高温平菇品种,以北京地区种植品种灰平260为对照,于北京地区高温季节6-8月做出菇试验。通过对菇型的调查,海南2号、高平09、夏抗50叶片薄、易碎且畸形,因此商品性差,不适宜种植;另外,通过对产量的统计与分析,早秋615、2008A产量表现突出且菇型好,表现出较好的耐高温性,夏秀990、夏丰1号、基因2005、江都71在北京35～40℃极高温期仍能出菇且菇型好,表现出极耐高温性,以上6个品种在产量上均优于对照灰平260,是北京地区适宜高温季节栽培的平菇品种。 相似文献
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福建食用菌产业发展现状及对策分析 总被引：1，自引：0，他引：1
分析福建省食用菌产业发展现状,结果表明：食用菌产业产量、产值逐年增长,食用菌种类不断丰富,食用菌加工产业快速发展,并进一步分析福建食用菌产业发展过程中具有适宜的自然条件、丰富的原材料资源和劳动力资源等优势和存在的劣势,提出发展食用菌产业的相关政策建议。 相似文献
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5种无机物对猴头菌发菌期,产量及锌,硒富集影响的研究 总被引：3，自引：0，他引：3
应用正交试验设计研究了ＺｎＳＯ４、ＭｇＳＯ４、ＨＢＯ３、ＮａＨＳｅＯ３、ＫＣｌ对猴头菌发菌期、产量及Ｚｎ、Ｓｅ元素含量的影响。结果表明：利用关中地区的原料栽培猴头菌，在原料中添加一定量的ＺｎＳＯ４、ＭｇＳＯ４、ＮａＨＳｅＯ３、ＫＣｌ不会影响猴头菌的发菌期和产量，而加入的ＺｎＳＯ４和ＮａＨＳｅＯ３能显著地提高子实体中Ｚｎ、Ｓｅ元素的含量；在试验范围内，猴头菌对Ｚｎ和Ｓｅ的富集分别是线性和非线性规律；ＨＢＯ３对发菌期的影响符合二次多项式趋势，但对产量无显著影响。 相似文献
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四川松茸的特殊生态研究 总被引：7，自引：0，他引：7
四川松茸生态特殊。经研究表明:产菇地海拔高1900—3900米,坡度陡,可达70度;属山地寒温带湿润(或半湿润)气候,旱雨季分明,产菇于雨季,光照强,气温低、年较差小,日较差大;植被不为松、杉乔木,而多为栎,栲矮灌丛(或高灌丛、乔木)。由于特殊生态环境,松茸发生时间在7—9月,比日本早2—3个月上市,少病虫害、香味特浓,经济性状好。四川松茸特殊生态的发现,扩大了我国松茸的分布地区及松茸的共生植物范围,为此菌的生态研究提供了新内容,为开发松茸新产区及半人工栽培研究提供了依据。 相似文献
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用金针菇固体培养物经生化水解加工的金菇露营养液,含有18种游离氨基酸,氨基酸总量比栽培的及野生的子实体高1.2-1.85倍,8种人体必需的氨基酸含量也比鲜菇高,但在氨基酸总量中所占的比例较低,它与鲜菇类似含有多种维生素如 VA 原、VB、VB_2、VC 等,还含有维生素 E,对小白鼠肉瘤 S_(180)、S_(37)及宫颈癌 U_(14)有明显的抑制作用,抑瘤率都在40%左右,最高达48.2%。还观察了一些疾病患者服用金菇露后的初步疗效. 相似文献
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中红侧沟茧蜂触角超微结构 总被引：2，自引：0，他引：2
【目的】明确中红侧沟茧蜂触角感器的种类、分布、形态及内部结构。【方法】利用扫描电镜和透射电镜对中红侧沟茧蜂触角进行观察。【结果】扫描电镜结果表明中红侧沟茧蜂触角由柄节、梗节和16节鞭节组成;雌蜂、雄蜂触角上均存在以下6种感器：毛形感器、刺形感器、板形感器、锥形感器Ⅰ、锥形感器Ⅱ和腔锥感器;雌蜂、雄蜂间各种感器的长度、分布和数量没有明显差别。透射电镜结果表明毛形感器和腔锥感器角质层壁厚,壁上有孔,内腔有神经树突;刺形感器和锥形感器Ⅰ角质层壁厚,壁上无孔,内腔有神经树突;板形感器角质层壁薄,壁上有孔,内腔有神经树突;锥形感器Ⅱ角质层壁厚,壁上无孔,内腔无神经树突。【结论】明确了中红侧沟茧蜂触角感器内、外部超微结构,为寄生蜂嗅觉感知行为提供了理论依据。 相似文献
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昆虫利用嗅觉感器来感知环境中的气味物质,在昆虫的感器淋巴内存在着复杂的成份。其中较重要的是一些气味剂结合蛋白和酶类,它们在昆虫的嗅觉过程中起着非常重要的作用。本文综述昆虫气味剂结合蛋白的研究进展,主要集中在以下几方面：ＯＢＰ的结构,ＯＢＰ的特征,ＯＢＰ的表达时间和定位,ＯＢＰ的功能。 相似文献