Synaptic adjustment after deafferentation of the superior colliculus of the rat

Eyes were removed from rats shortly after birth, when there are few formed synapses in the colliculus. It was found that synaptogenesis continues to give a near-normal ratio of terminals containing either spheroidal or flattened vesicles. After eye removal in adult rats, however, reinvasion of synaptic sites vacated by degenerate optic terminals occurs, with an incomplete return toward a normal proportion of synaptic types.     

Descending efferents from the superior colliculus relay integrated multisensory information

By means of their efferent projections to motor and premotor structures, the cells in the deep superior colliculus are intimately involved in behaviors that control the orientation of the eyes, pinnae, and head. These same efferent cells receive multiple sensory inputs, thereby apparently enabling an animal to orient its receptor organs in response to a wide variety of cues. This sensory convergence also provides a system in which motor responses need not be immutably linked to individual stimuli but can vary in reaction to the multitude of stimuli present in the environment at any given moment.     

Variations of the visual responses of the superior colliculus in relation to body roll

A large percentage of the directional units of the superior colliculus of the curarized cat modify their response to a particular moving visual stimulus as a function of the position of rotation of the animal about its longitudinal axis.     

Two- rather than three-dimensional representation of saccades in monkey superior colliculus

Saccades are controlled by neurons in the brainstem reticular formation that receive input from the superior colliculus and cortex. Recently two quantitative models have been proposed for the role of the colliculus in the generation of three-dimensional eye movements. In order to test these models, three-dimensional eye movements were measured in the alert monkey to investigate whether the saccadic motor map of the superior colliculus is two-dimensional, representing retinal target vectors, or three-dimensional, representing three-dimensional motor error for the rotation of the eye. Electrical stimulation of the superior colliculus produced two-dimensional, not three-dimensional, eye movements. It is therefore concluded that the collicular motor map is two-dimensional.     

Nonoxidative glucose consumption during focal physiologic neural activity

Brain glucose uptake, oxygen metabolism, and blood flow in humans were measured with positron emission tomography, and a resting-state molar ratio of oxygen to glucose consumption of 4.1:1 was obtained. Physiological neural activity, however, increased glucose uptake and blood flow much more (51 and 50 percent, respectively) than oxygen consumption (5 percent) and produced a molar ratio for the increases of 0.4:1. Transient increases in neural activity cause a tissue uptake of glucose in excess of that consumed by oxidative metabolism, acutely consume much less energy than previously believed, and regulate local blood flow for purposes other than oxidative metabolism.     

A neural map of auditory space in the owl

Auditory units that responded to sound only when it originated from a limited area of space were found in the lateral and anterior portions of the midbrain auditory nucleus of the owl (Tyto alba). The areas of space to which these units responded (their receptive fields) were largely independent of the nature and intensity of the sound stimulus. The units were arranged systematically within the midbrain auditory nucleus according to the relative locations of their receptive fields, thus creating a physiological map of auditory space.     

Reshaping the cortical motor map by unmasking latent intracortical connections

The primary motor cortex (MI) contains a map organized so that contralateral limb or facial movements are elicited by electrical stimulation within separate medial to lateral MI regions. Within hours of a peripheral nerve transection in adult rats, movements represented in neighboring MI areas are evoked from the cortical territory of the affected body part. One potential mechanism for reorganization is that adjacent cortical regions expand when preexisting lateral excitatory connections are unmasked by decreased intracortical inhibition. During pharmacological blockade of cortical inhibition in one part of the MI representation, movements of neighboring representations were evoked by stimulation in adjacent MI areas. These results suggest that intracortical connections form a substrate for reorganization of cortical maps and that inhibitory circuits are critically placed to maintain or readjust the form of cortical motor representations.     

Visual instruction of the neural map of auditory space in the developing optic tectum

Neural maps of visual and auditory space are aligned in the adult optic tectum. In barn owls, this alignment of sensory maps was found to be controlled during ontogeny by visual instruction of the auditory spatial tuning of neurons. Large adaptive changes in auditory spatial tuning were induced by raising owls with displacing prisms mounted in spectacle frames in front of the eyes; neurons became tuned to sound source locations corresponding to their optically displaced, rather than their normal, visual receptive field locations. The results demonstrate that visual experience during development calibrates the tectal auditory space map in a site-specific manner, dictating its topography and alignment with the visual space map.     

Synchronous radiocarbon and climate shifts during the last deglaciation

Radiocarbon data from the Cariaco Basin provide calibration of the carbon-14 time scale across the period of deglaciation (15,000 to 10, 000 years ago) with resolution available previously only from Holocene tree rings. Reconstructed changes in atmospheric carbon-14 are larger than previously thought, with the largest change occurring simultaneously with the sudden climatic cooling of the Younger Dryas event. Carbon-14 and published beryllium-10 data together suggest that concurrent climate and carbon-14 changes were predominantly the result of abrupt shifts in deep ocean ventilation.     

The neural basis for learning of simple motor skills

The vestibulo-ocular reflex (VOR) is a simple movement that has been used to investigate the neural basis for motor learning in monkeys. The function of the VOR is to stabilize retinal images by generating smooth eye movements that are equal and opposite to each head movement. Learning occurs whenever image motion occurs persistently during head turns; as a result image stability is gradually restored. A hypothesis is proposed in which the output from the cerebellar cortex of the flocculus guides learning; the locus of learning is in the brain stem, in VOR pathways that are under inhibitory control from the flocculus. Other, parallel VOR pathways do not receive inputs from the flocculus and are not subject to learning. Similarities among the VOR and other motor systems suggest some organizing principles that may apply in many forms of motor learning.     

Estimating litchi flower number using a multicolumn convolutional neural network based on a density map

Precision Agriculture - To ensure litchi fruit yield and quality, reasonable blooming period management such as flower thinning is required during the early flowering period. A combination of the...     

Citrus fruits maturity detection in natural environments based on convolutional neural networks and visual saliency map

Citrus fruits do not ripen at the same time in natural environments and exhibit different maturity stages on trees, hence it is necessary to realize selective harvesting of citrus picking robots. The visual attention mechanism reveals a physiological phenomenon that human eyes usually focus on a region that is salient from its surround. The degree to which a region contrasts with its surround is called visual saliency. This study proposes a novel citrus fruit maturity method combining visual saliency and convolutional neural networks to identify three maturity levels of citrus fruits. The proposed method is divided into two stages: the detection of citrus fruits on trees and the detection of fruit maturity. In stage one, the object detection network YOLOv5 was used to identify the citrus fruits in the image. In stage two, a visual saliency detection algorithm was improved and generated saliency maps of the fruits; The information of RGB images and the saliency maps were combined to determine the fruit maturity class using 4-channel ResNet34 network. The comparison experiments were conducted around the proposed method and the common RGB-based machine learning and deep learning methods. The experimental results show that the proposed method yields an accuracy of 95.07%, which is higher than the best RGB-based CNN model, VGG16, and the best machine learning model, KNN, about 3.14% and 18.24%, respectively. The results prove the validity of the proposed fruit maturity detection method and that this work can provide technical support for intelligent visual detection of selective harvesting robots.

     

自组织神经影射网络排序及其在植物群落分析中的应用

自组织神经影射网络(SOFM)对复杂问题和非线性问题具有较强的分析和解决功能,其特征完全适合植物群落的排序研究。该文介绍了SOFM的基本原理和排序分析过程及方法,并应用SOFM网络排序对太行山中段植物群落进行了排序分析。其计算过程在Matlab 65神经网络工具箱中实现。结果将68个样方排列在SOFM拓扑空间,排序轴反映了明确的生态梯度,能够反映植物群落间的生态关系,生态意义明确,符合植被实际,表明SOFM网络是有效的植物群落排序方法。在SOFM排序过程中也很容易进行聚类,有利于群落分类和排序的结合。      

阳光体育运动过程监控体系智能评价系统研究

采用文献资料、专家访谈、实验等研究方法,运用现代科技新成果,以阳光体育运动过程监控体系智能评价系统为研究对象。该智能系统评价系统能够对学生参与阳光体育运动的过程和结果进行有效监控,极大减轻体育教师计算学生体育成绩的工作量,有效调动广大学生参与阳光体育运动,推动阳光体育运动的蓬勃开展,借以提高广大青少年学生的体质健康。     

民国时期乡村建设运动中政治·经济现代化的探索

通过对民国时期乡村建设运动中乡村政治、经济现代化的探索,反映了20世纪20-30年代我国农村社会改革可能采取的路径和方向,可为当今新农村建设借鉴。     

Echo-ranging neurons in the inferior colliculus of bats

Bats measure the distance to an object in terms of the time lag between their outgoing orientation sounds and the returning echo. For measurement of the time lag, the latency of response of a neuron to a stimulus must be nearly constant regardless of the stimulus amplitude and envelope. Otherwise, a large error would be introduced into the measurement. Bats have neurons that are specialized for echo ranging.     

BP人工神经网络用于食品防腐剂构效关系建模的研究

采用摇床培养,测试了20种食品防腐剂在实验条件下对大肠杆菌的最低抑菌浓度;计算了所有供试防腐剂的10种结构、电子、理化性质参数,随机抽取其中17种防腐剂作为训练样本,另外3种防腐剂作为预测样本,构造并训练得到能较好预测"未知"食品防腐剂在实验条件下对大肠杆菌的最低抑菌浓度的BP人工神经网络,建立了能较准确预测食品防腐剂抗菌活性的QSAR模型,该模型对防腐剂抗菌活性的预测值和实测值相对误差不超过±5%。     

竹材热压干燥过程中的水分迁移特性研究

研究了竹材热压干燥过程中的水分迁移特性．结果表明：在整个干燥过程中，前期含水率降低较快,后期含水率降低较慢．竹材平均干燥速度与次表层竹材的干燥速度相近；在含水率较高的干燥初期，水分迁移的阻力在竹材表面，水分迁移主要靠毛细管张力作用；在含水率较低的干燥后期．水分迁移的阻力在竹材内部．水分迁移主要以扩散方式进行，干燥速度取决于木材内部水分移动的速度．竹材热压干燥过程中的水分移动．主要受温度梯度和含水率梯度的共同作用．