Based on quantitative analyses of the response characteristics of visual neurons in the superior colliculus to moving optical bar stimuli, it is demonstrated for the first time that the visual neurons in superior coll...Based on quantitative analyses of the response characteristics of visual neurons in the superior colliculus to moving optical bar stimuli, it is demonstrated for the first time that the visual neurons in superior colliculus of the cat have, to some extent, orientational selectivity. The significance of this selectivity is discussed in reference to its morphological substrate and physiological functions. In addition, both the directional and orientational selectivities in the superior colliculus are relatively weak when compared with those in the primary visual cortex, and the majority of the neurons prefer upward or downward motion in the visual field.展开更多
The liver comprises cell layers of hepatocytes called trabeculae, which are separated by vascular sinusoids. Under- standing the structure of hepatic trabeculae and liver sinusoids in hematoxylin and eosin (HE)-staine...The liver comprises cell layers of hepatocytes called trabeculae, which are separated by vascular sinusoids. Under- standing the structure of hepatic trabeculae and liver sinusoids in hematoxylin and eosin (HE)-stained liver specimens is important for the differential diagnosis of liver diseases. In this study, we develop an approach to extracting liver sinusoids from HE-stained images. The proposed approach involves: 1) a new orientation-selective filter (OS filter) for edge enhancement and image denoising, 2) the clustering of image pixels to identify candidate sinusoids, and 3) a classification procedure that discards unlikely candidates and selects the final sinusoid areas. Experimental studies using a database of 16 images with a resolution of 512 × 512 pixels showed that the proposed approach could segment liver sinusoid pixels with 81% of specificity and 94% of sensitivity. A comparison with a method based on bilateral filters showed that this method improved the sensitivity for all images with an average improvement of 4% and no difference in specificity. The results were presented to a group of pathologists and they confirmed that the images were highly representative of the tissue morphology features.展开更多
In order to probe into the self-organizing emergence of simple cell orientation selectivity,we tried to construct a neural network model that consists of LGN neurons and simple cells in visual cortex and obeys the Heb...In order to probe into the self-organizing emergence of simple cell orientation selectivity,we tried to construct a neural network model that consists of LGN neurons and simple cells in visual cortex and obeys the Hebbian learning rule. We investigated the neural coding and representation of simple cells to a natural image by means of this model. The results show that the structures of their receptive fields are determined by the preferred orientation selectivity of simple cells.However, they are also decided by the emergence of self-organization in the unsupervision learning process. This kind of orientation selectivity results from dynamic self-organization based on the interactions between LGN and cortex.展开更多
局部场电位(local field potential,LFP)与神经元发放的锋电位(spike)之间的同步关系揭示了重要的神经编码信息。为了研究不同对比度的光栅刺激下猕猴视皮层V1区和V4区神经元的朝向选择性,本文将锋电位触发的相关矩阵同步方法应用于在...局部场电位(local field potential,LFP)与神经元发放的锋电位(spike)之间的同步关系揭示了重要的神经编码信息。为了研究不同对比度的光栅刺激下猕猴视皮层V1区和V4区神经元的朝向选择性,本文将锋电位触发的相关矩阵同步方法应用于在猕猴视皮层V1区和V4区记录的微电极信号,发现spike与gamma频段LFP之间的同步与光栅朝向之间存在较强的相关性,反映了视觉刺激的基本特征信息。另外,神经元spike的发放速率虽然会受到光栅朝向的影响,但是在不同对比度下发放速率并无明显区别,而spike-LFP同步会随着对比度的增加而增加,能够反映出同一朝向下对比度的变化。本文还利用圆方差来量化spike-LFP同步的朝向调谐曲线,发现对比度越大,V1区和V4区神经元的朝向选择性越强,V1区神经元比V4区神经元具有更强的朝向选择性。总之,spike-LFP同步能够更深入地揭示视皮层神经元的朝向调谐特性,为研究朝向选择性的形成机制提供新的方向。展开更多
A high-performance PMOSFET based on silicon material of hybrid orientation is obtained.Hybrid orientation wafers,integrated by（100） and（110） crystal orientation,are fabricated using silicon-silicon bonding, chemic...A high-performance PMOSFET based on silicon material of hybrid orientation is obtained.Hybrid orientation wafers,integrated by（100） and（110） crystal orientation,are fabricated using silicon-silicon bonding, chemical mechanical polishing,etching silicon and non-selective expitaxy.A PMOSFET with W/L = 50μm/8μm is also processed,and the measured results show that the drain-source current and peak mobility of the PMOSFET are enhanced by up to 50.7%and 150%at V_（gs） =-15 V and V_（ds） =-0.5 V,respectively.The mobility values are higher than that reported in the literature.展开更多
基金Project supported by the National Natural Science Foundation of China and the Chinese Academy of Sciences.
文摘Based on quantitative analyses of the response characteristics of visual neurons in the superior colliculus to moving optical bar stimuli, it is demonstrated for the first time that the visual neurons in superior colliculus of the cat have, to some extent, orientational selectivity. The significance of this selectivity is discussed in reference to its morphological substrate and physiological functions. In addition, both the directional and orientational selectivities in the superior colliculus are relatively weak when compared with those in the primary visual cortex, and the majority of the neurons prefer upward or downward motion in the visual field.
文摘The liver comprises cell layers of hepatocytes called trabeculae, which are separated by vascular sinusoids. Under- standing the structure of hepatic trabeculae and liver sinusoids in hematoxylin and eosin (HE)-stained liver specimens is important for the differential diagnosis of liver diseases. In this study, we develop an approach to extracting liver sinusoids from HE-stained images. The proposed approach involves: 1) a new orientation-selective filter (OS filter) for edge enhancement and image denoising, 2) the clustering of image pixels to identify candidate sinusoids, and 3) a classification procedure that discards unlikely candidates and selects the final sinusoid areas. Experimental studies using a database of 16 images with a resolution of 512 × 512 pixels showed that the proposed approach could segment liver sinusoid pixels with 81% of specificity and 94% of sensitivity. A comparison with a method based on bilateral filters showed that this method improved the sensitivity for all images with an average improvement of 4% and no difference in specificity. The results were presented to a group of pathologists and they confirmed that the images were highly representative of the tissue morphology features.
基金the National Natural Science Foundation of China (Grant Nos. 39893340-06, 69835020, 39670186).
文摘In order to probe into the self-organizing emergence of simple cell orientation selectivity,we tried to construct a neural network model that consists of LGN neurons and simple cells in visual cortex and obeys the Hebbian learning rule. We investigated the neural coding and representation of simple cells to a natural image by means of this model. The results show that the structures of their receptive fields are determined by the preferred orientation selectivity of simple cells.However, they are also decided by the emergence of self-organization in the unsupervision learning process. This kind of orientation selectivity results from dynamic self-organization based on the interactions between LGN and cortex.
基金supported by National Science Foundation of USA (No. DMS-1009575)the National Basic Research Development Program of China (973 Program, No. 2011CB809105)
文摘局部场电位(local field potential,LFP)与神经元发放的锋电位(spike)之间的同步关系揭示了重要的神经编码信息。为了研究不同对比度的光栅刺激下猕猴视皮层V1区和V4区神经元的朝向选择性,本文将锋电位触发的相关矩阵同步方法应用于在猕猴视皮层V1区和V4区记录的微电极信号,发现spike与gamma频段LFP之间的同步与光栅朝向之间存在较强的相关性,反映了视觉刺激的基本特征信息。另外,神经元spike的发放速率虽然会受到光栅朝向的影响,但是在不同对比度下发放速率并无明显区别,而spike-LFP同步会随着对比度的增加而增加,能够反映出同一朝向下对比度的变化。本文还利用圆方差来量化spike-LFP同步的朝向调谐曲线,发现对比度越大,V1区和V4区神经元的朝向选择性越强,V1区神经元比V4区神经元具有更强的朝向选择性。总之,spike-LFP同步能够更深入地揭示视皮层神经元的朝向调谐特性,为研究朝向选择性的形成机制提供新的方向。
基金supported by the National Basic Research Program of China(No.61398)
文摘A high-performance PMOSFET based on silicon material of hybrid orientation is obtained.Hybrid orientation wafers,integrated by（100） and（110） crystal orientation,are fabricated using silicon-silicon bonding, chemical mechanical polishing,etching silicon and non-selective expitaxy.A PMOSFET with W/L = 50μm/8μm is also processed,and the measured results show that the drain-source current and peak mobility of the PMOSFET are enhanced by up to 50.7%and 150%at V_（gs） =-15 V and V_（ds） =-0.5 V,respectively.The mobility values are higher than that reported in the literature.
