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2017 Vol. 36, No. 1 Published: 2017-02-20

Reviews Communications Regular Papers

Regular Papers

	1	A Contour Detection Method Based on Correlation of Orientation for Multiple Receptive Fields in Visual Pathway
		Li Kangqun, Fan Yingle, Gan Haitao, Wu Wei
		DOI: 10.3969/j.issn.0258-8021.2017.01.001
		Based on characteristics of receptive fields on different layers of human visual path and their correlation between every adjacent layer, a new method of image contour detection was proposed in this paper. Using the receptive feature of neurons with radial dendrite, a retina neuron network that has the capability to detect spatial difference was constructed for pre-coding of contour information. Taking the variety between adjacent layers into account, the adjustment mechanism for non-classical receptive field of LGN neurons was built to make a global adjustment on the pre-coding result. Next,a model of simple cell on primary visual cortex named orientation correlation of multiple receptive fields was proposed to realize the orientation selection of simple cells. At last,the fused contour response of all orientations was processed with non-maximum suppression and hysteresis thresholding to acquire the contour detecting result. In this paper, 40 images in the RuG library were taken for processing, and the mean value of measure P between detecting result and ground truth was 0.43, indicating that method in this paper could highlight principal contour and enhance the discrimination between contour and textured region. In this study, the correlate characteristics of multiple receptive fields were utilized to code and detect image contour, providing a new idea for the image processing and visual cognition of high-level visual cortex.
		2017 Vol. 36 (1): 1-11 [Abstract] ( 362 ) HTML (1 KB) PDF (19638 KB) ( 277 )

	12	The Classification of Pulmonary Nodules Based on Texture Features over Local Jet Transformation Space
		Dai Meiling, Qi Jin, Zhou Zhongxing, Gao Feng
		DOI: 10.3969/j.issn.0258-8021.2017.01.002
		A method of texture features extraction over local jet transformation space is presented in order to improve the recognition about benign/malignant nodules with texture features. In this method, the first three order partial differential functions of 2-D Gaussian were used to transform original image of nodule tolocal jet texture images space firstly, and then feature parameters were extracted over the local jet images space by texture descriptor. In our work, feature parameters were extracted from the original CT image and local jet images using the texture descriptors of first four moments of intensity and parameters based on gray level co-occurrence matrix. Then BP neural network was used to classify the benign/malignant nodules with the two texture features sets under the same texture descriptor that optimized by kernel principle component analysis. The compared experiment conducted based on 157 lung nodule(51 benign and 106 malignant) samples. The experiment result showed that the classification accuracy of two feature parameters sets extracted by the two texture descriptors on local jet space was 82.69% and 86.54% respectively, higher 6%～8% than feature parameters sets on original image space, and the value of AUC was increased about 10%. The experiment result indicated the texture features extracted from local jet transformation space could effectively improve the pattern recognition of benign/malignant of pulmonary nodules.
		2017 Vol. 36 (1): 12-19 [Abstract] ( 313 ) HTML (1 KB) PDF (3317 KB) ( 322 )

	20	Variability of Spontaneous Fluctuation in Resting-State Functional Connectivity of Human Brains
		Wang Yingjie, Shen Hui
		DOI: 10.3969/j.issn.0258-8021.2017.01.003
		The dynamics of the resting-state functional connectivity is believed to provide greater insight into fundamental properties of large-scale functional brain networks and has received increasing attention in recent years. However, few previous studies have characterized cortical distribution of resting-state connectivity fluctuation. The present work investigated the variability of resting-state brains’ low-frequency fluctuation in a cohort of young adults (n=396), using a sliding window approach and distant functional connectivity degree (dFCD). First, we used sliding windows with the size of 36 s to generate time courses of the whole brain’s dynamic connectivity. Second, taking the sphere of radius 14 mm as the neighboring region, we calculated the dFCD of each voxel within an individual window. Finally, the amplitude of low-frequency fluctuation (ALFF) was used to evaluate variability of connectivity degree at each voxel. We observed that regions within the default mode network exhibited the least variability (ALFF=402.3±79.9), implying a possible role of this network in stabilizing the spontaneous activity in the human brain. In contrast, the sensory and motor networks exhibited the greatest variability in their distant connectivity (ALFF=551.2±74.7), possibly due to subjects’ occasionally monitoring the external environment during the task-free scanning. Taken together, the present study for the first time demonstrated a significant difference (two-sample t-test: t=-6.38, P<0.0001) between the cognitive and sensorimotor networks in terms of dynamics of the spontaneous activity, providing new insights into the dynamics of resting-state connectivity and possible new means for ascertaining neuropsychiatric disorders.
		2017 Vol. 36 (1): 20-27 [Abstract] ( 408 ) HTML (1 KB) PDF (5692 KB) ( 400 )

	28	EEG-EMG Synchronization Analysis Based on Gabor Wavelet Transform-Granger Causality
		Xie Ping, Chen Yingya, Zhang Yuanyuan, Zou Ce, Chen Xiaoling, Zhang Litai
		DOI: 10.3969/j.issn.0258-8021.2017.01.004
		The corticomuscular coordinate mechanism of hand movements has important application values in prosthesis control, rehabilitation treatment and evaluation. This paper proposed Gabor wavelet transform-Granger causality (WT-GC) method to analyze corticomuscular coupling (CMC). Furthermore, the GC peak frequency and significant GC area were defined to quantitatively describe the corticomuscular function coupling and information flow direction at different frequencies. We collected the EEG and EMG datasets acquired simultaneously from 10 healthy subjects during maintaining static forces at 10% and 60% of their maximal voluntary contraction (MVC) isometrically. The proposed wavelet transform-Granger causality (WT-GC) method was used to analyze the synchronization between EEG and EMG data. Results showed a shift of GC peak frequency to higher frequency range for 60% MVC as compared with 10% MVC in both EEG→EMG and EMG→EEG directions. There was a decreased significant GC area appearing at beta band in EEG→EMG direction for 60% MVC. It was verified that the TF-GC method proposed could describe the corticomuscular coupling frequency and directional features. In addition, corticomuscular controls the force output of hand by adjusting neuronal oscillation amplitude, frequency and flow direction. In conclusion, this analysis provided a basis for exploring the motor control and feedback information encoding of hand.
		2017 Vol. 36 (1): 28-38 [Abstract] ( 408 ) HTML (1 KB) PDF (4927 KB) ( 734 )

	39	Study on Time-Effect on EEG-BasedEmotion Recognition Model and Countermeasures
		Liu Shuang, Tong Jingjing, Guo Dongyue, Ke Yufeng, Meng Jiayuan, Chen Long, Xu Minpeng, Qi Hongzhi, Ming Dong
		DOI: 10.3969/j.issn.0258-8021.2017.01.005
		There are numerous studies measuring the brain emotional status by analyzing EEGs under the emotional stimuli that have occurred, however, in practical application, an important but unresolved question is the extent to which the emotion model may generalize over time, since people could have a different expression of the same physiological signal on different days even when he experiences the same emotion. This paper attempted to add multiple days to the training set in purpose to weaken the impact of day-effect, and then to improve the generalization of the classifier. Eight subjects participated in this experiment, in which movie clips were presented to evoke the subjects’ three emotional states of neutral, positive and negative. Moreover, EEG was recorded 5 times within one month for each subjects. Support vector machine (SVM) was used to obtain the 3-class classification rates in all the collecting conditions including1-day collection, 2-day collection, 3-day collectionand 4-day collection. N-day collection represented the case in which data from N days were sent to train the SVM and the remaining (5-N) days were used to form the testing set. Results showed that the accuracy was increased with the number of days in the training set for most of the subjects. Compared with 1-day collection, the increasing rates of the accuracies were 6.45%(P=0.006), 10.48%(P=0.000), and 14.40%(P=0.000)in 2-day, 3-day and 4-day collections. These results suggested that adding data from more days to the training set could improve the performance and generalization of an emotion classifier. Though it is still a big challenge in EEG-based emotion recognition, these results provided a promising solution and take EEG-based model one step closer to being able to discriminate emotions in practical application.
		2017 Vol. 36 (1): 39-45 [Abstract] ( 414 ) HTML (1 KB) PDF (3069 KB) ( 618 )

	46	Research on Mental Fatigue Caused by Watching 3DTVBased on EEG Signal Tracing Analysis
		Li Jian, Chen Guozheng, Chen Chunxiao
		DOI: 10.3969/j.issn.0258-8021.2017.01.006
		With the popularization of 3DTV display technological, the mental fatigue caused by watching 3DTV is getting more and more attention. This paper aimed to explore the mental fatigue preliminary mechanism caused by prolonged watching of 3DTV. Five-minute EEG signals and subjective fatigue questionnaire forms from twenty subjects (sex ratio 1:1) were collected separately before and after one-hour watching of 2D/3DTV.Hilbert transform was utilized to analyze the EEG signals’ synchronism and spatial characteristics in different channels. Furthermore, the signal tracing analysis was used to localize the source of EEG activity.Based on the results of subjective fatigue questionnaire, significant mental fatigue was found one hour after watching 3DTV (P<0.01). Results indicated that the current density at the source was mostly reduced after watching 2D/3DTV with no significant differences (P>0.05). However, the current density of β₂ frequency band was significantly increased at occipital lobe after watching 3DTV (P<0.01), which was also greatly correlated to the subjective fatigue factor (P<0.01). Meanwhile, the current density of β₁ frequency band was significantly increased (P<0.05) after watching 3DTV at supramarginal gyrus (BA40), occipital lobe (BA18, BA19) and posterior central gyrus (BA3),which were related to the visual spatial information processing, compared with that of watching 2DTV. As a result, the brain would be in a state of fatigue after prolonged watching of 2D/3DTV. Compared with watching 2DTV, watching 3DTV would increase the burden of some local regions, such as occipital lobe and supramarginal gyrus, which might explain why it is easier to cause mental fatigue when watching 3DTV.
		2017 Vol. 36 (1): 46-52 [Abstract] ( 491 ) HTML (1 KB) PDF (5738 KB) ( 537 )

	53	Effects of Fear Memory Formation on Local Field Potential in Rat Prefrontal Cortex
		Zhang Bingshu, Sui Li, Huang Sijia
		DOI: 10.3969/j.issn.0258-8021.2017.01.007
		In this work, characteristics of local field potential before and after fear memory formation were studied to investigate the effects of fear memory formation on local field potential in rat medial prefrontal cortex. Eight healthy adult male SD rats were selected. The electrodes were implanted into the medial prefrontal cortex of the rats by stereotaxic apparatus. After one week, shuttle box test was used to induce fear memory in rats when rats were awake. The local field potential of rat medial prefrontal cortex was monitored by using Cerebus neural signals recording system, before and 6 h, 1 d, 2 d, 3 d, 4 d, 5 d, 6 d after fear memory formation. The Neuroexplorer software was introduced to analysis the local field potential. Power spectral density and power percentage of local field potentials were analyzed and compared with total power before and after the formation of fear memory and among different frequency bands (δ: 1-3 Hz, θ: 4-7 Hz, α: 8-13 Hz, β: 14-30 Hz, γ: 31-100 Hz). The results showed that the power percentage of θ and β at 6 h after fear memory formation was significantly different from that of before fear memory formation (P=0.017, P=0.017); The power percentage of θ was increased than that before fear memory formation. The power percentage of β was reduced than before fear memory formation. In addition, the power percentage of δ 1-2 days after fear memory formation was significantly different from that before fear memory formation (P=0.03, P=0.049). The power percentage of γ on 1～2 days after fear memory formation was significantly different from that before fear memory formation (P=0.013, P=0.019).These results indicated that activating mode of neural information processing in rat medial prefrontal cortex was significantly altered following fear memory formation.
		2017 Vol. 36 (1): 53-58 [Abstract] ( 438 ) HTML (1 KB) PDF (1465 KB) ( 442 )

	59	Research on the Changes of Intra-and Extra-Cellular Fluid within Small Intestine under Compression of Stapler
		Zhou Yu, Zhang Kuan, Xu Jingjing, Ren Binbin, Li Boting, Song Chengli
		DOI: 10.3969/j.issn.0258-8021.2017.01.008
		To explicitly understand the internal changes of gastrointestinal tissue compressed by stapler is a great precondition for optimizing the stapler’s engineering parameters. However, relevant work has not been adequate. By a modified stapler with embedded detection electrodes, the multi-frequency bio-impedance of porcine small intestine under compression of the stapler was measured. The Cole_Y model was used to fit the measurement results and changes within the tissue were analyzed according parameters of the model. G₀ represents the extracellular fluid conductance and ΔG was the intracellular fluid conductance. The changes of G₀ and ΔG under different compression strength were acquired by using spacers with different thickness. It turned out that the whole squeezing process was divided into two stages. At the first stage, two parameters were both falling fast. At the second stage, with the increase of compression strength, G₀ kept decreasing and the trend of ΔG was changed from a slight fluctuation into a slight decline. When the thickness of spacer increased from 0 mm to 0.52 mm, the percentage of samples with highly significant correlation between pressure and ΔG in all samples was increased from 40% to 100%, however, the percentage for G₀ was constant as 100%. It was concluded that under the effect of stapler, a part of tissue of the small intestine was firstly squeezed out of the measurement space, which led to a rapid decline of parameters. After that, with stapler continuous pressing the tissue, extracellular fluid was kept discharged, and intracellular fluid showed different trends under different pressing strength, which might be related to the compression deformation of cells. This research provided a basis for optimizing the parameters of a stapler.
		2017 Vol. 36 (1): 59-66 [Abstract] ( 320 ) HTML (1 KB) PDF (5443 KB) ( 387 )

	67	Simulation and Fabrication of Vascular Network in Biological Scaffolds Based on Three-Dimensional Cell Printing Technique
		Liu Chong, Xu Mingen, Wang Ling, Song Jiangxin
		DOI: 10.3969/j.issn.0258-8021.2017.01.009
		The three-dimensional scaffold cell culture technology has achieved a good spatial structure in the process of cell cultivation; however there are still lack of channel structures such as vascular network in the 3D scaffolds. Therefore current 3D scaffolds can not entirely simulate the growing environment of internal cells of the human body. Referring to the method of constrained structure optimization, this article built a simulated three-dimensional vascular network that was constructed inside the STL model of biological scaffold by computer software on the basis of common three-dimensional biological scaffold and created a new kind of three-dimensional biological scaffold model and printed the material objects using 3D biological printer. Through the statistical analysis of scaffold model and compared with the digital model, the differences between the printed scaffold model and the digital model were within 5%, which met the design requirements. By this technique the liquid circulation inside the cell culture scaffold was increased and the structure of scaffold was closer to the internal environment of the human body. The research can also make it possible to simulate and figure out factors of affecting the liquid circulation inside the human body has on the growth of cells.
		2017 Vol. 36 (1): 67-74 [Abstract] ( 433 ) HTML (1 KB) PDF (5966 KB) ( 736 )

	75	A Study on Cortical Bone Specimens Preparation and Method to Calculate the Mechanical Parameters
		Zhang Guanjun, Deng Xianpan, Yang Jie, Zhai Naichuan, Deng Xiaopeng, Cao Libo
		DOI: 10.3969/j.issn.0258-8021.2017.01.010
		The finite element method has become an important means of injury biomechanics, accurate cortical bone material constitutive parameters are important for the study of human impact injury and artificial bone. In this study, a method for processing high precision regular specimens is proposed and a quasi-static three-point bending test was applied. The beam theory and the optimization methodology with specimen-specific finite element models were applied to discuss the anisotropy and regional difference of cortical bone material, and a regression mode of material parameters obtained by the two methods was established based on linear regression analysis. Sixteen transverse and axial specimens were prepared, the proposed method can control the dimensions of specimens deviation of less than 4%. Using beam theory, Young's modulus of fresh bovine cortical bone in the axial and transverse was (21.70±3.33) GPa and (14.47±2.10) GPa, ultimate stress was (249.21±38.83) MPa and (106.81±21.05) MPa, and the ultimate strain was 1.95%±0.35% and 1.06%±0.20%, respectively, which were consistent with results reported by literatures. Linear regression analysis was applied to Young's modulus, yield stress and effective plastic strain obtained by beam theory and optimization, the fitting precision of the regression model was 96.4%, 98.7% and 89.3% (P<0.05), respectively. Results showed that the proposed method can efficiently prepare specimens with high dimensional accuracy and the biomechanical properties of the specimens were well maintained. In the quasi-static three point bending test of cortical bone, accurate material constitutive parameters were obtained by the optimization methodology with specimen-specific finite element models, and elastic modulus, yield stress and effective plastic strain were predicted quickly and accurately by beam theory based on the regression mode.
		2017 Vol. 36 (1): 75-82 [Abstract] ( 397 ) HTML (1 KB) PDF (5468 KB) ( 624 )

	83	Low Temperature Forming Tissue Engineering PLGA Scaffold to Repair Spinal Cord Injury in Rats
		Shi Tingchun, Zhou Tao, Sun Fangfang, Wang Ruiyan, An Xiao
		DOI: 10.3969/j.issn.0258-8021.2017.01.011
		With the rapid development of tissue engineering, scaffolds with 3D structures have become one of the key factors for the treatment of the spinal cord injury. In this work the PLGA porous scaffold fabricated with low temperature deposition manufacturing (LDM) technique was tested in rehabilitation of spinal cord injury. In the paper, poly (lactic-co-glycolic acid, PLGA) was selected to fabricate the spinal cord scaffold through LDM technique. The regeneration of spinal cord injury was induced by implanting the PLGA scaffold containing SCs into the transected spinal cords of Sprague Dawley (SD) rats (total 30). The PLGA scaffold was characterized as good porosity of 87.64%, hydrophilicity and considerable biodegradability. The degradation rate showed the trend of slow at the beginning and getting faster at the later period. In the experiment, the scaffolds were steady in the first 16 weeks, and the degradation rate began to be accelerated from the 20^th week. In addition, the effect of PLGA scaffold on the cell proliferation and cytotoxicity was evaluated by culturing Schwann cells (SCs) on the surface of the scaffold, showing that SCs spread and grew well on the PLGA scaffold with good proliferation. The BBB score indicated that paraplegia of the rats improved from the 4^th week, and slightly movement was visible on the posterior limbs of the injured rates. The investigation of section staining showed that the recovery of the spinal cord was considerably improved after implanting with the PLGA scaffold, which indicated that the PLGA scaffold exhibited great potential to be applied in the spinal cord injury. The PLGA porous scaffold fabricated with LDM has material effect in rehabilitation of spinal cord injury.
		2017 Vol. 36 (1): 83-91 [Abstract] ( 374 ) HTML (1 KB) PDF (24420 KB) ( 237 )

Reviews

	92	The Latest Research Progress of Freehand 3D US Volume Reconstruction
		Fan Yangyang, Ni Qian, Wen Tiexiang, Gu Jia, Wang Lei, Xie Yaoqin, Liu Jingen
		DOI: 10.3969/j.issn.0258-8021.2017.01.012
		Freehand 3D ultrasound imaging system is more in line with doctor's habits and the surrounding of operating room for its simple, useful, wider field of view and higher image resolution, which makes it one of the research focuses in the field of guidance of interventional surgery based on ultrasound imaging. Freehand 3D ultrasound produces 3D volume data of anatomical objects from a sequence of irregularly located 2D B-mode ultrasound images, and renders the reconstructed 3D volume data. Volume reconstruction is one of the key procedures in freehand 3D ultrasound imaging system and plays an important role in improving the reconstructed image quality. This paper summed up three kinds of volume reconstruction methods for freehand 3D ultrasound image, incuding voxel-based method, pixel-based method and function-based method. After that, some algorithms are presented with their merits and drawbacks. Finally, the research progress is summarized and future research directions are suggested.
		2017 Vol. 36 (1): 92-102 [Abstract] ( 701 ) HTML (1 KB) PDF (2824 KB) ( 1184 )

	103	Research Progress on Extracellular Matrix Materials in Bone Tissue Engineering
		Zhang Chi, Li Mei, Zhao Jiyuan
		DOI: 10.3969/j.issn.0258-8021.2017.01.013
		The limited ability of the body to fully repair large bone defects beyond critical sizes often necessitates the implantation of replacement material to promote healing.While the current clinical strategies to address such bone defects generally carry associated limitations, bone-tissue engineering approaches seek to minimize any adverse effects and facilitate complete regeneration of the lost tissue. Extracellular matrix, due to its excellent biocompatibility, unique biomechanical properties and biological activities,has been widely investigated as a scaffold in regenerative medicine. This review focused on hybrid constructs and modification on ECM materials, as well as its biological effects in vitro and in vivo. Application prospects in bone regeneration were also discussed.
		2017 Vol. 36 (1): 103-108 [Abstract] ( 390 ) HTML (1 KB) PDF (769 KB) ( 442 )

Communications

	109	Construction of Orthogonal Wavelet for ECG Signal Processing
		Zhu Junjiang, Zhang Yuanhui
		DOI: 10.3969/j.issn.0258-8021.2017.01.014

		2017 Vol. 36 (1): 109-113 [Abstract] ( 334 ) HTML (1 KB) PDF (1303 KB) ( 568 )

	114	Research on an Improved Algorithm for Wavelet Denoising of ECG
		Zheng Minmin, Gao Xiaorong, Xie Haihe
		DOI: 10.3969/j.issn.0258-8021.2017.01.015

		2017 Vol. 36 (1): 114-118 [Abstract] ( 490 ) HTML (1 KB) PDF (1026 KB) ( 1042 )

	119	A Simple Simulation Method of Positron Emission Tomography Imaging Focusing on Image Denoising
		Zhao Jie, Tang Heyun, Chen Zhicheng, Li Zhixian, Ren Zihui
		DOI: 10.3969/j.issn.0258-8021.2017.01.016

		2017 Vol. 36 (1): 119-123 [Abstract] ( 347 ) HTML (1 KB) PDF (6022 KB) ( 354 )

	124	Research of Range Adjustment for Fluorescent Immuno-Chromatographic Strip Analyzer
		GaoYueming, Huang Hongzhou, Lin Chuanyang, Wei Mengyu, Du Min, Pun Siohang
		DOI: 10.3969/j.issn.0258-8021.2017.01.017

		2017 Vol. 36 (1): 124-125 [Abstract] ( 337 ) HTML (1 KB) PDF (863 KB) ( 336 )

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