The Effects of Visual Object Size in The Depth Perception in KM Mouse

Whether mice perceive the depth of space dependent on the visual size of object targets was explored when visual cues such as perspective and partial occlusion in space were excluded. A mouse was placed on a platform the height of which is adjustable. The platform located inside a box in which all other walls were dark exception its bottom through that light was projected as a sole visual cue. The visual object cue was composed of 4x4 grids to allow a mouse estimating the distance of the platform relative to the grids. Three sizes of grids reduced in a proportion of 2/3 and seven distances with an equal interval between the platform and the grids at the bottom were applied in the experiments. The duration of a mouse staying on the platform at each height was recorded when the different sizes of the grids were presented randomly to test whether the Judgment of the mouse for the depth of the platform from the bottom was affected by the size information of the visual target. The results from all conditions of three object sizes show that time of mice staying on the platform became longer with the increase in height. In distance of 20 similar to 30 cm, the mice did not use the size information of a target to judge the depth, while mainly used the information of binocular disparity. In distance less than 20 cm or more than 30 cm, however, especially in much higher distance 50 cm, 60 cm and 70 cm, the mice were able to use the size information to do so in order to compensate the lack of binocular disparity information from both eyes. Because the mice have only 1/3 of the visual field that is binocular. This behavioral paradigm established in the current study is a useful model and can be applied to the experiments using transgenic mouse as an animal model to investigate the relationships between behaviors and gene functions.

从字形到语义：跨语言Stroop效应的ERP研究

According to the influential dual-route model of reading (Coltheart, Rastle et al. 2001), there are two routes to access the meaning of visual words: one directly by orthography (orthography-semantic) and the other indirectly via the phonology (phonology-semantic). Because of the dramatic difference between written Chinese and alphabetical languages, it is still on debate whether Chinese readers have the same semantic activation processes as readers of alphabetical languages. In this study, the semantic activation processes in alphabetical German and logographic Chinese were compared. Since the N450 for incongruent color words in the Stroop tasks was induced by the semantic conflict between the meaning of the incongruent color words and color naming, this component could be taken as an index for semantic activation of incongruent color words in Stroop tasks. Two cross-script Stroop experiments were adopted to investigate the semantic activation processes in Chinese and German. The first experiment focused on the the role of phonology, while the second one focused on the realative importance of orthography. Cultural differences in cognitive processing between individuals in western and eastern countries have been found (Nisbett & Miyamoto, 2005). In order to exclude potential differences in basic cognitive processes like visual discrimination capabilities during reading, a visual Oddball experiment with non-lexical materials was conducted with all participants. However, as indicated by the P300 elicited by deviant stimuli in both groups, no group difference was observed. In the first Stroop experiments, color words (e.g., “green”), color-word associates (e.g., “grass”), and homophones of color words were used. These words were embedded into color patches with either congruent color (e.g. word “green” in green color patch) or incongruent colors (e.g. word “green” in either red or yellow or blue color patch). The key point is to observe whether homophones in both languages could induce similar behavioral and ERP Stroop effects to that induced by color words. It was also interesting to observe to which extent the N450 was related to the semantic conflicts. Nineteen Chinese adult readers and twenty German adult readers were asked to respond to the back color of these words in the Stroop experiment in their native languages by pressing the corresponding keys. In the behavioral data, incongruent conditions (incongruent color words, incongruent color-word associates, incongruent homophones) had significantly longer reaction times as compared to corresponding congruent conditions. All incongruent conditions in the Geman group elicited an N450 in the 400 to 500 ms time window. In the Chinese group, the N450 in the same time window was also observed for the incongruent color words and incongruent color-word associates. These results indicated that the N450 was very sensitive to semantic conflict-even words with semantic association to colors (e.g. “grass”) could elicite similar N450. However, the N450 was absent for incongruent homophones of color words in the Chinese group. Instead, in a later time window (600-800 ms), incongruent homophones elicited a positivity over left posterior regions as compared to congruent homophones. Similar positivity was also observed for color words in the 700 to 1000 ms time window in the Chinese group and 600 to 1000 ms time window for incongruent color words and homophones in the Geman group. These results indicate that phonology plays an important role in Geman semantic activation processes, but not in Chinese. In the second Stroop experiment, color words and pseudowords which had similiar visual shape to color words in both languages were used as materials. Another group of eighteen Chinese and twenty Germans were involved in the Stroop experiment in their native languages.The ERPs were recorded during their performance. In the behavioral data, strong and comparable Stroop effects (as counted by substract the reaction times in the congruent conditions from reaction times in the incongruent conditions) were observed. In the ERP data, both incongruent color words and incongruent pseudowords elicited an N450 over the whole brain scalp in both groups. These results indicated that orthography played an equally important role in semantic activation processes in both languages. The results of the two Stroop experiments support the view that the semantic activation process in Chiense readers differs significantly from that in German readers. The former rely mainly on the direct route (orthography-semantic), while the latter use both direct route and incirect route (phonology-semantic). These findings also indicate that the characteritics of different languages shape the semantic activation processes.

Study of thermal behaviors in CO2 laser irradiated glass

To understand mechanisms underlying laser-induced damage of BK7 and fused silica, we calculate the temperature field of the substrates with CO2 laser irradiating at a given laser power and beam radius. We find that the two glasses show different thermal behaviors. A model is developed for estimating the time t to heat the surface of the substrates up to a particular temperature T with cw CO2 laser irradiation. We calculate theoretically the duration t that the samples are irradiated, from the beginning to visual catastrophic damage, with the assumption of damage threshold determined by the critical temperature. The duration t that the samples are irradiated, from the beginning to visual catastrophic damage, is investigated experimentally as well. Here we take the melting point or softening point as the critical temperature, given the thermomechanical coupling properties, which is enough to cause damage for BK7. Damage features are characterized by the sound of visual cracks. Finally, we calculate stresses induced by laser heating. The analysis of stress indicates that the damage of BK7 is due to the stresses induced by laser heating. (c) 2005 Society of Photo-Optical Instrumentation Engineers.

Study of thermal behaviors in CO2 laser irradiated glass

To understand mechanisms underlying laser-induced damage of BK7 and fused silica, we calculate the temperature field of the substrates with CO2 laser irradiating at a given laser power and beam radius. We find that the two glasses show different thermal behaviors. A model is developed for estimating the time t to heat the surface of the substrates up to a particular temperature T with cw CO2 laser irradiation. We calculate theoretically the duration t that the samples are irradiated, from the beginning to visual catastrophic damage, with the assumption of damage threshold determined by the critical temperature. The duration t that the samples are irradiated, from the beginning to visual catastrophic damage, is investigated experimentally as well. Here we take the melting point or softening point as the critical temperature, given the thermomechanical coupling properties, which is enough to cause damage for BK7. Damage features are characterized by the sound of visual cracks. Finally, we calculate stresses induced by laser heating. The analysis of stress indicates that the damage of BK7 is due to the stresses induced by laser heating. (c) 2005 Society of Photo-Optical Instrumentation Engineers.

Effects of subretinal implant materials on the viability, apoptosis and barrier function of cultured RPE cells

Background: Subretinal microphotodiode array (MPDA) is a type of visual prosthesis used for the implantation in the subretinal space of patients with progressive photoreceptor cell loss. The present study aimed to evaluate the effect of materials for MPDA on the viability, apoptosis and barrier function of cultured pig retinal pigment epithelium (RPE) cells.Methods: Primary culture of pig RPE cells was performed and 24 pig eyes were used to start RPE culture. The third passage of the cultures was plated on different materials for MPDA and MPDAs. The tetrazolium dye-reduction assay (MTT) was used to determine RPE cell viability. Flow cytometry was measured to indicate the apoptosis rates of RPE cells on different materials. RPE cells were also cultured on microporous filters, and the transepithelial resistance and permeability of the experimental molecule were measured to determine the barrier function.Results: The data from all the methods indicated no significant difference between the materials groups and the control group, and the materials tested showed good biocompatibility.Conclusions: The materials for MPDA used in the present study had no direct toxicity to the RPE cells and did not release harmful soluble factors that affected the barrier function of RPE in vitro.

图像不变局部特征研究及应用

图像不变局部特征是新近兴起的一类图像特征，基于不变局部特征的图像表示是计算机视觉的热点研究问题，在理论研究和实际应用上都具有重要意义。本论文针对图像不变局部特征的原理特性及应用展开研究：（1）当今流行的不变局部特征检测和描述方法；（2）局部特征组织方式；（3）基于局部不变特征的摄像机运动检测方法；（4）基于局部特征组合的目标模型及识别方法。 深入研究了当今流行的不变局部特征检测子，重点分析了其提取原理、特征结构、不变性阶次、精确度等特性，在此基础上对多种检测子进行比较分析，得出各自的适用范围，并总结出在具体应用环境下的特征选择原则。 针对视频分析中摄像机运动检测的具体应用，提出一种基于尺度不变局部特征的摄像机运动检测方法。该方法选取尺度不变局部特征，采用无序特征集合的方式表示图像帧，通过帧间局部特征的匹配，提出归一化软投票的方法鲁棒地估计特征匹配对的位置、尺度的变化，并根据各变化值和投票数的特点识别出摄像机的运动类型。该方法简单、鲁棒，满足了摄像机运动检测的处理速度和准确性需求。 针对基于局部特征的目标表示和识别问题，研究分析现有两种模型bag-of-words和part-based的优缺点，将二者结合，提出一种局部特征组合的目标表示模型和相应的识别算法。该方法在半局部区域内的特征同时进行外观描述和空间位置编码，并用数据挖掘中的频繁项挖掘技术自动提取出表征目标的特征组合，作为子模型。目标模型由一系列子模型构成，子模型的数量及每个子模型中包含的部件数目均自动从训练集中发现，是完全目标自适应的。所提方法克服了bag-of-words方法表达的精确性不足、part-based方法训练速度过慢的缺点，在识别问题上得到了较好的总体性能。

NMR-based metabonomic study on the subacute toxicity of aristolochic acid in rats

The subacute toxicity of aristolochic acid (AA) was investigated by H-1 NMR spectroscopic and pattern recognition (PR)-based metabonomic methods. Model toxins were used to enable comparisons of the urinary profiles from rats treated with known toxicants and AA at various time intervals. Urinary H-1 NMR spectra were data-processed and analyzed by pattern recognition method. The result of visual comparison of the spectra showed that AA caused a renal proximal tubular and papillary lesion and a slight hepatic impair. Pattern recognition analysis indicated that the renal proximal tubule lesion was the main damage induced by AA, and the renal toxicity induced by AA was a progressive course with the accumulation of dosage by monitoring the toxicological processes from onset, development and part-recovery. These results were also supported by the conventional clinical biochemical parameters.

左侧梭状回内文字的字形加工：中文正常阅读者，中文文盲、非中文母语被试的对比研究

Reading is an important human-specific skill obtained through extensive learning experience and is reliance on the ability to rapidly recognize single words. According to the behavioral studies, the most important stage of reading is the representation of “visual word form”, which is independent on surface visual features of the reading materials. The prelexical visual word form representation is characterized by the abstractive and highly effective and precise processing. Neuroimaging and neuropsychological studies have investigated the neural basis underlying the visual word form processing. On the basis of summary of the existing literature, the current thesis aimed to address three fundamental questions involving neural basis of word recognition. First, is there a dedicated neural network that is specialized for word recognition? Second, is the orthographic information represented in the putative word/character selective region (VWFA)? Third, what is the role of reading experience in the genesis of the VWFA, is experience a main driver to shape VWFA instead of evolutionary selectivity? Nineteen Chinese literate volunteers, 5 Chinese illiterates and 4 native English speakers participated in this study, and performed perceptual tasks during fMRI scanning. To address the first question, we compared the differential responses to three categories of visual objects, i.e., faces, line drawings of objects and Chinese characters, and defined the region of interesting (ROI) for the next experiment. To address the second question, Chinese character orthography was manipulated to reveal possible differential responses to real characters, false characters, radical combinations, and stroke combinations in the regions defined by the first experiment. To examine the role of reading experience in genesis of specialization for character, the responses for unfamiliar Chinese characters in Chinese illiterates and native English speakers were compared with that in the Chinese literates, and tracked the change in cortical activation after a short-term reading training in the illiterates. Data were analyzed in two dimensions. Both BOLD signal amplitude and spatial distribution pattern among multi-voxels were used to systematically investigate the responsiveness of the left fusiform gyrus to Chinese characters. Our results provide strong and clear evidence for the existence of functionally specialized regions in the human ventral occipital-temporal cortex. In the skilled readers a region specialized for written words could be consistently found in the lateral part of the left fusiform gyrus, line drawings in the median part and faces in the middle. Our results further show that spatial distribution analysis, a method that was not commonly used in neuroimaging of reading, appears to be a more effective measurement for category specialization for visual objects processing. Although we failed to provide evidence that VWFA processes orthographic information in terms of signal intensitiy, we do show that response pattern of real characters and radical collections in this area is different from that of false characters and random stroke combinations. Our last set of experiments suggests that the selective bias to reading material is clearly experience dependent. The response to unknown characters in both English speakers/readers and Chinese illiterates is fundamentally different from that of the skilled Chinese readers. The response pattern for unknown characters is more similar to that for line drawings rather as a weak version of character in skilled Chinese readers. Short-term training is not sufficient to produce VWFA bias even when tested with learned characters, rather the learned characters generated a overall upward shift of the activation of the left fusiform region. Formation of a dedicated region specialized for visual word/character might depend on long-term extensive reading experience, or there might be a critical period for reading acquisition.

左中部梭状回枕颞沟内皮质对汉字加工的必要性、选择性和作用性质

A number of functional neuroimaging studies with skilled readers consistently showed activation to visual words in the left mid-fusiform cortex in occipitotemporal sulcus (LMFC-OTS). Neuropsychological studies also showed that lesions at left ventral occipitotemporal areas result in impairment in visual word processing. Based on these empirical observations and some theoretical speculations, a few researchers postulated that the LMFC-OTS is responsible for instant parallel and holistic extraction of the abstract representation of letter strings, and labeled this piece of cortex as “visual word form area” (VWFA). Nonetheless, functional neuroimaging studies alone is basically a correlative rather than causal approach, and lesions in the previous studies were typically not constrained within LMFC-OTS but also involving other brain regions beyond this area. Given these limitations, it remains unanswered for three fundamental questions: is LMFC-OTS necessary for visual word processing? is this functionally selective for visual word processing while unnecessary for processing of non-visual word stimuli? what are its function properties in visual word processing? This thesis aimed to address these questions through a series of neuropsychological, anatomical and functional MRI experiments in four patients with different degrees of impairments in the left fusiform gyrus. Necessity: Detailed analysis of anatomical brain images revealed that the four patients had differential foci of brain infarction. Specifically, the LMFC-OTS was damaged in one patient, while it remained intact in the other three. Neuropsychological experiments showed that the patient with lesions in the LMFC-OTS had severe impairments in reading aloud and recognizing Chinese characters, i.e., pure alexia. The patient with intact LMFC-OTS but information from the left visual field (LVF) was blocked due to lesions in the splenium of corpus callosum, showed impairment in Chinese characters recognition when the stimuli were presented in the LVF but not in the RVF, i.e. left hemialexia. In contrast, the other two patients with intact LMFC-OTS had normal function in processing Chinese characters. The fMRI experiments demonstrated that there was no significant activation to Chinese characters in the LMFC-OTS of the pure alexic patient and of the patient with left hemialexia when the stimuli were presented in the LVF. On the other hand, this patient, when Chinese characters were presented in right visual field, and the other two with intact LMFC-OTS had activation in the LMFC-OTS. These results together point to the necessity of the LMFC-OTS for Chinese character processing. Selectivity: We tested selectivity of the LMFC-OTS for visual word processing through systematically examining the patients’ ability for processing visual vs. auditory words, and word vs. non-word visual stimuli, such as faces, objects and colors. Results showed that the pure alexic patients could normally process auditory words (expression, understanding and repetition of orally presented words) and non-word visual stimuli (faces, objects, colors and numbers). Although the patient showed some impairments in naming faces, objects and colors, his performance scores were only slightly lower or not significantly different relative to those of the patients with intact LMFC-OTS. These data provide compelling evidence that the LMFC-OTS is not requisite for processing non-visual word stimuli, thus has selectivity for visual word processing. Functional properties: With tasks involving multiple levels and aspects of word processing, including Chinese character reading, phonological judgment, semantic judgment, identity judgment of abstract visual word representation, lexical decision, perceptual judgment of visual word appearance, and dictation, copying, voluntary writing, etc., we attempted to reveal the most critical dysfunction caused by damage in the LMFC-OTS, thus to clarify the most essential function of this region. Results showed that in addition to dysfunctions in Chinese character reading, phonological and semantic judgment, the patient with lesions at LMFC-OTS failed to judge correctly whether two characters (including compound and simple characters) with different surface features (e.g., different fonts, printed vs. handwritten vs. calligraphy styles, simplified characters vs. traditional characters, different orientations of strokes or whole characters) had the same abstract representation. The patient initially showed severe impairments in processing both simple characters and compound characters. He could only copy a compound character in a stroke-by-stroke manner, but not by character-by-character or even by radical-by-radical manners. During the recovery process, namely five months later, the patient could complete the abstract representation tasks of simple characters, but showed no improvement for compound characters. However, he then could copy compound characters in a radical-by-radical manner. Furthermore, it seems that the recovery of copying paralleled to that of judgment of abstract representation. These observations indicate that lesions of the LMFC-OTS in the pure alexic patients caused several damage in the ability of extracting the abstract representation from lower level units to higher level units, and the patient had especial difficulty to extract the abstract representation of whole character from its secondary units (e.g., radicals or single characters) and this ability was resistant to recover from impairment. Therefore, the LMFC-OTS appears to be responsible for the multilevel (particularly higher levels) abstract representations of visual word form. Successful extraction seems independent on access to phonological and semantic information, given the alexic patient showed severe impairments in reading aloud and semantic processing on simple characters while maintenance of intact judgment on their abstract representation. However, it is also possible that the interaction between the abstract representation and its related information e.g. phonological and semantic information was damaged as well in this patient. Taken together, we conclude that: 1) the LMFC-OTS is necessary for Chinese character processing, 2) it is selective for Chinese character processing, and 3) its critical function is to extract multiple levels of abstract representation of visual word and possibly to transmit it to phonological and semantic systems.

视觉通路在汉字组块破解过程中的有效连接

The present study used Dynamical Causal Modeling (DCM) to reveal the influence of difficult to decompose Chinese characters on the effective connectivity of “where” and “what” visual stream。 Chunk decomposition is to decompose the familiar items to their components and then to make up new items with the decomposed components。 Some previous studies with eye movements and brain image had revealed that the chunk decomposition was involved visual-spatial information process, and suggested that “what” and “where” visual streams contributed to the course of chunk decomposition。 However, how they worked to complete the chunk decomposition task is still unknown。 The present study has two factors, familiarity and tightness of the spatial structures, each with 2 levels: real words vs. pseudowords and tight chunks vs. loose chunks。 The results indicates that in the loose conditions, familiarity increases the effective connectivity of “where ” stream, while in the pseudowords conditions, tightness of the spatial structures increases the effective connectivity of both “where” and “what” streams, and familiarity and tightness combined to increase not only both the “what” and “where” streams, but also the effective connectivity from the inferior temporal gyrus to the superior parietal lobule.