雄蝇追逐飞行的加速度分析

本文报导了采用高速摄影技术,通过分析雄蝇追逐飞行的加速度对视觉制导问题所进行的研究.我们的结果如下:1.目标蝇的角位置与追逐蝇相应的角加速度分量之间,在追逐蝇的全视场中呈现非线性的关系.追逐蝇的水平角加速度分量与水平误差角在前视场中有较好的线性关系.追逐蝇的俯仰角加速度分量与俯仰误差角之间,当目标蝇位于前上半视场中时,呈现较好的线性关系.2.目标蝇相对追逐蝇的角运动对追逐蝇的相应角加速度分量也有影响,这种影响与目标蝇位置的关系不大.3.对于目标蝇在前后视场中的两种情况,两蝇间的距离对追逐蝇加速度大小影响的规律是不同的:当目标蝇在前视场中时,只经过较短的延迟时间两蝇间的距离与追逐蝇加速度大小出现了正的相关峰,而后视场中的情况不然,它需要较长的延迟时间.两蝇间距离的变化对追逐蝇加速度大小的影响也有类似的现象.4.在追逐过程中雄蝇利用背前区的小眼来追逐带头的目标雌蝇,而组织学研究在雄蝇背前区的小眼中发现了性特化的中心小网膜细胞,与行为研究的结果相呼应.5.文中最后对蝇视觉神经系统中如何获取目标绳的位置和运动参数的问题进行了讨论.     

雄蝇追逐行为的分析

本文报告了在自由飞行条件下雄蝇追逐的行为实验及其分析的初步结果.其结果如下:1.追逐雄蝇水平方向偏转的角速度dF_1线性地依赖于目标蝇水平方位误差角T_1的大小.当目标在前视场中,即空间误差角|G|<π/4时,线性回归直线的斜率约为37**;而当空间误差角|G|>π/4时,线性回归直线的斜率约为6.7.2.追逐雄蝇俯仰方向偏转角速度dF_2在(-(π/2),π/2)的范围内线性依赖于俯仰误差角T_2的大小,其回归直线的斜率约为14.3.雄蝇追逐行为中,水平方位误差角频数分布的直方图呈现为峰值在零点的对称型分布;而俯仰误差角T_2频数分布的直方图是非对称型的,即仰角出现的频数大大超过俯角出现的频数.4.雄蝇主要利用了两蝇间距离变化dD的信息以及目标误差角来控制向前飞行的速度V.当误差角小时(即目标在前视场中),dD一般为负值,说明两蝇间的距离减小,而雄蝇追逐飞行的加速度A却与dD呈现正的线性关系.当误差角大时(即目标位于后视场中),dD一般为正值,说明两蝇间的距离增加.     

用红外方法对蝇翅视动行为的探索

本文报告了利用红外装置对蝇翅视动行为实验研究的初步结果及其分析:1.在红外探测器探测到的信号中找到了一个能反映蝇翅拍动幅度的参数.2.双侧、单侧刺激域的宽度及刺激域的高度对视动反应发生几率在一定范围内正相关,当超过一阈值(即饱和阈值)后,即出现稳定的视动反应,它们的饱和阈值分别为60°,30°,40°刺激条纹的亮度生有类似情况.刺激条纹的运动速度在一定范围内对视动反应无影响.3.当刺激没有达到饱和时,蝇翅出现断续的典型的视动反应,即“0-1波动反应”.4.单侧条纹由前向后运动时,蝇翅出现典型反应,而条纹从后向前运动时,不出现典型的视动反应或反应很弱.双侧刺激时,条纹向前运动几乎不诱发反应;条纹向后运动诱发明显的蝇翅视动反应,且蝇翅平面的方向在拍动过程中发生变化.     

用红外方法对蝇翅视动行为的探索

本文报告了利用红外装置对蝇翅视动行为实验研究的初步结果及其分析:1.在红外探测器探测到的信号中找到了一个能反映蝇翅拍动幅度的参数.2.双侧、单侧刺激域的宽度及刺激域的高度对视动反应发生几率在一定范围内正相关,当超过一阈值(即饱和阈值)后,即出现稳定的视动反应,它们的饱和阈值分别为60°,30°,40°刺激条纹的亮度生有类似情况.刺激条纹的运动速度在一定范围内对视动反应无影响.3.当刺激没有达到饱和时,蝇翅出现断续的典型的视动反应,即“0-1波动反应”.4.单侧条纹由前向后运动时,蝇翅出现典型反应,而条纹从后向前运动时,不出现典型的视动反应或反应很弱.双侧刺激时,条纹向前运动几乎不诱发反应;条纹向后运动诱发明显的蝇翅视动反应,且蝇翅平面的方向在拍动过程中发生变化.     

阻断泛素-蛋白酶体通路对人原代白血病细胞的作用

阻断泛素-蛋白酶体通路对不同类型细胞具有完全不同的结果, 但未见对原代白血病细胞作用的报道. 观察了阻断上述通路对8例白血病患者和10例正常人骨髓单个核细胞(MNC)的作用. 结果表明, 不同个体原代白血病细胞对阻断此通路的反应敏感性存在明显差异, 其中3例细胞极为敏感, 24 h以内90%细胞被迅速诱发凋亡, 而正常人骨髓MNC对阻断泛素蛋白酶体通路反应不敏感, 未观察到凋亡现象发生. 进一步的免疫印迹实验发现, 对上述通路敏感的原代白血病细胞Bcl-2蛋白表达量较高, 而且在凋亡过程中发生了特异位点的酶解;对上述通路不敏感的细胞(包括正常人骨髓MNC)Bcl-2蛋白低表达, 或Bcl-2高表达但未能检测到其特异性酶解现象. 结合其他实验结果, 提示细胞中Bcl-2蛋白是否发生特异位点酶解与细胞对阻断上述通路的敏感性之间具有相关性, 为进一步研究不同种类细胞对阻断泛素-蛋白酶体通路敏感性差异的机制提供了线索.     

联峰山10种草本植物营养器官形态结构与生态适应性

利用常规石蜡制片技术对生长在联峰山上的10种植物营养器官进行解剖学观察。主要结果如下:(1)叶表皮细胞均为1层,绝大多数无表皮毛,气孔少;异面叶或等面叶;中脉维管束束数1至多个。(2)根:主要为次生构造,也有初生构造的。但大多数植物无周皮;皮层细胞的层数在不同植物中差异较大;有些植物次生韧皮部普遍不发达,次生木质部较韧皮部明显。(3)茎:表皮细胞均为1层,具角质膜;皮层细胞层数普遍较少,外皮层有机械组织存在;维管束数目多个并呈一圈排列,外韧或双韧;髓部发达,髓射线明显。该研究结果表明10种植物具有中生植物或阴性植物的结构特点,是植物长期适应环境条件的结果;该研究为更好地开发和利用植物提供了解剖学依据。     

落葵粘液细胞分布及发育的解剖学研究

采用石蜡切片法对落葵粘液细胞的分布及发育构造进行观察研究.结果表明:(1)除花药、子房及种子外,粘液细胞普遍存在于落葵植株的地上部分内.茎中的粘液细胞多单个散生分布于皮层、髓及髓射线;叶内的粘液细胞主要分布于海绵组织,栅栏组织中则很少见;叶柄中的粘液细胞主要沿叶柄"U"型皮层的两边分布;发育后期作为果实的花萼片中粘液细胞则散生分布很多.(2)根据发育过程的不同形态,可将粘液细胞的发育分为4个阶段:原始细胞阶段、液泡化阶段、成熟阶段和细胞质解体阶段;粘液细胞最早可见于第三叶原基,并且粘液细胞的发育与植株器官的发育不同步.     

华虻小叶神经元运动敏感性的研究

用电生理细胞内记录的方法记录了１０个以上小叶神经元对闪光、运动光斑及运动光栅刺激的电生理反应特点,结果表明：（１）小叶神经元对闪光刺激具有特征性反应,细胞对给光和撤光刺激都会表现出不同程度的去极化和超极化,反应的波形不随闪光时间的改变而改变,两次去极化之间的时间间隔与闪光刺激的时间长度成线性关系;（２）小叶神经元对运动光斑的运动速度非常敏感,而对光斑的运动方向的改变却不敏感,尽管有的细胞存在一个能使反应的变化更快的优势方向,但并没有明显的运动方向选择性;（３）小叶神经元对运动光栅的响应频率受光栅的空间频率和运动速度的双重调制,与光栅的运动方向无关。     

鳜鱼视觉特性及其对捕食习性适应的研究III．视觉对猎物运动和形状的反应

作者采用行为学方法测定了伏击型凶猛鱼类鳜鱼视觉对猎物运动和形状特征的反应特性.鳜鱼对3种不同体形饵料鱼有最强的跟踪反应和攻击反应,对虾则有较强的跟踪反应而几乎没有攻击反应,对蜻蜒幼虫仅有不强的跟踪反应而完全没有攻击反应.它对低速(v≤5cm/s)一连续和等间歇不连续运动的饵料鱼有较强的跟踪反应和攻击反应,对中速和高速(v≥10cm/s)连续运动的饵料鱼有最强的跟踪反应而几乎没有或完全没有攻击反应,对中速和高速等间歇不连续运动的饵料鱼则有最强的跟踪反应和最强的攻击反应.它对不连续运动的a、b、c、d、e、f6种形状均有跟踪反应,但近距离跟踪反应的强度与形状特征有关系,对不连续运动的b、c、d3种形状完全没有攻击反应,而对不连续运动的a、e、f3种形状则有依次增强的攻击反应.鳜鱼视觉可对猎物运动进行远距离的识别,并决定其对猎物的远距离跟踪反应.且其视觉仅能对猎物的大致形状进行近距离识别,并决定其对猎物的近距离跟踪反应和攻击反应.       

运图象刺动激的视动振颤(OKN)眼动反应的速度跟踪特性

本文用传统的转筒式运动条纹刺激及电视运动条纹图形刺激两种方法进行了OKN实验,对所引起的OKN反应进行了定量比较,结果证明两者的刺激效果是相似的;用电视运动图象刺激方法,分别在中心视场和周边视场进行刺激实验,阐明了OKN主要是由作用于视网膜中央区域的运动图象刺激所引起的;并对OKN的动态反应进行了实验分析,在正弦速度刺激下,OKN增益主要取决于刺激运动的加速度,而不是单纯取决于刺激运动的速度或频率,并在脉冲速度刺激的OKN实验中,用动态反应时间阐明了这一结论.     

Tangential medulla neurons in the mothManduca sexta. Structure and responses to optomotor stimuli

InManduca sexta, large tangential cells connect the medulla via the lobula valley (LoV) tract to the midbrain and the contralateral medulla. Tract neurons have been stained and recorded to determine their responses to optomotor stimulation. Neurons in the LoV-tract comprise a physiologically and anatomically heterogeneous population:

1. Motion insensitive medulla tangential (Mt) neurons arise from cell bodies in the ventral rind. Heterolateral cells arborize massively in both medullae and one or both halves of the midbrain. Mt-neurons respond to changes in light intensity. Physiological and anatomical evidence argues for their monocularity and transmission from the medulla on the side of the soma to the central brain and the contralateral medulla.
2. Motion sensitive neurons with cell bodies behind the protocerebral bridge connect the midbrain to the ipsior contralateral medulla. Direction-selective responses are characterized by excitation to motion in the preferred and inhibition in the opposite direction with maxima either in a horizontal or vertical direction. Peak values appear at contrast frequencies of appr. 3/s. The results suggest that these neurons are binocular and relay information from the midbrain to the medulla. They have been labelled as centrifugal medulla tangential (cMt) neurons.

The possible roles for tract neurons in visually guided behaviour are discussed.     

A system of insect neurons sensitive to horizontal and vertical image motion connects the medulla and midbrain

Summary The response properties and gross morphologies of neurons that connect the medulla and midbrain in the butterfly Papilio aegeus are described. The neurons presented give direction-selective responses, i.e. they are excited by motion in the preferred direction and the background activity of the cells is inhibited by motion in the opposite, null, direction. The neurons are either maximally sensitive to horizontal motion or to slightly off-axis vertical upward or vertical downward motion, when tested in the frontal visual field. The responses of the cells are dependent on the contrast frequency of the stimulus with peak values at 5–10 Hz. The receptive fields of the medulla neurons are large and are most sensitive in the frontal visual field. Examination of the local and global properties of the receptive fields of the medulla neurons indicates that (1) they are fed by local elementary motion-detectors consistent with the correlation model and (2) there is a non-linear spatial integration mechanism in operation.     

Dissociation of neuronal and psychophysical responses to local and global motion

Most neurons in cortical area MT (V5) are strongly direction selective, and their activity is closely associated with the perception of visual motion. These neurons have large receptive fields built by combining inputs with smaller receptive fields that respond to local motion. Humans integrate motion over large areas and can perceive what has been referred to as global motion. The large size and direction selectivity of MT receptive fields suggests that MT neurons may represent global motion. We have explored this possibility by measuring responses to a stimulus in which the directions of simultaneously presented local and global motion are independently controlled. Surprisingly, MT responses depended only on the local motion and were unaffected by the global motion. Yet, under similar conditions, human observers perceive global motion and are impaired in discriminating local motion. Although local motion perception might depend on MT signals, global motion perception depends on mechanisms qualitatively different from those in MT. Motion perception therefore does not depend on a single cortical area but reflects the action and interaction of multiple brain systems.     

Cellular basis for the response to second-order motion cues in Y retinal ganglion cells.

We perceive motion when presented with spatiotemporal changes in contrast (second-order cue). This requires linear signals to be rectified and then summed in temporal order to compute direction. Although both operations have been attributed to cortex, rectification might occur in retina, prior to the ganglion cell. Here we show that the Y ganglion cell does indeed respond to spatiotemporal contrast modulations of a second-order motion stimulus. Responses in an OFF ganglion cell are caused by an EPSP/IPSP sequence evoked from within the dendritic field; in ON cells inhibition is indirect. Inhibitory effects, which are blocked by tetrodotoxin, clamp the response near resting potential thus preventing saturation. Apparently the computation for second-order motion can be initiated by Y cells and completed by cortical cells that sum outputs of multiple Y cells in a directionally selective manner.     

Insect detection of small targets moving in visual clutter

Detection of targets that move within visual clutter is a common task for animals searching for prey or conspecifics, a task made even more difficult when a moving pursuer needs to analyze targets against the motion of background texture (clutter). Despite the limited optical acuity of the compound eye of insects, this challenging task seems to have been solved by their tiny visual system. Here we describe neurons found in the male hoverfly,Eristalis tenax, that respond selectively to small moving targets. Although many of these target neurons are inhibited by the motion of a background pattern, others respond to target motion within the receptive field under a surprisingly large range of background motion stimuli. Some neurons respond whether or not there is a speed differential between target and background. Analysis of responses to very small targets (smaller than the size of the visual field of single photoreceptors) or those targets with reduced contrast shows that these neurons have extraordinarily high contrast sensitivity. Our data suggest that rejection of background motion may result from extreme selectivity for small targets contrasting against local patches of the background, combined with this high sensitivity, such that background patterns rarely contain features that satisfactorily drive the neuron.     

Analysis of erythroid differentiation in Friend cells using noninducible variants

A series of Friend cell variants has been isolated by selecting for resistance to different inducers of Friend cell differentiation. This procedure selects for cells which have lost the capacity to differentiate terminally in the presence of inducer. Fluctuation analysis shows that these variants arise during culture and are not induced by the selective conditions. Moreover, mutagenesis of parental cells increases the frequency of occurrence of DMSO-resistant variants. Our evidence suggests that these resistant variants arise by two mechanisms. Some arise spontaneously at a relatively high rate (5 × 10^?5?5 × 10^?6 per cell per generation), but their phenotypes are not necessarily stable on removal of the selective conditions. Stable variants arise spontaneously at a lower frequency which is consistent with a true mutational origin.Screening of these stable resistant variants shows that they have different phenotypes. Some fail to respond to any inducer; others respond to all inducers tested except the one used for selection, whereas others respond to some but not all inducers. Most of the DMSO-resistant variants are noninducible by DMSO for all aspects of Friend cell differentiation tested (that is, globin mRNA, hemoglobin, spectrin and the ability to undergo terminal differentiation). Two variants, however, are inducible for an early marker of differentiation, the erythrocyte membrane protein spectrin, but not for other markers such as hemoglobin, globin RNA or terminal differentiation. This implies that the regulation of the globin pathway can be uncoupled from that of spectrin.     

The optic lobes of Diptera

The optic lobes of Diptera have been examined by variants of the Golgi-Colonnier selective staining techniques and by reduced silver procedures. All, bar one, of the elements described by the earlier authors (Vigier 1908; Zawarzin 1913; Cajal & Sanchez 1915) have been seen, in part or in their entirely, in these preparations. Many other forms, hitherto unrecognized, have been found. Their perpendicular topographical relationships have been reconstructed in the optic lobe regions. Some lateral relationships have also been reconstructed between elements in regions whose columnar arrangement is clearly discernible in Golgi preparations; these include the lamina and the medulla. In the Diptera the projection pattern of the retina mosaic into the lamina neuropil involves complex chiasmata between the two regions (Braitenberg 1967); these have been confirmed from these species. The retina-lamina mosaic is, essentially, homotopically preserved in the columnar medulla, via long visual fibres and monopolar cells. The medullary mosaic is preserved through its strata by transmedullary cells and the longest small-field amacrine cells. The mosaic is projected to the two regions of the lobula complex by class I cells (see part I). The organization of the tangential cell processes suggests that some of them may interact with large or whole field aggragates of the relayed retinal mosaic. Others, especially in the lobula, may interact with small oval or narrow strip-field aggragates. Although there are many differences of neural form and number of neurons between species, both the Lepidoptera and Diptera have the same fundamental plan of neuroarchitecture.     

Motions Add,Orientations Don’t,in the Human Visual System

Humans can distinguish between contours of similar orientation, and between directions of visual motion. There is consensus that both of these capabilities depend on selective activation of tuned neural channels. The bandwidths of these tuned channels are estimated here by modelling previously published empirical data. Human subjects were presented with a rapid stream of randomly oriented gratings, or randomly directed motions, and asked to respond when they saw a target stimulus. For the orientation task, subjects were less likely to respond when two preceding orientations were close to the target orientation but differed from each other, presumably due to a failure of summation. For the motion data, by contrast, subjects were more likely to respond when the vector sum of two previous directions was in the target direction. Fitting a cortical signal-processing model to these data showed that the direction bandwidth of motion sensors is about three times the bandwidth of orientation sensors, and that it is the large bandwidth that allows the summation of motion stimuli. The differing bandwidths of orientation and motion sensors presumably equip them for differing tasks, such as orientation discrimination and estimation of heading, respectively.     

Connections between wide-field monocular and binocular movement detectors in the brain of a hawk moth

Summary Recordings were made in the brain of Sphinx ligustri of pairs of directionally selective movement detectors, and the spike trains analysed with a computer for possible synaptic connections between two classes of movement detector. (1) Neurones with large binocular fields which arise in the medial protocerebrum and project to the medulla or lobula of one optic lobe, or to the ventral nerve cord. (2) Movement detectors which project from the lobula complex of one optic lobe to the opposite medial protocerebrum. The majority of the second group had back-to-front preferred directions over the ipsilateral eye, and of these many were weakly sensitive to stimuli to the opposite eye. The ipsilateral receptive field covered most of the eye.Optic lobe output cells with the appropriate preferred direction provide a powerful excitatory input to the binocular movement detectors centrifugal to the medulla. Each centrifugal movement detector probably receives excitatory inputs from no more than two optic lobe output cells with back-to-front preferred direction. The same set of optic lobe output neurones probably feeds several cells projecting to the medulla and lobula of both optic lobes, and, possibly, to the ventral nerve cord.Evidence was obtained that the optic lobe output cells themselves receive few excitatory inputs, and that therefore the receptive fields of their input cells are large.Two moving stimuli were presented in different areas of the receptive field. Movement through the null direction in one area inhibited the response to movement in the preferred direction in another area. This suppression was stronger in optic lobe output cells with front-to-back preferred direction than in units with back-to-front preferred direction. Thus the optic lobe output cells, or wide-field units feeding them, receive inhibitory inputs from wide-field units with the opposite preferred direction.Similar tests in which moving stimuli were presented to both eyes gave results indicating that the binocular centrifugal movement detectors may receive inhibitory inputs from movement detectors with back-to-front preferred direction. The possible functional significance of these inhibitory inputs is discussed.I am very greatful to F. A. Miles for helpful discussion and criticism. Financial support came from the U. K. Science Research Council.