运动知觉中图形-背景分离的时间动态的神经模型。
A neural model of the temporal dynamics of figure-ground segregation in motion perception.
机构信息
Faculty of Engineering and Computer Sciences, Institute of Neural Information Processing, Ulm University, Ulm, Germany.
出版信息
Neural Netw. 2010 Mar;23(2):160-76. doi: 10.1016/j.neunet.2009.10.005. Epub 2009 Oct 30.
How does the visual system manage to segment a visual scene into surfaces and objects and manage to attend to a target object? Based on psychological and physiological investigations, it has been proposed that the perceptual organization and segmentation of a scene is achieved by the processing at different levels of the visual cortical hierarchy. According to this, motion onset detection, motion-defined shape segregation, and target selection are accomplished by processes which bind together simple features into fragments of increasingly complex configurations at different levels in the processing hierarchy. As an alternative to this hierarchical processing hypothesis, it has been proposed that the processing stages for feature detection and segregation are reflected in different temporal episodes in the response patterns of individual neurons. Such temporal epochs have been observed in the activation pattern of neurons as low as in area V1. Here, we present a neural network model of motion detection, figure-ground segregation and attentive selection which explains these response patterns in an unifying framework. Based on known principles of functional architecture of the visual cortex, we propose that initial motion and motion boundaries are detected at different and hierarchically organized stages in the dorsal pathway. Visual shapes that are defined by boundaries, which were generated from juxtaposed opponent motions, are represented at different stages in the ventral pathway. Model areas in the different pathways interact through feedforward and modulating feedback, while mutual interactions enable the communication between motion and form representations. Selective attention is devoted to shape representations by sending modulating feedback signals from higher levels (working memory) to intermediate levels to enhance their responses. Areas in the motion and form pathway are coupled through top-down feedback with V1 cells at the bottom end of the hierarchy. We propose that the different temporal episodes in the response pattern of V1 cells, as recorded in recent experiments, reflect the strength of modulating feedback signals. This feedback results from the consolidated shape representations from coherent motion patterns and the attentive modulation of responses along the cortical hierarchy. The model makes testable predictions concerning the duration and delay of the temporal episodes of V1 cell responses as well as their response variations that were caused by modulating feedback signals.
视觉系统如何将视觉场景分割成表面和物体,并将注意力集中在目标物体上?基于心理学和生理学的研究,人们提出,场景的感知组织和分割是通过视觉皮质层次的不同水平的处理来实现的。根据这一理论,运动起始检测、运动定义的形状分离和目标选择是通过将简单特征结合在一起,形成不同层次的处理层次上越来越复杂的配置片段的过程来完成的。作为对这种分层处理假设的替代,有人提出,特征检测和分离的处理阶段反映在个体神经元反应模式的不同时间片段中。在 V1 等低水平的神经元激活模式中已经观察到了这种时间间隔。在这里,我们提出了一个运动检测、图形-背景分离和注意选择的神经网络模型,该模型用一个统一的框架来解释这些反应模式。基于视觉皮层功能结构的已知原理,我们提出,初始运动和运动边界是在背侧通路的不同且分层组织的阶段检测到的。由相邻的对向运动生成的边界定义的视觉形状,在腹侧通路的不同阶段表示。不同通路中的模型区域通过前馈和调制反馈相互作用,而相互作用使运动和形状表示之间能够进行通信。通过从更高层次(工作记忆)向中间层次发送调制反馈信号,选择性注意致力于形状表示,以增强其反应。运动和形状通路中的区域通过自上而下的反馈与层次结构底部的 V1 细胞耦合。我们提出,最近实验记录的 V1 细胞反应模式中的不同时间间隔反映了调制反馈信号的强度。这种反馈是由连贯的运动模式产生的一致的形状表示以及沿着皮质层次的注意调制反应产生的。该模型对 V1 细胞反应的时间间隔的持续时间和延迟以及由调制反馈信号引起的反应变化做出了可测试的预测。