Brain imaging research on interactions of perceptual modules

本研究采用脑磁图、功能磁共振成像、心理物理学和模型化方法研究了人脑知觉整合过程。得到了以下结果。1.（1）在潜伏期80-150 ms的V1附近出现与主观轮廓感知相关的反应，而在潜伏期较长的V3/V3 A附近出现与图形-背景分割相关的反应。(2)众所周知，灵长类动物和猫V1区神经元的反应可能受到其经典感受野外的环境刺激的深刻调制。这种效果，最近被称为“上下文mokulation”。我们发现在人类V1/V2.2的MEG反应的上下文调制。fMRI分析（1）我们开发了一个集成的软件，旨在通过支持fMRI数据的表面重建，表面编辑，表面测量和表面采样来进行计算神经成像。(2)神经相关的颜色感应功能磁共振成像进行了研究。在所有视网膜定位区域中观察到与诱导颜色相关的突出fMRL响应，表明诱导可能在V1-V8.3的连续阶段进行。心理物理学与计算模型（1）提出了一种从运动中恢复航向的新方法。对该算法进行了仿真，仿真结果表明，该方法能够准确地估计航向。(2)运动同化/对比的心理物理学实验表明，有三种类型的相互作用，在人类的运动处理;一个是有效的附近区域内的求和过程，其他两个是促进和抑制诱导过程在更大的空间尺度上操作。(3)我们开发了一个基于对称轴的场景分割计算模型，对称轴是形状几何的原始模型。人的表现和VEP反应与模型的预测吻合良好。

We investigated perceptual integration processes in the human brain by using MEG, fMRI, psychophysics and modeling. Following results were obtained.1. MEG analyses(1) The MEG responses correlated with the perception of subjective contours were observed aroud V1 in the latency period of 80-150 ms but the responses correlated with figure-ground segmentation were observed around V3/V3A and had longer peck latencies.(2) It is well known that the responses of neurons in V1 of the primates and cats may be profoundly modulated by the surround stimuli presented outside their classical receptive field. Such effects, recently denoted by a generic term of 'contextual mokulation'. We found contextual modulation of MEG responses in the human V1/V2.2. fMRI analyses(1) We developed an integrated software designed to permit computational neuroimaging through the sopport of surface reconstruction, surface edition, surface measurement, and surface-vased sampling of fMRI data.(2) Neural correlates of color induction were investigated by fMRI. Prominent fMRL responses correlated with induced color were observed in all retinotopic areas, suggesting that the induction may proceed in successive stages of V1-V8.3. Psychophysics ＆ computational model(1) A new method for recovery of heading from motion is developed. The simulations of the algorithm were performed, and it was shown that the method edtimates the direction of heading accurately.(2) Psychophysical experiments on motion assimilation/contrast showed that there are three types of interactions in human motion processing ; one is a summation process effective within nearby regions, and the other two are facilitative and inhibitory induction processes operating over larger spatial scales.(3) We developed a computational model of scene segmentation based on symmetry axes, a primitive descripton of shape geometry. Human performance and VEP responses were in good agreement with perdictions from the model.