Influence of high-level visual processes on saccadic eye movements

过去50年的研究表明，灵长类动物的大脑皮层包含30多个专门的视觉区域。在视觉系统的研究中出现了一个重要的原则，即涉及视觉处理的特定功能方面的皮质区域的解剖分离。视觉系统似乎被组织成至少两个独立的通路，它们都起源于初级视觉皮层。背侧通路穿过顶叶皮层，而腹侧通路穿过颞叶皮层。根据一个有影响力的模型，假设这两个系统是独立运行的。背侧动作流为运动行为的产生提供了对系统发育过程中老的皮层下视觉运动模块的灵活控制，而腹侧“感知”流则为认知操作提供了丰富而详细的视觉世界表征。尽管这一假设得到了许多心理物理学和神经心理学研究的支持，但最近的一些发现表明，视觉流的相互作用可能比该模型所预期的要频繁。两种视觉流相互作用的最有力证据来自于研究，这些研究表明，面部是眼睛运动的有力目标，并且对象的凝视方向可以影响眼球运动的运动准备。这是令人惊讶的，因为颞叶参与高级视觉处理，包括面部处理，而额叶、顶叶和中脑的区域参与快速眼球运动的产生。在这个研究项目中，我们将研究导致面部对眼球运动影响的神经机制。

Research over the past 50 years has demonstrated that the primate cerebral cortex contains more than 30 specialised visual areas. An important principle that has emerged from research in the visual system is the anatomical segregation of cortical areas involved in specific functional aspects of visual processing. The visual system seems to be organised into at least two separate pathways that both originate in the primary visual cortex. A dorsal pathway projects through the parietal cortex whereas a ventral pathway projects through the temporal cortex. According to an influential model, the two systems are assumed to act independently. The dorsal action stream provides flexible control of phylogenetic old subcortical visuomotor modules for the generation of motor acts, while the ventral "perception" stream provides the rich and detailed representation of the visual world required for cognitive operations. Although this hypothesis has been supported by numerous psychophysical and neuropsychological studies, several recent findings suggest that the visual streams may interact more often than expected from this model. The strongest evidence for an interaction of the two visual streams has come from studies that have demonstrated that faces act as potent targets for movements of the eyes and that the gaze direction of a subject can influence the motor preparation of the eye movements. This is surprising as the temporal lobe is involved in high-level visual processing, including the processing of faces, whereas areas in the frontal lobe, parietal lobe and midbrain are involved the generation of fast eye movements. In this research project, we will investigate the neural mechanisms that lead to the effects of faces on eye movements.