Department of Psychology, University of Western Ontario, London, Canada.
Exp Brain Res. 2010 Jan;200(1):109-16. doi: 10.1007/s00221-009-2074-0.
According to Milner and Goodale's model (The visual brain in action, Oxford University Press, Oxford, 2006) areas in the ventral visual stream mediate visual perception and oV-line actions, whilst regions in the dorsal visual stream mediate the on-line visual control of action. Strong evidence for this model comes from a patient (DF), who suffers from visual form agnosia after bilateral damage to the ventro-lateral occipital region, sparing V1. It has been reported that she is normal in immediate reaching and grasping, yet severely impaired when asked to perform delayed actions. Here we investigated whether this dissociation would extend to saccade execution. Neurophysiological studies and TMS work in humans have shown that the posterior parietal cortex (PPC), on the right in particular (supposedly spared in DF), is involved in the control of memory-guided saccades. Surprisingly though, we found that, just as reported for reaching and grasping, DF's saccadic accuracy was much reduced in the memory compared to the stimulus-guided condition. These data support the idea of a tight coupling of eye and hand movements and further suggest that dorsal stream structures may not be sufficient to drive memory-guided saccadic performance.
根据米尔纳和古德尔的模型（《行动中的视觉大脑》，牛津大学出版社，牛津，2006 年），腹侧视觉流中的区域介导视觉感知和离线动作，而背侧视觉流中的区域则介导动作的在线视觉控制。该模型的有力证据来自于一名患者（DF），他在双侧腹外侧枕叶区域受损后患有视觉形态失认症，而 V1 未受损。据报道，她在即时伸手和抓握方面正常，但在被要求执行延迟动作时严重受损。在这里，我们研究了这种分离是否会扩展到扫视执行。神经生理学研究和人类 TMS 工作表明，后顶叶皮层（PPC），特别是右侧（据称在 DF 中未受损），参与了记忆引导扫视的控制。然而，令人惊讶的是，我们发现，正如在伸手和抓握方面报告的那样，DF 在记忆引导条件下的扫视准确性比刺激引导条件下要低得多。这些数据支持了眼睛和手部运动紧密耦合的观点，并进一步表明背侧流结构可能不足以驱动记忆引导扫视的表现。
