Neural mechanism of sustained spatial attention across saccades

自然视觉探索经常使用快速弹道眼球运动(扫视)和隐蔽的视觉注意力。虽然眼跳和注意系统在解剖学上和功能上是相关的，但以前的工作表明，视觉注意可以保持在一个稳定的位置，同时对视野中的其他位置执行眼跳。将注意力和眼球运动同时分配到不同的位置可以促进复杂的视觉运动任务和社会互动，这在精神疾病中经常受到损害。然而，由于视觉注意是在视网膜组织的皮质区域实现的，因此在眼球运动中维持注意力需要更新在扫视时表现出注意调制的神经元的数量。行为学研究表明，就在眼跳之前，在提示位置的后面和前面都观察到了短暂的注意促进，而在眼跳之后，在视网膜坐标中观察到了短暂的注意促进(即，沿着眼跳方向移动)。一个全面的神经机制，实现了眼跳前后注意力的更新，并解释了这些行为发现，这是假设的，并将在这个项目中进行测试。在目标1中，受试者将接受训练，在眼跳执行过程中将注意力分配到一个稳定的位置，同时从皮质区V4记录，以测试与这一机制一致的神经调制。具体地说，Aim 1将测试这样的假设：1)在扫视后将在代表被关注位置的神经元中发生扫视前预测性注意调制，以及2)在恰好在眼跳之前代表被关注位置的神经元中将发生眼跳后注意调制(随后衰退回到基线)。此外，这项工作将检验一种假设，即在眼跳之前重新映射其感受野的神经元，如在一些大脑皮层区域中观察到的那样，将在重新映射时携带注意力调制，解释了眼跳前注意便利移位在前眼跳方向。在目标2中，将使用相同的行为任务从V4和LIP进行记录，LIP是视觉运动顶区。这两个区域都表现出对注意力和眼跳反应的调制，但尚不清楚哪个区域指导视觉感受区和跨眼跳注意力的更新。通过对脉冲潜伏期、相关性、连贯性和格兰杰因果关系的分析，我们将检验这一假设，即嘴唇驱动维持稳定视觉注意所必需的接受场和注意力区的视交叉更新。对视觉注意和自主眼动整合的神经机制的理解将进一步理解神经扰动，这些神经扰动导致ADHD、自闭症和精神分裂症等精神疾病中复杂的社会互动和视觉运动规划的障碍，并将指导这些疾病的治疗。

Natural visual exploration frequently employs fast ballistic eye movements (saccades) and covert visual attention. Although the saccade and attention systems are anatomically and functionally related, previous work suggests that visual attention can be maintained at a stable location while executing saccades to other locations in the visual field. This simultaneous deployment of attention and eye movements to distinct locations can promote complicated visuomotor tasks and social interactions, which are often impaired in psychiatric diseases. However, since visual attention is implemented in retinotopically organized cortical areas, the maintenance of attention across eye movements requires updating the population of neurons exhibiting attentional modulation at the time of saccade. Behavioral studies have shown that just before a saccade, a transient attentional facilitation is observed both behind and ahead of the cued location, and that after a saccade, a transient attentional facilitation is observed in retinotopic coordinates (i.e., shifted in the prosaccade direction). A comprehensive neural mechanism that achieves the updating of attention around the time of saccades and accounts for these behavioral findings is hypothesized and will be tested in this project. In Aim 1, subjects will be trained to deploy attention to a stable location during saccade execution while recording from cortical area V4, an extrastriate visual area in the ventral stream, to test for neural modulations consistent with this mechanism. Specifically, Aim 1 will test the hypothesis that 1) presaccadic predictive attentional modulation will occur in neurons that will represent the attended location after the saccade, and 2) postsaccadic attentional modulation (with subsequent decay back to baseline) will occur in neurons that represented the attended location just before the saccade. Furthermore, this work will test the hypothesis that neurons that remap their receptive fields just before the saccade, as has been observed in some cortical areas, will carry attentional modulation with them as they remap, explaining presaccadic attentional facilitations displaced in the pro-saccade direction. In Aim 2, recordings will be made from V4 and LIP, a visuomotor parietal area, using the same behavioral task. Both areas show modulation in response to attention and saccades, but it is unknown which area directs the updating of visual receptive fields and attention across saccades. Using analyses of spike latency, correlation, coherence, and Granger causality, the hypothesis that LIP drives the perisaccadic updates in receptive and attentional fields that are necessary to maintain stable visual attention will be tested. An understanding of the neural mechanism underlying the integration of visual attention and voluntary eye movements will further understanding of the neural perturbations that lead to impairments in complex social interactions and visuomotor planning in psychiatric diseases such as ADHD, autism, and schizophrenia and will inform treatment of these diseases.