Brain and Behavior of Visual Expectations

描述（由申请人提供）：预知将会发生什么、什么时候发生、在哪里发生，可以帮助生物体找到食物和躲避捕食者。预备反应利用这种预知来准备感觉和运动系统。最近来自神经生理学和神经影像学的研究结果表明，部分后顶叶皮层（PPC）可能是一个预备区。例如，猴子PPC区域的神经元的反应就好像是一个短暂被遮挡的移动目标再次出现的信号。其他研究表明，在猴子看向某个方向或到达某个方向的几秒钟前，PPC的细胞就会开始放电。然而，PPC的功能是有争议的，因为许多研究已经报道了各种其他任务-注意力，工作记忆，形状处理-也依赖于PPC。

DESCRIPTION (provided by applicant): Foreknowledge about what will happen, when it will happen, and where it will happen, can help an organism find food and avoid predators. Preparatory responses use this foreknowledge to ready sensory and motor systems. Recent findings from neurophysiology and neuroimaging suggest that portions of the posterior parietal cortex (PPC) may function as a preparatory region. For instance, neurons in the monkey PPC region respond as though signaling the re-emergence of a briefly occluded moving target. Other studies have shown that cells in the PPC begin to fire seconds before a monkey looks a certain direction or reaches a certain direction. However, the functionality of the PPC is disputed because many studies have reported that various other tasks - attention, working memory, shape processing - also depend on the PPC. In this grant we advance the hypothesis that the PPC is importantly involved in linking sensory and motor signals in preparation to act. In Aim 1 we address the relationship of preparatory responses to working memory. In Aim 2 the relationship of sensory expectations to motor expectations is examined to gain some understanding of both the generality and specificity of preparatory processing. Last of all, in Aim 3 we do a finer grained analysis of preparatory processing by asking whether activity in the IPS is sensitive to the value of a preparatory cue. These questions will be addressed through functional magnetic resonance imaging (fMRI), transcranial magnetic stimulation (TMS), and behavioral experimentation.