THE ROLE OF THE PULVINAR IN VISUAL ATTENTION

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。目的：丘脑枕核是大脑中最神秘的结构之一。在丘脑核中，随着进化，它的大小增加最大，与灵长类动物新皮层的大小保持同步。尽管付出了巨大的努力，它的功能基本上仍然是完全未知的。目前，有两种相关的观点主导着人们对pulvinar的思考，每一种都有一些实验支持。然而，这两种观点都没有经过严格的检验，而本应用程序旨在为这两种观点提供这种严格的检验。第一个观点是，枕状核控制着定向注意力的空间位置。这一观点得到了病变研究和生理记录研究的支持——尽管不是结论性的。我们计划通过干扰枕核的活动来直接测试这个想法，同时记录在纹状体外皮层。我们知道，定向注意会引起外皮层神经元反应增益的局部变化；激活后应模仿这种变化，而可逆的失活后应消除这种变化。另一种关于枕状核作用的说法与感觉皮层中这种增益变化的机制有关。特别是，有人认为枕状核和皮质结构之间的反复投射控制了皮质区域之间的信息流；这种调节可能是引导空间注意力的任何作用的基础。我们计划在纹状体外皮层使用多个电极记录来测试这一想法。两个背外区，颞中区（MT）和内侧颞上区（MST）都连接到pulvinar （Plm）的同一分支，并且彼此相连- MT为MST提供了主要的前馈输入来源。我们将同时从这两个结构中进行记录，同时再次干扰pulvinar的活动。如果与枕核的连接调节了视觉皮层的信息流，我们预测这种扰动将调节MT和MST之间活动的相互关联。任何一个目标的成功都将极大地影响我们对丘脑皮质回路功能的思考。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Objective: The pulvinar nucleus of the thalamus is one of the most enigmatic structures in the brain. Of thalamic nuclei, it shows the largest increase in size with evolution, keeping pace with the size of primate neocortex. Despite considerable effort, its function remains essentially completely unknown. Two related suggestions dominate current thinking about the pulvinar, and each has some experimental support. Neither, however, has been critically tested, and the present application is intended to provide this critical test of both ideas. The first idea is that the pulvinar controls the spatial location of directed attention. This idea has support - though not conclusive - from lesion studies and physiological recording studies. We plan to directly test this idea by perturbing activity in the pulvinar while recording in extrastriate cortex. We know that directed attention produces local changes in the gain of response of extrastriate neurons; activation of the pulvinar should mimic this change and reversible inactivation of the pulvinar should eliminate it. The other suggestion for the role of the pulvinar concerns the mechanism of such gain changes in sensory cortex. In particular, it has been suggested that recurrent projections between the pulvinar and cortical structures control the flow of information between cortical areas; this regulation might underlie any role in directing spatial attention. We plan to test this idea using multiple electrode recording in extrastriate cortex. Two dorsal extrastriate areas, the middle temporal (MT) and the medial superior temporal (MST) are both connected to the same subdivision of the pulvinar (Plm), and also connected with each other - MT provides a dominant source of feedforward input to MST. We will record from both structures simultaneously while again perturbing the activity in the pulvinar. If the connections with the pulvinar regulate information flow in visual cortex, we predict that such perturbation will modulate the cross-correlation of activity between MT and MST. Success on either aim will dramatically influence our thinking about the function of thalamocortical circuits.