Attentional Modulation of Receptive Field Structure

描述（由申请人提供）：拟议的项目涉及在清醒的猴子中进行单单元记录研究，以测试一个简单的注意力皮层回路模型。如果支持经验，该模型有望提供一个主要的简化我们的理解空间注意的神经机制。在本研究计划的最后，我们希望能够对注意力的神经机制有一个重要而深刻的认识。我们将描述V4的关键对比度相关响应特性，这本身将构成向前迈出的重要一步（目标1）。我们将测试V4区的这些对比度依赖性响应特性是否与V1区（目标1）的特性相对应。了解V4和V1中对比度调制之间可能存在的任何差异非常重要。在某种程度上，他们是相似的，这将使我们能够建立一个机制之间的联系，这两个重要的视觉加工领域，并扩大的重要性，加工模型的V1。我们将测试空间注意是否调节中心-周围的相互作用（目标2），这对我们理解早期的研究有重大影响。例如，V2、V4、MT和TEO的单单位记录研究已经确定，当两个刺激一起出现在神经元的经典RF内时，响应优先由所关注的刺激驱动。拟议的研究将确定这种模式是否是由于早期阶段的偏置抑制性中心-周围相互作用而发生的。如果是这样的话，这将支持本提案中提出的简单模型。如果不是，这将强烈表明选择发生在RF足够大以包含两个刺激的第一阶段。最后，我们将测量对比度依赖的中心-周围调制和注意选择（目标3）之间的关系，提供最强有力的测试，注意通过增加关注刺激的有效对比度来运作。总的来说，拟议中的研究有望提供比迄今为止所取得的更深入的了解大脑皮层回路介导的注意力选择。

DESCRIPTION (provided by applicant): The proposed projects involve making single-unit recording studies in the awake monkey to test a simple cortical circuit model of attention. If supported empirically, the model promises to provide a major simplification in our understanding of the neural mechanisms of spatial attention. At the end of the proposed course of research, we expect to have achieved important and profoundly simplifying insights into the neural mechanisms of attention. We will have characterized key contrast-dependent response properties of V4, which itself will constitute an important step forward (Aim 1). We will have tested whether these contrast-dependent response properties in Area V4 mirror those of V1 (Aim 1). Understanding any differences that may exist between contrast modulation in V4 and V 1 is important. To the extent that they are similar, this will allow us to establish a mechanistic link between these two important visual processing areas, and to broaden the significance of models of processing in V 1. We will have tested whether spatial attention modulates center-surround interactions (Aim 2), which has major ramifications for our understanding of earlier studies. For example, single-unit recording studies in V2, V4, MT and TEO have established that when two stimuli appear together within a neuron's classical RF, the response is driven preferentially by the attended stimulus. The proposed studies will determine whether this pattern occurs as a result of biasing suppressive center-surround interactions at earlier stages. If so, this will support the simple model advanced in this proposal. If not, this would strongly suggest that the selection occurs at the first stage where RFs are large enough to encompass the two stimuli. Finally, we will have measured the relationship between contrast-dependent center-surround modulations and attentional selection (Aim 3), providing the strongest test yet of the proposal that attention operates by increasing the effective contrast of the attended stimulus. Taken together, the proposed research promises to provide a much deeper understanding of the cortical circuits that mediate attentional selection, than has been achieved to date.