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，以测试简单的注意力皮层回路模型。如果得到实证支持，该模型有望大大简化我们对空间注意力神经机制的理解。在拟议的研究课程结束时，我们期望对注意力的神经机制取得重要且深刻简化的见解。我们将表征 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 区域中这些依赖于对比度的响应特性是否反映了 V1 区域的响应特性（目标 1）。了解 V4 和 V 1 对比度调制之间可能存在的差异非常重要。在某种程度上，它们是相似的，这将使我们能够在这两个重要的视觉处理区域之间建立机械联系，并扩大 V 1 中处理模型的意义。我们将测试空间注意力是否调节中心-周围相互作用（目标 2），这对我们理解早期研究产生重大影响。例如，V2、V4、MT 和 TEO 中的单单元记录研究已经确定，当两个刺激同时出现在神经元的经典 RF 内时，响应优先由参与的刺激驱动。拟议的研究将确定这种模式的发生是否是由于早期阶段的偏压抑制中心-周围相互作用的结果。如果是这样，这将支持本提案中提出的简单模型。如果不是，这强烈表明选择发生在第一阶段，此时 RF 足够大以包含两个刺激。最后，我们将测量对比度相关的中心-环绕调制和注意力选择之间的关系（目标 3），为注意力通过增加关注刺激的有效对比度来发挥作用的提议提供迄今为止最有力的测试。总而言之，这项拟议的研究有望比迄今为止所取得的成果更深入地了解介导注意力选择的皮层回路。

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.