Attentional Modulation of Receptive Field Structure

描述(申请人提供)：建议的项目包括在清醒的猴子身上进行单单位记录研究，以测试一个简单的大脑皮质注意回路模型。如果得到经验支持，该模型有望大大简化我们对空间注意神经机制的理解。在拟议的研究过程结束时，我们希望对注意力的神经机制有重要的和深刻的简化的见解。我们将表征V4的关键对比度相关反应特性，这本身将构成向前迈出的重要一步(目标1)。我们将测试V4区的这些与对比度相关的反应特性是否反映了V1区的特性(目标1)。了解V4和V1的对比度调制之间可能存在的任何差异是重要的。在它们相似的程度上，这将使我们能够在这两个重要的视觉加工区域之间建立机制联系，并拓宽V1中加工模型的意义。我们将测试空间注意是否调节中心-周围相互作用(目标2)，这对我们理解早期的研究具有重要的影响。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，反应优先由参与的刺激驱动。拟议中的研究将确定这种模式是否由于在早期阶段偏向抑制性的中心-周围相互作用而发生。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，这将强烈地表明，选择发生在第一阶段，其中RF足够大，以包含这两个刺激。最后，我们将测量对比度依赖的中心-周围调制和注意选择之间的关系(目标3)，为注意力通过增加参与刺激的有效对比度来运作的提议提供迄今最强有力的测试。综上所述，这项拟议的研究有望对调节注意力选择的大脑皮层回路提供比迄今所取得的更深入的理解。

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.