Effects of V1 feedback on LGN function

描述（由申请人提供）：我们研究的长期目标是了解丘脑神经元如何整合其各种前馈和反馈输入，以及这些输入在通过丘脑从视网膜到皮质的信息流中起什么作用。哺乳动物外侧膝状体核（LGN）中的大多数输入和突触是视网膜外的，但是这些不同的输入被整合以控制视觉信息从视网膜到皮层的流动的方式还不清楚。特别是，下行输入从皮层和周围膝状体（PGN）的LGN中继神经元感受野的时空特性的影响是未知的。 为了解决这个差距，在我们的知识，我们将研究的时间和空间方面的感受野在猴LGN之前和期间的皮质反馈失活的LGN。动力学特性将与双m序列刺激范例，这将提供新的信息，这些神经元的线性和非线性动力学，并将暴露的影响，从V1的反馈对这种动力学行为进行了探讨。我们的假设是，离皮质反馈的LGN有四个具体方面的LGN功能的显着影响：动力学，感受野组织，从视网膜到皮层的传输和响应增益。 这些研究将为离皮质通路对LGN中继细胞感受野的几个重要动力学和空间参数的影响提供新的信息。这些发现将扩展和加深我们对这个庞大但难以捉摸的神经通路功能的理解，并为视觉系统早期阶段的现实建模铺平道路。由于这种下行通路在大脑中无处不在，因此这些发现可能与其他与之相连的大脑区域有关。

DESCRIPTION (provided by applicant): The long range goal of our research is to understand how thalamic neurons integrate their various feedforward and feedback inputs, and what role these inputs play in the flow of information from retina to cortex through the thalamus. Most of the inputs and synapses in the mammalian lateral geniculate nucleus (LGN) are extraretinal, but the way in which these diverse inputs are integrated to control the flow of visual information from retina to cortex is not understood. In particular, the influence of the descending inputs from the cortex and the perigeniculate nucleus (PGN) on the spatio-temporal properties of receptive fields of LGN relay neurons is unknown. To address this gap in our knowledge, we shall study the temporal and spatial aspects of receptive fields in monkey LGN before and during inactivation of the cortical feedback to the LGN. The dynamical properties will be probed with a double m-sequence stimulation paradigm, which will provide new information about both the linear and non-linear dynamics of these neurons, and will expose the effects that the feedback from V1 has on this dynamical behavior. Our hypothesis is that the corticofugal feedback to the LGN has a significant effect on four specific aspects of LGN function: dynamics, receptive field organization, transmission from retina to cortex and response gain. The proposed studies will furnish new information about the effects of the corticofugal pathway on several important dynamical and spatial parameters of the receptive fields of LGN relay cells. These findings will extend and deepen our understanding of the function of this massive yet elusive neural pathway, and pave the way for realistic modeling of the early stages of the visual system. Because such descending pathways are ubiquitous in the brain, the findings are likely to relevant to other reciprocally connected brain regions.