STRUCTURE-FUNCTION RELATIONSHIPS IN VISUAL CORTEX

这项研究计划的长期目标是了解 信息处理的结构/功能关系 外侧膝状体核（LGN）和视觉皮层。 重点是 LGN在时间转换传入信号中的作用， 从视网膜，以及这些修改后的信号的贡献， 感受野结构的产生与视觉反应 皮质区17和18中神经元的特性。 的动力 实验发现，LGN的A层含有两个 中继神经元群，称为滞后和非滞后细胞，它们不同 在对视觉刺激的反应时间上有显著的差异。 我们有 证据表明，这些时间差异是用于视觉皮层， 提升感受野的时空结构， 对刺激运动的方向敏感。 的 提出的实验将揭示神经元的时间特性， 膝状体复合体的其他部分及其潜力 对皮层细胞的响应特性的贡献，并确定 LGN和皮层的反应时间是否可以通过异常的 在发育过程中的视觉刺激。 具体目标如下：（1）反应时间的表征 膝状体C板层和内侧板层间的中继神经元 核（MIN），以完成我们正在进行的描述膝状体 输入到皮层区17和18。 (2)检查之间的关系 Aim中检查的细胞的形态和生理特性 1，作为阐明结构机制的基础， LGN中的信息处理。 (3)为了显示终端区域 在不同膝状体细胞类型的皮质中，并寻找一种 传入类型和/或反应时间的板层下分布作为 解释响应层流差异起源的依据 皮层细胞之间的时间。 (4)来描述时空 简单细胞感受野结构和方向选择性 并与膝状体的反应时间进行比较 传入神经 (5)为了调查在一个 频闪照明环境对细胞反应时间的影响 在LGN和（6和7）的时空结构上的感受性 17区和18区。 闪光灯饲养选择性地废除 方向选择性 响应时间的平行变化 这些动物的LGN和皮质之间的联系将提供进一步的证据， LGN在促进皮层方向选择性中的作用。 这些研究还将提供有关机制的第一个详细证据 在频闪饲养的动物中失去方向选择性的基础上， 因此有助于我们对基质的全面理解， 方向选择性

The long range goal of this research program is to understand the structure/function relationships that underlie information processing in the lateral geniculate nucleus (LGN) and visual cortex. Emphasis is on the role of the LGN in temporally transforming afferent signals derived from the retina, and on the contribution these modified signals make to the generation of receptive field structure and visual response properties of neurons in cortical areas 17 and 18. The impetus for the experiments is the finding that the A-laminae of the LGN contain two groups of relay neurons, termed lagged and nonlagged cells, which differ markedly in the timing of their responses to visual stimuli. We have evidence that these timing differences are used in visual cortex to set up the spatiotemporal structure of receptive fields and to create neurons that are sensitive to the direction of stimulus movement. The experiments proposed will reveal the timing properties of neurons in other divisions of the geniculate complex and their potential contribution to the response properties of cortical cells, and determine whether response timing in the LGN and cortex can be modified by abnormal visual stimulation during development. Specific aims are as follows: (1) To characterize the response timing of relay neurons in the geniculate C-laminae and the medial interlaminar nucleus (MIN) in order to complete our ongoing description of geniculate inputs to cortical areas 17 and 18. (2) To examine relationships between the morphological and physiological properties of cells examined in Aim 1, as a basis for elucidating structural mechanisms underlying information processing in the LGN. (3) To reveal the termination zones in cortex of different geniculate cell types, and to search for a sublaminar distribution of afferent types and/or response timing as a basis for interpreting the origin of laminar differences in response timing among cortical cells. (4) To characterize the spatiotemporal structure and direction selectivity of simple cell receptive fields in area 18 and to compare their response timing with that of the geniculate afferents. (5) To investigate the impact of raising animals in a stroboscopically illuminated environment on the response timing of cells in the LGN and (6 and 7) on the spatiotemporal structure of receptive fields in areas 17 and 18. Strobe rearing selectively abolishes direction selectivity in cortex. Parallel changes in response timing between LGN and cortex in these animals will provide further evidence for the role of the LGN in contributing to direction selectivity in cortex. These studies will also provide the first detailed evidence on mechanisms underlying the loss of direction selectivity in strobe-reared animals, and hence contribute to our overall understanding of the substrates for direction selectivity.