Synaptic Organization of Simple Cell Receptive Fields

项目摘要 初级视皮层中的图像表征严重依赖于图像的时空模式。 外侧膝状体轴突的会聚以及丘脑皮质的动力学特性 突触丘脑的输入仅代表大脑皮层细胞兴奋性驱动的一小部分， 第4层，但主导他们的视觉反应模式。我们将使用电生理学方法 在体内同时记录来自初级丘脑感受器神经元的视觉反应 视觉皮层和外侧膝状体中的几个输入细胞。在目标1中，我们 测试抑制控制第4层简单细胞的时间进程的假设。在Aim中 2、我们将描述单个LGN神经元突触后电位的特性 第四层的兴奋性和抑制性简单细胞。最后，在目标3中，我们将使用动态钳位 在第4层简单细胞中研究来自单个LGN神经元组合的会聚输入 （使用在目标1和2中获得的知识）而不伴随皮层回路的激活。 我们将估计局部抑制在建立L4简单细胞视觉中的贡献， 应答这些研究将产生关键的洞察力的转变视觉 发生在丘脑皮层突触的信息。

PROJECT SUMMARY Image representation in primary visual cortex depends critically on the spatiotemporal pattern of convergence of lateral geniculate axons as well as on the dynamic properties of thalamocortical synapses. Thalamic input represents only a fraction of the excitatory drive to cortical cells in layer 4 ,but dominates their visual response patterns. We will use electrophysiological methods in vivo to record visual responses simultaneously from thalamorecipient neurons in primary visual cortex and several of their input cells in the lateral geniculate nucleus. In Aim 1, we will test the hypothesis that inhibition controls the temporal course of simple cells in layer 4. In Aim 2, we will characterize the properties of the postsynaptic potentials from single LGN neurons onto excitatory and inhibitory simple cells in layer 4. Finally, in Aim 3, we will use dynamic clamp in layer 4 simple cells to study convergent input from combinations of single LGN neurons (using knowledge obtained in Aims 1 and 2) without concomitant activation of cortical circuits. We will estimate the contributions of local inhibition in establishing L4 simple cell visual responses. These studies will generate critical insight into the transformation of visual information that takes place in the thalamocortical synapse.