NEURONAL ACTIVITY AND VISUAL CORTICAL DEVELOPMENT

在视觉皮质内建立准确的突触连接模式的机制仍不清楚。虽然活动依赖机制已被证明在视觉皮质的发育中起着关键作用，但视觉皮质功能组织的许多方面，如定向和眼优势柱，在动物具有任何视觉经验之前就已经存在。因此，在视觉体验开始之前，自发活动被提出为指导皮质功能结构的发展提供指导性线索。拟议的实验集中在以下两个方面：1)检测视觉通路发育的多个阶段(包括外侧膝状核和视皮层)中神经元自发活动的相关结构，以及2)确定这些活动模式的慢性干扰或改变如何改变视觉皮质神经元的感受野特性的发育。这项工作是通过最近开发的方法实现的，利用长期植入的多电极记录阵列，记录自由行为动物的中央视觉结构内的神经活动模式。此外，将使用体内慢性刺激方法，通过对视神经施加周期性的电脉冲脉冲，将人工关联的神经元活动引入视觉通路。这些实验应该会对活动依赖机制在建立成人大脑内突触连接模式中的作用提供新的见解。

The mechanisms by which the precise patterns of synaptic connectivity are established within visual cortex remain unclear. While activity dependent mechanisms have been demonstrated to play a crucial role in the development of visual cortex, many aspects of visual cortical functional organization, such as orientation and ocular dominance columns, are present before animals have had any visual experience. Thus, before the onset of visual experience, spontaneous activity has been proposed to provide instructive cues for guiding the development of cortical functional architecture. The proposed experiments focus on l) examining the correlational structure of spontaneous neuronal activity within multiple stages of the developing visual pathway including the lateral geniculate nucleus (LGN) and visual cortex, and 2) determining how chronic disruption or modification of these activity patterns alters the development of receptive field properties of visual cortical neurons. This work is made possible by recently developed methods for recording patterns of neural activity within central visual structures of freely behaving animals, utilizing chronically implanted multi-electrode recording arrays. In addition, in vivo chronic stimulation methods will be used to introduce artificially correlated neuronal activity into the visual pathway through the application of periodic bursts of electrical pulses to the optic nerve. These experiments should provide new insight into the role of activity-dependent mechanisms in establishing adult patterns of synaptic connectivity within the brain.