NEURONAL ACTIVITY AND VISUAL CORTICAL DEVELOPMENT

突触连接的精确模式在视觉皮层内建立的机制尚不清楚。虽然活动依赖机制已被证明在视觉皮层的发育中起着至关重要的作用，但视觉皮层功能组织的许多方面，如定向和眼优势柱，在动物有任何视觉经验之前就存在了。因此，在视觉体验开始之前，自发活动已经被提出为指导皮质功能结构的发展提供指导性线索。本实验的重点是：1)研究包括外侧膝状核（LGN）和视觉皮层在内的视觉通路发育的多个阶段中自发神经元活动的相关结构；2)确定这些活动模式的慢性破坏或改变如何改变视觉皮层神经元感受野特性的发展。这项工作是通过最近开发的方法来记录自由行为动物的中央视觉结构中的神经活动模式，利用长期植入的多电极记录阵列。此外，体内慢性刺激方法将通过向视神经施加周期性电脉冲脉冲，将人工相关的神经元活动引入视觉通路。这些实验应该为活动依赖机制在建立成人大脑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.