FUNCTION OF GLUTAMATE RECEPTORS IN VISUAL CORTEX

描述(摘自申请人的摘要)：视觉上的可塑性 在整个动物中，大脑皮质的表现是通过眼睛优势转移 发生在单眼剥夺之后。它还可以以以下形式进行演示 长时程增强(LTP)和长时程增强(LTD)。即使是眼睛 显性可塑性需要几天的时间才能发生，并涉及解剖变化，以及 LTP和LTD是在几分钟内产生的生理变化，是 这两种形式的可塑性是相同的。例如，两者都在一定程度上取决于 NMDA受体的激活。这些初始步骤可以用LTP和 LTD的速度比在完好无损的动物身上进行研究要快得多。此外， 使用全细胞记录，人们可以研究皮质内的可塑性和 区分突触前机制和突触后机制，这两种机制 在完好无损的动物身上很难做到。眼优势可塑性和眼球可塑性 LTP有一个随年龄和视觉层次变化的关键期 大脑皮层。我们将继续提出这样一种假设，即在 不同的层次，也许在不同的年龄，解释了这些差异。 NMDA受体和代谢性谷氨酸受体都是已知的 与可塑性有关的。基于我们之前的工作，我们建议NMDA 在第II层和第II层的关键期晚期，受体是重要的 III，但不是在较低的第五层和第六层。根据我们目前的工作，我们 提示I组代谢型谷氨酸受体具有增强作用 在较低层，而第二类代谢性谷氨酸受体发挥作用 上层的压抑作用。第二信使阵营增加了 代谢性谷氨酸受体的数量与 关键时期。因此，我们还建议夏令营发挥长期作用 增强作用，而根据我们目前的工作，cGMP起到了抑郁的作用 角色。

DESCRIPTION (Adapted from applicant's abstract): Plasticity in the visual cortex is demonstrated in the whole animal by ocular dominance shifts that occur after monocular deprivation. It can also be demonstrated in the form of long-term potentiation (LTP) and long-term depression (LTD). Even though ocular dominance plasticity takes days to occur, and involves anatomical changes, and LTP and LTD are physiological changes produced in minutes, the initial steps in both forms of plasticity are same. For example, both depend in part on the activation of NMDA receptors.These initial steps can be studied with LTP and LTD much more quickly than they can be studied in the intact animal. Moreover, using whole cell recordings, one can study intracortical plasticity and distinguish presynaptic mechanisms from postsynaptic mechanisms, both of which are difficult to do in the intact animal. Both ocular dominance plasticity and LTP have a critical period that varies with age and layer in the visual cortex. We will pursue the hypothesis that there are different mechanisms in different layers and maybe at different ages that account for these variations. NMDA receptors and metabotropic glutamate receptors are both known to be involved in plasticity. Based on our previous work, we suggest that NMDA receptors are important late in the critical period in the upper layers II and III, but not in the lower layers V and VI. Based on our current work, we suggest that Group I metabotropic glutamate receptors play a potentiating role in lower layers, while Group II metabotropic glutamate receptors play a depressive role in upper layers. The second messenger cAMP is increased by metabotropic glutamate receptors by a quantity that is closely related to the critical period. We therefore also suggest that cAMP plays a long-term potentiating role, and based on our current work, that cGMP plays a depressive role.