FUNCTION OF GLUTAMATE RECEPTORS IN VISUAL CORTEX

描述（改编自申请人摘要）：视觉可塑性 皮质在整个动物中表现为眼优势转移， 发生在单眼剥夺之后。 它也可以以下列形式表现出来： 长时程增强（LTP）和长时程抑制（LTD）。虽然眼睛 显性可塑性需要几天的时间才能发生，并涉及解剖学变化， LTP和LTD是在几分钟内产生的生理变化， 两种形式的塑性是相同的。 例如，两者都部分依赖于 NMDA受体的激活。这些初始步骤可以用LTP和 LTD比在完整的动物中研究要快得多。此外，委员会认为， 使用全细胞记录，可以研究皮质内可塑性， 区分突触前机制和突触后机制，这两种机制 在完整的动物身上很难做到。眼优势可塑性和 LTP存在一个临界期，随年龄和视觉层次的不同而不同 皮层 我们将继续假设，有不同的机制， 不同的地层和不同的年龄可能会导致这些变化。 已知NMDA受体和代谢型谷氨酸受体都是 与可塑性有关。 根据我们以前的工作，我们建议NMDA 受体在上层II的关键期后期是重要的， III，但不是在较低的层V和VI。根据我们目前的工作，我们 提示I组代谢型谷氨酸受体在增强 在较低层，而II组代谢型谷氨酸受体发挥作用， 在上层起抑制作用。第二信使cAMP增加， 代谢型谷氨酸受体的数量密切相关， 关键时期。因此，我们也认为cAMP在体内起着长期的作用。 增强作用，并根据我们目前的工作，cGMP起着抑制作用， 作用

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.