CONTROL OF CENTRAL VISUAL PATHWAYS BY THE BRAINSTEM

描述（来自研究者摘要）：视网膜信号 有意识的知觉必须首先通过 丘脑外侧膝状体核（LGN）。传入 来自眼睛的信号并不会原封不动地传递到大脑皮层，相反， 在LGN中被主动门控和修改。皮层处理必须 关键取决于提供大脑皮层信号的性质 输入.我们的长期目标是了解全方位的行动 LGN能够执行皮质定向信号，以及 因此，为了更全面地了解这个重要的神经系统的作用， 视觉结构。我们认为，空间和时间 视觉信号的特征在LGN中被调制为函数 的行为状况。这些研究将使我们能够比较 LGN中的调制，其在唤醒状态下由三个 脑干和下丘脑的不同投射 肾上腺素能、组胺能和先前研究的胆碱能 系统虽然我们和其他人已经揭示了存在，解剖和 这些系统的药理学，尚不清楚每个系统如何改变 传递到大脑皮层的视觉信号。体外研究 表明这些系统有一个共同的方法，直接激励 皮质投射中继细胞，但它们有着完全不同的 对膝状体抑制细胞的影响， LGN细胞生理反应的特征。 因此，我们建议， 调节系统将非常不同地塑造视觉信号， 被传送到大脑皮层在具体目标#1中，我们将确定 组胺能和组胺能系统改变 膝状体神经元与已知的胆碱能药物的作用相反， 系统，这主要是对LGN中继细胞去抑制，我们预测 组胺能系统的激活，甚至更多， 能系统将加强抑制依赖性 视觉反应的特征。在具体目标#2中，我们将 确定这些系统如何结合联合收割机来改变LGN的视觉反应 因为所有的神经元在清醒状态下都是活跃的。要全面完成 这些目的是通过在体内记录LGN神经元对 复杂的视觉刺激在特定的神经调节激活。

DESCRIPTION (from the investigator's abstract): Retinal signals destined for the visual cortex for conscious perception must first pass through the lateral geniculate nucleus (LGN) of the thalamus. The afferent signals from the eye are not relayed unchanged to cortex; instead, they are actively gated and modified in the LGN. Cortical processing must depend critically on the nature of the signals that provide cortical input. Our long-term goal is to understand the full spectrum of action that the LGN is capable of enacting on cortically-directed signals, and thus to more fully understand the role of this important neural structure in vision. We believe that the spatial and temporal characteristics of visual signals are modulated in the LGN as a function of the behavioral condition. These studies will enable us to compare the modulation in the LGN that is controlled in the awake state by three fundamentally different projections from the brainstem and hypothalamus: the serotonergic, histaminergic, and previously-studied cholinergic system. While we and others have revealed the existence, anatomy and pharmacology of these systems, it is not clear how each system alters the visual signal that is transmitted to cortex. In vitro studies indicated that these systems share a common method of directly exciting cortically-projecting relay cells, but they have radically different effects on geniculate inhibitory cells, which critically shape important features of LGN cell physiological responses. Thus, we propose that each modulatory system will very differently sculpt the visual signals that are transmitted to cortex. In Specific Aim #1, we will determine how the histaminergic and serotonergic systems alter the visual response of geniculate neurons. In contrast to the known effects of the cholinergic system, which are primarily disinhibitory on LGN relay cells, we predict that activation of the histaminergic system, and even more so, the serotonergic system will strengthen the inhibition-dependent characteristics of the visual responses. In Specific Aim #2, we will determine how these systems combine to alter visual responses in LGN neurons, because all are active in the awake state. We will accomplish these aims by recording in vivo the responses of LGN neurons to sophisticated visual stimuli during specific neuromodulatory activation.