Bi-directional, task-dependent control of thalamic input gain, in layer 4c of the primary visual cortex, by the cholinergic and serotonergic neuromodulatory systems.

项目总结/摘要 控制从眼睛到达初级视觉皮层（V1）的输入是改变视觉系统的一种强有力的手段。 所有后续视觉信息处理的结果。这种视觉输入的强度（或增益） 皮质可以动态修改是没有争议的，但争论仍在继续关于如何 实现了增益控制。目前，存在用于修改微球的强度的良好描述的机制。 基于其他视觉输入的视觉输入（例如对比度增益控制和归一化）。然而，在这方面， 行为和认知状态（如注意力）对皮层处理的改变几乎肯定会出现 我们对视网膜外的视觉控制机制知之甚少 办妥了一批对猕猴的解剖学研究表明，胆碱能和 多巴胺能系统强烈地指向视觉输入到皮层的部位--丘脑受体层 (4c)在V1中。这种定位定位胆碱能和胆碱能系统，以控制程度， 来自眼睛的信息得到处理，因此它是否以及如何被感知。我们假设 乙酰胆碱和5-羟色胺双向控制皮层的“门”，使得乙酰胆碱增加（和 5-羟色胺降低）来自眼睛的输入的强度。我们将因果地操纵这种调节 控制层4c在主动视觉期间，并确定对神经反应和 行为在神经水平，我们将确定在层4c中引起的增益变化传播的程度 到其他层，包括传播发生的条件，以及传播信号的形式 代价我们还将确定这些增益效应对行为的影响。了解如何 神经调节剂允许状态变量（如唤醒和动机）动态地重新平衡皮质 处理是至关重要的：十种最常用的精神病药物中有八种针对神经调节 系统，以及唯一批准的治疗痴呆症的药物。因此，通过控制 我们（和大脑）修改感知，认知和行为的神经调节剂。一般认为 这些药物通过改变后期皮层处理来起作用，但解剖学告诉我们， 皮层输入的早期改变。我们将阐明背后的机制，并确定 这是早期控制的结果，所有后来的处理都依赖于早期控制。

PROJECT SUMMARY / ABSTRACT Controlling the input that arrives at the primary visual cortex (V1) from the eyes is a powerful means for altering the outcome of all subsequent processing of visual information. That the strength (or gain) of this visual input to cortex can be dynamically modified is not controversial, but debate continues regarding the means by which that gain control is achieved. Currently, there are well-described mechanisms for modifying the strength of visual input based on other visual input (such as contrast gain control and normalization). However, modification of cortical processing by behavioral and cognitive states (such as attention) almost certainly arises from circuits outside the visual pathway, and we know far less about how this extra-retinal control of vision is achieved. Anatomical studies in macaque monkeys indicate that modulation by the cholinergic and serotonergic systems is strongly directed toward the site of visual input to cortex – the thalamic-recipient layer (4c) in V1. This localization positions the cholinergic and serotonergic systems to control the extent to which information from the eyes gets processed, and therefore whether and how it is perceived. We hypothesize that acetylcholine and serotonin bi-directionally control the “gate” to cortex, such that acetylcholine increases (and serotonin decreases) the strength of the input from the eyes. We will causally manipulate this modulatory control of layer 4c during active vision, and determine the resulting effects on both neural responses and behavior. At the neural level, we will determine the extent to which gain changes induced in layer 4c propagate to other layers, including the conditions under which propagation occurs, and the form the propagated signal takes. We will also determine the impact of these gain effects on behavior. Understanding how neuromodulators allow state variables (such as arousal and motivation) to dynamically rebalance cortical processing is critically important: Eight of the ten most-prescribed psychiatric drugs target neuromodulatory systems, as does the only approved drug treatment for dementia. Thus, it is through controlling neuromodulators that we (and the brain) modify perception, cognition, and behavior. It is generally assumed that these drugs act by altering late-stage cortical processing, but the anatomy points us towards a concurrent early modification of cortical input. We will elucidate the mechanism(s) behind, and determine the consequences of, that early control upon which all later processing depends.