CRCNS: Formation of stimulus selective neural assemblies in piriform cortex

感觉皮层将复杂的输入分解成基于特征的成分，并将它们的表示分布在神经元群体中。在特殊情况下，这种分布是非常清楚的--例如，视觉和听觉系统分别沿皮质内的空间维度映射视网膜图像和声音频率。然而，一般而言，丰富的感觉场景是各种特征的混合体，目前尚不清楚大脑皮层如何在神经群体中混合和分离复杂感觉表征的各个方面。 嗅觉刺激是非常复杂的，有不同的气味由化合物的混合物组成。嗅皮层的回路也同样错综复杂，神经元群体以看似随机的规则相互耦合，并从较低的中枢接收类似的随机投射。这两个事实的结合混淆了气味表征的组织。我们的建议利用实验电路识别和操作方面的进展，以及大规模大脑皮层网络的理论框架，建立气味识别和浓度编码在嗅皮层中的分布原则。具体地说，我们的目标是在嗅觉回路和气味编码之间建立以下联系： 1)在嗅皮层的吻尾轴上，存在着特定的抑制亚回路的渐变分布。 2)抑制的嘴-尾分布与Hebbian可塑性机制相互作用，从而形成细胞沿嘴-尾轴的气味选择性。 这些进展将为大脑皮层结构如何代表和处理气味场景的不同方面提供亟需的见解。

Sensory cortex decomposes complex inputs into feature-based components, and distributes their representation over populations of neurons. In special cases this distribution is very clear--for instance the visual and auditory system respectively map retinal image and acoustic frequency along a spatial dimension within cortex. In general, however, rich sensory scenes are a mixture of features, and it remains unclear how the cortex mingles and segregates aspects of a complex sensory representation across neural populations. Olfactory stimuli are extraordinarily complex, with distinct odors comprised from a mixture of compounds. The circuitry in olfactory cortex is equally intricate, with populations of neurons coupling to one another with seemingly random rules, and receiving similarly random projections from lower centers. The combination of these two facts obfuscates the organization of odor representation. Our proposal leverages advances in experimental circuit identification and manipulation, as well as theoretical frameworks for large-scale cortical networks, to establish principles for the distribution of odor identity and concentration coding across olfactory cortex. Specifically, we aim to establish the following links between olfactory circuitry and odor coding: 1 )There exists a graded distribution of specific inhibitory sub-circuits along the rostral-caudal axis of the olfactory cortex. 2) The rostral-caudal distribution of inhibition interacts with Hebbian plasticity mechanisms so as to shape the odor selectivity of cells along the rostral-caudal axis. These advances will provide much needed insights into how cortical structures represent and process distinct aspects of an odor scene.