Juxtacellular Characterization of V1 Neurons

描述（由申请人提供）：了解大脑皮层的回路是如何组织的，以及它们是如何发挥作用的，这是神经科学的一个中心目标。我们一直在研究初级视觉皮层V1，以了解它在视觉中的作用，也因为V1是大脑皮层中最好理解的区域之一。一方面，我们经常有详细的知识，从V1神经元放电的神经元的感受野特性，一系列的视觉刺激，从细胞外记录。另一方面，从解剖学研究中，我们了解到V1内以及V1与纹外皮质之间复杂的神经元结构和突触连接模式。我们的建议旨在弥合猴初级视皮层回路中神经元结构与其感受野特性之间的差距。我们使用一种称为松斑细胞外记录的方法来监测细胞外动作电位，这使我们能够功能性地表征神经元的RF，然后我们用示踪分子标记相同的神经元，随后恢复和重建标记神经元的三维树突和轴突。层4a是来自外侧膝状体核的大细胞传入的主要目标，为层4 b提供输入。这两层都有各种不同形态的神经元。在两层中也存在一系列感受野特性。我们的第一个目标是表征层4ca和4 b中的兴奋性神经元。我们将测试的假设，有不同的功能特征，与不同的形态类型。在第6层的锥体神经元中，基于它们的皮质内轴突树枝化模式，存在不同的神经元类别。轴突模式与第4层的β-和β-细胞分裂有关。除了调整方向、空间频率、时间频率和大小之外，我们将使用功能测试来确定标记的神经元是否由大细胞或小细胞输入主导。我们的第二个目标是测试在何种程度上形态类具有特定的功能标签，如何路径特定的信息，如运动和颜色被保留在不同的皮层电路和在何种程度上的总和和环绕抑制的人口内的识别神经元。抑制性神经元被认为在决定V1感受野的涌现特性，如方向，方向和大小选择性中发挥特定的作用。兴奋性和抑制性群体之间的调谐程度或程度是未知的。我们的第三个目标是表征皮层的输入层和颗粒下层的抑制性神经元。有许多疾病是由于皮质回路中的结构-功能异常，包括弱视、癫痫和精神分裂症。了解正常回路的运作方式为了解神经元异常提供了机会。

DESCRIPTION (provided by applicant): Understanding how the circuits of the cortex are organized and how they function is a central goal of neuroscience. We have been studying the primary visual cortex, V1, in order to understand its role in vision and also because V1 is one of the best understood regions of the cerebral cortex. On one hand we often have detailed knowledge of the receptive field properties of neurons determined from neuronal firing in V1, to an array of visual stimuli, obtained from extracellular recording. On the other hand from anatomical studies we know about the intricate neuronal architecture and patterns of synaptic connections both within V1 and between V1 and extrastriate cortex. Our proposal aims to bridge the gap between the structure of neurons in circuits in monkey primary visual cortex and their receptive field properties. We use a method called loose-patch juxtacellular recording to monitor extracellular action potentials, that enables us to functionally characterize the RF of the neurons, and then we label same neuron with a tracer molecule and subsequently recover and reconstruct the three dimensional dendritic and axonal arbors of the labeled neurons. Layer 4a, the main target of the magnocellular afferents from the lateral geniculate nucleus, provides input to layer 4b. Both layers have a variety of neurons with distinct morphologies. There is also a range of receptive field properties in the two layers. Our first aim is to characterize the excitatory neurons in layers 4ca and 4b. We will test the hypothesis that there are distinct functional characteristics that associate with distinct morphological types. Among the pyramidal neurons of layer 6 there are distinct classes of neurons based on their pattern of intra-cortical axonal arborization. The axonal patterns are linked to the (vi- and P-cell divisions of layer 4. We will use functional tests that allow us to determine whether labeled neurons are dominated by magnocellular or parvocellular input in addition to tuning for orientation, spatial frequency, temporal frequency and size. Our second aim is to test to what degree morphological classes have specific functional labels, how pathway specific information such as motion and color are retained within different cortical circuits and the extent to which summation and surround suppression are represented within the population of identified neurons. Inhibitory neurons are thought to play specific roles in determining the emergent properties of V1 receptive fields such as orientation, direction and size selectivity. The extent or degree of tuning among the excitatory and inhibitory populations is unknown. Our third aim is to characterize inhibitory neurons in the input and infragranular layers of cortex. There are numerous disorders that are a result of structure-function abnormalities in cortical circuits including, amblyopia, epilepsy and schizophrenia. Understanding how the normal circuits operate provides opportunities for understanding neuronal abnormalities.