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，这是神经科学的中心目标。我们一直在研究初级视觉皮质V1，以了解它在视觉中的作用，也因为V1是大脑皮层中最被理解的区域之一。一方面，我们经常对神经元的感受场特性有详细的了解，这些特性是由V1中的神经元对一系列视觉刺激的放电决定的，这些视觉刺激来自细胞外记录。另一方面，通过解剖学研究，我们了解到V1内以及V1与纹外皮质之间错综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子初级视觉皮质回路中神经元的结构和它们的接受场特性之间的差距。我们使用一种称为松散贴片细胞旁记录的方法来监测细胞外动作电位，这使得我们能够从功能上表征神经元的RF，然后我们用示踪剂分子标记相同的神经元，然后恢复和重建标记神经元的三维树突和轴突。4a层是外侧膝状核大细胞传入的主要靶点，为4b层提供输入。这两层都有不同形态的神经元。这两个层中还有一系列接受场属性。我们的第一个目标是确定4ca和4b层的兴奋性神经元的特征。我们将检验这一假设，即存在与不同形态类型相关联的不同功能特征。在第6层的锥体神经元中，根据其皮质内轴突分支的模式，有不同类型的神经元。轴突模式与第四层的(VI和P细胞)分裂有关。我们将使用功能测试来确定标记神经元除了调节方向、空间频率、时间频率和大小外，是由大细胞还是小细胞输入主导的。我们的第二个目标是测试形态类别在多大程度上具有特定的功能标记，路径特定信息(如运动和颜色)如何保留在不同的皮质回路中，以及在已识别的神经元群体中表示总和和周围抑制的程度。抑制性神经元被认为在决定V1感受野的突现特性，如方向、方向和大小选择性方面发挥着特定的作用。兴奋性和抑制性群体之间的调谐程度和程度尚不清楚。我们的第三个目标是描述大脑皮层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的结构-功能异常造成的，包括弱视、癫痫和精神分裂症。了解正常电路是如何运作的，为理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.