Models of Correlation Based Neural Development

描述(摘自申请者的摘要)：这项工作的长期目标是了解大脑皮层的回路及其依赖活动的发育的规则。猫的初级视觉皮质(V1)被作为一个更广泛地理解皮质的模型系统而被研究。计算模型被用来确定什么模式的电路可以解释V1神经元的功能反应特性，以及什么规则的活动指导的突触修改可以产生这些电路模式的自组织。大脑皮层回路是大多数感觉知觉、大部分运动规划和大多数与人类智能相关的高级认知功能的基础，因此对皮质回路及其发展的了解将强烈地影响我们对正常和疾病大脑功能的理解。特别是，对V1回路和发育的了解将影响我们对正常视力和中枢视觉疾病(如弱视和斜视)的理解。 这项工作的具体目标是开发CAT V1的第四层(输入接收层)的电路以及该电路的开发的生物可识别和可测试的模型。对发育的研究将检验这样一种假设，即基于视觉经验影响发育之前存在的自发活动模式的峰时依赖可塑性(STDP)可以解释V1感受野和功能回路的组织。一个特别的重点将是了解方向选择性的发展和相关的皮质回路。对成熟回路的研究将建立在以前工作的基础上，表明“基于关联的”回路可以解释V1层4细胞的许多功能反应特性。在“相关”回路中，兴奋细胞倾向于投射到具有相似或良好关联的感受野(重叠的ON和OFF亚区)的细胞，而抑制性细胞倾向于投射到具有大致相反、反相关或反相感受野的细胞。这项工作将扩展到纳入关于电压噪声在V1反应中的作用、定向未调谐的复杂抑制神经元以及突触抑制在V1反应中的作用的新的实验发现。它还将通过结合输入神经元的时间响应特性的多样性以及通过将基于空间相关性的电路扩展到基于时空相关性的电路来解决方向选择性问题。

DESCRIPTION (adapted from applicant's abstract): The long-term goal of this work is to understand the circuitry of the cerebral cortex and the rules underlying its activity-dependent development. Primary visual cortex (V1) of the cat is studied as a model system for understanding cortex more generally. Computational modeling is used to determine what patterns of circuitry can account for the functional response properties of V1 neurons and what rules of activity-instructed synaptic modification can yield the self-organization of these patterns of circuitry. Cerebral cortical circuitry underlies most sensory perception, much of motor planning, and most of the higher cognitive functions associated with human intelligence, so an understanding of cortical circuitry and its development will strongly impact our understanding of both normal and diseased brain function. In particular, understanding of V1 circuitry and development will impact our understanding of normal vision and of central diseases of vision such as amblyopia and strabismus. The specific aims of this work are to develop biologically identifiable and testable models of the circuitry of layer 4, the input-recipient layer, of cat V1 and of the development of that circuitry. Studies of development will test the hypothesis that spike-timing-dependent plasticity (STDP), based on spontaneous patterns of activity that exist before visual experience impacts development, can account for the organization of V1 receptive fields and functional circuits. A particular focus will be to understand the development of direction selectivity and of the associated cortical circuitry. Studies of the mature circuit will build on previous work showing that a "correlation-based" circuit, in which excitatory cells tend to project to cells with similar or well correlated receptive fields (overlapping ON- and OFF-subregions) and inhibitory cells tend to project to cells with roughly opposite or anticorrelated or antiphase receptive fields, can account for many of the functional response properties of V1 layer 4 cells. This work will be extended to incorporate new experimental findings on the roles of voltage noise in V1 responses, of orientation-untuned complex inhibitory neurons, and of synaptic depression in V1 responses. It will also be extended to address direction selectivity by incorporating diversity of temporal response properties of input neurons and by extending the spatial correlation-based circuitry to circuitry based on spatiotemporal correlations.