The impact of the environment on sensorimotor cortex in rats: Functional organization, connections and behavior

新皮层的出现以及它被早期感觉和运动经验塑造的能力， 哺乳动物大脑进化的标志这种非凡的可塑性使新皮层能够被构造成一个 多感官环境，并在一生中产生灵活的行为。虽然众所周知， 早期的感觉经验可以改变感觉和运动皮层的功能组织，大多数研究都认为， 集中在躯体感觉或运动系统的隔离，几乎完全研究动物 在相对受限的实验室环境中饲养。因此，感官的复杂程度， 变异性，以及早期环境影响神经和行为发育的启示是未知的。 此外，这些类型的动态环境是否可以增加行为可塑性的能力， 从未被探索过。在目前的提议中，老鼠将在两个 不同的环境;实验室笼子，或在一个大的，高度富集，半天然的户外围栏。我们 将决定动物学习感觉运动任务的速度，表现的准确性， 学习新任务的策略与功能差异相关，并且可以预测功能差异。 组织，神经反应特性和新皮层的连接。我们专注于以下领域： 感觉运动整合和运动控制，我们认为这将受到饲养条件的高度影响： 初级躯体感觉皮层（S1）和运动皮层（M1）。我们将使用电生理记录 技术来检查S1的躯体组织和神经反应特性， 微刺激技术，以确定肌肉协同作用是如何在M1和S1代表。我们还将 量化M1和S1与其他皮质区域的神经解剖学连接差异， 以及背侧丘脑和脊髓。最后，为了确定这些 不同的环境对S1和M1的功能组织和连接影响最大， 我们将在4个重要的发育时间点和成年时检查动物。这些研究将揭示 早期感觉经验与各种运动机会的结合何时以及如何影响皮质组织 和连接性，以产生适合环境的行为;如果是动态和复杂的， 感觉运动环境使大脑和身体具有更大程度的行为可塑性 在一生中。

The emergence of the neocortex and its capacity to be shaped by early sensory and motor experience is the hallmark of mammalian brain evolution. This remarkable plasticity allows the neocortex to be constructed for a multi-sensory context, and to generate flexible behavior throughout a lifetime. While it is well established that early sensory experience can alter the functional organization of sensory and motor cortex, most studies have focused on either the somatosensory or the motor system in isolation, and almost exclusively studied animals reared in relatively restricted laboratory environments. Thus, the extent to which the sensory complexity, variability, and affordances of the early environment impact neural and behavioral development is unknown. Also, whether these types of dynamic environments can increase the capacity for behavioral plasticity throughout a lifetime has never been explored. In the current proposal, rats will be born and reared in two distinct environments; a laboratory cage, or in a large, highly enriched, semi-natural outdoor enclosure. We will determine if the speed with which an animal learns a sensory motor task, the accuracy of performance, and strategy by which novel tasks are learned correlate with, and can predict, differences in the functional organization, neural response properties and connections of the neocortex. We focus on areas involved in sensorimotor integration and motor control that we believe will be highly impacted by rearing condition: the primary somatosensory cortex (S1) and motor cortex (M1). We will use electrophysiological recording techniques to examine the somatotopic organization and neural response properties of S1, and intracortical microstimulation techniques to determine how muscle synergies are represented in M1 and S1. We will also quantify differences in the neuroanatomical connections of M1 and S1 with other cortical fields within and across hemispheres, as well as with the dorsal thalamus and spinal cord. Finally, to determine when these distinct environments have the greatest impact on the functional organization and connections of S1 and M1, we will examine animals at 4 important developmental time points and as adults. These studies will uncover when and how early sensory experience coupled with diverse motor opportunities impact cortical organization and connectivity in the developing brain to generate context-appropriate behavior; and if dynamic and complex sensorimotor environments generate brains and bodies capable of a larger degree of behavioral plasticity throughout a lifetime.