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

新皮质的出现及其由早期感觉和运动经验塑造的能力是 哺乳动物大脑进化的标志。这种非凡的可塑性使得新皮质能够被构建为 多感官环境，并在一生中产生灵活的行为。虽然众所周知 早期的感觉体验可以改变感觉和运动皮层的功能组织，大多数研究表明 单独关注体感或运动系统，并且几乎专门研究动物 在相对受限的实验室环境中培养。因此，感官复杂性的程度， 早期环境的可变性和可供性对神经和行为发展的影响尚不清楚。 此外，这些类型的动态环境是否可以提高行为可塑性的能力 一生中从未探索过。在目前的提案中，老鼠将分两次出生和饲养 不同的环境；实验室笼子，或大型、高度丰富的半自然室外围栏。我们 将决定动物学习感觉运动任务的速度、表现的准确性以及 学习新任务的策略与功能差异相关并可以预测 新皮质的组织、神经反应特性和连接。我们专注于涉及的领域 我们认为，感觉运动整合和运动控制将受到饲养条件的高度影响： 初级体感皮层（S1）和运动皮层（M1）。我们将使用电生理记录 检查 S1 和皮质内的体位组织和神经反应特性的技术 微刺激技术来确定 M1 和 S1 中肌肉协同作用的表现方式。我们还将 量化 M1 和 S1 与其他皮质区域的神经解剖学连接的差异 横跨半球，以及背侧丘脑和脊髓。最后，确定何时这些 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后对动物进行检查。这些研究将揭示 早期感觉体验与不同的运动机会何时以及如何影响皮质组织 发育中大脑的连接性，以产生适合情境的行为；如果动态且复杂 感觉运动环境产生具有更大程度行为可塑性的大脑和身体 一生。

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.