Experience Dependent Plasticity of The Developing Cortex

描述（由申请人提供）：我们的长期研究兴趣是了解感觉皮层的功能组织，其可塑性及其与行为的关系。我们的研究目标是大鼠的体感觉皮层，特别是处理面部胡须信息的细分，即后内侧桶子场（PMBSF）。利用慢性功能成像和单单元记录，我们已经证明，在成年大鼠的PMBSF中，须功能表征（WFR）的大小很大，因此与其他须的WFR广泛重叠。令人惊讶的是，我们发现这种对WFRs的描述仅适用于生活在标准笼子（SC）中的大鼠。如果老鼠被允许离开笼子，从而能够表达在SC中通常不表达的先天行为，比如依赖于须的导航，WFRs收缩并减弱，从而使它们的重叠最小化，但如果老鼠呆在自己的SC中，WFRs就会扩大和加强。WFRs的收缩既发生在被剥夺权利的成年大鼠身上，这些大鼠经历了除一根胡须外的所有胡须的去除，并被允许在笼子外导航几分钟，也发生在正常的、未被剥夺权利的成年大鼠身上，这些大鼠在自然栖息地（NH）中度过了一个月——一种模仿大鼠自然环境的新型住房环境，使大鼠能够从事天生的行为，如探索、挖掘隧道、地下导航、觅食和社会互动。由于皮层在发育过程中对环境影响特别敏感，我们建议研究这样一种假设，即在NH长大的小鼠自出生以来表达先天行为的能力，可能具有解剖学、功能和行为方面的影响，与sc饲养的大鼠相比，这将使皮层更好地优化胡须识别能力。为了验证这一假设，我们建议比较nh饲养大鼠和sc饲养大鼠的解剖、神经生理学和须依赖识别行为。这项研究的成功完成将强调在发育过程中表达先天行为对于与这种行为相关的皮质结构和功能的最佳成熟的重要性。这些发现可能对人类发育异常行为的最佳治疗以及损伤或疾病后的再生具有启示意义。此外，这些结果将有助于重新评估sc饲养的大鼠作为正常人脑模型的适用性。

DESCRIPTION (provided by applicant): Our long-range research interest is to understand the functional organization of sensory cortex, its plasticity and their relationship to behavior. The target of our research is the somatosensory cortex of the rat, especially the subdivision that processes information from the facial whiskers known as Postero Medial Barrel Sub Field (PMBSF). Using chronic functional imaging and single unit recordings we have demonstrated that in the adult rat the size of a whisker functional representation (WFR) in the PMBSF is large and consequently overlaps extensively with the WFRs of other whiskers. Surprisingly, we found that this description of the WFRs is valid only in rats that live in a standard cage (SC). If rats are allowed out of the cage and thus are able to express innate behaviors that are not typically expressed in the SC, such as whisker-dependent navigation, the WFRs contract and weaken and thus minimize their overlap, but if the rat stays in its SC the WFRSs expand and strengthen. The contraction of WFRs was found both in adult deprived rats that experienced a removal of all whiskers except one (spared whisker) and were allowed a few minutes of navigation outside the cage, or in normal, non deprived adult rats that were spending a month in a naturalistic habitat (NH) - a new type of housing environment that imitates the rat's natural environment by enabling rats to engage in innate behaviors such as exploration, tunnel digging, subterranean navigation, foraging and social interactions. Because the cortex is especially sensitive to environmental influences during development, we propose to investigate the hypothesis that the ability to express innate behaviors since birth by being raised in the NH, may have anatomical, functional and behavioral consequences that would refine the cortex to be better optimized for whisker discrimination abilities compared to SC-raised rats. To test the hypothesis, we propose to compare the anatomy, neurophysiology and whisker-dependent discrimination behavior of NH-raised rats vs. SC-raised rats. Successful completion of the proposal would highlight the importance of expressing innate behaviors during development for the optimal maturation of cortical structure, function that is associated with this behavior. Such findings could have implications for the optimal treatment of developmental abnormalities of behavior in humans, and regeneration after injury or disease. Further, such results would help in reassessment of the appropriateness of SC-raised rats to serve as models for the normal human brain.