Experience Dependent Plasticity of The Developing Cortex

描述(申请人提供)：我们的长期研究兴趣是了解感觉皮质的功能组织，它的可塑性及其与行为的关系。我们研究的目标是大鼠的躯体感觉皮层，特别是处理面部胡须信息的亚区，称为后内侧桶状亚场(PMBSF)。利用慢性功能成像和单单位记录，我们证明在成年大鼠的PMBSF中，胡须功能表征(WFR)的大小很大，因此与其他胡须的WFR广泛重叠。令人惊讶的是，我们发现这种对WFR的描述只适用于生活在标准笼子(SC)中的大鼠。如果允许大鼠走出笼子，从而能够表达在SC中通常不表达的先天行为，例如依赖胡须的导航，WFR收缩并减弱，从而将它们的重叠减少到最小，但如果大鼠留在SC中，WFRS会扩大和加强。在经历了除一根胡须(备用胡须)并被允许在笼子外航行几分钟的成年剥夺大鼠中，或者在正常的、未被剥夺的成年大鼠中发现了WFR的收缩，这些成年大鼠在一个月的自然栖息地(NH)中度过--NH是一种新型的住房环境，通过使老鼠能够从事探索、隧道挖掘、地下导航、觅食和社会互动等先天行为来模拟老鼠的自然环境。由于大脑皮层在发育过程中对环境影响特别敏感，我们建议调查一种假设，即自出生以来通过在NH中长大来表达先天行为的能力，可能会产生解剖学、功能和行为方面的后果，与SC饲养的大鼠相比，这些结果将使大脑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饲养的大鼠和SC饲养的大鼠的解剖学、神经生理学和胡须依赖的辨别行为。该提案的成功完成将突出在发育过程中表达先天行为对于与此行为相关的皮质结构和功能的最佳成熟的重要性。这些发现可能会对人类行为发育异常的最佳治疗以及受伤或疾病后的再生产生影响。此外，这些结果将有助于重新评估SC饲养的大鼠是否适合作为正常人脑的模型。

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.