| 题名 | 1.老年猴视皮层神经元对图形对比度的反应及其潜伏期特征; 2. 极低频磁场对脑功能的影响及眶额叶认知功能的研究 |
| 作者 | 王秀松 |
| 学位类别 | 博士 |
| 答辩日期 | 2009-06 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 马原野 |
| 关键词 | 对比度 潜伏期 老化 初级视觉皮层 内侧颞叶 猕猴 极低频磁场 学习记忆 背侧海马 眶额叶 探索行为 大鼠 小鼠 |
| 其他题名 | 1.Visual cortical neuron responses to pattern contrasts and its latency characteristics in senescent rhesus monkeys；/2.Researches on the effects of the extremely-low frequency magnetic fields on brain function and cognitive function of orbitofrontal cortex |
| 学位专业 | 动物学 |
| 中文摘要 | 1.老年猴视皮层神经元对图形对比度的反应及潜伏期特征: 在正常衰老过程中人类的视觉功能受到严重影响，例如空间和时间对比度敏感性下降以及信息处理时间的延长。虽然部分视觉功能的退化与眼睛的光学系统老化有关，但是它并不能解释所有视觉功能的下降。此外，我们以前的研究和别人的研究结果都表明衰老过程中视觉中枢系统功能的改变可能是视觉功能下降的主要原因。因此，利用单位放电记录技术（single-unit recording technique），我们比较了年轻猕猴和老年猕猴的初级视觉皮层（primary visual cortex，又称V1）神经元对比度反应之间的差异，以及V1和内侧颞叶（medial temporal cortex，MT）视觉区神经元反应潜伏期及其变异性之间的差异。结果显示，与年轻猴相比，老年猴V1区神经元对比度敏感性降低，同时伴随着神经元活动信噪比下降；老年猴V1区和MT区神经元反应潜伏期及其变异性显著增加。然而，两个年龄组MT区神经元平均潜伏期之间差异小于V1区神经元平均潜伏期之间的差异，说明MT区神经元能够自我调整老化带来的影响。另外，两个年龄组V1区神经元潜伏期和变异性都具有正相关关系，但是MT区神经元则没有这种相关性。这些结果表明，在老化过程中皮层神经元的对比度和潜伏期反应特性发生了改变。我们推测这种改变可能与视觉皮层内抑制系统功能的降低有关，但是具体的分子机制和神经环路还不清楚。总之，本实验的研究结果为更好的理解老年人在视觉信息处理中时间和空间对比度敏感性及处理速度下降提供了新线索。2.极低频磁场对脑功能的影响及眶额叶认知功能的研究: 实验目的：（1）研究极低频磁场(20 Hz, 14 mT)照射对长期吗啡处理引起的大鼠背侧海马神经元多巴胺D2密度降低的影响；（2）小鼠青春期长期极低频磁场(50 Hz, 2 mT)照射对空间学习记忆的影响；（3）初步探讨了眶额叶在大鼠新异性探索行为中的作用。实验1，我们用免疫组化的方法检测了大鼠背侧海马神经元多巴胺D2受体密度的变化。结果显示，在长期吗啡处理后戒断早期背侧海马神经元多巴胺D2受体密度相对于对照组减少，磁场和吗啡共同作用会强化这种适应，但是这种变化很快恢复正常。这些结果表明长期吗啡处理会引起海马多巴胺系统产生适应；磁场强化了长期吗啡处理对背侧海马多巴胺系统的影响,这为我们先前发现磁场照射延缓了大鼠条件位置偏好消退的研究结果提供了一个内在神经基础。实验2，我们分别用Y-迷宫（two-trial Y-maze）和Morris水迷宫两种行为装置研究了青春期早期磁场暴露对小鼠短时空间识别记忆和长时空间参考记忆的影响。结果显示，磁场暴露并没有影响小鼠Y-迷宫作业，但是提高了水迷宫任务的学习以及记忆保持。这些结果表明磁场对空间记忆的影响是任务依赖性的。实验3，我们用旷场和Y-迷宫两种行为装置研究了眶额叶电损伤对大鼠新异性探索行为的影响。结果显示，眶额叶受损并没有影响大鼠的神经运动能力，但是降低了大鼠在旷场中的行走距离和直立次数以及降低了在Y-迷宫新异臂中的探索时间和穿梭次数。这些结果表明，眶额叶的完整性对大鼠探索新异环境行为是必要的，这可能与眶额叶参与记忆或行为决策功能有关。 |
| 英文摘要 | 1. Visual cortical neuron response to pattern contrast and its latency characteristics in senescent rhesus monkeys: It is well known that visual function is affected significantly by normal aging, such as decreased spatial and temporal contrast sensitivity as well as prolonged visual information processing. Although some of declines of visual function are related to the optical changes of eyes, these changes can not explain most of the aging-related visual deficits. The results from our previous studies and other data indicate that the visual function declines are underpinned mainly by the functional changes of the central visual system. Therefore, in the present study, we used single-unit recording technique to compare the contrast response property of neurons in the primary visual cortex (V1) between young and old rhesus monkeys, and also the response latency and its variability of neurons in the V1 and the middle temporal cortex (MT). The results showed that the contrast sensitivity of old monkey V1 neurons decreased, accompanied by reduced signal-to-noise ratios when compared with that of young adult monkey V1 neurons, and as well that response latency and its variability of old monkey V1 and MT neurons increased when compared with those of young adult monkey V1 and MT neurons. However, the mean difference in response latency of V1 neurons between young adult and old animals was larger than that of MT neurons, indicating that MT neurons could compensate the aging effects by unclear mechanisms. Additionally, there were the positive correlations between response latency and variability of neurons in V1 area in both age groups, but no correlations in MT area in either the young group or the old group. These findings suggest that the response properties of contrast and latency of the cortical neurons generate alterations which may be related to a degeneration of inhibitory intracortical circuits in the central visual system, but the underlying molecular mechanisms and neural circuits remain unclear. In conclusion, these results provide a new clue for a better understanding about the neural mechanisms underlying the decreased spatial and temporal contrast sensitivity, and also prolonged visual information processing of aged human. 2. Researches on the effects of the extremely-low frequency magnetic fields on brain function and cognitive function of orbitofrontal cortex: The aims of these studies were (1) to investigate the effects of the extremely low-frequency (ELF) magnetic field (20 Hz, 14 mT) exposure during morphine treatment on dopamine D2 receptor density in the rat dorsal hippocampus following withdrawal; (2) to evaluate the effects of the ELF magnetic field (50 Hz, 2 mT) exposure during the early adolescent period of mice on spatial memory performance; (3) to preliminarily investigate the role of orbitofrontal cortex (OFC) in the novelty-seeking behavior of rats. In Experiment 1, we used the immunohistochemical approach to examine the alterations of the dopamine D2 receptor density in the rat dorsal hippocampus. The results showed that the density of dopamine D2 receptor in morphine-treated rats was significantly lower than that of the saline control group during early withdrawal days, and that the combination of ELF magnetic field exposure and morphine treatment strengthened this downregulation. However, the D2 receptor density tended to normalize as morphine withdrawal days increased. These findings suggest that withdrawal from chronic morphine treatment may lead to neuroadapatation of the hippocampus dopamine system, and that the combination of ELF magnetic field exposure and morphine treatment may strengthen this adaptation, which provides a possible neural mechanism underlying the potentiating effect of ELF magnetic field exposure on morphine-induced conditioned place preference observed in our previous behavioral studies. In Experiment 2, we used the two-trial Y-maze and Morris water maze tasks to investigate the effects of the ELF magnetic field exposure in the early adolescent period of mice on spatial memory performance. The results showed that the magnetic field exposure did not affect Y-maze performance, but improved spatial learning acquisition and memory retention in the water maze task. Under the present experimental conditions, our data indicate the task-specific effects of chronic exposure to the ELF magnetic field during early adolescence on spatial memory performance. In Experiment 3, we used both the open-field and Y-maze behavioral paradigms to examine the role of orbitofrontal cortex in the novelty-seeking behavior of rats. Male Sprague-Dawley rats received bilateral electrolytic lesions of the OFC or sham lesions. The results showed that OFC lesions did not impair neuromotor ability of rats, but rats with lesions of the OFC exhibited reduced ambulation distance and numbers of rearing, and also reduced duration and number of visits in the novel arm when compared with the sham controls. The findings suggest that the intact OFC is crucial for the novelty-seeking behavior of rats, which may be related to the implications of the OFC in memory or decision-making on behavior. |
| 语种 | 中文 |
| 公开日期 | 2010-10-22 |
| 内容类型 | 学位论文 |
| 源URL | [http://159.226.149.42:8088/handle/152453/6292]  |
| 专题 | 昆明动物研究所_认知障碍病理学 |
| 推荐引用方式 GB/T 7714 | 王秀松. 1.老年猴视皮层神经元对图形对比度的反应及其潜伏期特征; 2. 极低频磁场对脑功能的影响及眶额叶认知功能的研究[D]. 北京. 中国科学院研究生院. 2009. |
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