老化影响猕猴、猫视觉系统神经元的空间与时间频率调谐特性
发布时间：2018-08-27 11:46
【摘要】：老年人的视觉系统存在多种多样的功能衰退,例如空间对比度分辨,视觉信息处理速度,视觉运动知觉等。这些视觉功能障碍严重影响了老年人的日常生活、工作,例如阅读,以及驾驶等。 前人的研究表明,老年人的视觉功能障碍不能单由眼睛光学系统的退化介导,提示老化过程中存在视觉中枢神经系统的衰退。与此一致的是,本实验室以往的研究发现,以老年猴和老年猫为动物模型,神经元的反应在多个方面、多个视觉皮层均受到了老化的影响,具体表现为：反应潜伏期增长(老年猴V1区、V2区)、对重复刺激的反应变异性增大(老年猴V1区、MT区)、方位方向选择性降低(老年猴V1区、MT区,老年猫V1区)、对比敏感度降低(老年猴V1区、MT区)等。 本研究旨在进一步探索老化引起视觉功能衰退的神经元反应机制。在视觉研究领域,基于视觉图像可以被大脑以不同的傅里叶成分进行解码处理的假说,视觉研究工作者对神经元的空间、时间频率反应特性的探索由来已久。本研究使用了两种动物模型——猕猴(Macaca Mulatta)和猫(Falis Catus),在麻醉麻痹的状态下,使用胞外单细胞记录的方法,研究了视觉系统神经元的空间频率、时间频率反应特性。 猕猴中颞叶皮层(MT区/V5)在视觉信息处理通路中位于初级视觉皮层的下游,是运动视觉信息处理的关键皮层。我们检测了MT区神经元的空间和时间频率反应调谐特性,结果显示：相对于青年猕猴,老年猕猴MT区神经元的最优空间频率降低,最优时间频率降低,空间分辨率降低,时间频率高频截止频率降低,同时空间频率调谐带宽增宽,自发放增大,信噪比降低。这些结果表明老化显著改变了MT区神经元的空间和时间频率反应调谐特性。 我们在猫视觉通路多个级别(LGN、A17区、A18区、PMLS区)检测了老化对神经元空间频率反应特性的影响模式。结果显示,位于丘脑的外侧膝状体的神经元,其空间频率调谐特性并未受老化的影响；而位于皮层区域(A17区、A18区、PMLS区)的神经元,其偏好的最优空间频率虽未受老化影响,但其空间频率调谐带宽均表现为不同程度地增宽。这一结果表明老化降低了猫视觉皮层神经元的空间频率选择性。 我们的研究为老化引起的视觉功能衰退,尤其是视觉信息的空间和时间处理能力的衰退,提供了新的生理学依据。
[Abstract]:There are a variety of functional degradation in the visual system of the elderly, such as spatial contrast resolution, visual information processing speed, visual motion perception and so on. These visual disorders severely affect the elderly's daily life, work, such as reading, and driving. Previous studies have shown that the visual dysfunction of the elderly can not only be mediated by the degeneration of the optical system of the eyes, suggesting that there is a decline in the visual central nervous system during aging. Consistent with this, previous studies in our laboratory have found that the responses of neurons to aging are affected by aging in many ways, using old monkeys and cats as animal models. The specific manifestations were as follows: increased latency (V1 / V2), increased response variability to repeated stimulation (V1 / MT), and decreased azimuth selectivity (V1 / MT). In elderly cats, the contrast sensitivity was decreased (V 1 area and MT area), and so on. The aim of this study was to further explore the mechanism of neuronal response to visual impairment induced by aging. In the field of visual research, based on the hypothesis that visual images can be decoded by different Fourier components of the brain, visual researchers have been exploring the spatial and time-frequency response characteristics of neurons for a long time. In this study, two animal models, rhesus monkey (Macaca Mulatta) and cat (Falis Catus), were used to study the spatial frequency and time-frequency response of neurons in the visual system under anesthetic paralysis using extracellular single cell recording. The middle temporal cortex (MT / V 5) is located downstream of the primary visual cortex in the visual information processing pathway, and is the key cortex in the motor visual information processing. We examined the spatial and temporal response tuning characteristics of neurons in the MT region. The results showed that the optimal spatial frequency, the optimal time frequency and the spatial resolution of the neurons in the MT region of the old macaque were lower than those of the young macaque. The high frequency cutoff frequency of time and frequency is decreased, while the bandwidth of spatial frequency tuning is widened, the self-broadcasting is increased, and the signal-to-noise ratio is decreased. These results indicate that aging significantly changes the spatial and temporal response tuning characteristics of neurons in the MT region. We examined the effects of aging on the spatial frequency response of neurons at multiple levels of the visual pathway in cats (the A18 region of the LGN,A17 region). The results showed that the spatial frequency tuning characteristics of the neurons located in the lateral geniculate body of the thalamus were not affected by aging, while the preferred spatial frequency of the neurons located in the cortical region (A17 / A18 / PMLS) was not affected by aging. However, the spatial frequency tuning bandwidth is widened to some extent. These results suggest that aging reduces spatial frequency selectivity of visual cortical neurons in cats. Our research provides a new physiological basis for the decline of visual function caused by aging, especially the decline of spatial and temporal processing ability of visual information.
【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：Q42
[Abstract]:There are a variety of functional degradation in the visual system of the elderly, such as spatial contrast resolution, visual information processing speed, visual motion perception and so on. These visual disorders severely affect the elderly's daily life, work, such as reading, and driving. Previous studies have shown that the visual dysfunction of the elderly can not only be mediated by the degeneration of the optical system of the eyes, suggesting that there is a decline in the visual central nervous system during aging. Consistent with this, previous studies in our laboratory have found that the responses of neurons to aging are affected by aging in many ways, using old monkeys and cats as animal models. The specific manifestations were as follows: increased latency (V1 / V2), increased response variability to repeated stimulation (V1 / MT), and decreased azimuth selectivity (V1 / MT). In elderly cats, the contrast sensitivity was decreased (V 1 area and MT area), and so on. The aim of this study was to further explore the mechanism of neuronal response to visual impairment induced by aging. In the field of visual research, based on the hypothesis that visual images can be decoded by different Fourier components of the brain, visual researchers have been exploring the spatial and time-frequency response characteristics of neurons for a long time. In this study, two animal models, rhesus monkey (Macaca Mulatta) and cat (Falis Catus), were used to study the spatial frequency and time-frequency response of neurons in the visual system under anesthetic paralysis using extracellular single cell recording. The middle temporal cortex (MT / V 5) is located downstream of the primary visual cortex in the visual information processing pathway, and is the key cortex in the motor visual information processing. We examined the spatial and temporal response tuning characteristics of neurons in the MT region. The results showed that the optimal spatial frequency, the optimal time frequency and the spatial resolution of the neurons in the MT region of the old macaque were lower than those of the young macaque. The high frequency cutoff frequency of time and frequency is decreased, while the bandwidth of spatial frequency tuning is widened, the self-broadcasting is increased, and the signal-to-noise ratio is decreased. These results indicate that aging significantly changes the spatial and temporal response tuning characteristics of neurons in the MT region. We examined the effects of aging on the spatial frequency response of neurons at multiple levels of the visual pathway in cats (the A18 region of the LGN,A17 region). The results showed that the spatial frequency tuning characteristics of the neurons located in the lateral geniculate body of the thalamus were not affected by aging, while the preferred spatial frequency of the neurons located in the cortical region (A17 / A18 / PMLS) was not affected by aging. However, the spatial frequency tuning bandwidth is widened to some extent. These results suggest that aging reduces spatial frequency selectivity of visual cortical neurons in cats. Our research provides a new physiological basis for the decline of visual function caused by aging, especially the decline of spatial and temporal processing ability of visual information.
【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：Q42
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