Understanding Degeneration and the Capacity for Reorganisation in the Adult Human Visual Cortex

了解成人视觉皮层的退化和重组能力

• 批准号: 1959793
• 金额: --
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2017
• 资助国家: 英国
• 起止时间: 2017 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-1959793
• 关键词: Understanding; Degeneration; Capacity; Reorganisation; Adult

Loss of vision in infancy results in functional reorganisation of the visual cortex1-3;this shows how the brain can adapt to an altered sensory input early in life. Much lessis known about how the adult brain reorganises in response to abnormal visual inputor how it might adapt to treatments that try to restore visual function. Since inheritedretinal diseases are the leading cause of blindness in the developed world, the demandfor therapy will increase in the next decade. Even where therapy is available, the brainneeds to be able to interpret the restored sensory input, and it is not clear whether thiswill be possible following prolonged loss of input. In order to optimally restorefunction it is vital to understand the principles of how the adult brain responds to aloss of sensory input.Stargardt disease (STGD) is a type of retinal disease in which central vision is mostaffected. This project will measure the longitudinal changes in the visual system ofpatients with STGD and will be completed under the supervision of Professor HollyBridge.Aims1) Cortical effects of retinal degeneration in STGDPrevious research has investigated structural and functional cortical changes in retinaldiseases4, 5. 25 STGD patients and 25 age-matched controls will be recruited toundertake a cross-sectional investigation of the cortical changes associated withSTGD. This will be measured using Magnetic resonance spectroscopy imaging(MRSI), structural MRI, diffusion-weighted imaging and population receptive field(pRF) mapping. Clinical measures of retinal function will then be compared to thesemeasures.2) Longitudinal investigation of reorganisation due to degeneration in STGDSince retinal degeneration can be rapid in STGD, many patients show a decrease invisual function after two years. To quantify the effects of this loss of input andfunction on the visual cortex, patients will be rescanned after two years. By measuringdifferences in the same MRI quantities, I will be able to directly demonstrate theeffects of retinal degeneration on the brain.3) Assessing the potential for boosting plasticity in the healthy visual systemIncreasing excitability in the brain is thought to boost the amount of reorganisationthat can take place; studies in adult animals have shown that this change can occurwhen manipulating the neurochemical environment6. In order to maximise visualfunction following visual restoration it may be necessary to boost the ability of thecortex to respond to restored input. In the motor system tDCS has been used as anadjunct procedure to increase behavioural effects of training or rehabilitation7, muchless is known of its effects in the visual system. 20 volunteers will be scanned usingMRSI and fMRI (7T) to investigate changes that occur following tDCS applicationfirstly to the occipital pole, and secondly to hMT+.To summarise, this project will determine the direct consequences of visual loss dueto retinal degeneration, specifically the changes that occur in individual patients overtime. Additionally, this project will assess the potential to boost plasticity in the visualsystem using tDCS, which may be important for optimising visual function.

婴儿期视力丧失会导致视觉皮层 1-3 的功能重组；这表明大脑如何适应生命早期改变的感觉输入。关于成人大脑如何重组以响应异常视觉输入或如何适应试图恢复视觉功能的治疗，人们知之甚少。由于遗传性视网膜疾病是发达国家失明的主要原因，因此未来十年对治疗的需求将会增加。即使在可以进行治疗的情况下，大脑也需要能够解释恢复的感觉输入，并且尚不清楚在长期失去输入后这是否可能。为了最佳地恢复功能，了解成人大脑如何应对感觉输入丧失的原理至关重要。斯塔加特病 (STGD) 是一种视网膜疾病，其中中央视力受影响最严重。该项目将测量 STGD 患者视觉系统的纵向变化，并将在 HollyBridge 教授的监督下完成。 目标 1) STGDP 中视网膜变性的皮质影响 之前的研究已经调查了视网膜疾病中的结构和功能皮质变化4, 5。将招募 25 名 STGD 患者和 25 名年龄匹配的对照者，对 STGDP 进行横断面调查。 与 STGD 相关的皮质变化。这将使用磁共振波谱成像 (MRSI)、结构 MRI、扩散加权成像和群体感受野 (pRF) 映射来测量。然后将视网膜功能的临床测量结果与这些测量结果进行比较。2) STGD 中由于变性而导致的重组的纵向研究由于 STGD 中视网膜变性可能很快，因此许多患者在两年后表现出视功能下降。为了量化输入和功能丧失对视觉皮层的影响，患者将在两年后接受重新扫描。通过测量相同 MRI 数量的差异，我将能够直接证明视网膜变性对大脑的影响。3) 评估增强健康视觉系统可塑性的潜力 增加大脑的兴奋性被认为可以增加可能发生的重组量；对成年动物的研究表明，当操纵神经化学环境时，就会发生这种变化6。为了在视觉恢复后最大化视觉功能，可能有必要增强皮质对恢复的输入做出反应的能力。在运动系统中，经颅直流电刺激 (tDCS) 已被用作增加训练或康复的行为效果的辅助程序，但对其在视觉系统中的影响知之甚少。将使用 MRSI 和 fMRI (7T) 对 20 名志愿者进行扫描，以调查 tDCS 应用后发生的变化，首先是枕极，其次是 hMT+。总而言之，该项目将确定由于视网膜变性导致视力丧失的直接后果，特别是个别患者随着时间的推移发生的变化。此外，该项目将评估使用 tDCS 增强视觉系统可塑性的潜力，这对于优化视觉功能可能很重要。