Sensory cortical organization and cross-modal plasticity in blind subjects

盲人受试者的感觉皮层组织和跨模式可塑性

• 批准号: 7895576
• 负责人: JOSEF P RAUSCHECKER
• 金额: $ 34.24万
• 依托单位: GEORGETOWN UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-01 至 2012-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7895576
• 关键词: Acoustic Stimulation; Adopted; Animals; Area; Auditory; Behavioral; Blindness; Brain; Brain Injuries; Brain imaging; Brain region; Cell Density; Cerebrum; Cognitive; Development; Devices; Diffusion Magnetic Resonance Imaging; Evaluation; Face; Fiber; Functional Magnetic Resonance Imaging; Hearing; Housing; Human; Imaging Techniques; Investigation; Letters; Magnetic Resonance Imaging; Methods; Modality; Nature; Occipital lobe; Ocular Prosthesis; Parietal Lobe; Pathway interactions; Patients; Pattern; Perception; Performance; Persons; Physiological; Process; Psychophysiology; Recruitment Activity; Rehabilitation therapy; Relative (related person); Research; Resolution; Role; Self-Help Devices; Sensory; Source; Specificity; Stimulus; Structure-Activity Relationship; Tactile; Testing; Vision; Visual; Visual Cortex; base; blind; cognitive function; density; extrastriate visual cortex; gray matter; morphometry; neuropsychological; novel; public health relevance; rehabilitation strategy; research study; response; segregation; somatosensory; sound; visual deprivation; visual information; visual stimulus; volunteer; white matter

DESCRIPTION (provided by applicant): Visual deprivation is one of the most extreme conditions leading brain regions to adopt new functions in response to environmental constraints, that is, to compensate for the loss of a sensory modality. Studies in visually deprived animals and in blind humans have long demonstrated the cross-modal recruitment of the visual cortex to process non-visual information. Yet, little is known about the functional parcellation of the reorganized occipital cortex and its precise role in the processing of non-visual information and in higher cognitive functions. The main aims of the present project are (1) to determine the sensory organization of the occipital cortex in blind subjects, (2) to identify the source of non-visual input to occipital cortex in the blind, and (3) to determine the functional role of the occipital cortex of blind subjects in the processing of non-visual stimuli, particularly when using a sensory substitution device. Using functional Magnetic Resonance Imaging (fMRI), we will examine brain activity related to tactile and auditory stimulation while subjects try to either identify or localize stimuli. This will allow us to determine whether domain specificity exists within the reorganized occipital cortex for sensory modality and/or for identification and localization. Using Diffusion Tensor Imaging (DTI) and Voxel-Based Morphometry (VBM), two relatively novel structural MRI techniques, we will investigate the structural basis of cerebral adaptive changes in blind subjects. VBM will allow us to examine if grey-matter cell density and volume in the blind occipital cortex are the same as those in the occipital cortex of sighted persons; DTI will examine the strength of white-matter fiber tracts projecting to and from occipital cortex in both subject groups, thus determining relative changes in the source of non-visual input in the blind. To test to what extent blindness is accompanied by enhanced non-visual abilities and to determine the functional role of occipital cortex in the blind, we will supplement brain imaging with extended psychophysical evaluations. We will examine the co-variance of behavioral performance with activation of brain regions by tactile or auditory stimulation, and in particular with occipital activation elicited by perception through a visual- to-auditory sensory substitution device. We predict that brain areas that are normally not recruited by sounds can be activated during the use of the sensory substitution device according to the stimuli perceived and/or the task performed and commensurate with proficiency of use. PUBLIC HEALTH RELEVANCE A better understanding of the physiological mechanisms underlying brain and cognitive plasticity in blindness will help to develop more adequate rehabilitation strategies and assistive devices for the blind, such as visual prostheses or sensory substitution devices. In a wider perspective, this will provide us with valuable information regarding brain plasticity in general and how the brain modifies its own organization in response to environmental constraints. This could further inspire the development of neuropsychological and rehabilitation methods for patients with brain injuries.

描述（申请人提供）：视觉剥夺是最极端的条件之一，导致大脑区域采用新功能，以应对环境限制，即弥补感官方式的丧失。长期以来，在视觉剥夺动物和盲人中进行的研究表明，视觉皮层的跨模式募集以处理非视觉信息。然而，关于重组枕皮层的功能分析及其在处理非视觉信息和较高认知功能中的精确作用知之甚少。本项目的主要目的是（1）确定盲目受试者枕皮层的感官组织，（2）确定盲人对枕皮层的非视觉输入的来源，（3）确定盲人枕皮层在使用非视觉刺激时的枕皮层的功能作用，尤其是使用感觉式替代设备。使用功能磁共振成像（fMRI），我们将检查与触觉和听觉刺激有关的大脑活动，而受试者试图识别或定位刺激。这将使我们能够确定在重组的枕皮层中是否存在域特异性，以进行感觉方式和/或用于识别和定位。使用扩散张量成像（DTI）和基于体素的形态计量学（VBM），两种相对新的结构MRI技术，我们将研究盲目受试者脑自适应变化的结构基础。 VBM将使我们能够检查盲枕皮质中的灰色细胞密度和体积是否与视力人的枕骨皮层中的细胞密度和体积相同。 DTI将检查两个受试者组中枕皮层和从枕皮层投射的白色纤维道的强度，从而确定盲人中非视觉输入源的相对变化。为了测试失明在多大程度上伴随着增强的非视觉能力并确定枕皮层在盲人中的功能作用，我们将通过扩展的心理物理评估来补充大脑成像。我们将通过触觉或听觉刺激来研究行为性能的共同变异，尤其是通过视觉效率的感觉替代设备引起的枕形激活。我们预测，通常在使用感觉替代设备期间，根据感知和/或熟练使用的刺激和/或任务，可以在使用感觉替代装置时激活声音招募的大脑区域。公共卫生相关性可以更好地理解盲目性大脑和认知可塑性的生理机制，将有助于制定更适当的康复策略和盲人辅助设备，例如视觉假体或感觉替代设备。从更广泛的角度来看，这将为我们提供有关大脑可塑性的宝贵信息，以及大脑如何根据环境限制来修改其自己的组织。这可以进一步激发针对脑损伤患者的神经心理学和康复方法的发展。