Mapping the Deaf Auditory Cortex

描述（由申请人提供）：传统上，大脑的感觉区域被认为专门用于处理来自一组感觉器官的感觉信息，即单模态。来自动物和人类研究的越来越多的证据表明，即使是最初级的感觉皮层也有能力处理来自其他模式的信息。更好地理解跨模态可塑性的神经机制对于感觉剥夺者的康复和神经假体的发展至关重要。最近对先天性失聪成人的影像学研究表明，失聪的“听觉”皮层可以处理视觉和触觉信息。然而，聋人“听觉”皮层的功能组织尚不清楚，因为视觉和触觉信息的时空处理尚未在同一受试者中进行研究。此外，先天失聪者的听觉皮层可以被不同感觉模式的刺激激活，这一事实并没有告诉我们这些可塑性变化发生的听觉通路的水平。测量到的皮质激活可以反映丘脑核的重组，和/或丘脑-皮质以及皮质-皮质连接的可塑性。在具体目标1中，研究人员将描述皮层和皮层下水平的结构可塑性。他们将对先天性耳聋和年龄匹配的听力受试者进行解剖和扩散张量磁共振成像，以揭示假定的丘脑和轴突连通性差异。在具体目标2中，研究人员将结合功能性磁共振成像和电磁记录来揭示在视觉和振动触觉刺激下聋人“听觉”皮层激活的可能时空差异。这将使研究人员能够区分重叠或分离的神经网络是否支持聋人“听觉”皮层的跨模态可塑性。

DESCRIPTION (provided by applicant): Traditionally, the sensory areas of the brain were believed to be exclusively devoted for processing of sensory information from one set of sensory organs, i.e., uni-modal. Increasing evidence from both animal and human studies now suggest that even the very primary sensory cortices have the capacity to process information from the other modalities. Greater understanding of the neural mechanisms underlying cross-modal plasticity is crucial for the rehabilitation of sensory deprived humans and development of neural prostheses. Recent imaging studies on congenitally deaf adults have shown that the deaf "auditory" cortex can process both visual and tactile information. However, the functional organization of the deaf "auditory" cortex is not known, as spatiotemporal processing of both visual and tactile information has not been investigated in the same subjects. Furthermore, the mere fact that the auditory cortices of the congenitally deaf can be activated by stimuli of different sensory modalities tells us very little about the level of the auditory pathway where these plastic changes take place. The measured cortical activations could reflect reorganization of the thalamic nuclei, and/or plasticity in thalamo-cortical as well as in cortico-cortical connections. In Specific Aim 1 the investigators will delineate structural plasticity both at the cortical and sub-cortical level. They will use anatomical and diffusion tensor magnetic resonance imaging in a cohort of congenitally deaf and age-matched hearing subjects to reveal putative thalamic and axonal connectivity differences. In Specific Aim 2 the investigators will combine functional magnetic resonance imaging with electromagnetic recordings to reveal the possible spatiotemporal differences in the activation of the deaf "auditory" cortex during visual and vibratory tactile stimulation. This will allow the investigators to distinguish whether overlapping or separate neuronal networks support the cross-modal plasticity of the deaf 'auditory' cortex.