Apraxia, agnosias, and higher visual function abnormalities
Apraxia, agnosias, and higher visual function abnormalities
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DOI：
10.1136/jnnp.2005.081885
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发表时间：
2005-12-01
影响因子：
11
通讯作者：
Greene, JDW
中科院分区：
文献类型：
--
作者：
Greene, JDW
病人必须有意识才能感知周围的世界。对意识的探索超出了本文的范围，尽管最近有人对此进行了评论。1 2患者还必须有选择性地注意的能力，以便专注于感觉区的一部分。然后，感知处理是必要的，以确定通过各种感官形式（即视觉，听觉，触觉，嗅觉，味觉）感知到什么，从而允许获得语义知识并通过这种对环境的理解。最初，感知信息是基本的和模态特定的，但当它被高阶中心处理时，意义被赋予感知对象，信息变得多模态（图1）。最终，语义知识是使用各种感官流访问的。例如，如果站在迎面而来的火车的路径上，基本的感知将涉及视觉信息，听到火车来了，感觉地面的振动。然后，这些独立的信息流汇集在一起，访问相关的语义知识，从而使个人能够理解正在发生的事情。在讨论知觉时，我将主要集中在视觉和听觉上，因为其他三种形式的知觉在临床上的重要性较小。感知不是一个被动的过程，而是由注意力调节的。从更高级的中枢到初级感觉皮层都有反馈。同样，注意力也会影响所感知的内容。注意力本身有许多层次或子成分，包括选择性的、分散的、持续的注意力等。与感知相关的是选择性注意力，一个个体专门关注感官体验的特定领域的过程，而不是简单地被动地吸收所有这些体验。皮质下痴呆患者可能会失去这种选择性注意的能力，由于无法忽略背景外部刺激而导致注意力分散。
A patient must be conscious in order to perceive the world around them. An exploration of consciousness is outside the remit of this article though recently reviewed by others. 1 2 The patient must also have the capacity to attend selectively in order to focus on one part of the sensorium. Perceptual processing is then necessary to identify what is being perceived through the various sensory modalities (namely vision, hearing, touch, smell, taste), thus allowing access to semantic knowledge and through this understanding of the environment. Initially, perceptual information is basic and modality specific, but as it is processed by higher order centres, meaning is ascribed to percepts, and information becomes multi-modal (fig 1). Ultimately, semantic knowledge is accessed using the various sensory streams. For example, if standing in the path of an oncoming train, basic perception will involve visual information, hearing the train coming, and feeling vibration from the ground. These separate streams then come together, accessing relevant semantic knowledge and thus allowing the individual to understand what is taking place. In discussing perception, I shall focus mainly on vision and hearing, as the other three forms of perception are of lesser clinical importance. Perception is not a passive process, but is modulated by attention. There is feedback from higher order centres down to primary sensory cortex. Similarly, attention influences what is perceived. Attention itself has many levels or subcomponents, including selective, divided, sustained attention, etc. Of relevance to perception is selective attention, a process by which the individual focuses specifically on particular areas of sensory experience, rather than simply passively absorbing all such experience. Patients with subcortical dementia can lose this ability to attend selectively, resulting in increased distractibility due to inability to ignore background extraneous stimuli.