Safran A B, Landis T
Department of Clinical Neurosciences, Geneva University Hospitals, Switzerland.
Curr Opin Ophthalmol. 1996 Dec;7(6):53-64. doi: 10.1097/00055735-199612000-00009.
It has recently been shown that, contrary to long-held beliefs, sensory and motor maps are not stable in the adult cerebral cortex. Alteration of input from the periphery results in changes in topography in the cortex, including the primary visual cortex. Mechanisms involved consist mainly of reshaping the receptive field of cortical cells and increasing the sensitivity of deprived cells in the visual cortex. Cortical plasticity allows the brain to adapt to background modifications or to damage of the nervous system. It also underlies learning and attention processes. Cortical changes occurring after focal visual differentiation modify visual perception by filling in visual field defects with information from the area surrounding the scotoma. This modification causes affected subjects to ignore or underestimate their defects. With visual field defects, cortical plasticity also causes distortion in spatial perception. Although the effects of cortical plasticity are prominent in neuro-ophthalmological daily practice, they are usually unrecognized or greatly underestimated. These effects cause delay in recognizing visual field defects, and hence in receiving therapy, while affecting the results of some procedures for testing the visual field. Affected individuals who are unaware of their defects may have increased difficulty in coping with activities in everyday life. Up to now, phenomena related to plasticity in the visual system have been investigated mainly by psychophysicists and neurophysiologists. It is essential to start considering the various effects of cortical reorganization in clinical practice. It is especially important to introduce into clinics the concept of dissociation between actual and perceived defects in the visual field, resulting from the filling-in process, and the need to measure it. This dissociation should also be demonstrated to the affected subjects.
最近研究表明，与长期以来的观点相反，感觉和运动图谱在成人大脑皮层中并不稳定。外周输入的改变会导致皮层地形图的变化，包括初级视觉皮层。涉及的机制主要包括重塑皮层细胞的感受野以及提高视觉皮层中被剥夺细胞的敏感性。皮层可塑性使大脑能够适应背景变化或神经系统损伤。它也是学习和注意力过程的基础。局灶性视觉分化后发生的皮层变化通过用暗点周围区域的信息填补视野缺损来改变视觉感知。这种改变导致受影响的个体忽略或低估他们的缺损。对于视野缺损，皮层可塑性还会导致空间感知的扭曲。尽管皮层可塑性的影响在神经眼科日常实践中很突出，但它们通常未被认识到或被大大低估。这些影响导致视野缺损的识别延迟，进而导致治疗延迟，同时影响一些视野测试程序的结果。未意识到自身缺损的受影响个体在应对日常生活活动时可能会增加困难。到目前为止，与视觉系统可塑性相关的现象主要由心理物理学家和神经生理学家进行研究。在临床实践中开始考虑皮层重组的各种影响至关重要。尤其重要的是要将由于填补过程导致的视野实际缺损和感知缺损之间的分离概念引入临床，并向受影响的患者说明需要测量这种分离。
