Cohen L G, Celnik P, Pascual-Leone A, Corwell B, Falz L, Dambrosia J, Honda M, Sadato N, Gerloff C, Catalá M D, Hallett M
Human Cortical Physiology Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892-1428, USA.
Nature. 1997 Sep 11;389(6647):180-3. doi: 10.1038/38278.
Functional imaging studies of people who were blind from an early age have revealed that their primary visual cortex can be activated by Braille reading and other tactile discrimination tasks. Other studies have also shown that visual cortical areas can be activated by somatosensory input in blind subjects but not those with sight. The significance of this cross-modal plasticity is unclear, however, as it is not known whether the visual cortex can process somatosensory information in a functionally relevant way. To address this issue, we used transcranial magnetic stimulation to disrupt the function of different cortical areas in people who were blind from an early age as they identified Braille or embossed Roman letters. Transient stimulation of the occipital (visual) cortex induced errors in both tasks and distorted the tactile perceptions of blind subjects. In contrast, occipital stimulation had no effect on tactile performance in normal-sighted subjects, whereas similar stimulation is known to disrupt their visual performance. We conclude that blindness from an early age can cause the visual cortex to be recruited to a role in somatosensory processing. We propose that this cross-modal plasticity may account in part for the superior tactile perceptual abilities of blind subjects.
对自幼失明者的功能成像研究表明，他们的初级视觉皮层可通过盲文阅读及其他触觉辨别任务被激活。其他研究还显示，在盲人受试者而非有视力者中，视觉皮层区域可被躯体感觉输入激活。然而，这种跨模态可塑性的意义尚不清楚，因为目前尚不清楚视觉皮层是否能够以功能相关的方式处理躯体感觉信息。为解决这一问题，我们利用经颅磁刺激来干扰自幼失明者在识别盲文或浮雕罗马字母时不同皮层区域的功能。对枕叶（视觉）皮层的短暂刺激在两项任务中均引发了错误，并扭曲了盲人受试者的触觉感知。相比之下，枕叶刺激对视力正常受试者的触觉表现没有影响，而类似刺激已知会干扰他们的视觉表现。我们得出结论，自幼失明会导致视觉皮层被征募到躯体感觉处理中发挥作用。我们提出，这种跨模态可塑性可能部分解释了盲人受试者卓越的触觉感知能力。
