Gizewski E R, Gasser T, de Greiff A, Boehm A, Forsting M
Department of Neuroradiology, University Hospital, Essen, Germany.
Neuroimage. 2003 Jul;19(3):968-75. doi: 10.1016/s1053-8119(03)00114-9.
Experimental data on cortical reorganization in blind subjects using H(2)(15)O positron emission tomography and functional magnetic resonance imaging (fMRI) showed activation of the visual cortex related to Braille reading and tactile discrimination tasks in congenitally and early blind subjects. The purpose of our study was to differentiate whether occipital activation of blind subjects during Braille reading is task specific or only triggered by sensory or motor area activation. Twelve congenitally and early-onset blind subjects were studied with fMRI during Braille reading, discriminating nonsense dots, sensory stimulation with electromagnetic pulses, and finger tapping. All experiments were performed utilizing a block design with 6 active epochs alternating with 6 rest conditions lasting 34 s each. Echo-planar imaging sequences with 34 transversal slices were performed on a 1.5-T MR scanner. All blind individuals reading Braille and discriminating nonsense dots showed robust activation of the primary, secondary, and higher visual cortex. Application of peripheral electrical stimuli to the reading hand revealed expected sensory activation of the primary somatosensory cortex, but no activation in the visual cortex. Pure motor activation during finger tapping with the reading hand showed expected precentral activation and no activation of visual cortex. In conclusion, occipital activation during Braille reading and discrimination tasks is not due to plasticity of sensory or motor function; pure motor or sensory tasks do not lead to an activation of striate cortex. The brain learns to differentiate between "finger touching" and "finger reading." Our results suggest that activation of the visual cortex in blind subjects is related to higher and more complex brain functions.
使用H(2)(15)O正电子发射断层扫描和功能磁共振成像（fMRI）对盲人受试者进行的皮质重组实验数据显示，先天性和早期失明受试者在盲文阅读和触觉辨别任务中，视觉皮层有激活现象。我们研究的目的是区分盲人受试者在盲文阅读过程中枕叶的激活是任务特异性的，还是仅由感觉或运动区域的激活所触发。对12名先天性和早发性失明受试者在进行盲文阅读、辨别无意义点、电磁脉冲感觉刺激以及手指敲击时进行了fMRI研究。所有实验均采用组块设计，6个激活期与6个休息期交替进行，每个持续34秒。在1.5-T磁共振扫描仪上采用具有34个横向切片的回波平面成像序列。所有阅读盲文和辨别无意义点的盲人个体均显示初级、次级和更高视觉皮层有强烈激活。对阅读手施加外周电刺激显示初级体感皮层有预期的感觉激活，但视觉皮层无激活。用阅读手进行手指敲击时的纯运动激活显示中央前回有预期激活，视觉皮层无激活。总之，盲文阅读和辨别任务期间的枕叶激活并非由于感觉或运动功能的可塑性；纯运动或感觉任务不会导致纹状皮层激活。大脑学会区分“手指触摸”和“手指阅读”。我们的结果表明，盲人受试者视觉皮层的激活与更高和更复杂的脑功能有关。
