Department of Experimental Psychology, University of Oxford, Oxford, OX1 3UD, United Kingdom, Functional MRI of the Brain Centre, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DU, United Kingdom, and Department of Biological and Medical Sciences, Oxford Brookes University, Oxford, OX3 0BP, United Kingdom.
J Neurosci. 2013 Nov 13;33(46):18242-6. doi: 10.1523/JNEUROSCI.2546-13.2013.
Previous imaging studies of congenital blindness have studied individuals with heterogeneous causes of blindness, which may influence the nature and extent of cross-modal plasticity. Here, we scanned a homogeneous group of blind people with bilateral congenital anophthalmia, a condition in which both eyes fail to develop, and, as a result, the visual pathway is not stimulated by either light or retinal waves. This model of congenital blindness presents an opportunity to investigate the effects of very early visual deafferentation on the functional organization of the brain. In anophthalmic animals, the occipital cortex receives direct subcortical auditory input. We hypothesized that this pattern of subcortical reorganization ought to result in a topographic mapping of auditory frequency information in the occipital cortex of anophthalmic people. Using functional MRI, we examined auditory-evoked activity to pure tones of high, medium, and low frequencies. Activity in the superior temporal cortex was significantly reduced in anophthalmic compared with sighted participants. In the occipital cortex, a region corresponding to the cytoarchitectural area V5/MT+ was activated in the anophthalmic participants but not in sighted controls. Whereas previous studies in the blind indicate that this cortical area is activated to auditory motion, our data show it is also active for trains of pure tone stimuli and in some anophthalmic participants shows a topographic mapping (tonotopy). Therefore, this region appears to be performing early sensory processing, possibly served by direct subcortical input from the pulvinar to V5/MT+.
先前对先天性失明的影像学研究集中于具有不同失明原因的个体，这些原因可能影响跨模态可塑性的性质和程度。在这里，我们扫描了一组由双侧先天性无眼症的盲人组成的同质群体，在这种情况下，双眼都没有发育，因此，视觉通路既不受光也不受视网膜波的刺激。这种先天性失明模型为研究非常早期的视觉去传入对大脑功能组织的影响提供了机会。在无眼动物中，枕叶皮层接收来自皮质下的直接听觉输入。我们假设，这种皮质下重组的模式应该导致听觉频率信息在无眼者的枕叶皮层中的拓扑映射。使用功能磁共振成像，我们检查了高频、中频和低频纯音刺激的听觉诱发活动。与视力正常的参与者相比，无眼参与者的颞上皮层的活动显著减少。在枕叶皮层中，与视觉正常的对照组相比，无眼参与者的与细胞构筑区 V5/MT+相对应的区域被激活，但视觉正常的对照组没有被激活。尽管先前的盲人研究表明，该皮质区域会被听觉运动激活，但我们的数据显示，它也会对纯音刺激的音束激活，并且在一些无眼参与者中显示出拓扑映射（音位图）。因此，该区域似乎在执行早期的感官处理，可能由来自丘脑枕的皮质下直接输入到 V5/MT+提供服务。
