Institute of Neuroscience and Pharmacology, Panum Institute, University of Copenhagen, Blegdamsvej 3B, 2300 Copenhagen, Denmark.
Neuropsychologia. 2011 Jun;49(7):2037-44. doi: 10.1016/j.neuropsychologia.2011.03.033. Epub 2011 Mar 30.
Adaptive neuroplastic changes have been well documented in congenitally blind individuals for the processing of tactile and auditory information. By contrast, very few studies have investigated olfactory processing in the absence of vision. There is ample evidence that the olfactory system is highly plastic and that blind individuals rely more on their sense of smell than the sighted do. The olfactory system in the blind is therefore likely to be susceptible to cross-modal changes similar to those observed for the tactile and auditory modalities. To test this hypothesis, we used functional magnetic resonance imaging to measure changes in the blood-oxygenation level-dependent signal in congenitally blind and blindfolded sighted control subjects during a simple odor detection task. We found several group differences in task-related activations. Compared to sighted controls, congenitally blind subjects more strongly activated primary (right amygdala) and secondary (right orbitofrontal cortex and bilateral hippocampus) olfactory areas. In addition, widespread task-related activations were found throughout the whole extent of the occipital cortex in blind but not in sighted participants. The stronger recruitment of the occipital cortex during odor detection demonstrates a preferential access of olfactory stimuli to this area when vision is lacking from birth. This finding expands current knowledge about the supramodal function of the visually deprived occipital cortex in congenital blindness, linking it also to olfactory processing in addition to tactile and auditory processing.
适应性神经可塑性变化在先天性失明者处理触觉和听觉信息方面已有充分记录。相比之下，很少有研究调查过在没有视觉的情况下嗅觉的处理。有充分的证据表明嗅觉系统具有高度的可塑性，而且失明者比视力正常者更依赖嗅觉。因此，盲人的嗅觉系统可能容易受到类似于触觉和听觉模式所观察到的跨模式变化的影响。为了验证这一假设，我们使用功能磁共振成像来测量先天性失明者和蒙住眼睛的视力正常对照者在简单嗅觉检测任务中血氧水平依赖信号的变化。我们发现，在与任务相关的激活方面存在几个群体差异。与视力正常的对照组相比，先天性失明者的初级（右侧杏仁核）和次级（右侧眶额皮质和双侧海马体）嗅觉区域的激活更为强烈。此外，在盲人和视力正常的参与者中，都发现了广泛的与任务相关的激活，遍及整个枕叶皮层。在嗅觉检测过程中，枕叶皮层的强烈募集表明，当从出生起就缺乏视觉时，嗅觉刺激更优先进入该区域。这一发现扩展了关于先天性失明时视觉剥夺的枕叶皮层的超模态功能的现有知识，将其与嗅觉处理以及触觉和听觉处理联系起来。
