INTRODUCTION Charles Bonnet syndrome is characterized by simple or complex visual hallucinations (VH) due to damage along the visual pathways. We report a functional MRI study of brain correlates of VH in the context of a severe optic atrophy in a patient with Leber's Hereditary Optic Neuropathy (LHON). CASE REPORT A 62-year-old man was diagnosed with LHON (11778/ND4 mtDNA mutation) after subacute visual loss in left eye (right eye was amblyopic). One month later, he experienced VH of a few seconds consisting in "moving red and blue miniature cartoons". One year later VH content changed in colored mosaic (10-15 s duration), usually stress-related, and blue and white flashes (2-5 s), triggered by unexpected auditory stimuli. Audiometry revealed mild sensorineural hearing loss. Three block design functional MRI paradigms were administrated: 1) random "clap", 2) "checkerboard" and 3) non-random "beep". After random "claps" simple flashes were evoked with bilateral activation of primary and secondary visual cortex, cuneus, precuneus and insula. Neither hallucinations nor cortex activation were registered after "checkerboard" stimulation, due to the severe visual impairment. Primary and secondary auditory cortices were "beep"-activated, without eliciting VH by non-random "beep". CONCLUSIONS The peculiarity of our case is that VH were triggered by random auditory stimuli, possibly due to a cross-modal plasticity between visual and auditory networks, likely influenced by the sensorineural deafness. Functional alterations of both networks in resting conditions have been demonstrated in LHON patients, even without an auditory deficit. Finally, the absence of VH triggered by expected stimuli is consistent with the "expectation suppression theory", based on increased neural activations after unexpected but not by predicted events.

中文翻译：

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在与LHON相关的Charles Bonnet综合征的病例中进行功能MRI研究。

引言查尔斯·邦内特综合征的特征是由于视觉通路的损伤而导致的简单或复杂的幻觉（VH）。我们报告了严重的视神经萎缩在Leber遗传性视神经病变（LHON）患者中对VH的大脑相关性进行的功能性MRI研究。病例报告一名62岁的男性在左眼亚急性视力丧失（右眼弱视）后被诊断出患有LHON（11778 / ND4 mtDNA突变）。一个月后，他经历了几秒钟的VH，包括“移动红色和蓝色的微型卡通”。一年后，由于意外听觉刺激，彩色马赛克（持续时间为10-15 s）中的VH含量发生了变化，通常与压力有关，蓝白色闪烁（2-5 s）。听力测验发现轻度的感音神经性听力损失。管理了三个模块设计功能性MRI范例：1）随机“拍手”，2）“棋盘格”和3）非随机的“哔声”。经过随机的“拍手”后，伴随着初级和次级视觉皮层，楔形肌，早神经瘤和岛状肌的双侧激活，引起了简单的闪光。由于严重的视觉障碍，“棋盘”刺激后既没有幻觉也没有皮质激活。初级和次级听觉皮层被“嘟嘟”激活，而不是由非随机的“嘟嘟”引起VH。结论我们的病例的特殊性是VH是由随机听觉刺激触发的，这可能是由于视觉和听觉网络之间的交叉模态可塑性，可能受感觉神经性耳聋的影响。在LHON患者中，即使没有听觉缺陷，也已经证明了两种网络在静止状态下的功能改变。最后，由预期刺激引起的VH缺失与“预期抑制理论”相一致，其基于意外事件后神经激活增加，但不是预测事件引起的。