Centre for Neuroimaging Sciences, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK.
Department of Old Age Psychiatry, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK.
Cortex. 2021 Feb;135:311-325. doi: 10.1016/j.cortex.2020.10.024. Epub 2020 Dec 5.
Hallucinations, percepts in the absence of external stimuli, are a shared feature of eye-disease (Charles Bonnet Syndrome, CBS) and Parkinson's disease (PD) thought to arise through pathophysiologically distinct mechanisms: deafferentation and attentional network dysfunction respectively. Recent studies have found an association between visual hallucinations and structural changes in the cerebellum without obvious link to either mechanism. Here, we employed Voxel Based Morphometry (VBM), optimised for the cerebellum using the Spatially Unbiased Infratentorial Template (SUIT), to characterise similarities and differences in cerebellar structure associated with visual hallucinations in PD and CBS. Grey and white matter volume (GMV & WMV) from patients with eye-disease (n = 12 hallucinators; n = 9 non-hallucinators) and PD (n = 7 hallucinators; n = 9 non-hallucinators) was examined in a 2-way ANOVA controlling for age, sex, and intracranial volume. Comparing hallucinators to controls across both groups, lower GMV was found bilaterally within cerebellar lobule VIII extending to IX/VII. GMV reductions were also found in Crus 1, greater in PD than eye-disease. Predominantly within PD, hallucination-related lower WMV was found in the medulla. No regions of increased GMV or WMV were found. A correlation was observed between brainstem WMV and lobule VIIIb GMV suggesting a functional association. Lobule VIII comprises a functional node within the Dorsal Attention Network (DAN), linking these findings to current attentional theories of hallucinations, while Crus 1 is linked to cortical visual processing. These findings provide preliminary evidence of a cerebellar contribution to hallucinations that transcends clinical conditions.
幻觉是指在没有外部刺激的情况下产生的知觉，是眼部疾病（Charles Bonnet 综合征，CBS）和帕金森病（PD）的共同特征，据认为它们分别通过病理生理学上不同的机制产生：去传入和注意力网络功能障碍。最近的研究发现，视觉幻觉与小脑的结构变化之间存在关联，而与这两种机制都没有明显联系。在这里，我们使用基于体素的形态计量学（VBM），使用空间无偏下脑模板（SUIT）对小脑进行优化，来描述与 PD 和 CBS 中的视觉幻觉相关的小脑结构的相似性和差异。通过 2 方式方差分析，对眼部疾病患者（n=12 名幻觉者；n=9 名非幻觉者）和 PD 患者（n=7 名幻觉者；n=9 名非幻觉者）的灰质和白质体积（GMV 和 WMV）进行了检查，同时控制了年龄、性别和颅内体积。在两组患者中，将幻觉者与对照组进行比较，发现双侧小脑叶 VIII 到 IX/VII 范围内的 GMV 降低。在 PD 中，Crus 1 的 GMV 减少更为明显。主要在 PD 中，在延髓中发现与幻觉相关的 WMV 降低。未发现 GMV 或 WMV 增加的区域。观察到脑干 WMV 与 VIIIb 小叶 GMV 之间存在相关性，提示存在功能关联。VIII 小叶包含背侧注意网络（DAN）中的一个功能节点，将这些发现与当前关于幻觉的注意力理论联系起来，而 Crus 1 与皮质视觉处理有关。这些发现提供了小脑对幻觉有贡献的初步证据，这种贡献超越了临床条件。
