Walpola Ishan C, Muller Alana J, Hall Julie M, Andrews-Hanna Jessica R, Irish Muireann, Lewis Simon J G, Shine James M, O'Callaghan Claire
Brain and Mind Centre and Central Clinical School, Faculty of Medicine and Health, University of Sydney, Sydney, Australia.
Brain and Mind Centre and Central Clinical School, Faculty of Medicine and Health, University of Sydney, Sydney, Australia; School of Social Sciences and Psychology, Western Sydney University, Sydney, Australia.
Cortex. 2020 Apr;125:233-245. doi: 10.1016/j.cortex.2019.12.023. Epub 2020 Jan 22.
Visual hallucinations are an underappreciated symptom affecting the majority of patients during the natural history of Parkinson's disease. Little is known about other forms of abstract and internally generated cognition - such as mind-wandering - in this population, but emerging evidence suggests that an interplay between the brain's primary visual and default networks might play a crucial role in both internally generated imagery and hallucinations. Here, we explored the association between mind-wandering and visual hallucinations in Parkinson's disease, and their relationship with brain network coupling. We administered a validated thought-sampling task to 38 Parkinson's disease patients (18 with hallucinations; 20 without) and 40 controls, to test the hypothesis that individuals with hallucinations experience an increased frequency of mind-wandering. Group differences in the association between mind-wandering frequency and brain network coupling were also examined using resting state functional magnetic resonance imaging. Our results showed that patients with hallucinations exhibited significantly higher mind-wandering frequencies compared to non-hallucinators, who in turn had reduced levels of mind-wandering relative to controls. At the level of brain networks, inter-network connectivity and seed-to-voxel analyses identified that increased mind-wandering in the hallucinating versus non-hallucinating group was associated with greater coupling between the primary visual cortex and dorsal default network. Taken together, our results suggest a relative preservation of mind-wandering in Parkinson's disease patients who experience visual hallucinations, which is associated with increased visual cortex-default network coupling. We propose that the preservation of florid abstract and internally generated cognition in the context of the Parkinson's disease can contribute to visual hallucinations, whereas healthy individuals experience only the vivid images of the mind's eye. These findings refine current models of visual hallucinations by identifying a specific cognitive phenomenon and neural substrate consistent with the top-down influences over perception that have been implicated in hallucinations across neuropsychiatric disorders.
视幻觉是帕金森病自然病程中影响大多数患者但未得到充分认识的一种症状。对于该人群中其他形式的抽象和内在产生的认知（如意念性思维漫游），我们了解甚少，但新出现的证据表明，大脑的初级视觉网络和默认网络之间的相互作用可能在内在产生的意象和幻觉中都起着关键作用。在此，我们探讨了帕金森病中意念性思维漫游与视幻觉之间的关联，以及它们与脑网络耦合的关系。我们对38名帕金森病患者（18名有幻觉；20名无幻觉）和40名对照者进行了一项经过验证的思维抽样任务，以检验幻觉患者意念性思维漫游频率增加这一假设。还使用静息态功能磁共振成像检查了意念性思维漫游频率与脑网络耦合之间关联的组间差异。我们的结果表明，与无幻觉者相比，有幻觉的患者表现出显著更高的意念性思维漫游频率，而无幻觉者相对于对照者的意念性思维漫游水平则有所降低。在脑网络层面，网络间连接性和种子点到体素分析表明，幻觉组与非幻觉组相比，意念性思维漫游增加与初级视觉皮层和背侧默认网络之间更强的耦合相关。综合来看，我们的结果表明，在经历视幻觉的帕金森病患者中，意念性思维漫游相对保留，这与视觉皮层 - 默认网络耦合增加有关。我们提出，在帕金森病背景下保留丰富的抽象和内在产生的认知可能导致视幻觉，而健康个体仅体验到脑海中的生动图像。这些发现通过识别一种特定的认知现象和神经基质，完善了当前的视幻觉模型，该认知现象和神经基质与跨神经精神疾病的幻觉中涉及的对感知的自上而下影响一致。
