Sheffield Cognition and Neuroimaging Laboratory, Academic Clinical Psychiatry, Department of Neuroscience, Faculty of Medicine, Dentistry and Health, University of Sheffield, The Longley Centre, Norwood Grange Drive, Sheffield S5 7JT, UK.
Neuroimage. 2011 Aug 1;57(3):1154-61. doi: 10.1016/j.neuroimage.2011.04.058. Epub 2011 May 3.
Investigating auditory hallucinations that occur in health may help elucidate brain mechanisms which lead to the pathological experience of auditory hallucinations in neuropsychiatric disorders such as schizophrenia. In this study, we investigated healthy individuals who reported auditory hallucinations whilst falling asleep (hypnagogic hallucinations; HG) and waking up (hypnopompic hallucinations; HP). In an initial behavioural study, we found that subjects with a history of auditory HG/HP hallucinations (n = 26) reported significantly greater subjective sensitivity to environmental sounds than non-hallucinator controls (n = 74). Then, two fMRI experiments were performed. The first examined speech-evoked brain activation in 12 subjects with a history of auditory HG/HP hallucinations and 12 non-hallucinator controls matched for age, gender and IQ. The second fMRI experiment, in the same subjects, probed how brain activation was modulated by auditory attention using a bimodal selective attention paradigm. In the first experiment, the hallucinator group demonstrated significantly greater speech-evoked activation in the left supramarginal gyrus than the control group. In the second experiment, directing attention towards the auditory (vs. visual) modality induced significantly greater activation of the anterior cingulate gyrus in the hallucinator group than in the control group. These results suggest that hallucination proneness is associated with increased sensitivity of auditory and polysensory association cortex to auditory stimulation, an effect which might arise due to enhanced attentional bias from the anterior cingulate gyrus. Our data support the overarching hypothesis that top-down modulation of auditory cortical response characteristics may be a key mechanistic step in the generation of auditory hallucinations.
研究健康人群中出现的幻听现象有助于阐明导致精神神经障碍（如精神分裂症）中病理性幻听体验的大脑机制。在这项研究中，我们调查了报告入睡时（催眠幻觉；HG）和醒来时（催眠幻觉；HP）出现幻听的健康个体。在一项初始行为研究中，我们发现有 HG/HP 幻听史的受试者（n = 26）报告对环境声音的主观敏感性明显高于非幻听者对照组（n = 74）。然后进行了两项 fMRI 实验。第一项实验检查了 12 名有 HG/HP 幻听史的受试者和 12 名年龄、性别和智商匹配的非幻听者对照组的听觉诱发大脑激活情况。第二项 fMRI 实验在同一受试者中，使用双模态选择性注意范式探测听觉注意如何调节大脑激活。在第一项实验中，与对照组相比，幻听者组的左侧缘上回表现出显著更强的言语诱发激活。在第二项实验中，与对照组相比，将注意力集中在听觉（而不是视觉）模式上，会导致幻听者组的前扣带皮层的激活显著增强。这些结果表明，易出现幻觉与听觉和多感觉联合皮层对听觉刺激的敏感性增加有关，这种效应可能是由于前扣带皮层增强的注意力偏向所致。我们的数据支持这样一个总体假设，即听觉皮层反应特征的自上而下调节可能是产生听觉幻觉的一个关键机制步骤。
