Auditory verbal hallucinations (hearing voices) are typically associated with psychosis, but a minority of the general population also experience them frequently and without distress. Such ‘non-clinical’ experiences offer a rare and unique opportunity to study hallucinations apart from confounding clinical factors, thus allowing for the identification of symptom-specific mechanisms. Recent theories propose that hallucinations result from an imbalance of prior expectation and sensory information, but whether such an imbalance also influences auditory-perceptual processes remains unknown. We examine for the first time the cortical processing of ambiguous speech in people without psychosis who regularly hear voices. Twelve non-clinical voice-hearers and 17 matched controls completed a functional magnetic resonance imaging scan while passively listening to degraded speech (‘sine-wave’ speech), that was either potentially intelligible or unintelligible. Voice-hearers reported recognizing the presence of speech in the stimuli before controls, and before being explicitly informed of its intelligibility. Across both groups, intelligible sine-wave speech engaged a typical left-lateralized speech processing network. Notably, however, voice-hearers showed stronger intelligibility responses than controls in the dorsal anterior cingulate cortex and in the superior frontal gyrus. This suggests an enhanced involvement of attention and sensorimotor processes, selectively when speech was potentially intelligible. Altogether, these behavioural and neural findings indicate that people with hallucinatory experiences show distinct responses to meaningful auditory stimuli. A greater weighting towards prior knowledge and expectation might cause non-veridical auditory sensations in these individuals, but it might also spontaneously facilitate perceptual processing where such knowledge is required. This has implications for the understanding of hallucinations in clinical and non-clinical populations, and is consistent with current ‘predictive processing’ theories of psychosis.

中文翻译：

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非临床性听觉幻觉患者对歧义性言语的不同处理

听觉的口头幻觉（听见声音）通常与精神病有关，但是少数普通人群也经常经历这种情况，而不会感到困扰。除了混淆临床因素之外，这种“非临床”经历为幻觉研究提供了难得的独特机会，因此可以确定症状特异性机制。最近的理论认为，幻觉是由先前的期望和感官信息的不平衡引起的，但是这种不平衡是否还会影响听觉-知觉过程仍然是未知的。我们第一次检查了在没有精神病的人中经常听到声音的歧义性语音的皮层处理。十二个非临床语音听者和17个匹配的控件完成了功能性磁共振成像扫描，同时被动地听取了可能是可理解的或难以理解的退化语音（“正弦波”语音）。听到声音的人报告说，他们在控制之前和明确知道其清晰度之前就已经意识到了语音在刺激中的存在。在两组中，可理解的正弦波语音都参与了典型的左偏语音处理网络。然而，值得注意的是，听觉听觉者在背前扣带回皮层和上额额回中显示出比对照组更强的清晰度反应。这表明，当语音可能可理解时，选择性地增加了注意力和感觉运动过程的参与度。共，这些行为和神经发现表明，有幻觉经历的人对有意义的听觉刺激表现出不同的反应。对先前知识和期望的更大重视可能会在这些个体中引起非垂直的听觉感觉，但在需要此类知识的地方，它也可能会自发地促进感知过程。这对理解临床和非临床人群的幻觉有影响，并且与当前的精神病“预测加工”理论相一致。但是在需要此类知识的地方，它也可以自发地促进感知处理。这对理解临床和非临床人群的幻觉有影响，并且与当前的精神病“预测加工”理论相一致。但是在需要此类知识的地方，它也可以自发地促进感知处理。这对理解临床和非临床人群的幻觉有影响，并且与当前的精神病“预测加工”理论相一致。