The neural and computational mechanisms underlying conditioning-induced verbal hallucinations in psychotic patients and healthy controls

Auditory verbal hallucinations (AVHs) or "hearing voices" are a characteristic symptom of psychosis, and a main clinical feature of schizophrenia. The most prominent "inner speech" model of AVH proposes that hallucinations result from a failure in monitoring one's own inner speech, leading to misattribution of inner speech to an external source (Frith & Done, 1989; Frith, 1992). This model has been supported by cognitive studies demonstrating self- and other-monitoring deficits in AVH-experiencing psychotic patients (Brookwell, Bental, & Varese, 2013; Waters, Woodward, Allen, Aleman, & Sommer, 2012), neuroimaging studies showing the involvement of language networks (Allen et al., 2012) and bilateral inferior frontal gyrus (Kuhn & Gallinat, 2012) during AVHs, and speech-processing atypicality in AVH-experiencing schizophrenic patients.
There are, however, three outstanding challenges in endorsing an inner speech account of AVH. First, most studies have relied on self-reported questionnaires and experience sampling methods. A new paradigm is needed for eliciting spontaneous, verbal hallucinations on demand. Second, although AVHs and inner speech seem to recruit overlapping brain circuits, the key mechanism, i.e. the misattribution of inner speech, remains underspecified. Third, the standard inner speech model may explain how AVH occurs but does not recognise the dialogic and evaluative qualities of AVHs (Alderson-Day et al., 2014; McCarthy-Jones & Fernyhough, 2011).
The present project aims to develop a hallucination induction paradigm based on conditioning and the use of speech quotations (Yao, Belin & Scheepers, 2011). We will use this paradigm to elicit inner speech experimentally and examine the neural and computational mechanisms underlying the misattribution of inner speech in AVH-experiencing psychotic patients, non-hallucinating psychotic patients and healthy controls. We will model how perceptual and articulatory priors predict the detection and attribution of hallucinations. Finally, we will probe the evaluative quality of AVHs by manipulating the valence of inner speech and examine its neural and computational consequences.
The project has the potential for specifying the key mechanisms underlying the misattribution of inner speech in AVHs. The successful applicant will enjoy an interdisciplinary and vibrant research environment. They will be trained in experimental design, programming (MatLab, R), fMRI experimentation and analysis (SPM), computational modelling and working with clinical populations. There are also many opportunities to become involved in other activities such as teaching and public engagement events.