Hallucination, imagery, dreaming: reassembling stimulus-independent perceptions based on Edmund Parish's classic misperception framework.

Within the broad field of human perception lies the category of stimulus-independent perceptions, which draws together experiences such as hallucinations, mental imagery and dreams. Traditional divisions between medical and psychological sciences have contributed to these experiences being investigated separately. This review aims to examine their similarities and differences at the levels of phenomenology and underlying brain function and thus reassemble them within a common framework. Using Edmund Parish's historical work as a guiding tool and the latest research findings in the cognitive, clinical and computational sciences, we consider how different perspectives may be reconciled and help generate novel hypotheses for future research. This article is part of the theme issue 'Offline perception: voluntary and spontaneous perceptual experiences without matching external stimulation'.

Psychological therapies for auditory hallucinations (voices): current status and key directions for future research.

This report from the International Consortium on Hallucinations Research considers the current status and future directions in research on psychological therapies targeting auditory hallucinations (hearing voices). Therapy approaches have evolved from behavioral and coping-focused interventions, through formulation-driven interventions using methods from cognitive therapy, to a number of contemporary developments. Recent developments include the application of acceptance- and mindfulness-based approaches, and consolidation of methods for working with connections between voices and views of self, others, relationships and personal history. In this article, we discuss the development of therapies for voices and review the empirical findings. This review shows that psychological therapies are broadly effective for people with positive symptoms, but that more research is required to understand the specific application of therapies to voices. Six key research directions are identified: (1) moving beyond the focus on overall efficacy to understand specific therapeutic processes targeting voices, (2) better targeting psychological processes associated with voices such as trauma, cognitive mechanisms, and personal recovery, (3) more focused measurement of the intended outcomes of therapy, (4) understanding individual differences among voice hearers, (5) extending beyond a focus on voices and schizophrenia into other populations and sensory modalities, and (6) shaping interventions for service implementation.

Evidence of abnormalities in mid-latency auditory evoked responses (MLAER) in cognitive subtypes of patients with schizophrenia.

Abnormalities in measures of mid-latency auditory evoked responses (MLAER) have frequently been reported in schizophrenia, while few studies have examined whether these measures could distinguish cognitive subtypes of schizophrenia. The aim of this study was to investigate whether patterns of performance on MLAER measures could differentiate a cognitive subtype of patients characterized by pervasive cognitive deficits (CD) from patients with only mild cognitive deficits (CS) and controls. An auditory paired-click conditioning test was administered to 55 schizophrenia patients (26 CD, 29 CS) and 49 healthy controls. Amplitudes, latencies and sensory gating indices of the P50, N100, and P200 MLAER were analysed. The results showed that CD patients exhibited smaller S1 amplitudes of N100 and P200 than controls, while CS patients were comparable to controls. Binary logistic regression identified the P200 S1 amplitude as a significant predictor of patients' membership in the CD subtype. However, none of the other MLAER measures could differentiate the two subtypes of schizophrenia. These findings suggest that the abnormal pathophysiologic mechanisms underlying the electrophysiological brain responses to auditory stimulation are associated with the pervasive cognitive deficits, which characterize the CD subtype of schizophrenia. This finding might provide additional electrophysiological endophenotypes for future genetic research of schizophrenia.

Electrophysiological brain activity and antisaccade performance in schizophrenia patients with first-rank (passivity) symptoms.

Few studies have examined electrophysiological functioning in schizophrenia patients with first-rank (passivity) symptoms (FRS). In this study, we conducted a broad assessment of FRS patients' performance using data collected as part of the Western Australia Family Study of Schizophrenia, with a focus on event-related potential (ERP) measures [P50 suppression, mismatch negativity (MMN), the auditory oddball target (P300)], and the antisaccade task. A total of 39 patients (23 patients with, and 16 patients without FRS) and 80 controls were included. The results showed that patients with FRS had significantly reduced amplitude and longer latencies on the P300, as compared to controls. In addition, patients with FRS demonstrated more abnormalities on antisaccade error measures (error rate, self-correction latencies) relative to controls. On these measures, the performance of patients without FRS was not significantly different from controls. P300 and antisaccade error abnormalities in patients with FRS could not be accounted for by clinical variables, medication effects, or cognitive abilities. These results provide support for the proposal that FRS reflect a specific dysfunction in the monitoring and evaluation of sensory information.