Schizophrenia Bulletin
October 6, 2012
Robin Carhart‐Harris, Robert Leech, David Erritzøe et al.
267 citations
Psilocybin, a classic psychedelic, increases functional connectivity between the default-mode network (DMN) and task-positive network (TPN), reducing the normal orthogonality between these networks. In 15 healthy volunteers, intravenous psilocybin (vs placebo) during resting-state fMRI scans led to greater DMN-TPN connectivity, a pattern also seen in psychosis and meditative states. Thalamocortical connectivity remained unchanged, suggesting it relates to arousal rather than the separateness of internal versus external focus. The findings support psilocybin as a model for early psychosis, where compromised DMN-TPN orthogonality may explain phenomenological overlaps.
Schizophrenia Bulletin
June 8, 2016
Ben Alderson‐day, Kelly Diederen, Charles Fernyhough et al.
134 citations
Resting-state brain networks may help explain hallucinations across different sensory modalities and populations. This report from the International Consortium on Hallucination Research reviews evidence linking resting-state alterations to auditory hallucinations, finding connectivity differences in left-hemisphere auditory and language regions, plus atypical interactions of the default mode network with networks for cognitive control and salience. Similar patterns appear in visual hallucinations, suggesting both domain-general and modality-specific network changes. However, high methodological heterogeneity across studies limits direct comparisons. The authors offer recommendations for future research on resting-state connectivity and hallucinations.
Schizophrenia Bulletin
January 1, 1983
Lawrence Fischman
109 citations
Dreams, hallucinogenic drug states, and schizophrenia share fundamental similarities, particularly in the breakdown of ego boundaries—the capacity to synthesize self-representations into a coherent self. This impairment compromises reality-oriented secondary process thinking and allows florid primary process attributes to emerge, explaining many common features of these states. The hallucinogenic drug model of psychosis was initially attractive but has fallen out of favor. Current neurophysiological theories emphasize serotonin neurotransmission in regulating dream and hallucinogenic states, and the analogy suggests serotonin may also play a role in regulating schizophrenic states.
Schizophrenia Bulletin
March 14, 2017
Georg Northoff, Paola Magioncalda, Matteo Martino et al.
95 citations
In bipolar disorder, the sense of time's speed is distorted: manic patients experience inner time as too fast and outer time as too slow, while depressed patients experience inner time as too slow and outer time as too fast. This desynchronization between self-time and world-time arises from opposite changes in neuronal variability—specifically, the standard deviation ratio between somatomotor and sensory brain networks. The authors' empirical data show abnormal SD balance in both manic and depressed bipolar patients, as well as in major depressive disorder. These findings suggest that individualized stimulation techniques like TMS or tDCS might normalize the neuronal variability patterns in these networks, potentially correcting the distorted time perception.
Schizophrenia Bulletin
August 5, 2020
Pantelis Leptourgos, Martin Fortier-Davy, Robin Carhart‐Harris et al.
88 citations
A multidisciplinary working group reviewed evidence on the similarities and differences between hallucinations induced by psychedelics and those occurring in schizophrenia-spectrum disorders, examining data from pharmacology, brain imaging, phenomenology, and anthropology. The authors highlight both shared features and distinct characteristics across these scales, and attempt to integrate findings using computational approaches. They conclude with recommendations for future research, emphasizing the need for further study to clarify the relationship between these types of hallucinations.
Schizophrenia Bulletin
August 8, 2018
T. M. Luhrmann, Ben Alderson‐day, Vaughan Bell et al.
74 citations
Trauma can contribute to voice-hearing but is not necessary for it. This article uses ethnographic and other data to show multiple pathways to voice-hearing in both clinical and nonclinical populations, excluding known causes like drugs or epilepsy. Trauma sometimes plays a major role, sometimes a minor role, and sometimes no role at all. Distinct phenomenological patterns in voice-hearing may reflect different salience of trauma for those who hear voices.
Schizophrenia Bulletin
January 1, 1981
P. Buckley
70 citations
Acute mystical experiences and schizophrenia share several features, including a powerful sense of noesis, heightened perception, feelings of communion with the divine, and exultation. However, the thought disruption typical of acute psychosis is absent from the mystical accounts examined, and auditory hallucinations are less common than visual hallucinations in mystical states. The ease of inducing mystical-like experiences in possession cults or experimental settings suggests that the capacity for such altered states may be latently present in many people. It is proposed that the nervous system has a limited repertoire of responses for altered states like acute psychosis and mystical experience, despite their different causes.
Schizophrenia Bulletin
June 19, 2020
Ben Alderson‐day, Angela Woods, Peter Moseley et al.
59 citations
Auditory verbal hallucinations (AVH) often become personified, but little is known about how this happens. In interviews with 40 early psychosis service users, 40% reported complex personification of their voices. Personified voices were more likely to be experienced as conversational and companionable, but not as commanding or trauma-related. The duration of voice-hearing or age at onset did not predict personification. The findings suggest that personification is linked to the social affordances of voices—their capacity for conversation and companionship—rather than their threatening or commanding qualities.
Schizophrenia Bulletin
January 1, 1978
Gordon Claridge
59 citations
Establishing an animal model of schizophrenia faces difficulties. After reviewing evidence on experimental psychopathology, particularly attention and arousal, the core feature needing modeling is some aspect of 'input dysfunction.' LSD-25 best meets this requirement because its 'model psychosis' closely parallels the natural disease, and its experimental effects in animals and humans align theoretically with schizophrenia. Work from the author's laboratory found LSD produced psychophysiological effects virtually identical to those in acute psychotic patients and normal subjects with high 'psychotic' personality traits. Rejection of LSD as a drug model was premature, especially since the preference for amphetamine has not been vindicated by its ability to mimic a central feature of psychosis or by work on dopamine as a common mediator.
Schizophrenia Bulletin
December 18, 2015
Filip Španiel, Jaroslav Tintěra, Jan Rydlo et al.
55 citations
Disturbance of the sense of self may be a core marker of schizophrenia. In patients with first-episode schizophrenia-spectrum disorders compared with healthy controls, self-agency experience was associated with reduced cortical activation in the medial frontal gyrus and posterior cingulate gyrus. The ability to judge whether an action is one's own or another's depends on anti-correlated switching between the default mode and central-executive networks, a mechanism substantially impaired in the patient group during the task.
Schizophrenia Bulletin
July 28, 2015
Jeffrey D. Robinson, Nils-Frederic Wagner, Georg Northoff
47 citations
Schizophrenia involves a disturbance of the self, particularly the sense of agency—the feeling of controlling one's own actions and thoughts. Current models of agency involve both bottom-up sensory processes and top-down cognitive influences. This review proposes that ongoing brain activity in self-referential regions, especially the default mode network, adds a deeper layer of influence. Neuroimaging studies show that aberrant activity in these regions in schizophrenia can lead to misattributing internally generated stimuli as external, producing symptoms like thought insertion and delusions of control. This framework suggests neuroimaging can improve conceptualization, measurement, and treatment of agency disturbances.
Schizophrenia Bulletin
July 21, 2023
Predrag Petrović, Philipp Sterzer
42 citations
Delusions in psychotic disorders are hard to reconcile with the predictive processing (PP) framework, which suggests psychosis involves reduced weighting of prior beliefs relative to sensory data—yet delusions are highly resistant to change. This paradox can be resolved by a hierarchical PP model: reduced weighting of low-level priors may be compensated by increased influence of higher-order beliefs, including delusional beliefs, which then shape perception and resist contradictory evidence. A review of experimental evidence supports decreased weighting of low-level priors and increased weighting of high-level priors in both delusional and delusion-prone individuals. The prefrontal cortex is highlighted as a neural basis for this increased weighting of high-level priors, with clinical implications discussed.
Schizophrenia Bulletin
December 7, 2020
Ilvana Dzafic, Kit Melissa Larsen, Hayley Darke et al.
26 citations
People with schizophrenia have reduced neural prediction-error signals (mismatch negativity in stable contexts, P300 in volatile contexts) that are specific to the schizophrenia spectrum, whereas altered brain connectivity—decreased intrinsic connectivity in the left primary auditory cortex and right inferior frontal gyrus (IFG), reduced bottom-up and increased top-down frontotemporal connectivity—occurs across all participants as psychotic experiences intensify. Impaired sensory learning behavior was linked to lower intrinsic connectivity in the IFG, which also decreased with greater severity of psychotic experiences. The findings suggest that distinct neural mechanisms underlie schizophrenia-specific deficits versus general psychosis-related connectivity changes.
Schizophrenia Bulletin
January 1, 1977
J.e. Kleinman, J. Christian Gillin, Richard Jed Wyatt
20 citations
Most reviews comparing the phenomenology of hallucinogens and schizophrenia rely on scientists' summaries of research-subject interviews. Autobiographical accounts of both drug experiences and schizophrenia exist but are rarely compared directly. This paper identifies a gap: no review has compared the subjective phenomenology of drug experiences and schizophrenia using only first-person autobiographies. Previous work by Hoffer and Osmond drew conclusions from second-hand accounts; Kaplan edited autobiographical accounts from people with mental illnesses and drug experiences; Metzner collected autobiographical accounts of mescaline, psilocybin, and LSD experiences; Freedman reviewed autobiographical accounts of schizophrenia, focusing on the structure and process of schizophrenic thinking.
Schizophrenia Bulletin
October 8, 2019
Julian Rössler, Wulf Rössler, Erich Seifritz et al.
16 citations
Dopamine reduces functional connectivity between the right anterior insula, a central hub of the salience network, and the left auditory cortex planum polare. In healthy men given a placebo, higher psychotic-like experiences correlated with weaker connectivity between these regions; in those given L-DOPA, higher psychotic-like experiences correlated with stronger connectivity. The score on a measure of psychotic-like experiences explained about 30% of the variation in connectivity between the two groups. These results suggest that psychotic-like experiences are linked to dopamine-induced disruption of auditory input to the salience network, potentially leading to aberrant attribution of salience.
Schizophrenia Bulletin
June 20, 2024
Mary F. Brunette, Robert M. Roth, Christi L. Trask et al.
5 citations
A single modest dose of oral THC (15 mg dronabinol) worsened verbal learning and attention in people with schizophrenia and co-occurring cannabis use disorder, without exacerbating psychotic symptoms several hours after administration. Smoked low-dose THC cigarettes did not produce these cognitive effects. Higher blood THC levels were linked to increased negative symptoms. Drug liking was greater with THC than placebo. The findings suggest that oral THC may impair cognition in this population even at modest doses, while not acutely worsening psychosis.
Schizophrenia Bulletin
April 17, 2025
Nathan H. Heller, Frederick S. Barrett, Tobias Buchborn et al.
3 citations
Visual hallucinations in Lewy body diseases (Parkinson's disease and dementia with Lewy bodies) and those induced by serotonergic psychedelics (psilocybin, mescaline) share overlapping phenomenology and neural mechanisms, despite different underlying causes. Both conditions produce visual aberrations from minor distortions to complex hallucinations, including illusory motion and entity encounters. Neuroimaging shows a common pattern of overactive associative cortex and underactive sensory cortex. Serotonin 2A receptor modulation is involved in both: psychedelics act through 5-HT2A and 5-HT1A receptors, while in Lewy body diseases, 5-HT2A receptor upregulation correlates with increased hallucinations, and blocking it with pimavanserin reduces them. Shared cortical signatures include reduced visual evoked responses and shifts toward visual excitation.