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Journal of Neuroradiology = Journal de... Sep 2023First-episode psychosis (FEP) is defined as the first occurrence of delusions, hallucinations, or psychic disorganization of significant magnitude, lasting more than 7... (Review)
Review
First-episode psychosis (FEP) is defined as the first occurrence of delusions, hallucinations, or psychic disorganization of significant magnitude, lasting more than 7 days. Evolution is difficult to predict since the first episode remains isolated in one third of cases, while recurrence occurs in another third, and the last third progresses to a schizo-affective disorder. It has been suggested that the longer psychosis goes unnoticed and untreated, the more severe the probability of relapse and recovery. MRI has become the gold standard for imaging psychiatric disorders, especially first episode psychosis. Besides ruling out some neurological conditions that may have psychiatric manifestations, advanced imaging techniques allow for identifying imaging biomarkers of psychiatric disorders. We performed a systematic review of the literature to determine how advanced imaging in FEP may have high diagnostic specificity and predictive value regarding the evolution of disease.
Topics: Humans; Psychotic Disorders; Hallucinations; Magnetic Resonance Imaging
PubMed: 37028754
DOI: 10.1016/j.neurad.2023.04.001 -
Scientific Reports Dec 2023The sense of self is a foundational element of neurotypical human consciousness. We normally experience the world as embodied agents, with the unified sensation of our...
The sense of self is a foundational element of neurotypical human consciousness. We normally experience the world as embodied agents, with the unified sensation of our selfhood being nested in our body. Critically, the sense of self can be altered in psychiatric conditions such as psychosis and altered states of consciousness induced by psychedelic compounds. The similarity of phenomenological effects across psychosis and psychedelic experiences has given rise to the "psychotomimetic" theory suggesting that psychedelics simulate psychosis-like states. Moreover, psychedelic-induced changes in the sense of self have been related to reported improvements in mental health. Here we investigated the bodily self in psychedelic, psychiatric, and control populations. Using the Moving Rubber Hand Illusion, we tested (N = 75) patients with psychosis, participants with a history of substantial psychedelic experiences, and control participants to see how psychedelic and psychiatric experience impacts the bodily self. Results revealed that psychosis patients had reduced Body Ownership and Sense of Agency during volitional action. The psychedelic group reported subjective long-lasting changes to the sense of self, but no differences between control and psychedelic participants were found. Our results suggest that while psychedelics induce both acute and enduring subjective changes in the sense of self, these are not manifested at the level of the bodily self. Furthermore, our data show that bodily self-processing, related to volitional action, is disrupted in psychosis patients. We discuss these findings in relation to anomalous self-processing across psychedelic and psychotic experiences.
Topics: Humans; Hallucinogens; Psychotic Disorders; Illusions; Consciousness; Mental Health
PubMed: 38040825
DOI: 10.1038/s41598-023-47600-z -
British Journal of Psychology (London,... Nov 2023Night-time is a period of great significance for many people who report paranormal experiences. However, there is limited understanding of the associations between sleep... (Review)
Review
Night-time is a period of great significance for many people who report paranormal experiences. However, there is limited understanding of the associations between sleep variables and seemingly paranormal experiences and/or beliefs. The aim of this review is to improve our understanding of these associations while unifying a currently fragmented literature-base into a structured, practical review. In this pre-registered scoping review, we searched for relevant studies in MEDLINE (PubMed), PsycINFO (EBSCO), Web of Science and EMBASE using terms related to sleep and ostensibly paranormal experiences and beliefs. Forty-four studies met all inclusion criteria. All were cross-sectional and most investigated sleep paralysis and/or lucid dreaming in relation to ostensibly paranormal experiences and paranormal beliefs. Overall, there were positive associations between many sleep variables (including sleep paralysis, lucid dreams, nightmares, and hypnagogic hallucinations) and ostensibly paranormal experiences and paranormal beliefs (including those of ghosts, spirits, and near-death experiences). The findings of this review have potential clinical implications such as reducing misdiagnosis and treatment development and provide foundations for further research. Our findings also highlight the importance of understanding why so many people report 'things that go bump in the night'.
Topics: Humans; Sleep Paralysis; Sleep; Hallucinations
PubMed: 37070349
DOI: 10.1111/bjop.12655 -
Anticancer Research Aug 2023Pre-emptive targeted muscle reinnervation (TMR) at the time of amputation results in less phantom limb pain (PLP) compared with untreated amputee controls. There is... (Review)
Review
BACKGROUND/AIM
Pre-emptive targeted muscle reinnervation (TMR) at the time of amputation results in less phantom limb pain (PLP) compared with untreated amputee controls. There is limited literature describing the technique in patients undergoing hindquarter amputation despite up to 90% of these patients reporting PLP and 50% presenting with painful neuroma. The purpose of the current study was to describe the motor nerves accessible through a primary hind-quarter amputation to be used for TMR and review pain outcomes in clinical case correlates of patients with TMR.
PATIENTS AND METHODS
Six limbs were obtained from three fresh adult cadavers and proximal sensory and motor nerves were dissected. A review of patients undergoing hindquarter amputation with TMR was conducted.
RESULTS
Transfers for the sciatic, femoral, and obturator nerves were identified in cadavers. In reviews of patients, they were taking narcotic and neuro-leptic pain medication for a mean of 23 days and 168 days. At most recent follow-up, no patient reported debilitating phantom pain nor pain associated with neuromas.
CONCLUSION
Given the positive preliminary results in our study group as well as the accessible neuroanatomy, pre-emptive TMR should be considered at the time of surgery to limit PLP and dependence on pain medications.
Topics: Adult; Humans; Amputation, Surgical; Phantom Limb; Neurosurgical Procedures; Pain, Postoperative; Neuroma; Muscles; Muscle, Skeletal
PubMed: 37500121
DOI: 10.21873/anticanres.16528 -
PloS One 2023Bodily awareness arises from somatosensory, vestibular, and visual inputs but cannot be reduced to these incoming sensory signals. Cognitive factors are known to also...
Bodily awareness arises from somatosensory, vestibular, and visual inputs but cannot be reduced to these incoming sensory signals. Cognitive factors are known to also impact bodily awareness, though their specific influence is poorly understood. Here we systematically compared the effects of sensory (bottom-up) and cognitive (top-down) manipulations on the estimated size of body parts. Toward this end, in a repeated-measures design, we sought to induce the illusion that the right index finger was elongating by vibrating the biceps tendon of the left arm whilst participants grasped the tip of their right index finger (Lackner illusion; bottom-up) and separately by hypnotic suggestion (top-down), with a sham version of the Lackner illusion as an active control condition. The effects of these manipulations were assessed with perceptual and motor tasks to capture different components of the representation of body size. We found that hypnotic suggestion significantly induced the illusion in both tasks relative to the sham condition. The magnitudes of these effects were stronger than those in the Lackner illusion condition, which only produced a significantly stronger illusion than the sham condition in the perceptual task. We further observed that illusion magnitude significantly correlated across tasks and conditions, suggesting partly shared mechanisms. These results are in line with theories of separate but interacting representational processes for perception and action and highlight the influence of cognitive factors on low-level body representations.
Topics: Humans; Illusions; Body Size; Fingers; Hypnotics and Sedatives; Research Design
PubMed: 37699046
DOI: 10.1371/journal.pone.0291493 -
Psychonomic Bulletin & Review Dec 2023Previous studies have demonstrated that visual memory is improved when stimuli are processed by larger cortical regions. For example, a physically large stimulus that...
Previous studies have demonstrated that visual memory is improved when stimuli are processed by larger cortical regions. For example, a physically large stimulus that recruits larger areas of the retinotopic cortex is better remembered. However, the spatial extent of neural responses in the visual cortex is not only modulated by the retinal size of a stimulus, but also by the perceived size of the stimulus. In this online study, we modulated the perceived size of the visual stimuli using the Ebbinghaus illusion and asked participants to remember the stimuli. The results showed that perceptually larger images were remembered better than perceptually smaller but physically same-sized images. Our finding supports the idea that visual memory is modulated by top-down feedback from higher visual regions to the early visual cortex.
Topics: Humans; Memory; Illusions; Mental Recall; Brain Mapping; Photic Stimulation; Visual Perception
PubMed: 37268748
DOI: 10.3758/s13423-023-02313-2 -
Cognitive Neuropsychology 2023Visual imagery has a close overlapping relationship with visual perception. Posterior cortical atrophy (PCA) is a neurodegenerative syndrome marked by early impairments...
Visual imagery has a close overlapping relationship with visual perception. Posterior cortical atrophy (PCA) is a neurodegenerative syndrome marked by early impairments in visuospatial processing and visual object recognition. We asked whether PCA would therefore also be marked by deficits in visual imagery, tested using objective forced-choice questionnaires, and whether imagery deficits would be selective for certain properties. We recruited four patients with PCA and a patient with integrative visual agnosia due to bilateral occipitotemporal strokes for comparison. We administered a test battery probing imagery for object shape, size, colour lightness, hue, upper-case letters, lower-case letters, word shape, letter construction, and faces. All subjects showed significant impairments in visual imagery, with imagery for lower-case letters most likely to be spared. We conclude that PCA subjects can show severe deficits in visual imagery. Further work is needed to establish how frequently this occurs and how early it can be found.
Topics: Humans; Male; Female; Atrophy; Aged; Imagination; Middle Aged; Cerebral Cortex; Neuropsychological Tests; Agnosia; Pattern Recognition, Visual; Visual Perception; Magnetic Resonance Imaging; Perceptual Disorders
PubMed: 38698499
DOI: 10.1080/02643294.2024.2346362 -
PloS One 2023Pareidolias, or the misperception of ambiguous stimuli as meaningful objects, are complex visual illusions thought to be phenomenologically similar to Visual...
Pareidolias, or the misperception of ambiguous stimuli as meaningful objects, are complex visual illusions thought to be phenomenologically similar to Visual Hallucination (VH). VH are a major predictor of dementia in Parkinson's Disease (PD) and are included as a core clinical feature in Dementia with Lewy Bodies (DLB). A newly developed Noise Pareidolia Test (NPT) was proposed as a possible surrogate marker for VH in DLB patients as increased pareidolic responses correlated with informant-corroborated accounts of VH. This association could, however, be mediated by visuoperceptual impairment. To understand the drivers of performance on the NPT, we contrasted performances in patient groups that varied both in terms of visuoperceptual ability and rates of VH. N = 43 patients were studied of whom n = 13 had DLB or PD with Dementia (PDD); n = 13 had PD; n = 12 had typical, memory-onset Alzheimer's Disease (tAD); and n = 5 had Posterior Cortical Atrophy (PCA) due to Alzheimer's disease. All patient groups reported pareidolias. Within the Lewy body disorders (PD, DLB, PDD), there was no significant difference in pareidolic response rates between hallucinating and non-hallucinating patients. Visuoperceptual deficits and pareidolic responses were most frequent in the PCA group-none of whom reported VH. Regression analyses in the entire patient cohort indicated that pareidolias were strongly predicted by visuoperceptual impairment but not by the presence of VH. These findings suggest that pareidolias reflect the underlying visuoperceptual impairment of Lewy body disorders, rather than being a direct marker for VH.
Topics: Humans; Lewy Body Disease; Alzheimer Disease; Parkinson Disease; Hallucinations; Illusions
PubMed: 37930972
DOI: 10.1371/journal.pone.0293942 -
Science Advances Nov 2023Visual illusions provide valuable insights into the brain's interpretation of the world given sensory inputs. However, the precise manner in which brain activity...
Visual illusions provide valuable insights into the brain's interpretation of the world given sensory inputs. However, the precise manner in which brain activity translates into illusory experiences remains largely unknown. Here, we leverage a brain decoding technique combined with deep neural network (DNN) representations to reconstruct illusory percepts as images from brain activity. The reconstruction model was trained on natural images to establish a link between brain activity and perceptual features and then tested on two types of illusions: illusory lines and neon color spreading. Reconstructions revealed lines and colors consistent with illusory experiences, which varied across the source visual cortical areas. This framework offers a way to materialize subjective experiences, shedding light on the brain's internal representations of the world.
Topics: Humans; Illusions; Form Perception; Brain; Neural Networks, Computer; Visual Cortex; Visual Perception
PubMed: 37967184
DOI: 10.1126/sciadv.adj3906 -
Gastrointestinal Endoscopy Sep 2023
Topics: Humans; Illusions; Endoscopy
PubMed: 37150415
DOI: 10.1016/j.gie.2023.05.001