-
Investigative Ophthalmology & Visual... Dec 2023Visual snow syndrome-characterized by flickering specks throughout the visual field and accompanied by other symptoms-can disrupt daily life and affects roughly 2% of...
PURPOSE
Visual snow syndrome-characterized by flickering specks throughout the visual field and accompanied by other symptoms-can disrupt daily life and affects roughly 2% of the population. However, its neural bases remain mysterious, and treatments are lacking. Here, we report the first intervention that can temporarily eliminate the visual snow symptom, allowing many observers to see the world without snow for the first time since symptom onset. Prolonged viewing of a visual stimulus strongly reduces the responsiveness of the visual pathways to subsequent stimuli, and we tested whether such adaptation could affect visual snow.
METHODS
Participants with visual snow (total n = 27) viewed high-contrast dynamic noise patterns, resembling television static, and then judged the strength of the symptom.
RESULTS
Visual snow was temporarily reduced in strength to the point that it was invisible at longer adaptation durations for most observers. The effect followed typical trends of adaptation for physical stimuli in normally sighted observers: Effect duration increased monotonically with duration of exposure to the adapter and was specific to dynamic noise.
CONCLUSIONS
These results establish that spontaneous neural activity in the visual system is causally related to the visual snow percept. Because they perceive this activity, people with visual snow may provide a unique window into the generation and suppression of noise in the visual system. Adaptation allows reliable experimental control over visual snow, and so is a strong candidate for diagnostic testing and a promising tool for further understanding its neural origins, which could in turn aid the development of treatments.
Topics: Humans; Perceptual Disorders; Software; Visual Fields; Visual Pathways
PubMed: 38117246
DOI: 10.1167/iovs.64.15.23 -
Wiadomosci Lekarskie (Warsaw, Poland :... 2024Aim: To study the psychopathological mechanisms of the development of the prodromal stage of psychosis in order to identify risk factors for the formation of psychosis.
OBJECTIVE
Aim: To study the psychopathological mechanisms of the development of the prodromal stage of psychosis in order to identify risk factors for the formation of psychosis.
PATIENTS AND METHODS
Materials and Methods: In this research 137 patients with newly diagnosed psychosis were examined: 65 patients with a diagnosis of paranoid schizophrenia; 72 patients - with a diagnosis of acute polymorphic psychotic disorder.
RESULTS
Results: According to the analysis of symptoms using the PANSS, the absence of signs of an anxious state, conceptual disorganization of thinking, emotional withdrowal are reliable signs of PPP in PS, and unusual thought content, absence of signs of stereotyped thinking, tension, anxiety, and hallucinations are reliable signs of PPP in APPD. According to the analysis of symptoms using the SOPS, unusual thought content/delusional ideas, bizarre thinking, social anhedonia, suspiciousness/persecutory ideas, decrease in expressiveness of emotions are reliable signs of PPP in PS, and bizarre thinking, impaired tolerance to normal stress, sleep disturbance, perceptual abnormalities/hallucinations, trouble with focus and attention are reliable signs of PPP in APPD.
CONCLUSION
Conclusions: In the process of studying the clinical-psychopathological and pathopsychological aspects of the development of the PPP, a number of risk factors for the formation of psychosis were identified. We found that he most important diagnostic signs of PPP in PS patients are: stereotyped thinking, social isolation, disorganizational thinking disorders, passive-apathetic social detachment, suspiciousness. The most informative prodromal symptoms of HP in PS patients are: conceptual disorganization of thinking, bizzare thinking, social isolation, suspiciousness/persecutory ideas, reduced expression of emotions.
Topics: Male; Humans; Prodromal Symptoms; Psychotic Disorders; Anxiety; Risk Factors; Hallucinations
PubMed: 38431807
DOI: 10.36740/WLek202401107 -
The Journal of Nervous and Mental... Mar 2024Psychotic experiences have been shown to be comparable in borderline personality disorder (BPD) and schizophrenia. Preliminary evidence suggests differences in the...
Psychotic experiences have been shown to be comparable in borderline personality disorder (BPD) and schizophrenia. Preliminary evidence suggests differences in the impact of psychotic experiences on daily functioning. Therefore, in this study, we aimed to investigate the role of psychotic experiences in daily functioning in BPD compared with schizophrenia. We performed post hoc analyses on data from 23 inpatients with BPD and 21 inpatients with schizophrenia, for whom results from the Psychotic Symptom Rating Scales were available. No differences were found in frequency, intensity, and disruption of life in relation to auditory verbal hallucinations and the amount of preoccupation and conviction with regard to delusions. Significant differences were found in the disruption of life due to delusions. The results emphasize that the quality of psychotic experiences in BPD and schizophrenia is comparable, but the impact of delusions on daily life is different, which may improve differential diagnosis.
Topics: Humans; Schizophrenia; Borderline Personality Disorder; Psychotic Disorders; Hallucinations
PubMed: 38412244
DOI: 10.1097/NMD.0000000000001755 -
Schizophrenia Research Oct 2023
Topics: Humans; Psychotic Disorders; Hallucinations; Delusions
PubMed: 37625225
DOI: 10.1016/j.schres.2023.08.010 -
Current Opinion in Neurology Jun 2024Visual snow syndrome (VSS) is a disorder characterized by persistent visual disturbances, including the visual snow phenomenon, palinopsia, heightened perception of... (Review)
Review
PURPOSE OF REVIEW
Visual snow syndrome (VSS) is a disorder characterized by persistent visual disturbances, including the visual snow phenomenon, palinopsia, heightened perception of entoptic phenomena, impaired night vision, and photophobia. The purpose of this review is to provide an update on recent findings over the past 18 months in VSS research and to summarize the current state of treatment approaches.
RECENT FINDINGS
Electrophysiological studies have revealed cortical hyperresponsivity in visual brain areas, imaging studies demonstrated microstructural and functional connectivity alterations in multiple cortical and thalamic regions and investigated glutamatergic and serotoninergic neurotransmission. These findings suggest that VSS might be a network disorder.Only few treatment studies are currently available demonstrating limited response to medication and even worsening or triggering of visual symptoms by certain antidepressants. Promising nonpharmacological treatments include mindfulness-based cognitive therapy, the use of chromatic filters, and research on visual noise adaption and neuro-optometric visual rehabilitation therapy (NORT). However, the level of evidence is still low and further research is needed including larger trials and involving objective measures of individual dysfunction.
SUMMARY
Although there has been recent progress, we still have not fully understood the nature of VSS. Further research is needed on a clinical and pathophysiological level to successfully treat the condition.
Topics: Humans; Vision Disorders; Syndrome; Perceptual Disorders
PubMed: 38465699
DOI: 10.1097/WCO.0000000000001258 -
Neurological Sciences : Official... Oct 2023Parkinson's disease (PD) is one of the common causes of disability in the elderly. This study aims to estimate the prevalence of hallucinations in Parkinson's patients... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Parkinson's disease (PD) is one of the common causes of disability in the elderly. This study aims to estimate the prevalence of hallucinations in Parkinson's patients in the world.
METHODS
A systematic review of PubMed/Medline, ISI Web of Knowledge, and Google Scholar was conducted from 2017 to 2022. This study investigated the prevalence of hallucinations in Parkinson's patients. Point prevalence was analyzed with a 95% confidence interval. The variances of each study were calculated using the binomial distribution formula The researcher used Cochrane Q-test with a significance level of less than 0.1 to check the heterogeneity between studies and the change index assigned to heterogeneity I. Due to the heterogeneity between the studies, the random effects model was used to combine the results of the studies. All statistical analyses were performed by STATA version 14 software using meta-analysis commands.
RESULTS
Reports indicated that the prevalence of hallucinations in Parkinson's patients in 32 studies was 28% (0.22-0.34 = 95%CI). The highest prevalence was 34% and 95% CI = 0.07- 0.61 in developing countries and 27% with CI = 0.33-0.21 in developed countries. Reports showed the prevalence in men was 30% (CI = 0.22-0.38) and in women 23% (95% CI = 0.14-0.31).
CONCLUSIONS
Considering the relatively high prevalence of hallucinations in these patients, checking up for the presence of hallucinations on every visit of Parkinson's patients is recommended, and providing appropriate treatment for that is necessary.
Topics: Male; Humans; Female; Aged; Parkinson Disease; Prevalence; Hallucinations
PubMed: 37140832
DOI: 10.1007/s10072-023-06831-8 -
Vision Research Feb 2024The saccadic chronostasis illusion refers to the duration overestimation of the first visual stimulation after saccadic eye movement, which is also known as "stopped...
The saccadic chronostasis illusion refers to the duration overestimation of the first visual stimulation after saccadic eye movement, which is also known as "stopped clock illusion." The present study investigated whether saccadic chronostasis would be observed in the auditory modality and whether the saccade-induced time dilation in the visual modality would be reduced by a synchronously presented sound. In each trial, a unisensory visual stimulus, unisensory sound, or bimodal audio-visual stimulus with a duration of 200-800 ms (probe stimulus) was presented at the saccade target location and temporally around the offset of the saccade, followed by a unisensory visual or auditory standard stimulus for a fixed 500 ms. Participants were required to identify which of the two stimuli (probe or standard) presented in the target modality (visual or auditory) was perceived as longer. The results showed that no saccadic chronostasis was observed in the auditory modality, regardless of whether the sound was presented alone or synchronously accompanied by a visual stimulus. Interestingly, the magnitude of the saccadic chronostasis illusion was reduced by the synchronously presented sound. Moreover, the combined effect of the saccade and sound on visual time perception fits well with the standard scalar model, and the weight of the cross-modal effect was higher than that of saccadic visual time dilation. These results suggest that sound dominates vision in time processing during saccades and linearly modulates saccadic chronostasis, which follows the Scalar Expectancy Theory.
Topics: Humans; Saccades; Illusions; Visual Perception; Time Perception; Photic Stimulation
PubMed: 38109820
DOI: 10.1016/j.visres.2023.108344 -
Multisensory Research Oct 2023Vection is typically defined as the embodied illusion of self-motion in the absence of real physical movement through space. Vection can occur in real-life situations... (Review)
Review
Vection is typically defined as the embodied illusion of self-motion in the absence of real physical movement through space. Vection can occur in real-life situations (e.g., 'train illusion') and in virtual environments and simulators. The vast majority of vection research focuses on vection caused by visual stimulation. Even though visually induced vection is arguably the most compelling type of vection, the role of nonvisual sensory inputs, such as auditory, biomechanical, tactile, and vestibular cues, have recently gained more attention. Non-visual cues can play an important role in inducing vection in two ways. First, nonvisual cues can affect the occurrence and strength of vection when added to corresponding visual information. Second, nonvisual cues can also elicit vection in the absence of visual information, for instance when observers are blindfolded or tested in darkness. The present paper provides a narrative review of the literature on multimodal contributions to vection. We will discuss both the theoretical and applied relevance of multisensory processing as related to the experience of vection and provide design considerations on how to enhance vection in various contexts.
Topics: Humans; Illusions; Motion Perception; Sensation; Motion; Motion Sickness
PubMed: 37907066
DOI: 10.1163/22134808-bja10112 -
Handbook of Clinical Neurology 2024In neurology practice, it is common to encounter a variety of visual complaints. Historically, in the absence of known ocular pathology, epilepsy, or insult to the... (Review)
Review
In neurology practice, it is common to encounter a variety of visual complaints. Historically, in the absence of known ocular pathology, epilepsy, or insult to the central nervous system, positive symptoms were assumed to be migrainous in origin. This assumption was sometimes made even in the absence of a history of migraine. In the past decade, there has been considerable effort to better delineate and study nonmigrainous visual phenomena, with the most extensive focus on a newly defined syndrome, visual snow syndrome (VSS). The heightened awareness of visual snow as a symptom and syndrome has greatly enhanced the understanding of this visual phenomenon; however, in the last few years, there has been an almost pendulous swing in clinic, with patients now being given the diagnosis of VSS for any dots or flickering they may have in their vision. To avoid clinical misdiagnosis, it is critical that we expand our understanding not just of VSS but also of underlying pathologies that may present similarly. This chapter will review classical migraine aura, persistent migraine aura, visual snow and a number of positive and negative visual complaints that are on the differential when seeing patients with suspected aura or visual snow. This is followed by an in-depth discussion on the current understanding of the presenting symptoms, pathophysiology, evaluation and management of VSS. We also outline secondary causes of visual snow.
Topics: Humans; Vision Disorders; Migraine Disorders; Migraine with Aura; Perceptual Disorders; Epilepsy; Syndrome
PubMed: 38307662
DOI: 10.1016/B978-0-12-823357-3.00018-5 -
The Primary Care Companion For CNS... Jan 2024
Topics: Humans; Duloxetine Hydrochloride; Hallucinations
PubMed: 38277643
DOI: 10.4088/PCC.23cr03595