scholarly journals Overconfidence in visual perception in Parkinson’s disease

2020 ◽  
Author(s):  
Orly Halperin ◽  
Roie Karni ◽  
Simon Israeli-Korn ◽  
Sharon Hassin-Baer ◽  
Adam Zaidel

AbstractBackgroundIncreased dependence on visual cues in Parkinson’s disease (PD) can unbalance the perception-action loop, impair multisensory integration, and affect everyday function of PD patients. It is currently unknown why PD patients seem to be more reliant on their visual cues.ObjectivesWe hypothesized that PD patients may be overconfident in the reliability (precision) of their visual cues. In this study we tested coherent visual motion perception in PD, and probed subjective (self-reported) confidence in their visual motion perception.Methods20 patients with idiopathic PD, 21 healthy aged-matched controls and 20 healthy young adult participants were presented with visual stimuli of moving dots (random dot kinematograms). They were asked to report: (1) whether the aggregate motion of dots was to the left or to the right, and (2) how confident they were that their perceptual discrimination was correct.ResultsVisual motion discrimination thresholds were similar (unimpaired) in PD compared to the other groups. By contrast, PD patients were significantly overconfident in their visual perceptual decisions (p=0.002 and p<0.001 vs. the age-matched and young adult groups, respectively).ConclusionsThese results suggest intact visual motion perception, but overestimation of visual cue reliability, in PD. Overconfidence in visual (vs. other, e.g., somatosensory) cues could underlie accounts of increased visual dependence and impaired multisensory integration in PD, and could contribute to gait and balance impairments. Future work should investigate PD confidence in somatosensory function. A better understanding of altered sensory reliance in PD might open up new avenues to treat debilitating symptoms.

2020 ◽  
Vol 2 (1) ◽  
Author(s):  
Sol Yakubovich ◽  
Simon Israeli-Korn ◽  
Orly Halperin ◽  
Gilad Yahalom ◽  
Sharon Hassin-Baer ◽  
...  

Abstract Parkinson’s disease is prototypically a movement disorder. Although perceptual and motor functions are highly interdependent, much less is known about perceptual deficits in Parkinson’s disease, which are less observable by nature, and might go unnoticed if not tested directly. It is therefore imperative to seek and identify these, to fully understand the challenges facing patients with Parkinson’s disease. Also, perceptual deficits may be related to motor symptoms. Posture, gait and balance, affected in Parkinson’s disease, rely on veridical perception of one’s own motion (self-motion) in space. Yet it is not known whether self-motion perception is impaired in Parkinson’s disease. Using a well-established multisensory paradigm of heading discrimination (that has not been previously applied to Parkinson’s disease), we tested unisensory visual and vestibular self-motion perception, as well as multisensory integration of visual and vestibular cues, in 19 Parkinson’s disease, 23 healthy age-matched and 20 healthy young-adult participants. After experiencing vestibular (on a motion platform), visual (optic flow) or multisensory (combined visual–vestibular) self-motion stimuli at various headings, participants reported whether their perceived heading was to the right or left of straight ahead. Parkinson’s disease participants and age-matched controls were tested twice (Parkinson’s disease participants on and off medication). Parkinson’s disease participants demonstrated significantly impaired visual self-motion perception compared with age-matched controls on both visits, irrespective of medication status. Young controls performed slightly (but not significantly) better than age-matched controls and significantly better than the Parkinson’s disease group. The visual self-motion perception impairment in Parkinson’s disease correlated significantly with clinical disease severity. By contrast, vestibular performance was unimpaired in Parkinson’s disease. Remarkably, despite impaired visual self-motion perception, Parkinson’s disease participants significantly overweighted the visual cues during multisensory (visual–vestibular ) integration (compared with Bayesian predictions of optimal integration) and significantly more than controls. These findings indicate that self-motion perception in Parkinson’s disease is affected by impaired visual cues and by suboptimal visual–vestibular integration (overweighting of visual cues). Notably, vestibular self-motion perception was unimpaired. Thus, visual self-motion perception is specifically impaired in early-stage Parkinson’s disease. This can impact Parkinson’s disease diagnosis and subtyping. Overweighting of visual cues could reflect a general multisensory integration deficit in Parkinson’s disease, or specific overestimation of visual cue reliability. Finally, impaired self-motion perception in Parkinson’s disease may contribute to impaired balance and gait control. Future investigation into this connection might open up new avenues of alternative therapies to better treat these difficult symptoms.


2019 ◽  
Author(s):  
Sol Yakubovich ◽  
Simon Israeli-Korn ◽  
Orly Halperin ◽  
Gilad Yahalom ◽  
Sharon Hassin-Baer ◽  
...  

AbstractBackgroundParkinson’s disease (PD) is prototypically a movement disorder. Although perceptual and motor functions are interdependent, much less is known about perceptual dysfunction in PD. Perceptual deficits can impact activities of daily living, and contribute to motor symptoms, but might go unnoticed if not tested directly. Posture, gait and balance, affected in PD, rely on veridical perception of one’s own motion in space. Yet it is unknown whether self-motion perception is impaired in PD.ObjectivesTo test self-motion perception in PD, separately for visual and vestibular cues (unisensory), and multisensory integration thereof.MethodsParticipants (19 early stage PD, 23 age-matched and 20 young adult controls) experienced vestibular (motion platform), visual (optic flow), and combined visual-vestibular self-motion stimuli, and discriminated whether the stimulus headings were rightward or leftward of straight ahead. PD participants and age-matched controls were tested on two visits (PD on and off medication).ResultsPD participants had significantly impaired visual self-motion perception, both on and off medication. This deficit correlated significantly with clinical disease severity. By contrast, their vestibular performance was unimpaired. Remarkably, despite impaired visual self-motion perception, PD participants significantly over-weighted visual cues during multisensory (visual-vestibular) integration.ConclusionsSelf-motion perception is affected already in early stage PD, specifically by impaired visual (vs. vestibular) function, and by suboptimal visual-vestibular integration. This may contribute to impaired balance and gait control. Future investigation into this connection might open up new avenues for alternative therapies to better treat these symptoms. Furthermore, these results may also impact early PD diagnosis and subtyping.


2019 ◽  
Vol 5 (1) ◽  
pp. 247-268 ◽  
Author(s):  
Peter Thier ◽  
Akshay Markanday

The cerebellar cortex is a crystal-like structure consisting of an almost endless repetition of a canonical microcircuit that applies the same computational principle to different inputs. The output of this transformation is broadcasted to extracerebellar structures by way of the deep cerebellar nuclei. Visually guided eye movements are accommodated by different parts of the cerebellum. This review primarily discusses the role of the oculomotor part of the vermal cerebellum [the oculomotor vermis (OMV)] in the control of visually guided saccades and smooth-pursuit eye movements. Both types of eye movements require the mapping of retinal information onto motor vectors, a transformation that is optimized by the OMV, considering information on past performance. Unlike the role of the OMV in the guidance of eye movements, the contribution of the adjoining vermal cortex to visual motion perception is nonmotor and involves a cerebellar influence on information processing in the cerebral cortex.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sichao Yang ◽  
Johannes Bill ◽  
Jan Drugowitsch ◽  
Samuel J. Gershman

AbstractMotion relations in visual scenes carry an abundance of behaviorally relevant information, but little is known about how humans identify the structure underlying a scene’s motion in the first place. We studied the computations governing human motion structure identification in two psychophysics experiments and found that perception of motion relations showed hallmarks of Bayesian structural inference. At the heart of our research lies a tractable task design that enabled us to reveal the signatures of probabilistic reasoning about latent structure. We found that a choice model based on the task’s Bayesian ideal observer accurately matched many facets of human structural inference, including task performance, perceptual error patterns, single-trial responses, participant-specific differences, and subjective decision confidence—especially, when motion scenes were ambiguous and when object motion was hierarchically nested within other moving reference frames. Our work can guide future neuroscience experiments to reveal the neural mechanisms underlying higher-level visual motion perception.


Author(s):  
Hector Riquelme-Heras

Background: Parkinson's disease was described for the first time by James Parkinson in 1817 in the trial "Shaking Palsy," and thus there is also evidence of this disease in the Indian medical system 4500 years ago, for the diagnosis and its management with Mucuna pruriens.Years later, it was subsequently determined to contain levodopa. Two types of manifestations of Parkinson's disease are currently known, such as motor and non-motor, the first being the one that usually leads to diagnosis. Success in this will depend on the skill of the primary care physician, the ability to recognize the first symptoms by the patient, and the health systems in the management of care for the timely referral. This work shows the comprehensive management of a patient who arrives at Primary Care services, presenting vague and specific symptoms. These symptoms were treated with medications or remedies in order to calm the condition temporarily. It is convenient to call the specific symptoms such as headache, nausea, pain, dizziness, tiredness and weakness, poor motivation, sadness, easy crying, and sleep disturbances; A large percentage go to their health centers for presenting motor alterations, many times identified by their relatives or by themselves and despite being recognized as something abnormal, many of them come when the tremor intervenes with the activities of daily life. At this point, the management of the disease would begin, making clear the importance of education for the population to attend abnormal situations on time and not in late stages, significantly improving the quality of life or the prognosis of the disease Parkinson's, as is the case that occurred in our institution; A 64-year-old female patient who presents with tremor in the fifth finger of the right hand, she mentions that it is more intense when there are apparently stress situations, hyposmia and sleep disturbances, going to different health centers where they were controlled the discomfort with essential medications, many of these not requiring a prescription, temporarily decreasing in intensity; This being the beginning of multi-causality for proper management from considering the first contact doctor as a resource manager with the use of diagnostic skills to recognize characteristic signs in early stages of the disease and the ability to maintain continuity with the patients and their families as a model of family system. Studies were determined that non-motor manifestations could appear months or years before they manifest as motor symptoms to give comprehensive management to patients from their first contact with the health centers closest to them. The diagnostic presumption and its referral to the neurology and timely treatment service, until evaluating the functionality and efficacy of health policies, avoiding the delay in pharmacological treatment and access to specific neuroimaging studies at any stage of the disease. Objective: The objective of this report is to present a clinical case of a patient diagnosed with Parkinson's disease, from its management in the first contact medical services to have comprehensive management by a neurologist, thus in this way the period of latency to start treatment. Methods: We present a clinical case of a 64-year-old patient who came to consultation due to a tremor in the fifth finger of the right hand.A review of her medical history is performed, and management by different specialties is identified, for mood disorders, insomnia, essential tremor in addition to allergic rhinitis, already with drug treatment with slight or no improvement. The patient underwent a neurological examination and imaging and laboratory studies. She was referred to the neurology service as soon as possible. Result: After the interrogation and physical examination, the patient was referred to the Neurology service to confirm the presumption of diagnosis as a movement disorder under study. This process is often called the "latency period" of the diagnosis. The present work is shown as a decisive factor in giving a verdict on this problem. It is known that this level of resolution takes into account the pillars of first contact medicine as health resource managers. In this way, pharmacological treatment was started with a decrease in tremor as a motor symptom and an increase in quality and amount of sleep, increased mood, and affect as non-motor symptoms. Conclusion: The patient is under established medical and pharmacological control, and the long diagnostic latency period could be evidenced, as it usually happens in many movement disorders or their early stages, in this case, Parkinson's disease. Likewise, the family doctor is an instrument that allows the resolution of more than 90% of health problems in general, and the proper management of the remaining percentage is multifactorial, as well as medical skill and experience, the capacity of the patient or the family members. in recognizing early-stage motor disorders and health systems that often make a referral to other medical specialties difficult.


2018 ◽  
Vol 10 ◽  
pp. 117957351880358 ◽  
Author(s):  
Ashish Kumar Gupta ◽  
Komal Rani ◽  
Surabhi Swarnkar ◽  
Gaurav Khunger Kumar ◽  
Mohd Imran Khan ◽  
...  

Aim of the Study: Parkinson’s disease and schizophrenia are disease end points of dopaminergic deficit and hyperactivity, respectively, in the mid brain. Accordingly, current medications aim to restore normal dopamine levels, overshooting of which results in adverse effects of psychosis and extra-pyramidal symptoms, respectively. There are currently no available laboratory tests to guide treatment decisions or help predict adverse side effects of the drugs. The aim was to therefore explore the possibility of using apolipoprotein E as a biomarker to monitor pharmacological intervention in dopamine dictated states of Parkinson’s disease and schizophrenia for optimum therapy. Methods: Naïve and treated, Parkinson’s disease and schizophrenic patients were recruited from neurology and psychiatry clinics. Serum of healthy volunteers was collected as controls. Serum concentrations of apolipoprotein E was estimated by enzyme-linked immunosorbent assay (ELISA). Pathway analysis was carried out to delineate the interactions of apolipoprotein E in Parkinson’s disease and schizophrenia. Results: Apolipoprotein E levels are higher in Parkinson’s disease patients as compared with schizophrenic samples ( P < .05). Also, post-treatment apolipoprotein E levels in both disease states were at par with levels seen in healthy controls. The interactions of apolipoprotein E validate the results and place the differential expression of the protein in Parkinson’s disease and schizophrenia in the right perspective. Conclusion: Apolipoprotein E concentration across the dopaminergic spectrum suggests that it can be pursued not only as a potential biomarker in schizophrenia and Parkinson’s disease, but can also be an effective tool for clinicians to determine efficacy of drug-based therapy.


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