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Adhanom IB, MacNeilage P, Folmer E. Eye Tracking in Virtual Reality: a Broad Review of Applications and Challenges. VIRTUAL REALITY 2023; 27:1481-1505. [PMID: 37621305 PMCID: PMC10449001 DOI: 10.1007/s10055-022-00738-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 11/30/2022] [Indexed: 08/26/2023]
Abstract
Eye tracking is becoming increasingly available in head-mounted virtual reality displays with various headsets with integrated eye trackers already commercially available. The applications of eye tracking in virtual reality are highly diversified and span multiple disciplines. As a result, the number of peer-reviewed publications that study eye tracking applications has surged in recent years. We performed a broad review to comprehensively search academic literature databases with the aim of assessing the extent of published research dealing with applications of eye tracking in virtual reality, and highlighting challenges, limitations and areas for future research.
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Affiliation(s)
| | - Paul MacNeilage
- University of Nevada Reno, 1664 N Virginia St, Reno, NV 89557, USA
| | - Eelke Folmer
- University of Nevada Reno, 1664 N Virginia St, Reno, NV 89557, USA
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2
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Dowiasch S, Blanke M, Knöll J, Bremmer F. Spatial localization during open-loop smooth pursuit. Front Neurosci 2023; 17:1058340. [PMID: 36816133 PMCID: PMC9932511 DOI: 10.3389/fnins.2023.1058340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 01/11/2023] [Indexed: 02/05/2023] Open
Abstract
Introduction Numerous previous studies have shown that eye movements induce errors in the localization of briefly flashed stimuli. Remarkably, the error pattern is indicative of the underlying eye movement and the exact experimental condition. For smooth pursuit eye movements (SPEM) and the slow phase of the optokinetic nystagmus (OKN), perceived stimulus locations are shifted in the direction of the ongoing eye movement, with a hemifield asymmetry observed only during SPEM. During the slow phases of the optokinetic afternystagmus (OKAN), however, the error pattern can be described as a perceptual expansion of space. Different from SPEM and OKN, the OKAN is an open-loop eye movement. Methods Visually guided smooth pursuit can be transformed into an open-loop eye movement by briefly blanking the pursuit target (gap). Here, we examined flash localization during open-loop pursuit and asked, whether localization is also prone to errors and whether these are similar to those found during SPEM or during OKAN. Human subjects tracked a pursuit target. In half of the trials, the target was extinguished for 300 ms (gap) during the steady-state, inducing open-loop pursuit. Flashes were presented during this gap or during steady-state (closed-loop) pursuit. Results In both conditions, perceived flash locations were shifted in the direction of the eye movement. The overall error pattern was very similar with error size being slightly smaller in the gap condition. The differences between errors in the open- and closed-loop conditions were largest in the central visual field and smallest in the periphery. Discussion We discuss the findings in light of the neural substrates driving the different forms of eye movements.
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Affiliation(s)
- Stefan Dowiasch
- Department Neurophysics, Philipps-Universität Marburg, Marburg, Germany,Center for Mind, Brain and Behavior (CMBB), Philipps-Universität Marburg and Justus–Liebig–Universität Gießen, Gießen, Germany,*Correspondence: Stefan Dowiasch,
| | - Marius Blanke
- Department Neurophysics, Philipps-Universität Marburg, Marburg, Germany
| | - Jonas Knöll
- Department Neurophysics, Philipps-Universität Marburg, Marburg, Germany,Institute of Animal Welfare and Animal Husbandry, Friedrich-Loeffler-Institut, Celle, Germany
| | - Frank Bremmer
- Department Neurophysics, Philipps-Universität Marburg, Marburg, Germany,Center for Mind, Brain and Behavior (CMBB), Philipps-Universität Marburg and Justus–Liebig–Universität Gießen, Gießen, Germany
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Giersch A, Laprévote V. Perceptual Functioning. Curr Top Behav Neurosci 2023; 63:79-113. [PMID: 36306053 DOI: 10.1007/7854_2022_393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Perceptual disorders are not part of the diagnosis criteria for schizophrenia. Yet, a considerable amount of work has been conducted, especially on visual perception abnormalities, and there is little doubt that visual perception is altered in patients. There are several reasons why such perturbations are of interest in this pathology. They are observed during the prodromal phase of psychosis, they are related to the pathophysiology (clinical disorganization, disorders of the sense of self), and they are associated with neuronal connectivity disorders. Perturbations occur at different levels of processing and likely affect how patients interact and adapt to their surroundings. The literature has become very large, and here we try to summarize different models that have guided the exploration of perception in patients. We also illustrate several lines of research by showing how perception has been investigated and by discussing the interpretation of the results. In addition to discussing domains such as contrast sensitivity, masking, and visual grouping, we develop more recent fields like processing at the level of the retina, and the timing of perception.
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Affiliation(s)
- Anne Giersch
- University of Strasbourg, INSERM U1114, Centre Hospitalier Régional Universitaire de Strasbourg, Strasbourg, France.
| | - Vincent Laprévote
- University of Strasbourg, INSERM U1114, Centre Hospitalier Régional Universitaire de Strasbourg, Strasbourg, France
- CLIP Centre de Liaison et d'Intervention Précoce, Centre Psychothérapique de Nancy, Laxou, France
- Faculté de Médecine, Université de Lorraine, Vandoeuvre-lès-Nancy, France
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Al-Hindawi A, Vizcaychipi MP, Demiris Y. Continuous Non-Invasive Eye Tracking In Intensive Care. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2021; 2021:1869-1873. [PMID: 34891652 DOI: 10.1109/embc46164.2021.9630999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Delirium, an acute confusional state, is a common occurrence in Intensive Care Units (ICUs). Patients who develop delirium have globally worse outcomes than those who do not and thus the diagnosis of delirium is of importance. Current diagnostic methods have several limitations leading to the suggestion of eye-tracking for its diagnosis through in-attention. To ascertain the requirements for an eye-tracking system in an adult ICU, measurements were carried out at Chelsea & Westminster Hospital NHS Foundation Trust. Clinical criteria guided empirical requirements of invasiveness and calibration methods while accuracy and precision were measured. A non-invasive system was then developed utilising a patient-facing RGB camera and a scene-facing RGBD camera. The system's performance was measured in a replicated laboratory environment with healthy volunteers revealing an accuracy and precision that outperforms what is required while simultaneously being non-invasive and calibration-free The system was then deployed as part of CONfuSED, a clinical feasibility study where we report aggregated data from 5 patients as well as the acceptability of the system to bedside nursing staff. To the best of our knowledge, the system is the first eye-tracking systems to be deployed in an ICU for delirium monitoring.
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Bell IH, Nicholas J, Alvarez-Jimenez M, Thompson A, Valmaggia L. Virtual reality as a clinical tool in mental health research and practice
. DIALOGUES IN CLINICAL NEUROSCIENCE 2021; 22:169-177. [PMID: 32699517 PMCID: PMC7366939 DOI: 10.31887/dcns.2020.22.2/lvalmaggia] [Citation(s) in RCA: 65] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Virtual reality (VR) is a potentially powerful technology for enhancing assessment
in mental health. At any time or place, individuals can be transported into immersive
and interactive virtual worlds that are fully controlled by the researcher or clinician.
This capability is central to recent interest in how VR might be harnessed in both
treatment and assessment of mental health conditions. The current review provides a
summary of the advantages of using VR for assessment in mental health, focusing on
increasing ecological validity of highly controlled environments, enhancing
personalization and engagement, and capturing real-time, automated data in real-world
contexts. Considerations for the implementation of VR in research and clinical settings
are discussed, including current issues with cost and access, developing evidence base,
technical challenges, and ethical implications. The opportunities and challenges of VR
are important to understand as researchers and clinicians look to harness this
technology to improve mental health outcomes.
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Affiliation(s)
- Imogen H Bell
- Orygen, Melbourne, Australia; Centre for Youth Mental Health, The University of Melbourne, Australia
| | - Jennifer Nicholas
- Orygen, Melbourne, Australia; Centre for Youth Mental Health, The University of Melbourne, Australia
| | - Mario Alvarez-Jimenez
- Orygen, Melbourne, Australia; Centre for Youth Mental Health, The University of Melbourne, Australia
| | - Andrew Thompson
- Orygen, Melbourne, Australia; Centre for Youth Mental Health, The University of Melbourne, Australia; University of Warwick - Division of Mental Health and Wellbeing, University of Warwick, UK
| | - Lucia Valmaggia
- King's College London, Institute of Psychiatry, Psychology & Neuroscience, London, UK; South London and Maudsley NHS Foundation Trust, London, UK
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Puyo L, David C, Saad R, Saad S, Gautier J, Sahel JA, Borderie V, Paques M, Atlan M. Laser Doppler holography of the anterior segment for blood flow imaging, eye tracking, and transparency assessment. BIOMEDICAL OPTICS EXPRESS 2021; 12:4478-4495. [PMID: 34457427 PMCID: PMC8367265 DOI: 10.1364/boe.425272] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 05/28/2021] [Accepted: 05/30/2021] [Indexed: 05/04/2023]
Abstract
Laser Doppler holography (LDH) is a full-field blood flow imaging technique able to reveal human retinal and choroidal blood flow with high temporal resolution. We here report on using LDH in the anterior segment of the eye without making changes to the instrument. Blood flow in the bulbar conjunctiva and episclera as well as in corneal neovascularization can be effectively imaged. We additionally demonstrate simultaneous holographic imaging of the anterior and posterior segments by simply adapting the numerical propagation distance to the plane of interest. We used this feature to track the movements of the retina and pupil with high temporal resolution. Finally, we show that the light backscattered by the retina can be used for retro-illumination of the anterior segment. Hence digital holography can reveal opacities caused by absorption or diffusion in the cornea and eye lens.
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Affiliation(s)
- Léo Puyo
- Centre Hospitalier National d’Ophtalmologie des Quinze-Vingts, INSERM-DHOS CIC 1423, 28 rue de Charenton, 75012 Paris, France
- Paris Eye Imaging, France
- Institute of Biomedical Optics, University of Lübeck. Peter-Monnik-Weg 4, 23562 Lübeck, Germany
| | - Clémentine David
- Centre Hospitalier National d’Ophtalmologie des Quinze-Vingts, INSERM-DHOS CIC 1423, 28 rue de Charenton, 75012 Paris, France
| | - Rana Saad
- Centre Hospitalier National d’Ophtalmologie des Quinze-Vingts, INSERM-DHOS CIC 1423, 28 rue de Charenton, 75012 Paris, France
- Paris Eye Imaging, France
| | - Sami Saad
- Centre Hospitalier National d’Ophtalmologie des Quinze-Vingts, INSERM-DHOS CIC 1423, 28 rue de Charenton, 75012 Paris, France
| | - Josselin Gautier
- Centre Hospitalier National d’Ophtalmologie des Quinze-Vingts, INSERM-DHOS CIC 1423, 28 rue de Charenton, 75012 Paris, France
- Paris Eye Imaging, France
| | - José Alain Sahel
- Centre Hospitalier National d’Ophtalmologie des Quinze-Vingts, INSERM-DHOS CIC 1423, 28 rue de Charenton, 75012 Paris, France
- Paris Eye Imaging, France
- Department of Ophthalmology, The University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
- Institut de la Vision, Sorbonne Université, INSERM, CNRS, 17 Rue Moreau, 75012 Paris, France
| | - Vincent Borderie
- Centre Hospitalier National d’Ophtalmologie des Quinze-Vingts, INSERM-DHOS CIC 1423, 28 rue de Charenton, 75012 Paris, France
| | - Michel Paques
- Centre Hospitalier National d’Ophtalmologie des Quinze-Vingts, INSERM-DHOS CIC 1423, 28 rue de Charenton, 75012 Paris, France
- Paris Eye Imaging, France
- Institut de la Vision, Sorbonne Université, INSERM, CNRS, 17 Rue Moreau, 75012 Paris, France
| | - Michael Atlan
- Paris Eye Imaging, France
- Institut Langevin, CNRS, PSL University, ESPCI Paris, 1 rue Jussieu, 75005 Paris, France
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Shmukler A, Latanov AV, Karyakina M, Anisimov VN, Churikova MA, Sukhachevsky IS, Spektor VA. Eye Movements and Cognitive Functioning in Patients With Schizophrenia Spectrum Disorders: Network Analysis. Front Psychiatry 2021; 12:736228. [PMID: 34858224 PMCID: PMC8631397 DOI: 10.3389/fpsyt.2021.736228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2021] [Accepted: 10/14/2021] [Indexed: 11/13/2022] Open
Abstract
Background: Eye movement parameters are often used during cognitive functioning assessments of patients with psychotic spectrum disorders. It is interesting to compare these oculomotor parameters with cognitive functions, as assessed using psychometric cognitive tests. A network analysis is preferable for understanding complex systems; therefore, the aim of this study was to determine the multidimensional relationships that exist between oculomotor reactions and neurocognition in patients with schizophrenia spectrum disorders. Materials and Methods: A total of 134 subjects (93 inpatients with schizophrenia spectrum disorders (ICD-10) and 41 healthy volunteers) participated in this study. Psychiatric symptom severity was assessed using the Positive and Negative Syndrome Scale, the Calgary Depression Scale for Schizophrenia, and the Young Mania Rating Scale. Extrapyramidal symptoms were assessed using the Simpson-Angus Scale, and akathisia was assessed using the Barnes Akathisia Rating Scale. Eye movements were recorded using an eye-tracker SMI RED 500, and cognitive function was assessed using the Brief Assessment of Cognition in Schizophrenia. The statistical analyses were conducted using Minitab 17 Statistical Software, version 17.2.1. Data visualization and additional analyses were performed in the R 4.0.3 environment, using RStudio V 1.3.1093 software. Results: A network model of neurocognitive and oculomotor functions was constructed for the patients. In the full network (which includes all correlations) the median antisaccade latency value is the central element of the oculomotor domain, and the Symbol Coding test, the Digit Sequencing test, and the Verbal Fluency test are central elements in the neurocognitive domain. Additionally, there were connections between other cognitive and oculomotor functions, except for the antisaccade error latency in the oculomotor domain and the Token Motor Task in the neurocognitive domain. Conclusion: Network analysis provides measurable criteria for the assessment of neurophysiological and neurocognitive abnormalities in patients with schizophrenic spectrum disorders and allows to select key targets for their management and cognitive remediation.
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Affiliation(s)
- Alexander Shmukler
- Department of Psychotic Spectrum Disorders, Moscow Research Institute of Psychiatry, The Branch of V. Serbsky National Medical Research Center for Psychiatry and Narcology, Moscow, Russia
| | | | - Maria Karyakina
- Department of Psychotic Spectrum Disorders, Moscow Research Institute of Psychiatry, The Branch of V. Serbsky National Medical Research Center for Psychiatry and Narcology, Moscow, Russia
| | - Victor N Anisimov
- Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia
| | | | - Ivan S Sukhachevsky
- Department of Psychotic Spectrum Disorders, Moscow Research Institute of Psychiatry, The Branch of V. Serbsky National Medical Research Center for Psychiatry and Narcology, Moscow, Russia
| | - Valery A Spektor
- Department of Psychotic Spectrum Disorders, Moscow Research Institute of Psychiatry, The Branch of V. Serbsky National Medical Research Center for Psychiatry and Narcology, Moscow, Russia
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Giersch A, Huard T, Park S, Rosen C. The Strasbourg Visual Scale: A Novel Method to Assess Visual Hallucinations. Front Psychiatry 2021; 12:685018. [PMID: 34177666 PMCID: PMC8219930 DOI: 10.3389/fpsyt.2021.685018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 05/14/2021] [Indexed: 11/13/2022] Open
Abstract
The experience of oneself in the world is based on sensory afferences, enabling us to reach a first-perspective perception of our environment and to differentiate oneself from the world. Visual hallucinations may arise from a difficulty in differentiating one's own mental imagery from externally-induced perceptions. To specify the relationship between hallucinations and the disorders of the self, we need to understand the mechanisms of hallucinations. However, visual hallucinations are often under reported in individuals with psychosis, who sometimes appear to experience difficulties describing them. We developed the "Strasbourg Visual Scale (SVS)," a novel computerized tool that allows us to explore and capture the subjective experience of visual hallucinations by circumventing the difficulties associated with verbal descriptions. This scale reconstructs the hallucinated image of the participants by presenting distinct physical properties of visual information, step-by-step to help them communicate their internal experience. The strategy that underlies the SVS is to present a sequence of images to the participants whose choice at each step provides a feedback toward re-creating the internal image held by them. The SVS displays simple images on a computer screen that provide choices for the participants. Each step focuses on one physical property of an image, and the successive choices made by the participants help them to progressively build an image close to his/her hallucination, similar to the tools commonly used to generate facial composites. The SVS was constructed based on our knowledge of the visual pathways leading to an integrated perception of our environment. We discuss the rationale for the successive steps of the scale, and to which extent it could complement existing scales.
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Affiliation(s)
- Anne Giersch
- University of Strasbourg, INSERM U1114, Strasbourg, France.,Department of Psychiatry, University Hospital of Strasbourg, Strasbourg, France
| | - Thomas Huard
- University of Strasbourg, INSERM U1114, Strasbourg, France
| | - Sohee Park
- Department of Psychology, Vanderbilt University, Nashville, TN, United States
| | - Cherise Rosen
- Department of Psychiatry, University of Illinois at Chicago, Chicago, IL, United States
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Mehta ND, Won MJ, Babin SL, Patel SS, Wassef AA, Chuang AZ, Sereno AB. Differential benefits of olanzapine on executive function in schizophrenia patients: Preliminary findings. Hum Psychopharmacol 2020; 35:e2718. [PMID: 31837056 DOI: 10.1002/hup.2718] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 11/12/2019] [Accepted: 11/14/2019] [Indexed: 11/10/2022]
Abstract
OBJECTIVE Schizophrenia patients show executive function (EF) impairments in voluntary orienting as measured by eye-movements. We tested 14 inpatients to investigate the effects of the antipsychotic olanzapine on EF, as measured by antisaccade eye-movement performance. METHODS Patients were tested at baseline (before olanzapine), 3-5 days post-medication, and 12-14 days post-medication. Patients were also assessed on the Positive and Negative Syndrome Scale (PANSS) to measure the severity of schizophrenia-related symptoms, and administered the Stroop task, a test of EF. Nine matched controls were also tested on the antisaccade and Stroop. RESULTS Both groups showed improvement on Stroop and antisaccade; however, the schizophrenia group improved significantly more on antisaccade, indicating an additional benefit of olanzapine on EF performance. Patients with poorer baseline antisaccade performance (High-Deficit) showed significantly greater improvement on the antisaccade task than patients with better baseline performance (Low-Deficit), suggesting that baseline EF impairment predicts the magnitude of cognitive improvement with olanzapine. These subgroups showed significant and equivalent improvement on PANSS scores, indicating that improvement on the antisaccade task with olanzapine was not a result of differences in magnitude of clinical improvement. CONCLUSIONS This preliminary study provides evidence that olanzapine may be most advantageous for patients with greater baseline EF deficits.
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Affiliation(s)
- Neeti D Mehta
- Department of Neurobiology and Anatomy, University of Texas Health Science Center at Houston, Houston, Texas.,Rice University, Houston, Texas
| | - Michelle J Won
- Department of Neurobiology and Anatomy, University of Texas Health Science Center at Houston, Houston, Texas.,Rice University, Houston, Texas
| | - Shelly L Babin
- Department of Neurobiology and Anatomy, University of Texas Health Science Center at Houston, Houston, Texas
| | - Saumil S Patel
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas
| | - Adel A Wassef
- Department of Psychiatry, University of Texas Health Science Center at Houston, Houston, Texas
| | - Alice Z Chuang
- Department of Ophthalmology and Visual Science, University of Texas Health Science Center at Houston, Houston, Texas
| | - Anne B Sereno
- Department of Neurobiology and Anatomy, University of Texas Health Science Center at Houston, Houston, Texas.,Department of Psychological Sciences, Purdue University, Indiana.,Weldon School of Biomedical Engineering, Purdue University, Indiana
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Juvrud J, Gredebäck G, Åhs F, Lerin N, Nyström P, Kastrati G, Rosén J. The Immersive Virtual Reality Lab: Possibilities for Remote Experimental Manipulations of Autonomic Activity on a Large Scale. Front Neurosci 2018; 12:305. [PMID: 29867318 PMCID: PMC5951925 DOI: 10.3389/fnins.2018.00305] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 04/19/2018] [Indexed: 11/24/2022] Open
Abstract
There is a need for large-scale remote data collection in a controlled environment, and the in-home availability of virtual reality (VR) and the commercial availability of eye tracking for VR present unique and exciting opportunities for researchers. We propose and provide a proof-of-concept assessment of a robust system for large-scale in-home testing using consumer products that combines psychophysiological measures and VR, here referred to as a Virtual Lab. For the first time, this method is validated by correlating autonomic responses, skin conductance response (SCR), and pupillary dilation, in response to a spider, a beetle, and a ball using commercially available VR. Participants demonstrated greater SCR and pupillary responses to the spider, and the effect was dependent on the proximity of the stimuli to the participant, with a stronger response when the spider was close to the virtual self. We replicated these effects across two experiments and in separate physical room contexts to mimic variability in home environment. Together, these findings demonstrate the utility of pupil dilation as a marker of autonomic arousal and the feasibility to assess this in commercially available VR hardware and support a robust Virtual Lab tool for massive remote testing.
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Affiliation(s)
- Joshua Juvrud
- Department of Psychology, Uppsala University, Uppsala, Sweden
| | | | - Fredrik Åhs
- Department of Psychology, Uppsala University, Uppsala, Sweden
| | | | - Pär Nyström
- Department of Psychology, Uppsala University, Uppsala, Sweden
| | - Granit Kastrati
- Department of Psychology, Uppsala University, Uppsala, Sweden
| | - Jörgen Rosén
- Department of Psychology, Uppsala University, Uppsala, Sweden
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The Role of Dopamine in Anticipatory Pursuit Eye Movements: Insights from Genetic Polymorphisms in Healthy Adults. eNeuro 2017; 3:eN-NWR-0190-16. [PMID: 28101524 PMCID: PMC5223055 DOI: 10.1523/eneuro.0190-16.2016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 12/08/2016] [Accepted: 12/09/2016] [Indexed: 12/12/2022] Open
Abstract
There is a long history of eye movement research in patients with psychiatric diseases for which dysfunctions of neurotransmission are considered to be the major pathologic mechanism. However, neuromodulation of oculomotor control is still hardly understood. We aimed to investigate in particular the impact of dopamine on smooth pursuit eye movements. Systematic variability in dopaminergic transmission due to genetic polymorphisms in healthy subjects offers a noninvasive opportunity to determine functional associations. We measured smooth pursuit in 110 healthy subjects genotyped for two well-documented polymorphisms, the COMT Val158Met polymorphism and the SLC6A3 3′-UTR-VNTR polymorphism. Pursuit paradigms were chosen to particularly assess the ability of the pursuit system to initiate tracking when target motion onset is blanked, reflecting the impact of extraretinal signals. In contrast, when following a fully visible target sensory, retinal signals are available. Our results highlight the crucial functional role of dopamine for anticipatory, but not for sensory-driven, pursuit processes. We found the COMT Val158Met polymorphism specifically associated with anticipatory pursuit parameters, emphasizing the dominant impact of prefrontal dopamine activity on complex oculomotor control. In contrast, modulation of striatal dopamine activity by the SLC6A3 3′-UTR-VNTR polymorphism had no significant functional effect. Though often neglected so far, individual differences in healthy subjects provide a promising approach to uncovering functional mechanisms and can be used as a bridge to understanding deficits in patients.
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Abstract
It is accepted that the formulation of the motor program in the brain is not only the perceptual and motor function but also the cognitive one. Therefore it is not surprising that the execution of saccadic eye movements can by substantially affected be the on-going mental activity of a given person. Not only the distribution of attention, but also the focusing the attention may influence the main gain of saccades, their accuracy. Patients suffering from mental disorders have strongly engaged their attention focused at their mental processes. The nature of their problems may be linked to perceptual and/or analytical processing. Such so-called mental set may significantly affect their oculomotor activity in the course of their saccadic eye movement examinations. This short comment points out not only to the influence of the contextually guided and generated saccadic eye movements upon their accuracy but also to the distribution and focusing the attention. The effect of the functional brain asymmetry upon the visually generated saccades and the possible effect of biologically active substances upon the voluntary generated saccades are briefly mentioned. All these influences should be taken into account when planning the saccadic eye movement task. It may be concluded that the repetition of the same oculomotor task in a given person has to be introduced. This may help to follow the effect of complex therapy namely.
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Affiliation(s)
- F Jagla
- Institute of Normal and Pathological Physiology, Slovak Academy of Sciences, Bratislava, Slovakia.
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13
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McCammon JM, Sive H. Challenges in understanding psychiatric disorders and developing therapeutics: a role for zebrafish. Dis Model Mech 2016; 8:647-56. [PMID: 26092527 PMCID: PMC4486859 DOI: 10.1242/dmm.019620] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The treatment of psychiatric disorders presents three major challenges to the research and clinical community: defining a genotype associated with a disorder, characterizing the molecular pathology of each disorder and developing new therapies. This Review addresses how cellular and animal systems can help to meet these challenges, with an emphasis on the role of the zebrafish. Genetic changes account for a large proportion of psychiatric disorders and, as gene variants that predispose to psychiatric disease are beginning to be identified in patients, these are tractable for study in cellular and animal systems. Defining cellular and molecular criteria associated with each disorder will help to uncover causal physiological changes in patients and will lead to more objective diagnostic criteria. These criteria should also define co-morbid pathologies within the nervous system or in other organ systems. The definition of genotypes and of any associated pathophysiology is integral to the development of new therapies. Cell culture-based approaches can address these challenges by identifying cellular pathology and by high-throughput screening of gene variants and potential therapeutics. Whole-animal systems can define the broadest function of disorder-associated gene variants and the organismal impact of candidate medications. Given its evolutionary conservation with humans and its experimental tractability, the zebrafish offers several advantages to psychiatric disorder research. These include assays ranging from molecular to behavioural, and capability for chemical screening. There is optimism that the multiple approaches discussed here will link together effectively to provide new diagnostics and treatments for psychiatric patients. Summary: In this review, we discuss strengths and limitations of prevalent laboratory models that are used for understanding psychiatric disorders and developing therapeutics, with emphasis on the zebrafish.
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Affiliation(s)
- Jasmine M McCammon
- Whitehead Institute for Biomedical Research, Nine Cambridge Center, Cambridge, MA 02142, USA
| | - Hazel Sive
- Whitehead Institute for Biomedical Research, Nine Cambridge Center, Cambridge, MA 02142, USA Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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Damilou A, Apostolakis S, Thrapsanioti E, Theleritis C, Smyrnis N. Shared and distinct oculomotor function deficits in schizophrenia and obsessive compulsive disorder. Psychophysiology 2016; 53:796-805. [PMID: 26914941 DOI: 10.1111/psyp.12630] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Accepted: 01/11/2016] [Indexed: 02/06/2023]
Abstract
Detailed analysis of oculomotor function phenotypes in antisaccade, smooth eye pursuit, and active fixation tasks was performed in a sample of 44 patients with schizophrenia, 34 patients with obsessive compulsive disorder (OCD), and 45 matched healthy controls. A common pattern of performance deficits in both schizophrenia and OCD emerged including higher antisaccade error rate, increased latency for corrective antisaccades, as well as higher rates of unwanted saccades in smooth eye pursuit compared to healthy controls. This common pattern could be related to the dysfunction of a network of cognitive control that is present in both disorders, including the dorsolateral prefrontal cortex, the posterior parietal cortex, and the anterior cingulate cortex. In contrast, only patients with schizophrenia showed a specific increase for correct antisaccade mean latency and the intrasubject variability of latency for error prosaccades as well as a decrease in the gain for smooth eye pursuit, suggesting a specific deficit in saccadic motor control and the frontal eye field in schizophrenia that is not present in OCD. A specific deficit in fixation stability (increased frequency of unwanted saccades during active fixation) was observed only for OCD patients pointing to a deficit in the frontostriatal network controlling fixation. This deficit was pronounced for OCD patients receiving additional antipsychotic medication. In conclusion, oculomotor function showed shared and distinct patterns of deviance for schizophrenia and OCD pointing toward shared and specific neurobiological substrates for these psychiatric disorders.
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Affiliation(s)
- Angeliki Damilou
- Laboratory of Sensorimotor Control, University Mental Health Research Institute, Athens, Greece
| | - Sotirios Apostolakis
- Laboratory of Sensorimotor Control, University Mental Health Research Institute, Athens, Greece
| | - Eleftheria Thrapsanioti
- Laboratory of Sensorimotor Control, University Mental Health Research Institute, Athens, Greece
| | - Christos Theleritis
- Laboratory of Sensorimotor Control, University Mental Health Research Institute, Athens, Greece.,Department of Psychiatry, National University of Athens, Eginition Hospital, Athens, Greece
| | - Nikolaos Smyrnis
- Laboratory of Sensorimotor Control, University Mental Health Research Institute, Athens, Greece.,Department of Psychiatry, National University of Athens, Eginition Hospital, Athens, Greece
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15
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McCammon JM, Sive H. Addressing the Genetics of Human Mental Health Disorders in Model Organisms. Annu Rev Genomics Hum Genet 2015; 16:173-97. [DOI: 10.1146/annurev-genom-090314-050048] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Jasmine M. McCammon
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142;
| | - Hazel Sive
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142;
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
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Schwab S, Jost M, Altorfer A. Impaired top-down modulation of saccadic latencies in patients with schizophrenia but not in first-degree relatives. Front Behav Neurosci 2015; 9:44. [PMID: 25759644 PMCID: PMC4338814 DOI: 10.3389/fnbeh.2015.00044] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 02/06/2015] [Indexed: 02/03/2023] Open
Abstract
Impaired eye movements have a long history in schizophrenia research and meet the criteria of a reliable biomarker. However, the effects of cognitive load and task difficulty on saccadic latencies (SL) are less understood. Recent studies showed that SL are strongly task dependent: SL are decreased in tasks with higher cognitive demand, and increased in tasks with lower cognitive demand. The present study investigates SL modulation in patients with schizophrenia and their first-degree relatives. A group of 13 patients suffering from ICD-10 schizophrenia, 10 first-degree relatives, and 24 control subjects performed two different types of visual tasks: a color task and a Landolt ring orientation task. We used video-based oculography to measure SL. We found that patients exhibited a similar unspecific SL pattern in the two different tasks, whereas controls and relatives exhibited 20–26% shorter average latencies in the orientation task (higher cognitive demand) compared to the color task (lower cognitive demand). Also, classification performance using support vector machines suggests that relatives should be assigned to the healthy controls and not to the patient group. Therefore, visual processing of different content does not modulate SL in patients with schizophrenia, but modulates SL in the relatives and healthy controls. The results reflect a specific oculomotor attentional dysfunction in patients with schizophrenia that is a potential state marker, possibly caused by impaired top-down disinhibition of the superior colliculus by frontal/prefrontal areas such as the frontal eye fields.
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Affiliation(s)
- Simon Schwab
- Department of Psychiatric Neurophysiology, University Hospital of Psychiatry, University of Bern , Bern , Switzerland
| | - Miriam Jost
- Department of Psychiatric Neurophysiology, University Hospital of Psychiatry, University of Bern , Bern , Switzerland
| | - Andreas Altorfer
- Department of Psychiatric Neurophysiology, University Hospital of Psychiatry, University of Bern , Bern , Switzerland
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Giersch A, Lalanne L, van Assche M, Elliott MA. On disturbed time continuity in schizophrenia: an elementary impairment in visual perception? Front Psychol 2013; 4:281. [PMID: 23755027 PMCID: PMC3664782 DOI: 10.3389/fpsyg.2013.00281] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Accepted: 05/02/2013] [Indexed: 11/13/2022] Open
Abstract
Schizophrenia is associated with a series of visual perception impairments, which might impact on the patients' every day life and be related to clinical symptoms. However, the heterogeneity of the visual disorders make it a challenge to understand both the mechanisms and the consequences of these impairments, i.e., the way patients experience the outer world. Based on earlier psychiatry literature, we argue that issues regarding time might shed a new light on the disorders observed in patients with schizophrenia. We will briefly review the mechanisms involved in the sense of time continuity and clinical evidence that they are impaired in patients with schizophrenia. We will then summarize a recent experimental approach regarding the coding of time-event structure in time, namely the ability to discriminate between simultaneous and asynchronous events. The use of an original method of analysis allowed us to distinguish between explicit and implicit judgments of synchrony. We showed that for SOAs below 20 ms neither patients nor controls fuse events in time. On the contrary subjects distinguish events at an implicit level even when judging them as synchronous. In addition, the implicit responses of patients and controls differ qualitatively. It is as if controls always put more weight on the last occurred event, whereas patients have a difficulty to follow events in time at an implicit level. In patients, there is a clear dissociation between results at short and large asynchronies, that suggest selective mechanisms for the implicit coding of time-event structure. These results might explain the disruption of the sense of time continuity in patients. We argue that this line of research might also help us to better understand the mechanisms of the visual impairments in patients and how they see their environment.
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Affiliation(s)
- Anne Giersch
- INSERM U1114, Department of Psychiatry, Fédération de Médecine Translationnelle de Strasbourg (FMTS), University Hospital of Strasbourg Strasbourg, France
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Bolding MS, Lahti AC, Gawne TJ, Hopkins KB, Gurler D, Gamlin PD. Ocular convergence deficits in schizophrenia. Front Psychiatry 2012; 3:86. [PMID: 23087652 PMCID: PMC3474129 DOI: 10.3389/fpsyt.2012.00086] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2012] [Accepted: 09/19/2012] [Indexed: 12/12/2022] Open
Abstract
Individuals with schizophrenia (SZ) have been reported to exhibit a higher prevalence of convergence insufficiency (CI) than the "normal" adult population. The purpose of this study was to determine if individuals with SZ exhibit clinical signs of CI and to determine if the Convergence Insufficiency Symptom Survey (CISS) is an effective instrument for identifying CI in this population. Twenty participants with SZ and 20 healthy controls (HC) completed the study. The prevalence of CI (15%) in the SZ group was slightly higher than reported norms, but the difference was not significant. The SZ group had significantly higher scores on the CISS than the HC group, but the CISS scores did not correlate with clinical measures of CI in individuals with SZ. The only exception was that SZ patients had a significantly reduced fusional reserve as determined by Sheard's criteria. Further study is needed to determine why individuals with SZ reported symptoms associated with CI even though clinical measures did not support this diagnosis.
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Affiliation(s)
- Mark S Bolding
- Department of Vision Sciences, University of Alabama at Birmingham Birmingham, AL, USA
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Koychev I, Barkus E, Ettinger U, Killcross S, Roiser JP, Wilkinson L, Deakin B. Evaluation of state and trait biomarkers in healthy volunteers for the development of novel drug treatments in schizophrenia. J Psychopharmacol 2011; 25:1207-25. [PMID: 21994315 DOI: 10.1177/0269881111414450] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Antipsychotic drugs are the mainstay of treatment for schizophrenia but they have little effect on core negative symptoms or cognitive impairment. To meet the deficiencies of current treatments, novel potential compounds are emerging from preclinical research but translation to clinical success has been poor. This article evaluates the possibility that cognitive and physiological abnormalities in schizophrenia can be used as central nervous system biomarkers to predict, in healthy volunteers, the likely efficacy of entirely new pharmacological approaches to treatment. Early detection of efficacy would focus resource on rapidly developing, effective drugs. We review the relevance of selected cognitive and physiological abnormalities as biomarkers in schizophrenia and three of its surrogate populations: (i) healthy volunteers with high trait schizotypy; (ii) unaffected relatives of patients; and (iii) healthy volunteers in a state of cortical glutamate disinhibition induced by low-dose ketamine. Several biomarkers are abnormal in these groups and in some instances there has been exploratory work to determine their sensitivity to drug action. They are generally insensitive to current antipsychotics and therefore their predictive validity cannot be established until novel, therapeutically useful drugs are discovered. Until then such biomarker studies can provide evidence of drugs engaging with the mechanism of interest and encouragement of the concept.
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Affiliation(s)
- Ivan Koychev
- Neuroscience and Psychiatry Unit, School of Community Based Medicine, University of Manchester, Manchester, UK.
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20
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Jaafari N, Rigalleau F, Rachid F, Delamillieure P, Millet B, Olié JP, Gil R, Rotge JY, Vibert N. A critical review of the contribution of eye movement recordings to the neuropsychology of obsessive compulsive disorder. Acta Psychiatr Scand 2011; 124:87-101. [PMID: 21631433 DOI: 10.1111/j.1600-0447.2011.01721.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Dysfunctions of saccadic and/or smooth pursuit eye movements have been proposed as markers of obsessive compulsive disorder (OCD), but experimental results are inconsistent. The aim of this paper was to review the literature on eye movement dysfunctions in OCD to assess whether or not saccades or smooth pursuit may be used to diagnose and characterize OCD. METHOD Literature was searched using PubMed, ISI Web of Knowledge, and PsycINFO databases for all studies reporting eye movements in adult patients suffering from OCD. RESULTS Thirty-three articles were found. As expected, eye movements of the patients with OCD were mostly assessed with simple oculomotor paradigms involving saccadic and/or smooth pursuit control. In contrast to patients with schizophrenia, however, patients with OCD only displayed rather unspecific deficits, namely slight smooth pursuit impairments and longer response latencies on antisaccade tasks. There was no relationship between these deficits and the severity of patients' symptoms. Interestingly, eye movements of the patients with OCD were almost never recorded during more complex cognitive tasks. CONCLUSION As in schizophrenia and autism, eye movement recordings during more complex tasks might help to better characterize the cognitive deficits associated with OCD. Such recordings may reveal specific OCD-related deficits that could be used as reliable diagnostic and/or classification tools.
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Affiliation(s)
- N Jaafari
- Unité de Recherche Clinique Intersectorielle en Psychiatrie du Centre Hospitalier Henri Laborit, Université de Médecine et de Pharmacie de Poitiers, CHU de Poitiers, France.
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21
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Brennan CH. Zebrafish behavioural assays of translational relevance for the study of psychiatric disease. Rev Neurosci 2011; 22:37-48. [PMID: 21615260 DOI: 10.1515/rns.2011.006] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Understanding the pathogenesis of the complex behavioural disorders that constitute psychiatric disease is a major challenge for biomedical research. Assays in rodents have contributed significantly to our understanding of the neural basis of behavioural disorders and continue to be one of the main focuses for the development of novel therapeutics. Now, owing to their genetic tractability and optical transparency (allowing in vivo imaging of circuit function) and the rapid expansion of genetic tools, zebrafish are becoming increasingly popular for behavioural genetic research. The increased development of behavioural assays in zebrafish raises the possibility of exploiting the advantages of this system to identify molecular mechanisms contributing to behavioural phenotypes associated with psychiatric disorders as well as potential therapeutics. This mini-review describes behavioural paradigms in zebrafish that can be used to address endophenotypes associated with psychiatric disease. The content reflects the interests of the author and covers tests of cognitive functions, response choice and inhibition, social interaction and executive function.
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Affiliation(s)
- Caroline H Brennan
- Queen Mary University of London, Biological and Experimental Psychology Group, School of Biological and Chemical Sciences, Mile End, London E1 4NS, UK.
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Citek K, Elmont AD, Jons CL, Krezelok CJ, Neron JD, Plummer TA, Tannenbaum T. Sleep deprivation does not mimic alcohol intoxication on field sobriety testing. J Forensic Sci 2011; 56:1170-9. [PMID: 21595697 DOI: 10.1111/j.1556-4029.2011.01813.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Previous research shows that sleep deprivation (SD) produces cognitive impairment similar to that caused by alcohol intoxication. Individual studies suggest that SD also causes deficits in motor skills that could be mistaken for intoxication. Consequently, SD often is used as a defense when an impaired driver is charged with driving while intoxicated. Twenty-nine adult subjects participated in two test sessions each, one after a full night's rest and the other after wakefulness of at least 24 h. Subjects consumed prescribed amounts of alcohol during each session. Law enforcement officers conducted field sobriety tests identical to those with which a driver would be assessed at roadside. Researchers also measured clinical responses of visual function and vital signs. The presence and number of validated impairment clues increase with increasing blood alcohol concentration but not with SD. Thus, SD does not affect motor skills in a manner that would lead an officer to conclude that the suspect is intoxicated, unless intoxication also is present.
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Affiliation(s)
- Karl Citek
- Pacific University College of Optometry, 2043 College Way, Forest Grove, OR 97116, USA.
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23
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Folta K, Mähler C. Schnelle Augenbewegungen und visuelle Fixation bei Kindern mit ADHS. KINDHEIT UND ENTWICKLUNG 2011. [DOI: 10.1026/0942-5403/a000037] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Die Aufmerksamkeitsdefizit/Hyperaktivitätsstörung (ADHS) gehört zu den bedeutendsten psychiatrischen Störungen des Kindes- und Jugendalters. Der Beitrag zeigt auf, wie moderne Blickbewegungs-Systeme helfen, die neurokognitiven Grundlagen der ADHS weitergehend zu erforschen. Exemplarisch wird eine Studie vorgestellt, die kompensatorische Effekte einer Stimulanzien-Medikation auf Fähigkeiten der exekutiven Kontrolle von ADHS-Kindern untersucht. Dazu wurden medikamentös behandelte ADHS-Kinder und gesunde Kontrollkinder in einer Zeitreproduktions- und einer Augenbewegungsaufgabe getestet, die entweder eine aktive Inhibition oder Ausführung von Prosakkaden erforderte. Beide Gruppen zeigten vergleichbar präzise und interferenzstabile Zeitreproduktionen sowie eine vergleichbare Anzahl, Latenz, Amplitude und Dauer von Prosakkaden. Die Ergebnisse lassen eine weitgehende pharmakologische Kompensation von Auffälligkeiten der exekutiven Kontrolle vermuten. Jedoch konnte für ADHS-Kinder unter Medikamenteneinfluss (im Vergleich zu gesunden Kindern) eine signifikant erhöhte Spitzengeschwindigkeit von Prosakkaden beobachtet werden, die einen diagnostisch relevanten Augenbewegungs-Parameter darstellen könnte.
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Affiliation(s)
- Kristian Folta
- Institut für Psychologie der Stiftung Universität Hildesheim
| | - Claudia Mähler
- Institut für Psychologie der Stiftung Universität Hildesheim
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Abstract
This study aimed to objectivize the quality of smooth pursuit eye movements in a standard laboratory task before and after an Eye Movement Desensitization and Reprocessing (EMDR) session run on seven healthy volunteers. EMDR was applied on autobiographic worries causing moderate distress. The EMDR session was complete in 5 out of the 7 cases; distress measured by SUDS (Subjective Units of Discomfort Scale) decreased to a near zero value. Smooth pursuit eye movements were recorded by an Eyelink II video system before and after EMDR. For the five complete sessions, pursuit eye movement improved after their EMDR session. Notably, the number of saccade intrusions-catch-up saccades (CUS)-decreased and, reciprocally, there was an increase in the smooth components of the pursuit. Such an increase in the smoothness of the pursuit presumably reflects an improvement in the use of visual attention needed to follow the target accurately. Perhaps EMDR reduces distress thereby activating a cholinergic effect known to improve ocular pursuit.
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25
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Nkam I, Bocca ML, Denise P, Paoletti X, Dollfus S, Levillain D, Thibaut F. Impaired smooth pursuit in schizophrenia results from prediction impairment only. Biol Psychiatry 2010; 67:992-7. [PMID: 20110087 DOI: 10.1016/j.biopsych.2009.11.029] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2008] [Revised: 10/12/2009] [Accepted: 11/18/2009] [Indexed: 11/27/2022]
Abstract
BACKGROUND Oculomotor abnormality is one of the endophenotypes in schizophrenia. The predictive component of smooth pursuit can be studied by comparing the gain, i.e., the ratio of smooth eye position to target position, during predictable (pure sinusoidal) and unpredictable (pseudorandom) target motions. The aim of this experiment was to study predictive and nonpredictive components of smooth pursuit in two groups of schizophrenia patients compared with control subjects. METHODS Fifty-one schizophrenia patients (40 nondeficit and 11 deficit) and 21 control subjects were studied. During a predictable task, subjects were asked to track a sinusoidal target (.4 Hz). For the unpredictable task, the pseudorandom target motion consisted of five superimposed sinusoidal waveforms (.1, .2, .4, .6, and .8 Hz). The smooth eye position (eye position without saccades), gain, and phase were calculated for each frequency in each participant and for both tasks. RESULTS The mean sinusoidal smooth eye position gain was significantly lower in patients than in control subjects with no significant difference between deficit and nondeficit patients. During the pseudorandom task, all groups had a similar gain at .4 Hz. CONCLUSIONS Our study reveals that patients have a normal nonpredictive component of smooth pursuit, regardless of their level of negative symptoms. In contrast, the predictive mechanisms involved in eye pursuit were impaired in schizophrenia patients. These results indicate that poor pursuit performance during smooth pursuit is primarily a consequence of a predictive problem and is not related to the ability to generate an accurate pursuit maintenance response.
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Affiliation(s)
- Irene Nkam
- Rouen University Hospital-Charles Nicolle and Le Rouvray Hospital, Rouen School of Medicine, Rouen, France.
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Haraldsson HM, Ettinger U, Magnusdottir BB, Ingason A, Hutton SB, Sigmundsson T, Sigurdsson E, Petursson H. Neuregulin-1 genotypes and eye movements in schizophrenia. Eur Arch Psychiatry Clin Neurosci 2010; 260:77-85. [PMID: 19575259 DOI: 10.1007/s00406-009-0032-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2009] [Accepted: 06/15/2009] [Indexed: 01/26/2023]
Abstract
Neuregulin-1 (NRG-1) is a putative susceptibility gene for schizophrenia but the neurocognitive processes that may involve NRG-1 in schizophrenia are unknown. Deficits in antisaccade (AS) and smooth pursuit eye movements (SPEM) are promising endophenotypes, which may be associated with brain dysfunctions underlying the pathophysiology of schizophrenia. The aim of this study was to investigate the associations of NRG-1 genotypes with AS and SPEM in schizophrenia patients and healthy controls. Patients (N = 113) and controls (N = 106) were genotyped for two NRG-1 single nucleotide polymorphisms (SNPs); SNP8NRG222662, a surrogate marker for the originally described Icelandic NRG-1 risk haplotype, and SNP8NRG243177, which has recently been associated with individual differences in brain function. Subjects underwent infrared oculographic assessment of AS and SPEM. The study replicates previous findings of impaired AS and SPEM performance in schizophrenia patients (all P < 0.005; all d = 0.5-1.5). SNP8NRG243177 risk allele carriers had marginally increased variability of AS spatial error (P = 0.050, d = 0.3), but there were no significant genotype effects on other eye movement variables and no significant diagnosis-by-genotype interactions. Generally, risk allele carriers (G allele for SNP8NRG222662 and T allele for SNP8NRG243177) had numerically worse performance than non-carriers on most AS and SPEM variables. The results do not suggest that NRG-1 genotype significantly affects AS and SPEM task performance. However, the power of the sample to identify small effects is limited and the possibility of a type II error must be kept in mind. Larger samples may be needed to reliably investigate such gene effects on oculomotor endophenotypes.
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Affiliation(s)
- H Magnus Haraldsson
- Division of Psychiatry, Landspitali University Hospital, Hringbraut, 101, Reykjavik, Iceland.
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Affiliation(s)
| | - Scott Johnson
- b Department of Psychology , UCLA , Los Angeles, California
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Haraldsson HM, Ettinger U, Magnusdottir BB, Sigmundsson T, Sigurdsson E, Ingason A, Petursson H. COMT val(158)met genotype and smooth pursuit eye movements in schizophrenia. Psychiatry Res 2009; 169:173-5. [PMID: 19647329 DOI: 10.1016/j.psychres.2008.10.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2008] [Revised: 08/13/2008] [Accepted: 10/13/2008] [Indexed: 10/20/2022]
Abstract
The association between the catechol-O-methyltransferase (COMT) val(158)met polymorphism (rs4680) and smooth pursuit eye movements (SPEM) was investigated in 110 schizophrenia patients and 96 controls. Patients had lower steady-state pursuit gain and made more frequent saccades than controls. Genotype was not associated with schizophrenia or SPEM, in either group or the combined sample. SPEM deficits in schizophrenia appear to be determined by genotypes other than rs4680, although the study may have lacked power to detect small effects.
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Affiliation(s)
- H Magnus Haraldsson
- Division of Psychiatry, Landspitali-University Hospital, Reykjavik, Iceland.
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29
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Fabisch K, Fitz W, Fabisch H, Haas-Krammer A, Klug G, Zapotoczky S, Kapfhammer HP. Sinusoidal smooth pursuit eye tracking at different stimulus frequencies: position error and velocity error before catch-up saccades in schizophrenia and in major depressive disorder. Aust N Z J Psychiatry 2009; 43:855-65. [PMID: 19670059 DOI: 10.1080/00048670903107542] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
OBJECTIVE The aim of the present study was to ascertain the extent of impairment of position error and velocity error processing in eye tracking dysfunction in schizophrenic and depressive patients. METHOD A total of 21 schizophrenic and 19 unipolar depressive patients and 21 healthy controls were subjected to an eye tracking test with electro-oculography using horizontal sinusoidal stimuli with frequencies of 0.2-0.7 Hz. Position error and velocity error were measured over a saccade-free range of 200 ms before catch-up saccades at 50 ms intervals. RESULTS For position error, the schizophrenia patients displayed increased values particularly compared to controls, more rarely compared to depressive patients, depending on the stimulus frequency used. The increase in stimulus frequency did not lead to an increase in position error in any group of subjects over a prolonged period. For velocity error, in contrast, the study groups differed only in a few, isolated pre-saccadic intervals. The increase in stimulus frequency, however, led to an increase in velocity error in the schizophrenia patients over the entire 200 ms interval. The depressive patients did not differ notably from the controls, neither in terms of position error nor velocity error. CONCLUSIONS Eye tracking dysfunction in schizophrenia can be described as follows with regard to position error and velocity error: On the one hand, there is an increased position error tolerance largely independent of stimulus frequency, possibly due to an impairment of processing localization information. On the other hand, velocity processing is more severely impaired by an increase in stimulus frequency.
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Affiliation(s)
- Karin Fabisch
- Department of Psychiatry, Medical University of Graz, Auenbruggerplatz 31, Graz, Austria.
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Schütz AC, Braun DI, Gegenfurtner KR. Chromatic Contrast Sensitivity During Optokinetic Nystagmus, Visually Enhanced Vestibulo-ocular Reflex, and Smooth Pursuit Eye Movements. J Neurophysiol 2009; 101:2317-27. [DOI: 10.1152/jn.91248.2008] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Recently we showed that sensitivity for chromatic- and high-spatial frequency luminance stimuli is enhanced during smooth-pursuit eye movements (SPEMs). Here we investigated whether this enhancement is a general property of slow eye movements. Besides SPEM there are two other classes of eye movements that operate in a similar range of eye velocities: the optokinetic nystagmus (OKN) is a reflexive pattern of alternating fast and slow eye movements elicited by wide-field visual motion and the vestibulo-ocular reflex (VOR) stabilizes the gaze during head movements. In a natural environment all three classes of eye movements act synergistically to allow clear central vision during self- and object motion. To test whether the same improvement of chromatic sensitivity occurs during all of these eye movements, we measured human detection performance of chromatic and luminance line stimuli during OKN and contrast sensitivity during VOR and SPEM at comparable velocities. For comparison, performance in the same tasks was tested during fixation. During the slow phase of OKN we found a similar enhancement of chromatic detection rate like that during SPEM, whereas no enhancement was observable during VOR. This result indicates similarities between slow-phase OKN and SPEM, which are distinct from VOR.
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Abstract
The objective of this paper is to highlight the potential role of eye tracking technology (ETT) in the assessment of delirious patients. Delirium occurs in one in five general hospital admissions (Siddiqi, 2006) and its frequency will increase as society gets older. Despite its frequency and significant independent impact upon morbidity and mortality, delirium remains under studied and is frequently missed, detected late, or misdiagnosed (Farrell & Ganzani, 1995; Inouye, 2001; Kakuma, 2003). Detection is a key target for both clinical and research efforts. Assessment of attention is key to diagnosing delirium, yet nurses and non-research medical staff often fail to correctly identify inattention (Inouye et al., 2001; Lemiengre et al., 2006; Ryan et al., 2008). Eye tracking measures have been used in a plethora of key areas of psychiatric research (Crawford et al., 2005; Corden, Chilvers, & Skuse, 2008; Hardin, Schroth, Pine, & Ernst, 2007; Holzman, Leonard, Proctor, & Hughes, 1973), and provide an accurate and non-invasive method in the assessment of cognitive function. The potential of ETT for direct clinical applications in the assessment of attention and comprehension, key cognitive symptoms of delirium, are promising. This paper considers potential new approaches which recent advancements in non-invasive ETT may bring to the examination and understanding of delirium.
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Affiliation(s)
- C Exton
- Department of Computer Science, University of Limerick, Limerick, Ireland.
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Rommelse NNJ, Van der Stigchel S, Sergeant JA. A review on eye movement studies in childhood and adolescent psychiatry. Brain Cogn 2008; 68:391-414. [PMID: 18835079 DOI: 10.1016/j.bandc.2008.08.025] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/26/2008] [Indexed: 10/21/2022]
Abstract
The neural substrates of eye movement measures are largely known. Therefore, measurement of eye movements in psychiatric disorders may provide insight into the underlying neuropathology of these disorders. Visually guided saccades, antisaccades, memory guided saccades, and smooth pursuit eye movements will be reviewed in various childhood psychiatric disorders. The four aims of this review are (1) to give a thorough overview of eye movement studies in a wide array of psychiatric disorders occurring during childhood and adolescence (attention-deficit/hyperactivity disorder, oppositional deviant disorder and conduct disorder, autism spectrum disorders, reading disorder, childhood-onset schizophrenia, Tourette's syndrome, obsessive compulsive disorder, and anxiety and depression), (2) to discuss the specificity and overlap of eye movement findings across disorders and paradigms, (3) to discuss the developmental aspects of eye movement abnormalities in childhood and adolescence psychiatric disorders, and (4) to present suggestions for future research. In order to make this review of interest to a broad audience, attention will be given to the clinical manifestation of the disorders and the theoretical background of the eye movement paradigms.
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Affiliation(s)
- Nanda N J Rommelse
- Department of Psychiatry, Radboud University Medical Center, Reinier Postlaan 12, 6525 GC Nijmegen, The Netherlands.
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Schechter I, Butler PD, Jalbrzikowski M, Pasternak R, Saperstein AM, Javitt DC. A new dimension of sensory dysfunction: stereopsis deficits in schizophrenia. Biol Psychiatry 2006; 60:1282-4. [PMID: 16945346 PMCID: PMC2901805 DOI: 10.1016/j.biopsych.2006.03.064] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2005] [Revised: 03/23/2006] [Accepted: 03/28/2006] [Indexed: 10/24/2022]
Abstract
BACKGROUND Schizophrenia is a neurocognitive disorder with a wide range of cognitive and sensory impairments. Early visual processing has been shown to be especially impaired. This article investigates the integrity of binocular depth perception (stereopsis) in schizophrenia. METHODS Seventeen schizophrenia patients and 19 healthy control subjects were compared on the Graded Circles Stereo Test. Results of stereoacuity were compared between patients and control subjects using t test. RESULTS Schizophrenia patients demonstrated significantly (p = .006) reduced stereoacuity (mean = 142 arcseconds) versus control subjects (mean = 55 arcseconds). At the normative level for adults, patients performed below chance. CONCLUSIONS These findings demonstrate an impairment of binocular depth perception and further confirm deficits of early visual processing in schizophrenia. Findings are discussed in context of magnocellular/dorsal stream processing with implications for visual processing and cognitive deficits.
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Affiliation(s)
- Isaac Schechter
- Program in Cognitive Neuroscience and Schizophrenia, Nathan Kline Institute for Psychiatric Research, Orangeburg, New York 10962, USA.
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Jazbec S, Hardin MG, Schroth E, McClure E, Pine DS, Ernst M. Age-related influence of contingencies on a saccade task. Exp Brain Res 2006; 174:754-62. [PMID: 16733706 PMCID: PMC2733163 DOI: 10.1007/s00221-006-0520-9] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2005] [Accepted: 04/24/2006] [Indexed: 10/24/2022]
Abstract
Adolescence is characterized by increased risk-taking and sensation-seeking, presumably brought about by developmental changes within reward-mediating brain circuits. A better understanding of the neural mechanisms underlying reward-seeking during adolescence can have critical implications for the development of strategies to enhance adolescent performance in potentially dangerous situations. Yet little research has investigated the influence of age on the modulation of behavior by incentives with neuroscience-based methods. A monetary reward antisaccade task (the RST) was used with 23 healthy adolescents and 30 healthy adults. Performance accuracy, latency and peak velocity of saccade responses (prosaccades and antisaccades) were analyzed. Performance accuracy across all groups was improved by incentives (obtain reward, avoid punishment) for both, prosaccades and antisaccades. However, modulation of antisaccade errors (direction errors) by incentives differed between groups: adolescents modulated saccade latency and peak velocity depending on contingencies, with incentives aligning their performance to that of adults; adults did not show a modulation by incentives. These findings suggest that incentives modulate a global measure of performance (percent direction errors) in adults and adolescents, and exert a more powerful influence on the control of incorrect motor responses in adolescents than in adults. These findings suggest that this task can be used in neuroimaging studies as a probe of the influence of incentives on cognitive control from a developmental perspective as well as in health and disease.
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Affiliation(s)
- Sandra Jazbec
- Emotional Development and Affective Neuroscience Branch, Mood and Anxiety Disorders Program, NIMH/NIH/HHS, Bethesda, MD 20892, USA
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Pan WH, Lynn KS, Chen CH, Wu YL, Lin CY, Chang HY. Using endophenotypes for pathway clusters to map complex disease genes. Genet Epidemiol 2006; 30:143-54. [PMID: 16437587 DOI: 10.1002/gepi.20136] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Nature determines the complexity of disease etiology and the likelihood of revealing disease genes. While culprit genes for many monogenic diseases have been successfully unraveled, efforts to map major complex disease genes have not been as productive as hoped. The conceptual framework currently adopted to deal with the heterogeneous nature of complex diseases focuses on using homogeneous internal features of the disease phenotype for mapping. However, phenotypic homogeneity does not equal genotypic homogeneity. In this report, we advocate working with well-measured phenotypes portrayed by amounts of transcripts and activities of gene products or their metabolites, which are pertinent to relatively small pathway clusters. Reliable and controlled measures for oligogenic traits resulting from proper dissection efforts may enhance statistical power. The large amounts of information obtained on gene and protein expression from technological advances can add to the power of gene finding, particularly for diseases with unclear etiology. Data-mining tools for dimension reduction can assist biologists to reveal novel molecular endophenotypes. However, there are still hurdles to overcome, including high cost, relatively poor reproducibility and comparability among platforms, the cross-sectional nature of the information, and the accessibility of human tissues. Concerted efforts are required to carry out large-scale prospective studies that are integrated at the levels of phenotype characterization, high throughput experimental techniques, data analyses, and beyond.
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Affiliation(s)
- Wen-Harn Pan
- Institute of Biomedical Sciences, Academia Sinica, No. 128 Section 2 Academia Road, Taipei, Taiwan 11529.
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Schechter I, Butler PD, Zemon VM, Revheim N, Saperstein AM, Jalbrzikowski M, Pasternak R, Silipo G, Javitt DC. Impairments in generation of early-stage transient visual evoked potentials to magno- and parvocellular-selective stimuli in schizophrenia. Clin Neurophysiol 2005; 116:2204-15. [PMID: 16055375 PMCID: PMC2901806 DOI: 10.1016/j.clinph.2005.06.013] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2004] [Revised: 06/06/2005] [Accepted: 06/11/2005] [Indexed: 10/25/2022]
Abstract
OBJECTIVE Patients with schizophrenia demonstrate significant impairments of early visual processing, potentially implicating dysfunction of the magnocellular visual pathway. The present study evaluates transient visual evoked potential (tVEP) responses to stimuli biased toward the magnocellular (M) or parvocellular (P) systems in patients with schizophrenia vs. normal volunteers first to evaluate relative contributions of M and P systems to specific tVEP components in schizophrenia and, second, to evaluate integrity of early M and P processing in schizophrenia. METHODS Seventy-four patients with schizophrenia and schizoaffective disorder were compared with 59 control subjects using separate stimuli to assess the tVEP response to M, P and mixed M/P conditions. Stimuli were biased toward M vs. P processing by manipulation of chromatic and achromatic contrast. C1, P1, N1 and P2 components were compared between patients and controls. All subjects showed 20/32 vision or better. RESULTS Waveforms were obtained to low contrast (M), chromatic contrast (P) and high contrast (mixed M/P) stimuli in both patients and controls. C1 was present to P and mixed M/P stimuli. Patients showed a significant reduction in amplitude and an increase in latency of the C1 component. P1 was elicited primarily by M and mixed M/P stimuli, whereas N1 was elicited primarily by P and mixed M/P stimuli. Patients showed reductions in both P1 and N1 amplitudes across conditions. However, only reductions in P1 amplitude survived covariation for between group differences in visual acuity. Further, P1 amplitude reductions in the M condition correlated with a proxy measure of global outcome. CONCLUSIONS M- and P-selective stimuli elicit differential components of the tVEP. Patients with schizophrenia show significant reductions in response even to simple visual stimuli. Deficits, particularly within the M system, may correlate significantly with global outcome and level of community functioning. SIGNIFICANCE Whereas deficits in high-order cognitive processing have been extensively documented in schizophrenia, integrity of early-stage sensory processing has been studied to a lesser degree. The present findings suggest that deficits in early-stage visual processing are significantly related to overall clinical outcome in schizophrenia. Further, between-group differences in visual acuity may influence VEP results, even for subjects with 'normal' vision (20/32 or better).
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Affiliation(s)
- Isaac Schechter
- Nathan Kline Institute, Program in Cognitive Neuroscience and Schizophrenia, Orangeburg, NY, USA
| | - Pamela D. Butler
- Nathan Kline Institute, Program in Cognitive Neuroscience and Schizophrenia, Orangeburg, NY, USA
- New York University School of Medicine, New York, NY, USA
- Corresponding author. Address: Nathan Kline Institute for Psychiatric Research, 140 Old Orangeburg Road, Orangeburg, NY 10962, USA. Tel.: +1 845 398 6537; fax: +1 845 398 6545. E-mail address: (P.D. Butler)
| | - Vance M. Zemon
- Nathan Kline Institute, Program in Cognitive Neuroscience and Schizophrenia, Orangeburg, NY, USA
- Ferkauf Graduate School of Psychology, Yeshiva University, Bronx, NY, USA
| | - Nadine Revheim
- Nathan Kline Institute, Program in Cognitive Neuroscience and Schizophrenia, Orangeburg, NY, USA
| | - Alice M. Saperstein
- Nathan Kline Institute, Program in Cognitive Neuroscience and Schizophrenia, Orangeburg, NY, USA
| | - Maria Jalbrzikowski
- Nathan Kline Institute, Program in Cognitive Neuroscience and Schizophrenia, Orangeburg, NY, USA
| | - Roey Pasternak
- Nathan Kline Institute, Program in Cognitive Neuroscience and Schizophrenia, Orangeburg, NY, USA
| | - Gail Silipo
- Nathan Kline Institute, Program in Cognitive Neuroscience and Schizophrenia, Orangeburg, NY, USA
| | - Daniel C. Javitt
- Nathan Kline Institute, Program in Cognitive Neuroscience and Schizophrenia, Orangeburg, NY, USA
- New York University School of Medicine, New York, NY, USA
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Hong LE, Avila MT, Thaker GK. Response to unexpected target changes during sustained visual tracking in schizophrenic patients. Exp Brain Res 2005; 165:125-31. [PMID: 15883805 DOI: 10.1007/s00221-005-2276-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2004] [Accepted: 01/05/2005] [Indexed: 11/29/2022]
Abstract
BACKGROUND Evidence supports an association between liability to schizophrenia and smooth-pursuit eye movement (SPEM) abnormalities. Knowledge of the biological mechanisms of SPEM abnormalities may provide critical insights into the etiology of schizophrenia. SPEM is elicited by sensory motor information from the movement of the object's image on the retina (retinal motion signal) and subsequent extraretinal motion signals. Previous studies suggest that a deficit in predictive responses to extraretinal motion signals may underlie the SPEM phenotype in schizophrenia. Data suggest that at-risk individuals for schizophrenia depend less on extraretinal and more on retinal motion signals to maintain pursuit than healthy individuals. METHODS We designed a pursuit task that employs unexpected changes in target direction during smooth pursuit. The unpredictable task is unique in that performance is expected to be better if the subject's response is biased towards retinal motion. RESULTS The study included 23 schizophrenia patients and 22 normal controls. Results showed that schizophrenia patients showed significantly superior performance (i.e. higher smooth pursuit gain) for a brief period after an unexpected change in target direction compared with healthy subjects. CONCLUSION Findings of superior performance by schizophrenic patients are interesting because they circumvent confounds of generalized deficits. These results provide further evidence of specific deficit in the predictive pursuit mechanism and over-reliance on retinal error signals to maintain pursuit in schizophrenia.
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Affiliation(s)
- L Elliot Hong
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, P.O. Box 21247, Baltimore, MD 21228, USA.
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