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Asanad S, O'Neill H, Addis H, Chen S, Wang J, Goldwaser E, Kochunov P, Hong LE, Saeedi OJ. Neuroretinal Biomarkers for Schizophrenia Spectrum Disorders. Transl Vis Sci Technol 2021; 10:29. [PMID: 34004009 PMCID: PMC8083086 DOI: 10.1167/tvst.10.4.29] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose We evaluated the patient-control differences and predictive value of the retina as potential biomarkers for schizophrenia. Methods The institutional study included both eyes of 58 schizophrenia spectrum disorder (SSD) patients (age 37.2 ± 12.3 years) and 35 controls (age 41.1 ± 15.2 years). Retinal nerve fiber layer (RNFL), ganglion cell–inner plexiform layer, outer retinal photoreceptor complex, and total macula thicknesses were measured by optical coherence tomography (OCT). Anterior segment parameters including central corneal thickness, anterior chamber depth, and axial length were measured to rule out confounds on the retinal measures. Results The peripapillary RNFL was overall significantly thinner in SSD relative to controls (F = 3.97, P = 0.049), most pronounced in the temporal (5.2 µm difference, F = 6.95, P = 0.010) and inferior quadrants (12.1 µm difference, F = 7.32, P = 0.009). There were no significant group differences in thickness for the macular RNFL, ganglion, or photoreceptor cell related measures (P > 0.05). Peripapillary RNFL, central macula, and outer photoreceptor complex thicknesses were together able to classify SSD patients with 80% sensitivity and 71% specificity; area under the curve = 0.82 (95% confidence interval, 0.75–0.88). Conclusions SSD patients exhibited significant RNFL thinning relative to controls. Notably, retinal thickness measures including both peripapillary and macular data exhibited improved diagnostic accuracy for SSD as compared to these regions alone. Translational Relevance This is the first study to evaluate the predictive value of both the inner and outer retina in SSD. OCT retinal thickness measures including peripapillary data in conjunction with macular data may provide an informative, noninvasive in vivo ocular biomarker for schizophrenia.
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Affiliation(s)
- Samuel Asanad
- Department of Ophthalmology and Visual Sciences, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Hugh O'Neill
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Hampton Addis
- Children's National Health System, Washington, DC, USA
| | - Shuo Chen
- Division of Biostatistics and Bioinformatics, Department of Epidemiology and Public Health, and Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Jingtao Wang
- Division of Biostatistics and Bioinformatics, Department of Epidemiology and Public Health, and Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Eric Goldwaser
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Peter Kochunov
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA
| | - L Elliot Hong
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Osamah J Saeedi
- Department of Ophthalmology and Visual Sciences, University of Maryland School of Medicine, Baltimore, MD, USA
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The P1 visual-evoked potential, red light, and transdiagnostic psychiatric symptoms. Brain Res 2018; 1687:144-154. [PMID: 29510142 DOI: 10.1016/j.brainres.2018.03.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Revised: 02/08/2018] [Accepted: 03/01/2018] [Indexed: 11/23/2022]
Abstract
A reduced P1 visual-evoked potential amplitude has been reported across several psychiatric disorders, including schizophrenia-spectrum, bipolar, and depressive disorders. In addition, a difference in P1 amplitude change to a red background compared to its opponent color, green, has been found in schizophrenia-spectrum samples. The current study examined whether specific psychiatric symptoms that related to these P1 abnormalities in earlier studies would be replicated when using a broad transdiagnostic sample. The final sample consisted of 135 participants: 26 with bipolar disorders, 25 with schizophrenia-spectrum disorders, 19 with unipolar depression, 62 with no current psychiatric disorder, and 3 with disorders in other categories. Low (8%) and high (64%) contrast check arrays were presented on gray, green, and red background conditions during electroencephalogram, while an eye tracker monitored visual fixation on the stimuli. Linear regressions across the entire sample (N = 135) found that greater severity of both clinician-rated and self-reported delusions/magical thinking correlated with a reduced P1 amplitude on the low contrast gray (neutral) background condition. In addition, across the entire sample, higher self-reported constricted affect was associated with a larger decrease in P1 amplitude (averaged across contrast conditions) to the red, compared to green, background. All relationships remained statistically significant after covarying for diagnostic class, suggesting that they are relatively transdiagnostic in nature. These findings indicate that early visual processing abnormalities may be more directly related to specific transdiagnostic symptoms such as delusions and constricted affect rather than specific psychiatric diagnoses or broad symptom factor scales.
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Suppression and Contrast Normalization in Motion Processing. J Neurosci 2017; 37:11051-11066. [PMID: 29018158 DOI: 10.1523/jneurosci.1572-17.2017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Revised: 08/11/2017] [Accepted: 08/18/2017] [Indexed: 11/21/2022] Open
Abstract
Sensory neurons are activated by a range of stimuli to which they are said to be tuned. Usually, they are also suppressed by another set of stimuli that have little effect when presented in isolation. The interactions between preferred and suppressive stimuli are often quite complex and vary across neurons, even within a single area, making it difficult to infer their collective effect on behavioral responses mediated by activity across populations of neurons. Here, we investigated this issue by measuring, in human subjects (three males), the suppressive effect of static masks on the ocular following responses induced by moving stimuli. We found a wide range of effects, which depend in a nonlinear and nonseparable manner on the spatial frequency, contrast, and spatial location of both stimulus and mask. Under some conditions, the presence of the mask can be seen as scaling the contrast of the driving stimulus. Under other conditions, the effect is more complex, involving also a direct scaling of the behavioral response. All of this complexity at the behavioral level can be captured by a simple model in which stimulus and mask interact nonlinearly at two stages, one monocular and one binocular. The nature of the interactions is compatible with those observed at the level of single neurons in primates, usually broadly described as divisive normalization, without having to invoke any scaling mechanism.SIGNIFICANCE STATEMENT The response of sensory neurons to their preferred stimulus is often modulated by stimuli that are not effective when presented alone. Individual neurons can exhibit multiple modulatory effects, with considerable variability across neurons even in a single area. Such diversity has made it difficult to infer the impact of these modulatory mechanisms on behavioral responses. Here, we report the effects of a stationary mask on the reflexive eye movements induced by a moving stimulus. A model with two stages, each incorporating a divisive modulatory mechanism, reproduces our experimental results and suggests that qualitative variability of masking effects in cortical neurons might arise from differences in the extent to which such effects are inherited from earlier stages.
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Charles L, Gaillard R, Amado I, Krebs MO, Bendjemaa N, Dehaene S. Conscious and unconscious performance monitoring: Evidence from patients with schizophrenia. Neuroimage 2017; 144:153-163. [DOI: 10.1016/j.neuroimage.2016.09.056] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 09/20/2016] [Accepted: 09/21/2016] [Indexed: 12/21/2022] Open
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Silver H, Bilker WB. Colour influences perception of facial emotions but this effect is impaired in healthy ageing and schizophrenia. Cogn Neuropsychiatry 2016; 20:438-55. [PMID: 26395165 DOI: 10.1080/13546805.2015.1080157] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
INTRODUCTION Social cognition is commonly assessed by identification of emotions in facial expressions. Presence of colour, a salient feature of stimuli, might influence emotional face perception. METHODS We administered 2 tests of facial emotion recognition, the Emotion Recognition Test (ER40) using colour pictures and the Penn Emotional Acuity Test using monochromatic pictures, to 37 young healthy, 39 old healthy and 37 schizophrenic men. RESULTS Among young healthy individuals recognition of emotions was more accurate and faster in colour than in monochromatic pictures. Compared to the younger group, older healthy individuals revealed impairment in identification of sad expressions in colour but not monochromatic pictures. Schizophrenia patients showed greater impairment in colour than monochromatic pictures of neutral and sad expressions and overall total score compared to both healthy groups. Patients showed significant correlations between cognitive impairment and perception of emotion in colour but not monochromatic pictures. CONCLUSIONS Colour enhances perception of general emotional clues and this contextual effect is impaired in healthy ageing and schizophrenia. The effects of colour need to be considered in interpreting and comparing studies of emotion perception. Coloured face stimuli may be more sensitive to emotion processing impairments but less selective for emotion-specific information than monochromatic stimuli. This may impact on their utility in early detection of impairments and investigations of underlying mechanisms.
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Affiliation(s)
- Henry Silver
- a Brain Behavior Laboratory , Sha'ar Menashe Mental Health Center , Mobile Post Hefer 37806, Israel.,b Rappaport Faculty of Medicine , Technion Institute of Technology , Haifa , Israel
| | - Warren B Bilker
- c Department of Biostatistics and Epidemiology , University of Pennsylvania , Philadelphia , PA , USA
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Bedwell JS, Butler PD, Chan CC, Trachik BJ. Transdiagnostic psychiatric symptoms related to visual evoked potential abnormalities. Psychiatry Res 2015; 230:262-70. [PMID: 26412383 DOI: 10.1016/j.psychres.2015.09.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 07/28/2015] [Accepted: 09/02/2015] [Indexed: 01/20/2023]
Abstract
Visual processing abnormalities have been reported across a range of psychotic and mood disorders, but are typically examined within a particular disorder. The current study used a novel transdiagnostic approach to examine diagnostic classes, clinician-rated current symptoms, and self-reported personality traits in relation to visual processing abnormalities. We examined transient visual-evoked potentials (VEPs) from 48 adults (56% female), representing a wide range of psychotic and mood disorders, as well as individuals with no history of psychiatric disorder. Stimuli were low contrast check arrays presented on green and red backgrounds. Pairwise comparisons between individuals with schizophrenia-spectrum disorders (SSD), chronic mood disorders (CMD), and nonpsychiatric controls (NC) revealed no overall differences for either P1 or N1 amplitude. However, there was a significant interaction with the color background in which the NC group showed a significant increase in P1 amplitude to the red, vs. green, background, while the SSD group showed no change. This was related to an increase in social anhedonia and general negative symptoms. Stepwise regressions across the entire sample revealed that individuals with greater apathy and/or eccentric behavior had a reduced P1 amplitude. These relationships provide clues for uncovering the underlying causal pathology for these transdiagnostic symptoms.
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Affiliation(s)
- Jeffrey S Bedwell
- Department of Psychology, University of Central Florida, Orlando, FL, USA.
| | - Pamela D Butler
- Nathan S. Kline Institute for Psychiatric Research, Orangeburg, NY, USA
| | - Chi C Chan
- Department of Psychology, University of Central Florida, Orlando, FL, USA
| | - Benjamin J Trachik
- Department of Psychology, University of Central Florida, Orlando, FL, USA
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7
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Herzog MH, Brand A. Visual masking & schizophrenia. SCHIZOPHRENIA RESEARCH-COGNITION 2015; 2:64-71. [PMID: 29114454 PMCID: PMC5609636 DOI: 10.1016/j.scog.2015.04.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Revised: 03/30/2015] [Accepted: 04/07/2015] [Indexed: 11/28/2022]
Abstract
Visual masking is a frequently used tool in schizophrenia research. Visual masking has a very high sensitivity and specificity and masking paradigms have been proven to be endophenotypes. Whereas masking is a powerful technique to study schizophrenia, the underlying mechanisms are discussed controversially. For example, for more than 25 years, masking deficits of schizophrenia patients were mainly attributed to a deficient magno-cellular system (M-system). Here, we show that there is very little evidence that masking deficits are magno-cellular deficits. We will discuss the magno-cellular and other approaches in detail and highlight their pros and cons.
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Affiliation(s)
- Michael H Herzog
- Laboratory of Psychophysics, Brain Mind Institute, École Polytechnique Fédérale de Lausanne (EPFL), Switzerland
| | - Andreas Brand
- Klinikum Bremen-Ost, Bremen, Germany.,Institute of Psychology and Cognition Research, University of Bremen, Germany
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Núñez D, Oelkers-Ax R, de Haan S, Ludwig M, Sattel H, Resch F, Weisbrod M, Fuchs T. Do deficits in the magnocellular priming underlie visual derealization phenomena? Preliminary neurophysiological and self-report results in first-episode schizophrenia patients. Schizophr Res 2014; 159:441-9. [PMID: 25239127 DOI: 10.1016/j.schres.2014.08.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Revised: 08/04/2014] [Accepted: 08/19/2014] [Indexed: 10/24/2022]
Abstract
BACKGROUND Early visual impairments probably partially caused by impaired interactions between magnocellular (M) and parvocellular (P) pathways (M priming deficit), and disturbances of basic self-awareness or self-disorders (SDs) are core features of schizophrenia. The relationships between these features have not yet been studied. We hypothesized that the M priming was impaired in first-episode patients and that this deficit was associated with visual aspects of SDs. AIM To investigate early visual processing in a sample of first-episode schizophrenia patients and to explore the relationships between M and P functioning and visual aspects of SDs addressed by the Examination of Anomalous Self-Experience (EASE) interview. METHOD Nine stimulating conditions were used to investigate M and P pathways and their interaction in a pattern reversal visually evoked potential (VEP) paradigm. N80 at mixed M- and P-conditions was used to investigate magnocellular priming. Generators were analyzed using source localization (Brain Electrical Source Analysis software: BESA). VEPs of nineteen first-episode schizophrenia patients were compared to those of twenty matched healthy controls by a bootstrap resample procedure. Visual aspects of SDs were analyzed through a factor analysis to separate symptom clusters of derealization phenomena. Thereafter, the associations between the main factors and the N80 component were explored using linear mixed models. RESULTS Factor analyses separated two EASE factors ("distance to the world", and "intrusive world"). The N80 component was represented by a single dipole located in the occipital visual cortex. The bootstrap analysis yielded significant amplitude reductions and prolonged latencies in first-episode patients relative to controls in response to mixed M-P conditions, and normal amplitudes and latencies in response to isolated P- and M-biased stimulation. Exploratory analyses showed significant negative correlations between the N80 amplitude values at mixed M-P conditions and the EASE factor "distance to the world", i.e. relatively higher amplitudes in the patient group were associated with higher subjective perceived derealization ("distance to the world"). CONCLUSIONS The early VEP component N80 evoked by mixed M-P conditions is assumed to be a correlate of M priming, and showed reduced amplitudes and longer latencies in first-episode patients. It probably reflects a hypoactivation of the M-pathway. The negative association between visual SDs (derealization phenomena characterized by visual experiences of being more distant to the world), and the M priming deficit was counterintuitive. It might indicate a dysregulated activity of the M-pathway in patients with SDs. Further research is needed to better understand this preliminary finding.
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Affiliation(s)
- D Núñez
- Faculty of Psychology, University de Talca, Chile; Psychiatry Department, Centre for Psychosocial Medicine, University of Heidelberg, Voßstr. 4, 69115 Heidelberg, Germany.
| | - R Oelkers-Ax
- Psychiatry Department, Centre for Psychosocial Medicine, University of Heidelberg, Voßstr. 4, 69115 Heidelberg, Germany; Department of Child and Adolescent Psychiatry, University of Heidelberg, Blumenstraße 8, 69115 Heidelberg, Germany.
| | - S de Haan
- Psychiatry Department, Centre for Psychosocial Medicine, University of Heidelberg, Voßstr. 4, 69115 Heidelberg, Germany
| | - M Ludwig
- Psychiatry Department, Centre for Psychosocial Medicine, University of Heidelberg, Voßstr. 4, 69115 Heidelberg, Germany
| | - H Sattel
- Department of Psychosomatic Medicine and Psychotherapy, Klinikum rechts der Isar, Technische Universitaet Muenchen, Langerstraße 3, 81675 Munich, Germany.
| | - F Resch
- Department of Child and Adolescent Psychiatry, University of Heidelberg, Blumenstraße 8, 69115 Heidelberg, Germany.
| | - M Weisbrod
- Psychiatry Department, Centre for Psychosocial Medicine, University of Heidelberg, Voßstr. 4, 69115 Heidelberg, Germany; Klinikum Karlsbad-Langensteinbach, Guttmannstrasse 1, 76307 Karlsbad, Germany.
| | - T Fuchs
- Psychiatry Department, Centre for Psychosocial Medicine, University of Heidelberg, Voßstr. 4, 69115 Heidelberg, Germany.
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Bakanidze G, Roinishvili M, Chkonia E, Kitzrow W, Richter S, Neumann K, Herzog MH, Brand A, Puls I. Association of the Nicotinic Receptor α7 Subunit Gene (CHRNA7) with Schizophrenia and Visual Backward Masking. Front Psychiatry 2013; 4:133. [PMID: 24155726 PMCID: PMC3805058 DOI: 10.3389/fpsyt.2013.00133] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2013] [Accepted: 10/01/2013] [Indexed: 01/16/2023] Open
Abstract
The nicotinic system is involved in the pathophysiology of schizophrenia. However, very little is known about its genetic basis and how it relates to clinical symptoms and potentially pharmacological intervention. Here, we investigated five single nucleotide polymorphisms (SNPs) [rs3826029] [rs2337506] [rs982574] [rs904952] [rs2337980] of the cholinergic nicotinic receptor gene, alpha 7 subunit (CHRNA7) and their association to schizophrenia. We found an association with rs904952 (p = 0.009) in a German sample of 224 schizophrenic patients and 224 healthy control subjects. The same trend was shown in an independent Georgian sample of 50 schizophrenic patients, 57 first order unaffected relatives, and 51 healthy controls. In addition, visual backward masking (VBM), a sensitive test for early visual information processing, was assessed in the Georgian sample. In line with prior studies, VBM performance deficits were much more pronounced in schizophrenic patients and their unaffected relatives compared to healthy controls (schizophrenic patients: 156 ms; unaffected relatives: 60 ms; healthy controls: 33 ms). VBM was strongly correlated with SNP rs904952 (H[2] = 7.3, p = 0.026). Our results further support the notion that changes in the nicotinic system are involved in schizophrenia and open the avenue for pharmacological intervention.
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Affiliation(s)
- George Bakanidze
- Genetic Section, Department of Psychiatry and Psychotherapy, CCM, Charité University Medicine, Berlin, Germany
| | - Maya Roinishvili
- Department of Behaviour and Cognitive Functions, I. Beritashvili Institute of Physiology, Tbilisi, Georgia
- Institute of Cognitive Neurosciences, Agricultural University of Georgia, Tbilisi, Georgia
| | - Eka Chkonia
- Institute of Cognitive Neurosciences, Agricultural University of Georgia, Tbilisi, Georgia
- Department of Psychiatry, Tbilisi State Medical University, Tbilisi, Georgia
| | - Werner Kitzrow
- Genetic Section, Department of Psychiatry and Psychotherapy, CCM, Charité University Medicine, Berlin, Germany
| | - Sarina Richter
- Genetic Section, Department of Psychiatry and Psychotherapy, CCM, Charité University Medicine, Berlin, Germany
| | - Konrad Neumann
- Institute of Biometry and Clinical Epidemiology, CCM, Charite University, Berlin, Germany
| | - Michael H. Herzog
- Laboratory of Psychophysics, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Andreas Brand
- Center for Psychiatry and Psychotherapy, Klinikum Bremen-Ost, Bremen, Germany
| | - Imke Puls
- Genetic Section, Department of Psychiatry and Psychotherapy, CCM, Charité University Medicine, Berlin, Germany
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Sponheim SR, Sass SM, Noukki AL, Hegeman BM. Fragile early visual percepts mark genetic liability specific to schizophrenia. Schizophr Bull 2013; 39:839-47. [PMID: 22446567 PMCID: PMC3686444 DOI: 10.1093/schbul/sbs041] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Disruption of visual percepts by a subsequent stimulus (ie, backward masking) has been consistently noted in schizophrenia, with some evidence that this fragility in early perception is present in people with genetic liability for the disorder. Given the potential of backward masking paradigms to mark neural processes that confer risk for schizophrenia, it is important to test the diagnostic specificity of abnormalities in visual perception. To more fully assess whether masking visual stimuli reveals a marker of genetic liability (ie, endophenotype) specific to schizophrenia, we tested 44 people with the disorder, 29 people with bipolar disorder, 56 first-degree biological relatives of people with schizophrenia, 26 first-degree biological relatives of people with bipolar disorder, and 43 nonpsychiatric control participants using a magnocellular-biased visual backward masking procedure that included target-to-mask onset asynchronies ranging from 0 to 80 ms. Relatives of people with schizophrenia who were without schizophrenia spectrum disorders exhibited impaired performance compared with nonpsychiatric control participants and relatives of people with bipolar disorder when a visual mask interrupted early perception (eg, 27 ms). A similar vulnerability of early processes was noted in people with schizophrenia, yet they also had impaired performance when masks occurred at later time points (ie, 80 ms). Performance deficits were not attributable to intellectual function, measures of attention and memory, symptomatology, or medication dosage. Bipolar patients and their relatives failed to exhibit deficits on the backward masking task. Fragility of early visual percepts appears to mark genetic liability specific to schizophrenia and may serve as an endophenotype for the disorder.
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Affiliation(s)
- Scott R. Sponheim
- Minneapolis Veterans Affairs Health Care System, One Veterans Drive, Minneapolis, MN 55417,Departments of Psychiatry and Psychology, University of Minnesota, Minneapolis, MN,To whom correspondence should be addressed; tel: 612-725-2074, fax: 612-727-5964, e-mail:
| | - Sarah M. Sass
- Department of Psychology, University of Texas at Tyler, Tyler, TX
| | - Althea L. Noukki
- Wisconsin Resource Center, Department of Health Services, Madison, WI
| | - Bridget M. Hegeman
- Minneapolis Veterans Affairs Health Care System, One Veterans Drive, Minneapolis, MN 55417
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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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Barbato M, Collinson SL, Casagrande M. Altered depth perception is associated with presence of schizotypal personality traits. Cogn Neuropsychiatry 2012; 17:115-32. [PMID: 21722047 DOI: 10.1080/13546805.2011.576864] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
INTRODUCTION Impaired depth perception, a fundamental aspect of early visual processing, has been shown in patients with schizophrenia suggesting a disturbance to magnocellular and possibly parvocellular pathways. Despite some evidence showing visual-perceptive deficits in people with schizotypal personality traits (SPT), depth perception has not been evaluated in these subjects. METHODS 12 clinically healthy schizotypy and 17 control participants were examined using a novel stereoscopic depth perception task. A mixed ANOVA design considered the Group (SPT/control) as independent factor, and trial Block (BD/BD+/BD-) and target Condition (SDSS/SDDS/DDSS/DDDS) were considered as repeated measures. RESULTS Schizotypal participants were not significantly different to controls on simple judgements of depth but demonstrated a subtle impairment in perceiving binocular depth when performing high difficulty judgements. CONCLUSIONS The presence of subtle depth perception problems in schizotypal subjects, similar but less marked than those of schizophrenia patients, may suggest a less pervasive disturbance of early information processing. If so, such deficits could be considered as innate neurological changes that may occur in people vulnerable for schizophrenia, thus with the potential to be a novel intermediate phenotype.
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Bedwell JS, Hernandez DC, Ranieri AY. The backward masking red light effect and schizotypy: the influence of sex. Psychiatry Res 2011; 189:228-32. [PMID: 21807416 DOI: 10.1016/j.psychres.2011.07.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2011] [Revised: 05/31/2011] [Accepted: 07/07/2011] [Indexed: 11/25/2022]
Abstract
Previous research has shown a unique effect of red light on visual processing related to both schizophrenia and positive schizotypy. The current study examined whether this effect is influenced by sex in a more broadly-defined schizotypy sample. A location backward masking (BM) task with red, green, and gray backgrounds was administered to 34 undergraduate students (59% female) with a high score on the Schizotypal Personality Questionnaire (SPQ) and 38 students (50% female) with a low score. Results revealed that the group by color interaction was significant for the male participants, while it did not approach significance in the females. The male schizotypy participants showed a significant decrease in BM accuracy to the red (vs. green) background, while the male control participants showed a non-significant mean increase in accuracy. A decrease in accuracy to the red background in the male schizotypy participants was related to a higher score on the Social Anxiety subscale of the SPQ. Findings suggest that the previously reported schizophrenia red light effect is limited to males when examining a SPQ-defined sample, and appears to be primarily related to negative schizotypy symptoms. The red light effect continues to show promise as a new endophenotype for schizophrenia-spectrum disorders.
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Affiliation(s)
- Jeffrey S Bedwell
- Department of Psychology, University of Central Florida, Orlando, FL, USA.
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Koychev I, El-Deredy W, Deakin JFW. New visual information processing abnormality biomarker for the diagnosis of Schizophrenia. EXPERT OPINION ON MEDICAL DIAGNOSTICS 2011; 5:357-368. [PMID: 22003364 PMCID: PMC3191521 DOI: 10.1517/17530059.2011.586029] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION: Schizophrenia is currently diagnosed on the basis of patient reports and clinical observations. A diagnosis based on aetiology is inherently more reliable due to being closer to the disease process than the overt clinical manifestations. Accordingly, recent research in schizophrenia has focused on the development of biomarkers in a bit to improve the reliability and neurobiological relevance of the diagnosis. Visual information processing is one of these promising fields of recent biomarker research. AREAS COVERED: This article provides an overview of the available literature regarding deficits in schizophrenia detectable through psychophysical (contrast and motion sensitivity, visual backward-masking), ERP (P1 and N1 visual evoked potentials) and oscillatory (signal power and phase-locking factor of evoked oscilations) measures and their validity as trait or state biomarkers of the disease. The methodology included a search on articles related to visual information processing in schizophrenia on the PubMed database. EXPERT OPINION: Biomarker research in schizophrenia is a rapidly expanding area. Evidence exists to suggest that both psychotic and manic symptoms are associated with visual processing abnormalities. A specific impairment confined to the magnocellular component of the visual system might be a trait biomarker of schizophrenia.
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Affiliation(s)
- Ivan Koychev
- Neuroscience and Psychiatry Unit, School of Community Based Medicine, The University of Manchester, Manchester, M13 9PT, UK
| | - Wael El-Deredy
- The University of Manchester, School of Psychology, Manchester, United Kingdom
| | - John Francis William Deakin
- Neuroscience and Psychiatry Unit, School of Community Based Medicine, The University of Manchester, Manchester, M13 9PT, UK
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Abstract
BACKGROUND Schizophrenia patients demonstrate impairment on visual backward masking, a measure of early visual processing. Most visual masking paradigms involve two distinct processes, an early fast-acting component associated with object formation and a later component that acts through object substitution. So far, masking paradigms used in schizophrenia research have been unable to separate these two processes. METHOD We administered three visual processing paradigms (location masking with forward and backward masking, four-dot backward masking and a cuing task) to 136 patients with schizophrenia or schizoaffective disorder and 79 healthy controls. A psychophysical procedure was used to match subjects on identification of an unmasked target prior to location masking. Location masking interrupts object formation, four-dot masking task works through masking by object substitution and the cuing task measures iconic decay. RESULTS Patients showed impairment on location masking after being matched for input threshold, similar to previous reports. After correcting for age, patients showed lower performance on four-dot masking than controls, but the groups did not differ on the cuing task. CONCLUSIONS Patients with schizophrenia showed lower performance when masking was specific to object substitution. The difference in object substitution masking was not due to a difference in rate of iconic decay, which was comparable in the two groups. These results suggest that, despite normal iconic decay rates, individuals with schizophrenia show impairment in a paradigm of masking by object substitution that did not also involve disruption of object formation.
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Affiliation(s)
- M F Green
- VA Desert Pacific Mental Illness Research, Education, and Clinical Center, Los Angeles, CA, USA.
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Abstract
Visual masking provides several key advantages for exploring the earliest stages of visual processing in schizophrenia: it allows for control over timing at the millisecond level, there are several well-supported theories of the underlying neurobiology of visual masking, and it is amenable to examination by electroencephalogram (EEG) and functional magnetic resonance imaging (fMRI). In this paper, we provide an overview of the visual masking impairment schizophrenia, including the relevant theoretical mechanisms for masking impairment. We will discuss its relationship to clinical symptoms, antipsychotic medications, diagnostic specificity, and presence in at-risk populations. As part of this overview, we will cover the neural correlates of visual masking based on recent findings from EEG and fMRI. Finally, we will suggest a possible mechanism that could explain the patterns of masking findings and other visual processing findings in schizophrenia.
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Affiliation(s)
- Michael F Green
- VA Greater Los Angeles Healthcare System, Los Angeles, CA 90073, USA.
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CHRISTIAN SKOTTUN BERNT. ON THE USE OF VISUAL MOTION PERCEPTION TO ASSESS MAGNOCELLULAR INTEGRITY. J Integr Neurosci 2011; 10:15-32. [DOI: 10.1142/s0219635211002592] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2010] [Accepted: 10/20/2010] [Indexed: 11/18/2022] Open
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Chkonia E, Roinishvili M, Makhatadze N, Tsverava L, Stroux A, Neumann K, Herzog MH, Brand A. The shine-through masking paradigm is a potential endophenotype of schizophrenia. PLoS One 2010; 5:e14268. [PMID: 21151559 PMCID: PMC3000331 DOI: 10.1371/journal.pone.0014268] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2010] [Accepted: 11/19/2010] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND To understand the genetics of schizophrenia, a hunt for so-called intermediate phenotypes or endophenotypes is ongoing. Visual masking has been proposed to be such an endophenotype. However, no systematic study has been conducted yet to prove this claim. Here, we present the first study showing that masking meets the most important criteria for an endophenotype. METHODOLOGY/PRINCIPAL FINDINGS We tested 62 schizophrenic patients, 39 non-affected first-degree relatives, and 38 healthy controls in the shine-through masking paradigm and, in addition, in the Continuous Performance Test (CPT) and the Wisconsin Card Sorting Test (WCST). Most importantly, masking performance of relatives was significantly in between the one of patients and controls in the shine-through paradigm. Moreover, deficits were stable throughout one year. Using receiver operating characteristics (ROC) methods, we show that the shine-through paradigm distinguishes with high sensitivity and specificity between schizophrenic patients, first-order relatives and healthy controls. CONCLUSIONS/SIGNIFICANCE The shine-through paradigm is a potential endophenotype.
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Affiliation(s)
- Eka Chkonia
- Department of Psychiatry, Tbilisi State Medical University, Tbilisi, Georgia.
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19
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Brittain PJ, Surguladze S, McKendrick AM, Ffytche DH. Backward and forward visual masking in schizophrenia and its relation to global motion and global form perception. Schizophr Res 2010; 124:134-41. [PMID: 20685082 DOI: 10.1016/j.schres.2010.07.008] [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: 02/21/2010] [Revised: 04/28/2010] [Accepted: 07/09/2010] [Indexed: 10/19/2022]
Abstract
Whilst visual backward masking deficits in schizophrenia have been reliably reported and may reveal magnocellular dysfunction, forward masking, which may rely more heavily on the parvocellular system, has been under investigated. In a group of 64 schizophrenia patients and 65 matched controls we undertook a visual masking paradigm containing both conditions, together with tests of 'global motion' and 'global form' perception, two 'down-stream' visual tasks reflecting later processing linked to magnocellular and parvocellular function respectively. In the patient group, a significant but small deficit on the masking task, equivalent across forward and backward conditions was seen. Correlations between the masking and motion/form tasks supported the predominant theoretical framework describing the neural processes involved in masking. Performance on the motion and form tasks was differentiated by a trend-level motion processing deficit but near-normal form processing. The results suggest an 'early visual' processing deficit in both magno- and parvocellular systems but one which is only transferred to 'down-stream' processing areas with predominantly magnocellular input.
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Affiliation(s)
- P J Brittain
- Affective Neuroscience Group, Section of Cognitive Neuropsychiatry, King's College London, Institute of Psychiatry, 16 De Crespigny Park, London SE5 8AF, UK.
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21
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Lee J, Cohen MS, Engel SA, Glahn D, Nuechterlein KH, Wynn JK, Green MF. Regional brain activity during early visual perception in unaffected siblings of schizophrenia patients. Biol Psychiatry 2010; 68:78-85. [PMID: 20494338 PMCID: PMC2921272 DOI: 10.1016/j.biopsych.2010.03.028] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2009] [Revised: 03/16/2010] [Accepted: 03/16/2010] [Indexed: 11/30/2022]
Abstract
BACKGROUND Visual masking paradigms assess the early part of visual information processing, which may reflect vulnerability measures for schizophrenia. We examined the neural substrates of visual backward performance in unaffected sibling of schizophrenia patients using functional magnetic resonance imaging (fMRI). METHODS Twenty-one unaffected siblings of schizophrenia patients and 19 healthy controls performed a backward masking task and three functional localizer tasks to identify three visual processing regions of interest (ROI): lateral occipital complex (LO), the motion-sensitive area, and retinotopic areas. In the masking task, we systematically manipulated stimulus onset asynchronies (SOAs). We analyzed fMRI data in two complementary ways: 1) an ROI approach for three visual areas, and 2) a whole-brain analysis. RESULTS The groups did not differ in behavioral performance. For ROI analysis, both groups increased activation as SOAs increased in LO. Groups did not differ in activation levels of the three ROIs. For whole-brain analysis, controls increased activation as a function of SOAs, compared with siblings in several regions (i.e., anterior cingulate cortex, posterior cingulate cortex, inferior prefrontal cortex, inferior parietal lobule). CONCLUSIONS The study found: 1) area LO showed sensitivity to the masking effect in both groups; 2) siblings did not differ from controls in activation of LO; and 3) groups differed significantly in several brain regions outside visual processing areas that have been related to attentional or re-entrant processes. These findings suggest that LO dysfunction may be a disease indicator rather than a risk indicator for schizophrenia.
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Affiliation(s)
- Junghee Lee
- Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, California 90095-6968, USA.
| | - Mark S. Cohen
- Semel Institute for Neuroscience and Human Behavior, UCLA
| | | | - David Glahn
- Olin Neuropsychiatry Research Center, Institute of Living, and Department of Psychiatry, Yale University School of Medicine
| | - Keith H. Nuechterlein
- Semel Institute for Neuroscience and Human Behavior, UCLA, Department of Psychology, UCLA
| | - Jonathan K. Wynn
- Semel Institute for Neuroscience and Human Behavior, UCLA, VA Greater Los Angeles Healthcare System
| | - Michael F. Green
- Semel Institute for Neuroscience and Human Behavior, UCLA, VA Greater Los Angeles Healthcare System
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Green MF, Lee J, Cohen MS, Engel SA, Korb AS, Nuechterlein KH, Wynn JK, Glahn DC. Functional neuroanatomy of visual masking deficits in schizophrenia. ARCHIVES OF GENERAL PSYCHIATRY 2009; 66:1295-303. [PMID: 19996034 PMCID: PMC2907419 DOI: 10.1001/archgenpsychiatry.2009.132] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
CONTEXT Visual masking procedures assess the earliest stages of visual processing. Patients with schizophrenia reliably show deficits on visual masking, and these procedures have been used to explore vulnerability to schizophrenia, probe underlying neural circuits, and help explain functional outcome. OBJECTIVE To identify and compare regional brain activity associated with one form of visual masking (ie, backward masking) in schizophrenic patients and healthy controls. DESIGN Subjects received functional magnetic resonance imaging scans. While in the scanner, subjects performed a backward masking task and were given 3 functional localizer activation scans to identify early visual processing regions of interest (ROIs). SETTING University of California, Los Angeles, and the Department of Veterans Affairs Greater Los Angeles Healthcare System. PARTICIPANTS Nineteen patients with schizophrenia and 19 healthy control subjects. Main Outcome Measure The magnitude of the functional magnetic resonance imaging signal during backward masking. RESULTS Two ROIs (lateral occipital complex [LO] and the human motion selective cortex [hMT+]) showed sensitivity to the effects of masking, meaning that signal in these areas increased as the target became more visible. Patients had lower activation than controls in LO across all levels of visibility but did not differ in other visual processing ROIs. Using whole-brain analyses, we also identified areas outside the ROIs that were sensitive to masking effects (including bilateral inferior parietal lobe and thalamus), but groups did not differ in signal magnitude in these areas. CONCLUSIONS The study results support a key role in LO for visual masking, consistent with previous studies in healthy controls. The current results indicate that patients fail to activate LO to the same extent as controls during visual processing regardless of stimulus visibility, suggesting a neural basis for the visual masking deficit, and possibly other visual integration deficits, in schizophrenia.
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Affiliation(s)
- Michael F Green
- Semel Institute for Neuroscience and Human Behavior, UCLA, Los Angeles, CA 90095-6968, USA.
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23
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Bedwell JS, Miller LS, Brown JM, Yanasak NE. SCHIZOPHRENIA AND RED LIGHT: fMRI EVIDENCE FOR A NOVEL BIOBEHAVIORAL MARKER. Int J Neurosci 2009; 116:881-94. [PMID: 16861153 DOI: 10.1080/00207450500516529] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Previous research has demonstrated the ability of diffuse red light to suppress activity in the magnocellular (M) visual pathway. An earlier psychophysical study found that a subset of nonpsychotic relatives of persons with schizophrenia showed the opposite effect when compared to healthy adults (Bedwell et al., 2003), suggesting a novel biobehavioral marker for the disorder. The present study attempted to replicate and explore the mechanism for this effect using fMRI. Results provide physiological evidence that the M pathway response to red light is in the opposite direction than expected in a subset of nonpsychotic relatives of persons with schizophrenia.
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Affiliation(s)
- Jeffrey S Bedwell
- Psychology Department, University of Central Florida, Orlando, 32816, USA.
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Herzog MH, Brand A. Pitting temporal against spatial integration in schizophrenic patients. Psychiatry Res 2009; 168:1-10. [PMID: 19467716 DOI: 10.1016/j.psychres.2008.03.020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2006] [Revised: 08/06/2007] [Accepted: 03/20/2008] [Indexed: 10/20/2022]
Abstract
Schizophrenic patients show strong impairments in visual backward masking possibly caused by deficits on the early stages of visual processing. The underlying aberrant mechanisms are not clearly understood. Spatial as well as temporal processing deficits have been proposed. Here, by combining a spatial with a temporal integration paradigm, we show further evidence that temporal but not spatial processing is impaired in schizophrenic patients. Eleven schizophrenic patients and ten healthy controls were presented with sequences composed of Vernier stimuli. Patients needed significantly longer presentation times for sequentially presented Vernier stimuli to reach a performance level comparable to that of healthy controls (temporal integration deficit). When we added spatial contextual elements to some of the Vernier stimuli, performance changed in a complex but comparable manner in patients and controls (intact spatial integration). Hence, temporal but not spatial processing seems to be deficient in schizophrenia.
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Affiliation(s)
- Michael H Herzog
- Laboratory of Psychophysics, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland.
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Bedwell JS, Orem DM, Rassovsky Y, Allen LG, Sutterby SR. A potential qualitative endophenotype for schizophrenia: backward masking response to red light. Psychiatry Res 2009; 166:166-73. [PMID: 19272655 DOI: 10.1016/j.psychres.2008.03.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2007] [Revised: 03/10/2008] [Accepted: 03/13/2008] [Indexed: 11/18/2022]
Abstract
Past research with unaffected relatives of individuals with schizophrenia has suggested a new qualitative endophenotype for schizophrenia that involves a unique change in visual processing response to red light. The current study provides the first report of this "red light effect" in individuals with schizophrenia (N=15), compared with nonpsychiatric controls (N=16), using a location backward masking by pattern paradigm with red and green background conditions. Analyses revealed a statistically significant group difference in the overall change in accuracy to a red background. Controls tended to show an increase in accuracy with the red (compared with green) background, although the medium effect size was not statistically significant in the small sample. In contrast, participants with schizophrenia showed a statistically significant decrease in accuracy with the red background. Results support recent reports which have suggested that a unique change in visual processing in response to red light may represent a new endophenotype for schizophrenia. This effect is unique from most existing endophenotypes in that it represents a distinct qualitative performance pattern rather than simply poorer performance relative to a comparison group.
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Affiliation(s)
- Jeffrey S Bedwell
- Department of Psychology, University of Central Florida, 4000 Central Florida Blvd., Orlando, FL 32816-1390, United States.
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26
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Skottun BC, Skoyles JR. Are masking abnormalities in schizophrenia limited to backward masking? Int J Neurosci 2009; 119:88-104. [PMID: 19116834 DOI: 10.1080/00207450802480168] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Schizophrenia, it has been proposed, is associated with deficits in the magnocellular part of the visual system. In support of this suggestion, it has been claimed that schizophrenic subjects have abnormal backward masking. However, if this abnormality is to be linked specifically to magnocellular defects, then it must be specific to backward masking, and not, also effect, for example, forward masking. We examined this issue by reviewing the studies of masking in schizophrenic subjects. We find: (i) Most studies (56 out of 67) of backward masking have researched only backward masking. This makes it impossible to determine if the abnormalities found in these studies are exclusively confined to backward masking. (ii) Of those studies (11) that have included both forward and backward masking conditions, the majority found some degree of abnormality under both forward and backward masking conditions. It is concluded that the evidence for linking the abnormalities found in those with schizophrenia specifically to backward masking, rather than masking in general, or more general visual impairments, is at present relatively weak. Given the rationale for using backward masking as a test of magnocellular sensitivity, research in this area does not point to a deficit specific to the magnocellular system.
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Bedwell JS, Orem DM. The effect of red light on backward masking in individuals with psychometrically defined schizotypy. Cogn Neuropsychiatry 2008; 13:491-504. [PMID: 19048441 DOI: 10.1080/13546800802605755] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
INTRODUCTION Previous research has suggested that individuals with schizophrenia and their relatives show a change in backward masking performance with a red background that is in the opposite qualitative direction as that found in nonpsychiatric controls. The present study examines this effect in individuals with psychometrically defined schizotypy to explore the potential of this effect to be a useful new qualitative endophenotype for schizophrenia-spectrum traits. METHODS The Abbreviated Youth Psychosis At-Risk Questionnaire was used to screen a large number of undergraduates for schizotypy symptoms. A sample of 23 participants scoring high on this measure were compared to a sample of 26 controls on a location backward masking task that was presented on both red and green backgrounds. RESULTS Consistent with findings in patients with schizophrenia, the participants reporting a high number of schizotypy features showed a decrease in performance to the red (compared to green) background and the controls showed a nonsignificant increase in performance--although this finding was limited to the stimulus-onset asynchrony (SOA) value that approximated the SOA with the largest effect size in the previous schizophrenia study (69 ms). CONCLUSIONS Although limited to one SOA, results extend earlier findings approximating this SOA to include a psychometrically defined schizotypy sample.
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Affiliation(s)
- Jeffrey S Bedwell
- Department of Psychology, University of Central Florida, Orlando, FL 32816-1390, USA.
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Stability of visual masking performance in recent-onset schizophrenia: an 18-month longitudinal study. Schizophr Res 2008; 103:266-74. [PMID: 18450427 PMCID: PMC2859819 DOI: 10.1016/j.schres.2008.03.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2007] [Revised: 03/04/2008] [Accepted: 03/05/2008] [Indexed: 11/23/2022]
Abstract
Visual masking deficit in schizophrenia has been suggested to be a potential vulnerability marker for schizophrenia. An important characteristic of a vulnerability marker is stability over time, but relatively little is known about the longitudinal course of masking performance of schizophrenia patients. In this study, we examined the stability of visual masking performance in recent-onset schizophrenia patients over an 18-month period. We administered both forward and backward masking trials with multiple stimulus onset asynchronies for four masking conditions at three time points (baseline, 6-month, and 18-month). Recent-onset schizophrenia patients showed stable masking performance for both forward and backward conditions over a period of 18 months. Furthermore, the stable performance was observed across all four masking conditions. The findings of this study provide further support for the view that visual masking deficits reflect a possible vulnerability marker for schizophrenia.
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Norton D, Ongur D, Stromeyer C, Chen Y. Altered 'three-flash' illusion in response to two light pulses in schizophrenia. Schizophr Res 2008; 103:275-82. [PMID: 18423984 PMCID: PMC2553681 DOI: 10.1016/j.schres.2008.03.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2007] [Revised: 02/27/2008] [Accepted: 03/05/2008] [Indexed: 11/30/2022]
Abstract
BACKGROUND Disorganization is a core dysfunction in schizophrenia. Coherent thought and behavior rely on the interactive neural responses to temporally discrete external events. Previous studies have demonstrated that a single visual stimulus (event) is abnormally affected by another (as in backward masking), but the integration (or 'synthesis') of temporally discrete events remains largely unexplored in schizophrenia. We examined the perceived interaction of two elementary visual events in schizophrenia patients, using a psychophysical approach. METHODS Two brief, spatially-coincident foveal light pulses (5 ms) were presented with different inter-stimulus intervals (ISIs). At ISIs around 100 ms, a substantial proportion of the light pulse pairs was paradoxically perceived as three flashes, a known phenomenon in normal subjects. The subjects reported the number of flashes perceived ('one', 'two' or 'three'). RESULTS Schizophrenia patients (n=28) reported fewer 'three flashes' than normal controls (n=26) at the ISIs where 'three flash' reports were greatest in normal subjects (90 to 110 ms). On the other hand, at longer ISIs (130-310 ms) patients reported 'three flashes' in more trials than did normal subjects. The perception of three flashes in patients was correlated with certain aspects of clinical status, including the positive and general subscales of the PANSS. DISCUSSION The alteration of the 'three-flash' illusion in schizophrenia suggests that the synthesis of discrete visual events is temporally 'dilated' or distorted, which might contribute to disorganized thought and behavior.
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Affiliation(s)
| | | | | | - Yue Chen
- McLean Hospital,Harvard Medical School
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Ducato MG, Michael GA, Thomas P, Despretz P, Monestes JL, Loas G, Boucart M. Attentional capture in schizophrenia: failure to resist interference from motion signals. Cogn Neuropsychiatry 2008; 13:185-209. [PMID: 18484287 DOI: 10.1080/13546800701706530] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
INTRODUCTION Patients with schizophrenia show high susceptibility to distraction but the neural mechanisms underlying sensitivity to distraction are not clearly established. We designed a paradigm to assess whether sensitivity to distraction and dorsal stream dysfunction are related in schizophrenia. METHOD 60 patients, 37 schizotypals, and 58 healthy controls were asked to locate a target square appearing above or below fixation and to ignore a distractor that either moved abruptly (in Experiments 1 and 3) or changed in colour (in Experiment 2). The distractor condition was compared to a baseline condition with no distractor. Resistance to interference was assessed by manipulating the probability of the distractor changing more frequently (50%, 75%, 100%) on one side of fixation. RESULTS Patients, schizotypals, and controls showed attentional capture with longer response times when the distractor changed as compared to the baseline condition. In contrast to controls, the magnitude of interference from distractors remained stable for patients and schizotypals across all probability conditions and this was confined to attentional capture by motion, not by colour. CONCLUSION We found a similar pattern of results in patients and in schizotypals. Our attentional capture paradigm could help to identify early cognitive impairments in populations at risk to develop schizophrenia. The data are interpreted in terms of dysfunction of frontal control on dorsal stream functions in schizophrenia.
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Affiliation(s)
- M G Ducato
- Lab. Neurosciences fonctionnelles & pathologies, CNRS Université Lille, Lille, France
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Balogh Z, Benedek G, Kéri S. Retinal dysfunctions in schizophrenia. Prog Neuropsychopharmacol Biol Psychiatry 2008; 32:297-300. [PMID: 17889979 DOI: 10.1016/j.pnpbp.2007.08.024] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2007] [Revised: 08/17/2007] [Accepted: 08/21/2007] [Indexed: 11/26/2022]
Abstract
The purpose of this study was to investigate the earliest stages of visual information processing using electroretinography (ERG) in patients with schizophrenia and bipolar disorder and to compare these values with those of healthy control volunteers. In the acute stage of the illness, patients with schizophrenia exhibited decreased a-wave amplitude (a measure of photoreceptor function) as compared with healthy controls. In patients with bipolar disorder, ERG measures were intact. At the baseline assessment, there was a significant negative relationship between a-wave amplitude and positive symptoms. After an 8-week follow-up period, clinical symptoms showed significant improvement and the amplitude of the a-wave significantly increased in patients with schizophrenia. At the follow-up assessment, there was no significant difference between patients with schizophrenia and controls. These results indicate that retinal dysfunctions are specific for schizophrenia, as compared with bipolar disorder, and are confined to the acute stage of the illness.
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Affiliation(s)
- Zita Balogh
- Semmelweis University, Department of Psychiatry and Psychotherapy, Ballassa u. 6, H1083, Budapest, Hungary
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Kéri S, Benedek G. Visual contrast sensitivity alterations in inferred magnocellular pathways and anomalous perceptual experiences in people at high-risk for psychosis. Vis Neurosci 2007; 24:183-9. [PMID: 17640409 DOI: 10.1017/s0952523807070253] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2006] [Accepted: 03/09/2007] [Indexed: 11/06/2022]
Abstract
Evidence suggests that patients with schizophrenia show impaired performances on tests assessing the magnocellular (M) visual pathway. The aim of this study was to investigate M pathway functioning in persons at high-risk of psychosis. Sixteen high-risk persons at the prodromal phase of psychosis and 20 healthy controls participated. Two types of contrast sensitivity measurements were used, during which participants were asked to detect a briefly presented target Gabor patch. In the pulsed-pedestal paradigm, the luminance of the background field was decreased to saturate M pathways and to bias information processing to parvocellular (P) pathways. In the steady-pedestal paradigm, the luminance of the background field was constant and briefly presented targets were processed by the M pathway. Anomalous perceptual experiences were assessed using the Structured Interview for Assessing Perceptual Anomalies (SIAPA). Results revealed that the high-risk persons showed elevated contrast sensitivity during the M pathway test, and normal sensitivity during the P pathway test. The visual SIAPA scores showed significant positive correlations with the M pathway sensitivity values. These results suggest that the high-risk mental state is associated with hyper-reactive M pathways, which may be responsible for some anomalous perceptual experiences, including abnormal intensity of environmental stimuli, feelings of being flooded and inundated, and inability to focus attention to relevant details.
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Affiliation(s)
- Szabolcs Kéri
- Semmelweis University, Department of Psychiatry and Psychotherapy, Budapest, Hungary.
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Luber B, Stanford AD, Malaspina D, Lisanby SH. Revisiting the backward masking deficit in schizophrenia: individual differences in performance and modeling with transcranial magnetic stimulation. Biol Psychiatry 2007; 62:793-9. [PMID: 17207777 PMCID: PMC3008418 DOI: 10.1016/j.biopsych.2006.10.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2006] [Revised: 10/04/2006] [Accepted: 10/05/2006] [Indexed: 11/18/2022]
Abstract
BACKGROUND Deficits in backward masking have been variably reported in schizophrenia patients, but individual differences in the expression of these deficits have not been explicitly investigated. In addition, increased knowledge of the visual system has opened the door for new techniques such as transcranial magnetic stimulation (TMS) to explore these deficits physiologically. METHODS Patients with schizophrenia and healthy controls were tested using a backward masking paradigm. In order to examine the functionality of visual pathways involved in backward masking, subjects were retested on a backward masking paradigm using single pulse TMS applied to occipital cortex in lieu of the masking stimuli. RESULTS Compared with controls, patients had significantly delayed recovery from visual backward masking. However, 23.5% of patients (compared to 5% of controls) never recovered to levels approaching unmasked performance. When these subjects were segregated from the analysis, group differences vanished. In addition, stimulus masking with occipital TMS followed the same pattern in both patients and controls. CONCLUSIONS Observations of individual differences in visual masking performance may identify a subgroup of schizophrenia patients. The TMS data suggest that this deficit may not localize to the occipital cortex. However, TMS can be a useful tool for localizing processing deficits in schizophrenia.
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Affiliation(s)
- Bruce Luber
- Brain Stimulation and Therapeutic Modulation Division, New York State Psychiatric Institute, New York, New York 10032, USA.
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Abstract
The idea that some phenotypes bear a closer relationship to the biological processes that give rise to psychiatric illness than diagnostic categories has attracted considerable interest. Much effort has been devoted to finding such endophenotypes, partly because it is believed that the genetic basis of endophenotypes will be easier to analyse than that of psychiatric disease. This belief depends in part on the assumption that the effect sizes of genetic loci contributing to endophenotypes are larger than those contributing to disease susceptibility, hence increasing the chance that genetic linkage and association tests will detect them. We examine this assumption by applying meta-analytical techniques to genetic association studies of endophenotypes. We find that the genetic effect sizes of the loci examined to date are no larger than those reported for other phenotypes. A review of the genetic architecture of traits in model organisms also provides no support for the view that the effect sizes of loci contributing to phenotypes closer to the biological basis of disease is any larger than those contributing to disease itself. While endophenotype measures may afford greater reliability, it should not be assumed that they will also demonstrate simpler genetic architecture.
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Affiliation(s)
- JONATHAN FLINT
- Wellcome Trust Centre for Human Genetics, University of
Oxford, Oxford, UK
| | - MARCUS R. MUNAFÒ
- Department of Experimental Psychology, University of
Bristol, Bristol, UK
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Del Cul A, Dehaene S, Leboyer M. Preserved subliminal processing and impaired conscious access in schizophrenia. ARCHIVES OF GENERAL PSYCHIATRY 2006; 63:1313-23. [PMID: 17146006 PMCID: PMC2901353 DOI: 10.1001/archpsyc.63.12.1313] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
BACKGROUND Studies of visual backward masking have frequently revealed an elevated masking threshold in schizophrenia. This finding has frequently been interpreted as indicating a low-level visual deficit. However, more recent models suggest that masking may also involve late and higher-level integrative processes, while leaving intact early bottom-up visual processing. OBJECTIVE To test the hypothesis that the backward-masking deficit in schizophrenia corresponds to a deficit in the late stages of conscious perception, whereas the subliminal processing of masked stimuli is fully preserved. DESIGN Twenty-eight patients with schizophrenia and 28 normal control subjects performed 2 backward-masking experiments. We used Arabic digits as stimuli and varied quasi-continuously the interval with a subsequent mask, thus allowing us to progressively unmask the stimuli. We finely quantified their degree of visibility using objective and subjective measures to evaluate the threshold duration for access to consciousness. We also studied the priming effect caused by the variably masked numbers in a comparison task performed on a subsequently presented and highly visible target number. RESULTS The threshold delay between the digit and mask necessary for the conscious perception of the masked stimulus was longer in patients compared with controls. This higher consciousness threshold in patients was confirmed by an objective and a subjective measure, and both measures were highly correlated for the patients and controls. However, subliminal priming of masked numbers was effective and identical in patients and controls. CONCLUSIONS Access to conscious report of masked stimuli is impaired in schizophrenia, whereas fast bottom-up processing of the same stimuli, as assessed by subliminal priming, is preserved. These findings suggest a high-level origin of the masking deficit in schizophrenia, although they leave open for further research its exact relation to previously identified bottom-up visual processing abnormalities.
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Affiliation(s)
- Antoine Del Cul
- INSERM Unit 562, Cognitive Neuroimaging Unit, Service Hospitalier Frédéric Joliot, Commissariat à l'Energie Atomique, 4 place du General Leclere, Orsay CEDEX 91401, France.
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Cimmer C, Szendi I, Csifcsák G, Szekeres G, Ambrus Kovács Z, Somogyi I, Benedek G, Janka Z, Kéri S. Abnormal neurological signs, visual contrast sensitivity, and the deficit syndrome of schizophrenia. Prog Neuropsychopharmacol Biol Psychiatry 2006; 30:1225-30. [PMID: 16644085 DOI: 10.1016/j.pnpbp.2006.03.021] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
This study was designed to investigate the relationship between abnormal neurological signs, visual contrast sensitivity, and the deficit syndrome of schizophrenia. Visual contrast sensitivity for counterphase-modulated low spatial frequency gratings was measured in 32 non-deficit and 12 deficit schizophrenia patients and 20 healthy controls subjects. Abnormal neurological signs were evaluated with the Neurological Evaluation Scale (NES). Compared with the controls, patients with schizophrenia displayed impaired visual contrast sensitivity, which was associated with sensory integration deficits, as measured with the NES. The deficit syndrome was predicted by negative symptoms and sensory integration deficits. These results suggest that early-stage perceptual dysfunctions, which may reflect the abnormality of precortical magnocellular visual pathways, are related to a specific group of abnormal neurological signs.
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Affiliation(s)
- Csongor Cimmer
- University of Szeged, Department of Psychiatry, Szeged, Hungary
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Delord S, Ducato MG, Pins D, Devinck F, Thomas P, Boucart M, Knoblauch K. Psychophysical assessment of magno- and parvocellular function in
schizophrenia. Vis Neurosci 2006; 23:645-50. [PMID: 16962008 DOI: 10.1017/s0952523806233017] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2005] [Accepted: 11/07/2005] [Indexed: 11/08/2022]
Abstract
Recently developed psychophysical techniques permit the biasing of the
processing of the stimulus by early visual channels so that responses
reflect characteristics of either magno- or parvocellular pathways
(Pokorny & Smith, 1997). We used such
techniques to test psychophysically whether the global magnocellular
dysfunction reported in schizophrenia also affects early processes. Seven
schizophrenic patients and 19 normal controls participated. The task was a
four-alternative forced-choice luminance discrimination, using a 2 ×
2 configuration of four 1-deg squares. Target luminance threshold was
determined in three conditions: the stimulus, including the target, was
pulsed for 17 ms (pulse paradigm); the target was presented on a
steady background of four squares (steady paradigm), or the
target was presented alone (no background paradigm). We
replicated previous results demonstrating magnocellular and parvocellular
signatures in control participants. No evidence for an early magnocellular
deficit could be detected as the thresholds of all schizophrenic observers
were higher both in the steady paradigm (presumed magnocellular mediation)
and in the pulse paradigm (presumed parvocellular mediation).
Magnocellular dysfunction, if present in schizophrenia, must concern more
integrated processes, possibly at levels at which parvocellular and
magnocellular paths interact.
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Affiliation(s)
- Sandrine Delord
- Equipe de Psychologie Cognitive, Laboratoire de Psychologie (EA 3662), Université Bordeaux 2, Bordeaux, France.
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Gutherie AH, McDowell JE, Hammond BR. Scotopic sensitivity in schizophrenia. Schizophr Res 2006; 84:378-85. [PMID: 16626942 DOI: 10.1016/j.schres.2006.02.024] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2005] [Revised: 02/23/2006] [Accepted: 02/28/2006] [Indexed: 11/18/2022]
Abstract
Among participants with schizophrenia there is evidence for early-stage visual processing deficits, which may arise in the rod pathways. Input to the earliest level of this pathway, however, has not been tested in this population. It has been widely hypothesized that schizophrenia participants have magnocellular deficits that occur at the pre-cortical level. To address this hypothesis, we studied absolute scotopic (dark-adapted) sensitivity in fifteen schizophrenia and fifteen matched control participants. Scotopic thresholds were assessed using a 1.85-deg, 510-nm circular test stimulus located at 10 degrees eccentricity in the left visual field and presented in Maxwellian-view. Thresholds were obtained using a two-alternative forced-choice paradigm (an average of 200 trials per participant was obtained). Threshold estimates were derived using probit analysis. In this procedure the transformed binomial data (the inverse of the normal probability integral) is fit with a weighted linear regression. Noise was defined as the average deviation from this line. Lens optical density was also assessed by comparing absolute scotopic thresholds to the extinction spectrum of rhodopsin. Scotopic thresholds and lens density values of the two groups were evaluated using independent samples t-tests. The scotopic thresholds, and associated noise, did not differ between the schizophrenia and control participants. Lens density was also nearly identical between groups. These results suggest that magnocellular deficits in schizophrenia may not be due to problems at the level of the rods but are more likely to occur later in the visual pathway.
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Green MF, Nuechterlein KH, Breitmeyer B, Mintz J. Forward and backward visual masking in unaffected siblings of schizophrenic patients. Biol Psychiatry 2006; 59:446-51. [PMID: 16139818 DOI: 10.1016/j.biopsych.2005.06.035] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2005] [Revised: 05/31/2005] [Accepted: 06/28/2005] [Indexed: 11/22/2022]
Abstract
BACKGROUND Visual masking tasks assess the earliest stages of visual processing. This study examined visual masking performance for forward and backward masking tasks in siblings of schizophrenic patients and healthy comparison subjects. METHODS A staircase method was used to ensure that unmasked target identification was equivalent across subjects to eliminate differences due to discrimination of simple perceptual inputs. Four computerized visual masking tasks were administered to 43 siblings of patients and 42 normal comparison subjects. The tasks included: 1) locating a target; 2) identifying a target with a high-energy mask; 3) identifying a target with a low-energy mask; and 4) a paracontrast/metacontrast procedure with nonoverlapping target and mask. RESULTS Across masking conditions, there was a significant group by forward/backward interaction, meaning that siblings showed a larger difference from control subjects in backward versus forward masking. This group difference was more pronounced in the location condition. CONCLUSIONS These results support the theory that visual masking procedures may be indicators of vulnerability to schizophrenia. The pattern of findings in this report (larger group differences on backward versus forward masking and on the location condition) suggests that the activity of transient visual channels may be particularly linked to vulnerability.
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Affiliation(s)
- Michael F Green
- Department of Psychiatry and Biobehavioral Sciences, Geffen School of Medicine at University of California, Los Angeles, USA.
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Kéri S, Kelemen O, Janka Z, Benedek G. Visual-perceptual dysfunctions are possible endophenotypes of schizophrenia: evidence from the psychophysical investigation of magnocellular and parvocellular pathways. Neuropsychology 2006; 19:649-656. [PMID: 16187883 DOI: 10.1037/0894-4105.19.5.649] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Visual information processing is impaired in schizophrenia patients and their biological relatives. The authors measured vernier thresholds in 72 schizophrenia patients, their 86 siblings, and 60 healthy control subjects. Subjects were asked to detect the direction of the horizontal displacement of 2 stimuli (left or right). During magnocellular (M) pathway tests, stimuli were dots with low contrast (5%) or counterphase-modulated gratings (25 Hz). For parvocellular (P) pathway tests, isoluminant blue-red dots with yellow-green background were used. Results revealed that patients with schizophrenia and their siblings were more impaired in M pathway conditions than in P pathway conditions. There was no color-specific impairment. The patients and their siblings displayed lower performances on tests of executive functions, psychomotor speed, and verbal memory compared with the controls. Visual-perceptual and neuropsychological data did not correlate. In conclusion, M pathway dysfunction is a potential endophenotype of schizophrenia.
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Koelkebeck K, Ohrmann P, Hetzel G, Arolt V, Suslow T. Visual backward masking: deficits in locating targets are specific to schizophrenia and not related to intellectual decline. Schizophr Res 2005; 78:261-8. [PMID: 16154058 DOI: 10.1016/j.schres.2005.01.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2004] [Revised: 01/24/2005] [Accepted: 01/26/2005] [Indexed: 11/21/2022]
Abstract
Visual backward masking deficits have been postulated as potential vulnerability markers for schizophrenia. This study investigated the diagnostic specificity of a location and an identification variant of the backward masking task for schizophrenia and analyzed masking performance during the course of the tasks. The influence of schizophrenia patients' intellectual decline on masking performance was also examined. Twenty-eight schizophrenia patients were compared to 28 patients with unipolar depression and 28 healthy controls on a letter location task and a letter identification task applying a low spatial frequency mask. Schizophrenia patients made significantly more detection errors on the location task than depressives at an interstimulus interval (ISI) of 50 ms and healthy controls at ISIs of 16.7, 33.3, 50, and 66.7 ms. Thus, the location masking dysfunction of schizophrenia patients was distinctive at a rather long interstimulus interval (50 ms). On the identification task the performance of schizophrenia patients did not differ from that of the two control groups. Identification but not location masking performance improved during the course of the task for all groups. Intellectual deterioration of schizophrenia patients was not correlated with location or identification masking performance. Schizophrenia patients are characterized by specific impairments in spatial visual processing which appear to be independent of intellectual decline. Potential explanations of the location masking deficit found in schizophrenia are discussed.
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Affiliation(s)
- Katja Koelkebeck
- Department of Psychiatry, School of Medicine, University of Muenster, Albert-Schweitzer-Strasse 11, 48149, Muenster, Germany.
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Chapman C, Hoag R, Giaschi D. The effect of disrupting the human magnocellular pathway on global motion perception. Vision Res 2005; 44:2551-7. [PMID: 15358070 DOI: 10.1016/j.visres.2004.06.003] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2003] [Revised: 05/28/2004] [Indexed: 11/23/2022]
Abstract
The purpose of this study was to demonstrate the effect of human magnocellular (M)-pathway disruption on global motion perception. Coherence thresholds for global motion direction discrimination in random dot patterns were determined at slow and moderate dot speeds: (1) after adaptation to full-field sinusoidal flicker or a steady gray field, and (2) on a red or a gray background. Adaptation to flicker and a red background increased motion coherence thresholds relative to the gray baseline conditions at both dot speeds. Physiological studies have shown that M cells in the retina and LGN are inhibited by red light and are a main contributor to flicker perception in monkeys. Therefore, our results suggest that interference with processing in the subcortical M pathway disrupts higher-level motion integration.
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Affiliation(s)
- Craig Chapman
- Department of Ophthalmology and Visual Sciences, University of British Columbia, 4480 Oak Street, Room A146, Vancouver, BC, Canada V6H 3V4
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Bedwell JS, Esposito S, Miller LS. Accelerated age-related decline of visual information processing in first-degree relatives of persons with schizophrenia. Psychiatry Res 2004; 125:225-35. [PMID: 15051183 DOI: 10.1016/j.psychres.2003.12.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2003] [Revised: 10/02/2003] [Accepted: 12/22/2003] [Indexed: 11/30/2022]
Abstract
A recent cross-sectional study suggested that persons with schizophrenia experience an accelerated age-related decline in performance on the Span of Apprehension task, a visual information processing paradigm. However, this study was not able to determine if such decline was primarily related to genetic loading for schizophrenia, as the decline may have been related to chronic neuroleptic use or other confounds found when studying persons with schizophrenia directly. To help address this question, the current study examined healthy first-degree relatives of persons with schizophrenia over a wide age range to investigate whether such age effects may be related to genetic loading for schizophrenia. Twenty-eight healthy first-degree relatives of persons with schizophrenia (ages 21-72) and 31 healthy controls (ages 19-75) were evaluated using the Span of Apprehension task with cross-sectional methodology. Results replicated and extended the earlier report examining persons with schizophrenia, as the data indicated a statistically significant accelerated age-related decline in performance in the relatives. While the study is limited by cross-sectional methodology, it suggests a genetically driven, age-related decline in visual information processing related to schizophrenia and informs future longitudinal studies that can more definitively address such a possibility.
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Affiliation(s)
- Jeffrey S Bedwell
- Psychology Department, Clinical Psychology Program, University of Georgia, Athens, GA 30602, USA.
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