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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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Barch DM, Boudewyn MA, Carter CC, Erickson M, Frank MJ, Gold JM, Luck SJ, MacDonald AW, Ragland JD, Ranganath C, Silverstein SM, Yonelinas A. Cognitive [Computational] Neuroscience Test Reliability and Clinical Applications for Serious Mental Illness (CNTRaCS) Consortium: Progress and Future Directions. Curr Top Behav Neurosci 2022; 63:19-60. [PMID: 36173600 DOI: 10.1007/7854_2022_391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The development of treatments for impaired cognition in schizophrenia has been characterized as the most important challenge facing psychiatry at the beginning of the twenty-first century. The Cognitive Neuroscience Treatment Research to Improve Cognition in Schizophrenia (CNTRICS) project was designed to build on the potential benefits of using tasks and tools from cognitive neuroscience to better understanding and treat cognitive impairments in psychosis. These benefits include: (1) the use of fine-grained tasks that measure discrete cognitive processes; (2) the ability to design tasks that distinguish between specific cognitive domain deficits and poor performance due to generalized deficits resulting from sedation, low motivation, poor test taking skills, etc.; and (3) the ability to link cognitive deficits to specific neural systems, using animal models, neuropsychology, and functional imaging. CNTRICS convened a series of meetings to identify paradigms from cognitive neuroscience that maximize these benefits and identified the steps need for translation into use in clinical populations. The Cognitive Neuroscience Test Reliability and Clinical Applications for Schizophrenia (CNTRaCS) Consortium was developed to help carry out these steps. CNTRaCS consists of investigators at five different sites across the country with diverse expertise relevant to a wide range of the cognitive systems identified as critical as part of CNTRICs. This work reports on the progress and current directions in the evaluation and optimization carried out by CNTRaCS of the tasks identified as part of the original CNTRICs process, as well as subsequent extensions into the Positive Valence systems domain of Research Domain Criteria (RDoC). We also describe the current focus of CNTRaCS, which involves taking a computational psychiatry approach to measuring cognitive and motivational function across the spectrum of psychosis. Specifically, the current iteration of CNTRaCS is using computational modeling to isolate parameters reflecting potentially more specific cognitive and visual processes that may provide greater interpretability in understanding shared and distinct impairments across psychiatric disorders.
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Affiliation(s)
- Deanna M Barch
- Department of Psychological & Brain Sciences, Washington University in St. Louis, St. Louis, MO, USA.
| | | | | | | | | | - James M Gold
- Maryland Psychiatric Research Center, Baltimore, MD, USA
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3
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Non-invasive neurostimulation modulates processing of spatial frequency information in rapid perception of faces. Atten Percept Psychophys 2021; 84:150-160. [PMID: 34668174 DOI: 10.3758/s13414-021-02384-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/21/2021] [Indexed: 11/08/2022]
Abstract
This study used high-frequency transcranial random noise stimulation (tRNS) to examine how low and high spatial frequency filtered faces are processed. Response times were measured in a task where healthy young adults categorised spatially filtered hybrid faces, presented at foveal and peripheral blocks, while sham and high-frequency random noise was applied to a lateral occipito-temporal location on their scalp. Both the Frequentist and Bayesian approaches show that in contrast to sham, active stimulation significantly reduced response times to peripherally presented low spatial frequency information. This finding points to a possible plasticity in targeted regions induced by non-invasive neuromodulation of spatial frequency information in rapid perception of faces.
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Silverstein SM, Lai A. The Phenomenology and Neurobiology of Visual Distortions and Hallucinations in Schizophrenia: An Update. Front Psychiatry 2021; 12:684720. [PMID: 34177665 PMCID: PMC8226016 DOI: 10.3389/fpsyt.2021.684720] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 05/14/2021] [Indexed: 12/15/2022] Open
Abstract
Schizophrenia is characterized by visual distortions in ~60% of cases, and visual hallucinations (VH) in ~25-50% of cases, depending on the sample. These symptoms have received relatively little attention in the literature, perhaps due to the higher rate of auditory vs. visual hallucinations in psychotic disorders, which is the reverse of what is found in other neuropsychiatric conditions. Given the clinical significance of these perceptual disturbances, our aim is to help address this gap by updating and expanding upon prior reviews. Specifically, we: (1) present findings on the nature and frequency of VH and distortions in schizophrenia; (2) review proposed syndromes of VH in neuro-ophthalmology and neuropsychiatry, and discuss the extent to which these characterize VH in schizophrenia; (3) review potential cortical mechanisms of VH in schizophrenia; (4) review retinal changes that could contribute to VH in schizophrenia; (5) discuss relationships between findings from laboratory measures of visual processing and VH in schizophrenia; and (6) integrate findings across biological and psychological levels to propose an updated model of VH mechanisms, including how their content is determined, and how they may reflect vulnerabilities in the maintenance of a sense of self. In particular, we emphasize the potential role of alterations at multiple points in the visual pathway, including the retina, the roles of multiple neurotransmitters, and the role of a combination of disinhibited default mode network activity and enhanced state-related apical/contextual drive in determining the onset and content of VH. In short, our goal is to cast a fresh light on the under-studied symptoms of VH and visual distortions in schizophrenia for the purposes of informing future work on mechanisms and the development of targeted therapeutic interventions.
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Affiliation(s)
- Steven M Silverstein
- Department of Psychiatry, University of Rochester Medical Center, Rochester, NY, United States.,Department of Neuroscience, University of Rochester Medical Center, Rochester, NY, United States.,Department of Ophthalmology, University of Rochester Medical Center, Rochester, NY, United States.,Center for Visual Science, University of Rochester Medical Center, Rochester, NY, United States
| | - Adriann Lai
- Department of Psychiatry, University of Rochester Medical Center, Rochester, NY, United States
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Dahdouh O, Haddad C, Hany Z, Azar G, Lahoud C, Hallit S, Hachem D. Colour discrimination among patients with schizophrenia in Lebanon. Int J Psychiatry Clin Pract 2020; 24:193-200. [PMID: 31916882 DOI: 10.1080/13651501.2019.1711421] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Background: Abnormalities and contrast sensitivity have already been studied in schizophrenia. However, the relationship between symptom severity in schizophrenia and colour vision sensitivity has not been studied systematically.Aim: Our objective was to evaluate colour discrimination in patients with schizophrenia compared to controls and examine if this colour discrimination is correlated with schizophrenia symptoms' severity.Methods: This case-control study, performed between January and April 2017, included 50 schizophrenic patients and 50 healthy controls matched for age and sex. The Positive and Negative Symptoms Scale (PANSS) was used to determine the schizophrenia symptoms' severity. Colour discrimination was evaluated using the total error score (TES) generated using the Farnsworth D-15 test. The higher the TES, the more severe colourblindness.Results: A significantly higher mean TES was found in schizophrenics (30.32) compared to healthy patients (13.07) (p < 0.001). Colour blindness was correlated to the severity of schizophrenic symptoms only in the subgroup of patients with severe schizophrenia.Conclusion: Colour vision defect is a common feature in schizophrenia, and may be more significant when related to psychotic symptoms.KEY POINTSA significantly higher mean TES was found in schizophrenics compared to healthy patients.Colour blindness was correlated to the severity of schizophrenic symptoms only in the subgroup of patients with severe schizophrenia.Colour vision defect is a common feature in schizophrenia, and may be more significant when related to psychotic symptoms.
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Affiliation(s)
| | - Chadia Haddad
- Psychiatric Hospital of the Cross, Jal Eddib, Lebanon
| | - Zeina Hany
- Psychiatric Hospital of the Cross, Jal Eddib, Lebanon
| | - Georges Azar
- Faculty of Medicine and Medical Sciences, Holy Spirit University of Kaslik (USEK), Jounieh, Lebanon
| | - Corinne Lahoud
- Faculty of Medicine and Medical Sciences, Holy Spirit University of Kaslik (USEK), Jounieh, Lebanon
| | - Souheil Hallit
- Faculty of Medicine and Medical Sciences, Holy Spirit University of Kaslik (USEK), Jounieh, Lebanon.,INSPECT-LB: Institut National de Sante Publique, Epidemiologie Clinique et Toxicologie, Beirut, Lebanon
| | - Dory Hachem
- Psychiatric Hospital of the Cross, Jal Eddib, Lebanon
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Wästlund E, Shams P, Otterbring T. Unsold is unseen … or is it? Examining the role of peripheral vision in the consumer choice process using eye-tracking methodology. Appetite 2018; 120:49-56. [DOI: 10.1016/j.appet.2017.08.024] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Revised: 08/11/2017] [Accepted: 08/23/2017] [Indexed: 10/19/2022]
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Timucin OB, Mutlu EA, Timucin D, Aslanci ME, Isikligil I, Karadag MF, Kizildag Ozbay E. Psychophysical assessment of koniocellular pathway in patients with schizophrenia versus healthy controls. Psychiatry Res Neuroimaging 2017; 266:27-34. [PMID: 28577432 DOI: 10.1016/j.pscychresns.2017.05.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Revised: 05/25/2017] [Accepted: 05/26/2017] [Indexed: 10/19/2022]
Abstract
This study was designed to perform psychophysical assessment of koniocellular pathway in patients with schizophrenia versus healthy controls. A total of 26 patients diagnosed with schizophrenia and 15 healthy controls were included. Snellen Visual Acuity Chart scores and Short Wavelength Automated Perimetry (SWAP) visual field testing including global visual field indices [mean deviation (MD), pattern standard deviation (PSD), test time (min)], reliability parameters [false negative responses (%), false positive responses (%) and fixed losses (%)] and average threshold sensitivity [central (parafovea), peripheral area, and four quadrants] were recorded in both groups. Significantly lower MD scores, higher PSD scores and lower average threshold sensitivity at each location across the visual field were noted in schizophrenia relative to control group. In conclusion, our findings revealed a deficit in koniocellular pathway with impaired SWAP global indices and lower threshold sensitivity at each location across the visual field among chronic schizophrenic patients as compared with control subjects. Our findings emphasize potential application of SWAP outside its original intended purpose as a glaucoma test, to provide deeper understanding of the specific contribution of lateral geniculate nucleus to the visual and cognitive disturbances of schizophrenia.
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Affiliation(s)
| | | | - Damla Timucin
- Department of Psychiatry, Van Training and Research Hospital, Van, Turkey
| | | | - Isil Isikligil
- Department of Ophthalmology Van Training and Research Hospital, Van, Turkey
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Gracitelli CPB, Abe RY, Diniz-Filho A, Vaz-de-Lima FB, Paranhos A, Medeiros FA. Ophthalmology issues in schizophrenia. Curr Psychiatry Rep 2015; 17:28. [PMID: 25773224 PMCID: PMC4523638 DOI: 10.1007/s11920-015-0569-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Schizophrenia is a complex mental disorder associated with not only cognitive dysfunctions, such as memory and attention deficits, but also changes in basic sensory processing. Although most studies on schizophrenia have focused on disturbances in higher-order brain functions associated with the prefrontal cortex or frontal cortex, recent investigations have also reported abnormalities in low-level sensory processes, such as the visual system. At very early stages of the disease, schizophrenia patients frequently describe in detail symptoms of a disturbance in various aspects of visual perception that may lead to worse clinical symptoms and decrease in quality of life. Therefore, the aim of this review is to describe the various studies that have explored the visual issues in schizophrenia.
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Affiliation(s)
- Carolina P. B. Gracitelli
- Hamilton Glaucoma Center and Department of Ophthalmology, University of California, 9500 Gilman Drive, La Jolla, CA 92093-0946, USA; Department of Ophthalmology, Federal University of São Paulo, Botucatu Street, 821. Vila Clementino, São Paulo, SP 04023-062, Brazil
| | - Ricardo Y. Abe
- Hamilton Glaucoma Center and Department of Ophthalmology, University of California, 9500 Gilman Drive, La Jolla, CA 92093-0946, USA; ; Department of Ophthalmology, University of Campinas, Vital Brasil Street, 251, Cidade Universitária Zeferino Vaz, Campinas, SP 13083-970, Brazil
| | - Alberto Diniz-Filho
- Hamilton Glaucoma Center and Department of Ophthalmology, University of California, 9500 Gilman Drive, La Jolla, CA 92093-0946, USA; ; Department of Ophthalmology and Otorhinolaryngology, Federal University of Minas Gerais, Alfredo Balena Avenue, 190 Santa Efigenia, Belo Horizonte, MG 30130-100, Brazil
| | | | - Augusto Paranhos
- Department of Ophthalmology, Federal University of São Paulo, Botucatu Street, 821. Vila Clementino, São Paulo, SP 04023-062, Brazil;
| | - Felipe A. Medeiros
- Hamilton Glaucoma Center and Department of Ophthalmology, University of California, 9500 Gilman Drive, La Jolla, CA 92093-0946, USA;
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9
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Contrast Sensitivity in Patients with Schizophrenia of Different Durations of Illness. ACTA ACUST UNITED AC 2015. [DOI: 10.1007/s11055-015-0103-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Cavalcanti-Galdino MK, Silva JAD, Mendes LC, Santos NAD, Simas MLB. Acute effect of alcohol intake on sine-wave Cartesian and polar contrast sensitivity functions. ACTA ACUST UNITED AC 2014; 47:321-7. [PMID: 24676473 PMCID: PMC4075296 DOI: 10.1590/1414-431x20143209] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Accepted: 01/22/2014] [Indexed: 11/21/2022]
Abstract
The aim of this study was to assess contrast sensitivity for angular frequency
stimuli as well as for sine-wave gratings in adults under the effect of acute
ingestion of alcohol. We measured the contrast sensitivity function (CSF) for
gratings of 0.25, 1.25, 2.5, 4, 10, and 20 cycles per degree of visual angle (cpd) as
well as for angular frequency stimuli of 1, 2, 4, 24, 48, and 96 cycles/360°. Twenty
adults free of ocular diseases, with normal or corrected-to-normal visual acuity, and
no history of alcoholism were enrolled in two experimental groups: 1) no alcohol
intake (control group) and 2) alcohol ingestion (experimental group). The average
concentration of alcohol in the experimental group was set to about 0.08%. We used a
paradigm involving a forced-choice method. Maximum sensitivity to contrast for
sine-wave gratings in the two groups occurred at 4 cpd sine-wave gratings and at 24
and 48 cycles/360° for angular frequency stimuli. Significant changes in contrast
sensitivity were observed after alcohol intake compared with the control condition at
spatial frequency of 4 cpd and 1, 24, and 48 cycles/360° for angular frequency
stimuli. Alcohol intake seems to affect the processing of sine-wave gratings at
maximum sensitivity and at the low and high frequency ends for angular frequency
stimuli, both under photopic luminance conditions.
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Affiliation(s)
| | - J A da Silva
- Departamento de Psicologia, Universidade Federal da Paraíba, João Pessoa, PB, Brasil
| | - L C Mendes
- Departamento de Psicologia, Pontifícia Universidade Católica do Rio de Janeiro, Rio de Janeiro, RJ, Brasil
| | - N A da Santos
- Departamento de Psicologia, Universidade Federal da Paraíba, João Pessoa, PB, Brasil
| | - M L B Simas
- Departamento de Psicologia, Universidade Federal de Pernambuco, Recife, PE, Brasil
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Khosravani N, Goodarzi MA. Patients with schizophrenia show deficits on spatial frequency doubling. Vision Res 2013; 93:49-53. [PMID: 24140959 DOI: 10.1016/j.visres.2013.10.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Revised: 10/04/2013] [Accepted: 10/07/2013] [Indexed: 11/16/2022]
Abstract
There are pieces of evidence indicating that visual deficits in patients with schizophrenia can be attributed to a deficiency in the magnocellular portion of the early visual system. The main objective of this study was to investigate the neurological dysfunction of the magnocellular pathway in patients with schizophrenia using the frequency doubling technology perimetry (FDT). The FDT has been developed based on particular neural magnocellular characteristics and can examine the magnocellular dysfunction hypothesis in schizophrenia. Twenty patients with schizophrenia (12 males and 8 females) and 20 normal subjects (10 males and 10 females) participated in this study. The spatial frequency doubling task was presented via the Humphrey perimetry instrument in order to examine the magnocellular pathway of the participants. Patients with schizophrenia showed less visual field sensitivity than normal controls and their standardized age cohort in both eyes (p<0.001). The results indicated impaired visual field sensitivity deficits in patients with schizophrenia that can be attributed to a deficit in the magnocellular neural pathways. This Magnocellular pathway defect may provide a physiological base to explain some of the deficits caused by schizophrenia such as cognitive deficits.
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Affiliation(s)
- Neda Khosravani
- Department of Clinical Psychology, College of Education and Psychology, Shiraz University, Shiraz, Iran
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Cadenhead KS, Dobkins K, McGovern J, Shafer K. Schizophrenia spectrum participants have reduced visual contrast sensitivity to chromatic (red/green) and luminance (light/dark) stimuli: new insights into information processing, visual channel function, and antipsychotic effects. Front Psychol 2013; 4:535. [PMID: 23970874 PMCID: PMC3747446 DOI: 10.3389/fpsyg.2013.00535] [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: 04/29/2013] [Accepted: 07/30/2013] [Indexed: 11/13/2022] Open
Abstract
Background: Individuals with schizophrenia spectrum diagnoses have deficient visual information processing as assessed by a variety of paradigms including visual backward masking, motion perception and visual contrast sensitivity (VCS). In the present study, the VCS paradigm was used to investigate potential differences in magnocellular (M) vs. parvocellular (P) channel function that might account for the observed information processing deficits of schizophrenia spectrum patients. Specifically, VCS for near threshold luminance (black/white) stimuli is known to be governed primarily by the M channel, while VCS for near threshold chromatic (red/green) stimuli is governed by the P channel. Methods: VCS for luminance and chromatic stimuli (counterphase-reversing sinusoidal gratings, 1.22 c/degree, 8.3 Hz) was assessed in 53 patients with schizophrenia (including 5 off antipsychotic medication), 22 individuals diagnosed with schizotypal personality disorder and 53 healthy comparison subjects. Results: Schizophrenia spectrum groups demonstrated reduced VCS in both conditions relative to normals, and there was no significant group by condition interaction effect. Post-hoc analyses suggest that it was the patients with schizophrenia on antipsychotic medication as well as SPD participants who accounted for the deficits in the luminance condition. Conclusions: These results demonstrate visual information processing deficits in schizophrenia spectrum populations but do not support the notion of selective abnormalities in the function of subcortical channels as suggested by previous studies. Further work is needed in a longitudinal design to further assess VCS as a vulnerability marker for psychosis as well as the effect of antipsychotic agents on performance in schizophrenia spectrum populations.
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Affiliation(s)
- Kristin S Cadenhead
- Department of Psychiatry, University of California San Diego La Jolla, CA, USA
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Abstract
Abnormal perceptual experiences are central to schizophrenia but the nature of these anomalies remains undetermined. We investigated contextual processing abnormalities across a comprehensive set of visual tasks. For perception of luminance, size, contrast, orientation and motion, we quantified the degree to which the surrounding visual context altered a center stimulus' appearance. Across tasks, healthy participants showed robust contextual effects, as evidenced by pronounced misperceptions of center stimuli. Schizophrenia patients exhibited intact contextual modulations of luminance and size, but showed weakened contextual modulations of contrast, performing more accurately than controls. Strong motion and orientation context effects correlated with worse symptoms and social functioning. Importantly, the overall strength of contextual modulation across tasks did not differ between controls and schizophrenia patients. Additionally, performance measures across contextual tasks were uncorrelated, implying discrete underlying processes. These findings reveal that abnormal contextual modulation in schizophrenia is selective, arguing against the proposed unitary contextual processing dysfunction.
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Affiliation(s)
- Eunice Yang
- Department of Psychology, Vanderbilt University, Nashville, TN USA ; Department of Brain and Cognitive Sciences, Seoul National University, Seoul, Republic of Korea
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Abstract
There is evidence to indicate that schizophrenic individuals, in addition to cognitive deficiencies, also suffer from visual deficits. These deficits, it has been proposed, are the result of a deficiency in the magnocellular portion of the early visual system. A number of approaches have been used in attempts to assess the sensitivity of the magnocellular system in individuals with schizophrenia. It has recently been proposed that magnocellular sensitivity can be tested by measuring stereo acuity, i.e. by measuring the accuracy with which visual depth can be detected based on differences in the retinal images in the two eyes. This suggestion was based on early claims which linked stereopsis, i.e. the visual perception of depth generated from differences in the two retinal images, to the magnocellular system. We here review more recent results which indicate that stereopsis and stereo acuity are more closely linked to the parvocellular system. It is concluded that stereo acuity is not an appropriate test for assessing magnocellular sensitivity. The present considerations undermine the claim that magnocellular deficits are linked to schizophrenia.
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Santos NAD, França VDCRDM, Alves PADA. Diferenças na detecção de frequências espaciais e radiais em crianças. PSICOLOGIA: TEORIA E PESQUISA 2009. [DOI: 10.1590/s0102-37722009000400013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
O objetivo deste estudo foi comparar curvas de sensibilidade ao contraste para estímulos radiais (FSCr) e grades senoidais (FSC) de 0,25, 0,5, 1 e 2 cpg em crianças de 6 a 13 anos. Foram mensurados limiares de contraste para 40 crianças, utilizando o método psicofísico da escolha forçada e níveis baixos de luminância. Todas estavam livres de doenças oculares e tinham acuidade visual normal. Os resultados mostraram que a sensibilidade das crianças foi maior para grades senoidais (FSC) do que para estímulos radiais (FSCr). Esses resultados sugerem que esses estímulos podem ser processados por áreas visuais distintas.
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Santos NAD, Mendes LC, França VDCRDM, Lacerda AM. Detecção de estímulos concêntricos mesópicos em crianças surdas e ouvintes. PSICOLOGIA: TEORIA E PESQUISA 2009. [DOI: 10.1590/s0102-37722009000200006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
O objetivo deste trabalho foi medir curvas de sensibilidade ao contraste de 10 crianças ouvintes e de 10 crianças com surdez pré-lingual, de 7 a 12 anos, utilizando frequências radiais circularmente concêntricas (FSCr) de 0,25-2,0 cpg em níveis baixos de luminância (0,7 cd/m²). Todos os participantes apresentavam acuidade visual normal e estavam livres de doenças oculares identificáveis. A FSCr foi medida com o método psicofísico da escolha forçada. Os resultados mostraram sensibilidade máxima na faixa de frequência radial de 0,25 cpg para os dois grupos. Os resultados mostraram ainda diferenças significantes entre as curvas de FSCr de crianças ouvintes e de crianças com surdez pré-lingual. Isto é, as crianças ouvintes precisaram de menos contraste do que as crianças surdas para detectar as frequências radiais. Esses resultados sugerem que, em níveis baixos de luminância, a FSCr das crianças ouvintes foi melhor do que a das crianças com surdez pré-lingual.
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Cavalcanti MK, Santos NAD. Alterações na sensibilidade ao contraste relacionadas à ingestão de álcool. PSICOLOGIA: TEORIA E PESQUISA 2008. [DOI: 10.1590/s0102-37722008000400015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
O objetivo deste trabalho foi caracterizar a função de sensibilidade ao contraste (FSC) para freqüências espaciais de 0,25, 1,0 e 4,0 cpg (ciclos por grau de ângulo visual) na ausência (Grupo Controle-GC) e após a ingestão moderada de álcool (Grupo Experimental-GE). Para tanto, foi utilizado o método psicofísico da escolha forçada. Participaram do estudo quatro mulheres, de 21 a 30 anos, com acuidade visual normal ou corrigida. Os resultados mostraram diferenças significativas entre os grupos na freqüência de 4,0 cpg (p = 0,039), sendo o GE mais sensível ao contraste do que o GC. Estes resultados sugerem alterações na FSC relacionadas à ingestão moderada de álcool.
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Butler PD, Tambini A, Yovel G, Jalbrzikowski M, Ziwich R, Silipo G, Kanwisher N, Javitt DC. What's in a face? Effects of stimulus duration and inversion on face processing in schizophrenia. Schizophr Res 2008; 103:283-92. [PMID: 18450426 PMCID: PMC2755251 DOI: 10.1016/j.schres.2008.03.007] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2007] [Revised: 03/05/2008] [Accepted: 03/07/2008] [Indexed: 11/15/2022]
Abstract
A number of studies show deficits in early-stage visual processing in schizophrenia. Deficits are also seen at more complex levels, such as ability to discriminate faces. This study investigated the "face inversion" effect, which reflects intrinsic cortical processing within the ventral visual stream, as well as contrast sensitivity, which reflects low-level visual processing, in order to evaluate integrity of specific stages of face processing in schizophrenia. Patients with schizophrenia and controls discriminated between pairs of upright or inverted faces or houses that had been manipulated to differ in the shape of the parts or the spatial distance among parts. The duration threshold for above chance performance on upright stimuli was obtained for patients using a house discrimination task. Contrast sensitivity was assessed for gratings of three spatial frequencies ranging from 0.5 to 21 cycles/degree. Patients needed significantly longer time to obtain 70% correct for upright stimuli and showed decreased contrast sensitivity. Increased duration threshold correlated with reduced contrast sensitivity to low (magnocellular-biased) but not medium or high spatial frequency stimuli. Using increased durations, patients showed significant inversion effects that were equivalent to those of controls on the face part and spacing tasks. Like controls, patients did not show inversion effects on the house tasks. These findings show that patients have difficulty integrating visual information as shown by increased duration thresholds. However, when faces were presented at these longer duration thresholds, patients showed the same relative processing ability for upright vs. inverted faces as controls, suggesting preserved intrinsic processing within cortical face processing regions. Similar inversion effects for face part and spacing for both groups suggest that they are using the same holistic face processing mechanism.
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Affiliation(s)
- Pamela D. Butler
- Cognitive Neuroscience and Schizophrenia Program, Nathan Kline Institute for Psychiatric Research, Orangeburg, NY 10962, United States, Department of Psychiatry, New York University School of Medicine, New York, NY 10016, United States, City College of the City University of New York, New York, NY 10031, United States, Corresponding author. Nathan Kline Institute for Psychiatric Research, 140 Old Orangeburg Road, Orangeburg NY, 10962, United States. Tel.: +1 845 398 6537; fax: +1 845 398 6545. (P.D. Butler)
| | - Arielle Tambini
- McGovern Institute for Brain Research, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Galit Yovel
- McGovern Institute for Brain Research, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Maria Jalbrzikowski
- Cognitive Neuroscience and Schizophrenia Program, Nathan Kline Institute for Psychiatric Research, Orangeburg, NY 10962, United States
| | - Rachel Ziwich
- Cognitive Neuroscience and Schizophrenia Program, Nathan Kline Institute for Psychiatric Research, Orangeburg, NY 10962, United States
| | - Gail Silipo
- Cognitive Neuroscience and Schizophrenia Program, Nathan Kline Institute for Psychiatric Research, Orangeburg, NY 10962, United States
| | - Nancy Kanwisher
- McGovern Institute for Brain Research, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Daniel C. Javitt
- Cognitive Neuroscience and Schizophrenia Program, Nathan Kline Institute for Psychiatric Research, Orangeburg, NY 10962, United States, Department of Psychiatry, New York University School of Medicine, New York, NY 10016, United States, City College of the City University of New York, New York, NY 10031, United States
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Butler PD, Silverstein SM, Dakin SC. Visual perception and its impairment in schizophrenia. Biol Psychiatry 2008; 64:40-7. [PMID: 18549875 PMCID: PMC2435292 DOI: 10.1016/j.biopsych.2008.03.023] [Citation(s) in RCA: 317] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2008] [Revised: 03/11/2008] [Accepted: 03/26/2008] [Indexed: 02/07/2023]
Abstract
Much work in the cognitive neuroscience of schizophrenia has focused on attention, memory, and executive functioning. To date, less work has focused on perceptual processing. However, perceptual functions are frequently disrupted in schizophrenia, and thus this domain has been included in the CNTRICS (Cognitive Neuroscience Treatment Research to Improve Cognition in Schizophrenia) project. In this article, we describe the basic science presentation and the breakout group discussion on the topic of perception from the first CNTRICS meeting, held in Bethesda, Maryland on February 26 and 27, 2007. The importance of perceptual dysfunction in schizophrenia, the nature of perceptual abnormalities in this disorder, and the critical need to develop perceptual tests appropriate for future clinical trials were discussed. Although deficits are also seen in auditory, olfactory, and somatosensory processing in schizophrenia, the first CNTRICS meeting focused on visual processing deficits. Key concepts of gain control and integration in visual perception were introduced. Definitions and examples of these concepts are provided in this article. Use of visual gain control and integration fit a number of the criteria suggested by the CNTRICS committee, provide fundamental constructs for understanding the visual system in schizophrenia, and are inclusive of both lower-level and higher-level perceptual deficits.
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Affiliation(s)
- Pamela D Butler
- Nathan Kline Institute for Psychiatric Research, Orangeburg, NY 10962, USA.
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20
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Santos NAD, França VDCRDM. Sensibilidade ao contraste a grades senoidais de freqüências espaciais baixas em crianças. ESTUDOS DE PSICOLOGIA (CAMPINAS) 2008. [DOI: 10.1590/s0103-166x2008000200002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
O objetivo deste trabalho foi determinar a função de sensibilidade ao contraste para freqüências espaciais de 0,25; 0,5; 1,0 e 2,0 ciclos por grau em crianças de 4 a 13 anos. Foram estimados limiares de contraste para 60 participantes (50 crianças e 10 adultos jovens), utilizando o método psicofísico da escolha forçada e nível baixo de luminância. Todos os participantes apresentavam acuidade visual normal e se encontravam livres de doenças oculares identificáveis. Os resultados mostraram que a função de sensibilidade ao contraste de crianças de 4-5, 6-7, 8-9, 10-11 e 12-13 anos melhora significativamente com a idade. Os resultados mostraram ainda que a função de sensibilidade ao contraste de crianças de 12-13 anos é semelhante à de adultos jovens (19-22 anos). Estes resultados sugerem que o desenvolvimento da função de sensibilidade ao contraste para grade senoidal em nível baixo de luminância melhora até os 12-13 anos.
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Skottun BC, Skoyles JR. Contrast sensitivity and magnocellular functioning in schizophrenia. Vision Res 2007; 47:2923-33. [PMID: 17825350 DOI: 10.1016/j.visres.2007.07.016] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2007] [Revised: 07/09/2007] [Accepted: 07/11/2007] [Indexed: 12/01/2022]
Abstract
It has been suggested that schizophrenia is associated with a magnocellular deficit. This would predict a loss of contrast sensitivity at low spatial and/or at high temporal frequencies. We here review research that tested contrast sensitivity in individuals with schizophrenia. We find that the results of this research tend to show uniform reductions in contrast sensitivity that are generally not consistent with a magnocellular deficit. While much of this data may be consistent with an attentional deficiency on the part of the schizophrenic individuals, it is difficult to link such an attentional deficiency specifically to the magnocellular system. The conclusion of the present review is that contrast sensitivity data do not indicate the existence of an association between magnocellular deficits and schizophrenia.
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Skottun BC, Skoyles JR. A few remarks on attention and magnocellular deficits in schizophrenia. Neurosci Biobehav Rev 2007; 32:118-22. [PMID: 17651801 DOI: 10.1016/j.neubiorev.2007.06.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2007] [Revised: 06/04/2007] [Accepted: 06/05/2007] [Indexed: 11/29/2022]
Abstract
In connection with schizophrenia, it has been proposed that the magnocellular system is specifically linked to the guiding of covert visual attention. The argument is that the magnocellular pathway provides input to the dorsal cortical stream which then projects back to area V1. We review problems with this model. (1) It requires that responses in the magnocellular system have a lead time over responses in the parvocellular system. However, measurements indicate that the actual response time difference between the two systems is small or negligible when entering the visual cortex. (2) Attention can be modified by stimuli that do not activate the magnocellular system. And, (3) lesions to area MT in the dorsal stream impair smooth pursuit eye movements, but not saccadic eye movements which are associated with shifts in attention. For these reasons, it is difficult to link attention defects in schizophrenia to potential magnocellular deficits.
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Slaghuis WL, Hawkes A, Holthouse T, Bruno R. Eye movement and visual motion perception in schizophrenia I: Apparent motion evoked smooth pursuit eye movement reveals a hidden dysfunction in smooth pursuit eye movement in schizophrenia. Exp Brain Res 2007; 182:399-413. [PMID: 17576546 DOI: 10.1007/s00221-007-1000-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2006] [Accepted: 05/19/2007] [Indexed: 11/27/2022]
Abstract
To date, smooth pursuit eye movement in schizophrenia has only been investigated using a target stimulus in continuous motion. However, smooth pursuit can also be evoked by an oscillating jumping dot that appears to be in apparent motion and although there is no continuous motion on the retinal surface this apparently moving stimulus can effortlessly elicit smooth-pursuit eye movement. In the first of two experiments smooth pursuit eye movement was evoked by target stimuli in continuous (real) motion at seven target velocities from 5.0 to 35.0 deg/s, and in a second experiment it was measured in response to an oscillating jumping dot in apparent motion at eight target velocities from 5.0 to 25.0 deg/s in a group with mixed-symptoms in schizophrenia and in a control group. The results of Experiment 1 provided no evidence for a dysfunction in continuous motion evoked smooth pursuit eye movement in the group with schizophrenia. However, following the removal of saccadic eye movements in smooth pursuit, the group with schizophrenia showed significantly lower smooth pursuit eye velocity at target velocities from 20.0 to 35.0 deg/s. The results of Experiment 2 revealed that apparent motion evoked smooth pursuit eye velocity in the group with schizophrenia was significantly lower in comparison with normal observers at all target velocities up to 25.0 deg/s with the inclusion or exclusion of saccadic eye movements. The findings demonstrate that overall smooth pursuit eye movement evoked in response to a continuous (real) motion target in the group with schizophrenia may nevertheless contain a hidden temporal resolution and integration dysfunction that is revealed when smooth pursuit eye movement is evoked in response to an oscillating jumping dot in apparent motion. The findings also demonstrate that normal smooth pursuit eye movement in normal observers can be made to resemble the dysfunctional smooth pursuit eye movement that is naturally found in some people with schizophrenia by using a target stimulus in apparent motion.
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Affiliation(s)
- W L Slaghuis
- School of Psychology, University of Tasmania, Hobart, Tasmania, 7001, Australia.
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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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Kim D, Zemon V, Saperstein A, Butler PD, Javitt DC. Dysfunction of early-stage visual processing in schizophrenia: harmonic analysis. Schizophr Res 2005; 76:55-65. [PMID: 15927798 DOI: 10.1016/j.schres.2004.10.011] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2003] [Revised: 10/11/2004] [Accepted: 10/13/2004] [Indexed: 11/16/2022]
Abstract
Schizophrenia is associated with severe neurocognitive deficits that constitute a core feature of the disorder. Deficits have been most extensively studied in relationship to higher-order processes. This study evaluated the integrity of early visual processing in order to evaluate the overall pattern of visual dysfunction in schizophrenia. Steady-state visual-evoked potentials (ssVEPs) were recorded over the occipital cortex (Oz) in patients with schizophrenia and schizoaffective disorder (N=26) and in age-matched comparison volunteers (N=22). Two stimuli were used: windmill-dartboard and partial-windmill, which are contrast-reversing ( approximately 4 Hz), radial patterns with dominant low spatial-frequency content. Each stimulus was presented for 1 min. Fourier analysis was performed on the ssVEP data to extract the relevant temporal frequency (i.e., harmonic) components. Magnitude-squared coherence (MSC) was computed to estimate the relative signal level for each frequency component. The patients showed reduced amplitude and coherence of second harmonic responses in both conditions, but intact first harmonic responses in the windmill-dartboard condition. This finding of a differential deficit may indicate a significant loss in the magnocellular pathway, which contributes to the generation of the second harmonic component under these conditions. Early sensory deficits may lead to impairments in subsequent stages of processing.
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Affiliation(s)
- Dongsoo Kim
- Program in Cognitive Neuroscience and Schizophrenia, Nathan Kline Institute for Psychiatric Research, Orangeburg, NY 10962, USA
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Butler PD, Zemon V, Schechter I, Saperstein AM, Hoptman MJ, Lim KO, Revheim N, Silipo G, Javitt DC. Early-stage visual processing and cortical amplification deficits in schizophrenia. ARCHIVES OF GENERAL PSYCHIATRY 2005; 62:495-504. [PMID: 15867102 PMCID: PMC1298183 DOI: 10.1001/archpsyc.62.5.495] [Citation(s) in RCA: 271] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND Patients with schizophrenia show deficits in early-stage visual processing, potentially reflecting dysfunction of the magnocellular visual pathway. The magnocellular system operates normally in a nonlinear amplification mode mediated by glutamatergic (N-methyl-D-aspartate) receptors. Investigating magnocellular dysfunction in schizophrenia therefore permits evaluation of underlying etiologic hypotheses. OBJECTIVES To evaluate magnocellular dysfunction in schizophrenia, relative to known neurochemical and neuroanatomical substrates, and to examine relationships between electrophysiological and behavioral measures of visual pathway dysfunction and relationships with higher cognitive deficits. DESIGN, SETTING, AND PARTICIPANTS Between-group study at an inpatient state psychiatric hospital and outpatient county psychiatric facilities. Thirty-three patients met DSM-IV criteria for schizophrenia or schizoaffective disorder, and 21 nonpsychiatric volunteers of similar ages composed the control group. MAIN OUTCOME MEASURES (1) Magnocellular and parvocellular evoked potentials, analyzed using nonlinear (Michaelis-Menten) and linear contrast gain approaches; (2) behavioral contrast sensitivity measures; (3) white matter integrity; (4) visual and nonvisual neuropsychological measures, and (5) clinical symptom and community functioning measures. RESULTS Patients generated evoked potentials that were significantly reduced in response to magnocellular-biased, but not parvocellular-biased, stimuli (P = .001). Michaelis-Menten analyses demonstrated reduced contrast gain of the magnocellular system (P = .001). Patients showed decreased contrast sensitivity to magnocellular-biased stimuli (P<.001). Evoked potential deficits were significantly related to decreased white matter integrity in the optic radiations (P<.03). Evoked potential deficits predicted impaired contrast sensitivity (P = .002), which was in turn related to deficits in complex visual processing (P< or =.04). Both evoked potential (P< or =.04) and contrast sensitivity (P = .01) measures significantly predicted community functioning. CONCLUSIONS These findings confirm the existence of early-stage visual processing dysfunction in schizophrenia and provide the first evidence that such deficits are due to decreased nonlinear signal amplification, consistent with glutamatergic theories. Neuroimaging studies support the hypothesis of dysfunction within low-level visual pathways involving thalamocortical radiations. Deficits in early-stage visual processing significantly predict higher cognitive deficits.
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Affiliation(s)
- Pamela D Butler
- Nathan Kline Institute for Psychiatric Research, Orangeburg, NY 10962, USA.
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Abstract
PURPOSE OF REVIEW While cognitive dysfunction including memory and attentional deficits are well known in schizophrenia, recent work has also shown basic sensory processing deficits. Deficits are particularly prominent in the visual system and may be related to cognitive deficits and outcome. This article reviews studies of early-stage visual processing in schizophrenia published during the past year. These studies reflect the growing interest and importance of sensory processing deficits in schizophrenia. RECENT FINDINGS The visual system is divided into magnocellular and parvocellular pathways which project to dorsal and ventral visual areas. Recent electrophysiological and behavioral investigations have found preferential magnocellular/dorsal stream dysfunction, with some deficits in parvocellular function as well. These early-stage deficits appear to be related to higher level cognitive, social, and community function. Structural studies of occipital cortex and particularly optic radiations provide anatomical support for early visual processing dysfunction. SUMMARY These findings highlight the importance of sensory processing deficits, in addition to higher cognitive dysfunction, for understanding the pathophysiology of schizophrenia. Understanding the nature of sensory processing deficits may provide insight into mechanisms of pathology in schizophrenia, such as N-methyl-D-aspartate dysfunction or impaired signal amplification, and could lead to treatment strategies including sensory processing rehabilitation that may improve outcome.
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Affiliation(s)
- Pamela D Butler
- Nathan Kline Institute for Psychiatric Research, Orangeburg, New York 10962, USA.
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Slaghuis WL. Spatio-temporal luminance contrast sensitivity and visual backward masking in schizophrenia. Exp Brain Res 2004; 156:196-211. [PMID: 14752582 DOI: 10.1007/s00221-003-1771-3] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2002] [Accepted: 10/30/2003] [Indexed: 10/26/2022]
Abstract
The aim of two experiments was to investigate the relationship between spatio-temporal contrast sensitivity and visual backward masking in normal observers and in subgroups with positive or negative symptoms in schizophrenia. Experiment 1 measured contrast sensitivity for stationary and counterphase-modulated sinusoidal gratings at four spatial (0.5, 2.0, 4.0, 8.0 cycles/degree) and four temporal frequencies (0, 4.0, 8.0, 16.0 Hz). The results showed that there were no differences in spatio-temporal contrast sensitivity between the control and positive-symptom group, and in comparison with these groups, contrast sensitivity was significantly lower at all spatial and temporal frequencies in the negative-symptom group. Experiment 2 measured the visibility of a Landolt C target with a constant target stimulus duration of 4.0 ms followed by a 150-ms backward mask, which was presented at 12 stimulus onset asynchronies from 0 to 110 ms in the same groups of observers. Consistent with the findings of the previous experiment, there were no significant differences in backward masking between the control and positive-symptom group, and in comparison with these groups, visual backward masking was significantly higher at all stimulus onset asynchronies from 40 to 110 ms in the negative-symptom group. The present findings show that there were no significant differences in contrast sensitivity and in backward masking between normal observers and a group with positive symptoms in schizophrenia. It was concluded that the reduction in contrast sensitivity for low spatial frequency counterphase flicker in the negative-symptom group is consistent with a reduction in the 'contrast gain control' mechanism of magnocellular channels, and that the reduction in contrast sensitivity for medium and high stationary gratings is consistent with a disorder in parvocellular channels. It was proposed that a disorder in magnocellular channels in the negative-symptom group may enforce a reliance on parvocellular channels that results in longer temporal summation and visible persistence, slower visual processing of single target stimuli at threshold and higher levels of sensory integration, and backward masking when multiple stimuli are presented rapidly in time.
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Affiliation(s)
- Walter L Slaghuis
- School of Psychology, University of Tasmania, Private Bag 30, 7001 Hobart, Tasmania, Australia.
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