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Wolf A, Ueda K, Hirano Y. Recent updates of eye movement abnormalities in patients with schizophrenia: A scoping review. Psychiatry Clin Neurosci 2021; 75:82-100. [PMID: 33314465 PMCID: PMC7986125 DOI: 10.1111/pcn.13188] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 11/27/2020] [Accepted: 12/09/2020] [Indexed: 12/15/2022]
Abstract
AIM Although eye-tracking technology expands beyond capturing eye data just for the sole purpose of ensuring participants maintain their gaze at the presented fixation cross, gaze technology remains of less importance in clinical research. Recently, impairments in visual information encoding processes indexed by novel gaze metrics have been frequently reported in patients with schizophrenia. This work undertakes a scoping review of research on saccadic dysfunctions and exploratory eye movement deficits among patients with schizophrenia. It gathers promising pieces of evidence of eye movement abnormalities in attention-demanding tasks on the schizophrenia spectrum that have mounted in recent years and their outcomes as potential biological markers. METHODS The protocol was drafted based on PRISMA for scoping review guidelines. Electronic databases were systematically searched to identify articles published between 2010 and 2020 that examined visual processing in patients with schizophrenia and reported eye movement characteristics as potential biomarkers for this mental illness. RESULTS The use of modern eye-tracking instrumentation has been reported by numerous neuroscientific studies to successfully and non-invasively improve the detection of visual information processing impairments among the screened population at risk of and identified with schizophrenia. CONCLUSIONS Eye-tracking technology has the potential to contribute to the process of early intervention and more apparent separation of the diagnostic entities, being put together by the syndrome-based approach to the diagnosis of schizophrenia. However, context-processing paradigms should be conducted and reported in equally accessible publications to build comprehensive models.
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Affiliation(s)
- Alexandra Wolf
- International Research Fellow of Japan Society for the Promotion of Science, Fukuoka, Japan.,Department of Human Science, Research Center for Applied Perceptual Science, Kyushu University, Fukuoka, Japan
| | - Kazuo Ueda
- Department of Human Science, Research Center for Applied Perceptual Science, Kyushu University, Fukuoka, Japan
| | - Yoji Hirano
- Department of Neuropsychiatry, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
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Bhinge S, Mowakeaa R, Calhoun VD, Adalı T. Extraction of Time-Varying Spatiotemporal Networks Using Parameter-Tuned Constrained IVA. IEEE TRANSACTIONS ON MEDICAL IMAGING 2019; 38:1715-1725. [PMID: 30676948 PMCID: PMC7060979 DOI: 10.1109/tmi.2019.2893651] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Dynamic functional connectivity analysis is an effective way to capture the networks that are functionally associated and continuously changing over the scanning period. However, these methods mostly analyze the dynamic associations across the activation patterns of the spatial networks while assuming that the spatial networks are stationary. Hence, a model that allows for the variability in both domains and reduces the assumptions imposed on the data provides an effective way for extracting spatiotemporal networks. Independent vector analysis (IVA) is a joint blind source separation technique that allows for estimation of spatial and temporal features while successfully preserving variability. However, its performance is affected for higher number of datasets. Hence, we develop an effective two-stage method to extract time-varying spatial and temporal features using IVA, mitigating the problems with higher number of datasets while preserving the variability across subjects and time. The first stage is used to extract reference signals using group-independent component analysis (GICA) that are used in a parameter-tuned constrained IVA framework to estimate time-varying representations of these signals by preserving the variability through tuning the constraint parameter. This approach effectively captures variability across time from a large-scale resting-state fMRI data acquired from healthy controls and patients with schizophrenia and identifies more functionally relevant connections that are significantly different among healthy controls and patients with schizophrenia, compared with the widely used GICA method alone.
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Affiliation(s)
| | - Rami Mowakeaa
- Department of Electrical and Computer Engineering, University of Maryland, Baltimore County, Baltimore, MD 21250 USA
| | - Vince D. Calhoun
- The Mind Research Network, Albuquerque, NM 87106 USA
- Department of Electrical and Computer Engineering, University of New Mexico, Albuquerque, NM 87131 USA
| | - Tülay Adalı
- Department of Electrical and Computer Engineering, University of Maryland, Baltimore County, Baltimore, MD 21250 USA
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Tannous J, Mwangi B, Hasan KM, Narayana PA, Steinberg JL, Walss-Bass C, Moeller FG, Schmitz JM, Lane SD. Measures of possible allostatic load in comorbid cocaine and alcohol use disorder: Brain white matter integrity, telomere length, and anti-saccade performance. PLoS One 2019; 14:e0199729. [PMID: 30625144 PMCID: PMC6326479 DOI: 10.1371/journal.pone.0199729] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 12/07/2018] [Indexed: 12/03/2022] Open
Abstract
Chronic cocaine and alcohol use impart significant stress on biological and cognitive systems, resulting in changes consistent with an allostatic load model of neurocognitive impairment. The present study measured potential markers of allostatic load in individuals with comorbid cocaine/alcohol use disorders (CUD/AUD) and control subjects. Measures of brain white matter (WM), telomere length, and impulsivity/attentional bias were obtained. WM (CUD/AUD only) was indexed by diffusion tensor imaging metrics, including radial diffusivity (RD) and fractional anisotropy (FA). Telomere length was indexed by the telomere to single copy gene (T/S) ratio. Impulsivity and attentional bias to drug cues were measured via eye-tracking, and were also modeled using the Hierarchical Diffusion Drift Model (HDDM). Average whole-brain RD and FA were associated with years of cocaine use (R2 = 0.56 and 0.51, both p < .005) but not years of alcohol use. CUD/AUD subjects showed more anti-saccade errors (p < .01), greater attentional bias scores (p < .001), and higher HDDM drift rates on cocaine-cue trials (Bayesian probability CUD/AUD > control = p > 0.99). Telomere length was shorter in CUD/AUD, but the difference was not statistically significant. Within the CUD/AUD group, exploratory regression using an elastic-net model determined that more years of cocaine use, older age, larger HDDM drift rate differences and shorter telomere length were all predictive of WM as measured by RD (model R2 = 0.79). Collectively, the results provide modest support linking CUD/AUD to putative markers of allostatic load.
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Affiliation(s)
- Jonika Tannous
- Program in Neuroscience, UTHealth Graduate School of Biomedical Sciences, Houston, Texas, United States of America
| | - Benson Mwangi
- Department of Psychiatry & Behavioral Sciences, UTHealth McGovern Medical School, Houston, Texas, United States of America
| | - Khader M. Hasan
- Department of Diagnostic and Interventional Imaging, UTHealth McGovern Medical School, Houston, Texas, United States of America
| | - Ponnada A. Narayana
- Program in Neuroscience, UTHealth Graduate School of Biomedical Sciences, Houston, Texas, United States of America
- Department of Diagnostic and Interventional Imaging, UTHealth McGovern Medical School, Houston, Texas, United States of America
| | - Joel L. Steinberg
- Department of Psychiatry, Institute for Drug and Alcohol Studies, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Consuelo Walss-Bass
- Program in Neuroscience, UTHealth Graduate School of Biomedical Sciences, Houston, Texas, United States of America
- Department of Psychiatry & Behavioral Sciences, UTHealth McGovern Medical School, Houston, Texas, United States of America
| | - F. Gerard Moeller
- Department of Psychiatry, Institute for Drug and Alcohol Studies, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Joy M. Schmitz
- Department of Psychiatry & Behavioral Sciences, UTHealth McGovern Medical School, Houston, Texas, United States of America
| | - Scott D. Lane
- Program in Neuroscience, UTHealth Graduate School of Biomedical Sciences, Houston, Texas, United States of America
- Department of Psychiatry & Behavioral Sciences, UTHealth McGovern Medical School, Houston, Texas, United States of America
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Bennett MR, Hatton S, Hermens DF, Lagopoulos J. Behavior, neuropsychology and fMRI. Prog Neurobiol 2016; 145-146:1-25. [PMID: 27393370 DOI: 10.1016/j.pneurobio.2016.07.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2016] [Revised: 06/14/2016] [Accepted: 07/03/2016] [Indexed: 11/19/2022]
Abstract
Cognitive neuroscientists in the late 20th century began the task of identifying the part(s) of the brain concerned with normal behavior as manifest in the psychological capacities as affective powers, reasoning, behaving purposively and the pursuit of goals, following introduction of the 'functional magnetic resonance imaging' (fMRI) method for identifying brain activity. For this research program to be successful two questions require satisfactory answers. First, as the fMRI method can currently only be used on stationary subjects, to what extent can neuropsychological tests applicable to such stationary subjects be correlated with normal behavior. Second, to what extent can correlations between the various neuropsychological tests on the one hand, and sites of brain activity determined with fMRI on the other, be regarded as established. The extent to which these questions have yet received satisfactory answers is reviewed, and suggestions made both for improving correlations of neuropsychological tests with behavior as well as with the results of fMRI-based observations.
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Affiliation(s)
- Maxwell R Bennett
- Brain & Mind Centre, University of Sydney, Camperdown, NSW 2050, Australia.
| | - Sean Hatton
- Brain & Mind Centre, University of Sydney, Camperdown, NSW 2050, Australia.
| | - Daniel F Hermens
- Brain & Mind Centre, University of Sydney, Camperdown, NSW 2050, Australia.
| | - Jim Lagopoulos
- Brain & Mind Centre, University of Sydney, Camperdown, NSW 2050, Australia; Sunshine Coast Mind and Neuroscience - Thompson Institute, Birtinya, QLD, Australia.
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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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Liu GT, Volpe NJ, Galetta SL. Eye movement disorders. Neuroophthalmology 2010. [DOI: 10.1016/b978-1-4160-2311-1.00016-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Levy DL, Sereno AB, Gooding DC, O'Driscoll GA. Eye tracking dysfunction in schizophrenia: characterization and pathophysiology. Curr Top Behav Neurosci 2010; 4:311-47. [PMID: 21312405 PMCID: PMC3212396 DOI: 10.1007/7854_2010_60] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Eye tracking dysfunction (ETD) is one of the most widely replicated behavioral deficits in schizophrenia and is over-represented in clinically unaffected first-degree relatives of schizophrenia patients. Here, we provide an overview of research relevant to the characterization and pathophysiology of this impairment. Deficits are most robust in the maintenance phase of pursuit, particularly during the tracking of predictable target movement. Impairments are also found in pursuit initiation and correlate with performance on tests of motion processing, implicating early sensory processing of motion signals. Taken together, the evidence suggests that ETD involves higher-order structures, including the frontal eye fields, which adjust the gain of the pursuit response to visual and anticipated target movement, as well as early parts of the pursuit pathway, including motion areas (the middle temporal area and the adjacent medial superior temporal area). Broader application of localizing behavioral paradigms in patient and family studies would be advantageous for refining the eye tracking phenotype for genetic studies.
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Affiliation(s)
- Deborah L Levy
- Psychology Research Laboratory, McLean Hospital, 115 Mill Street, Belmont, MA 02478, USA.
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Abstract
Smooth pursuit impairment is recognized clinically by the presence of saccadic tracking of a small object and quantified by reduction in pursuit gain, the ratio of smooth eye movement velocity to the velocity of a foveal target. Correlation of the site of brain lesions, identified by imaging or neuropathological examination, with defective smooth pursuit determines brain structures that are necessary for smooth pursuit. Paretic, low gain, pursuit occurs toward the side of lesions at the junction of the parietal, occipital and temporal lobes (area V5), the frontal eye field and their subcortical projections, including the posterior limb of the internal capsule, the midbrain and the basal pontine nuclei. Paresis of ipsiversive pursuit also results from damage to the ventral paraflocculus and caudal vermis of the cerebellum. Paresis of contraversive pursuit is a feature of damage to the lateral medulla. Retinotopic pursuit paresis consists of low gain pursuit in the visual hemifield contralateral to damage to the optic radiation, striate cortex or area V5. Craniotopic paresis of smooth pursuit consists of impaired smooth eye movement generation contralateral to the orbital midposition after acute unilateral frontal or parietal lobe damage. Omnidirectional saccadic pursuit is a most sensitive sign of bilateral or diffuse cerebral, cerebellar or brainstem disease. The anatomical and physiological bases of defective smooth pursuit are discussed here in the context of the effects of lesion in the human brain.
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Affiliation(s)
- James A Sharpe
- Division of Neurology, University Health Network WW5-440 TWH, University of Toronto, 399 Bathurst Street, Toronto, ON, Canada M5T 2S8.
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10
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Basal ganglia shape abnormalities in the unaffected siblings of schizophrenia patients. Biol Psychiatry 2008; 64:111-20. [PMID: 18295189 PMCID: PMC2486271 DOI: 10.1016/j.biopsych.2008.01.004] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2007] [Revised: 12/10/2007] [Accepted: 01/04/2008] [Indexed: 11/21/2022]
Abstract
BACKGROUND Abnormalities of basal ganglia structure in schizophrenia have been attributed to the effects of antipsychotic drugs. Our aim was to test the hypothesis that abnormalities of basal ganglia structure are intrinsic features of schizophrenia by assessing basal ganglia volume and shape in the unaffected siblings of schizophrenia subjects. METHOD The study involved 25 pairs of schizophrenia subjects and their unaffected siblings and 40 pairs of healthy control subjects and their siblings. Large-deformation, high-dimensional brain mapping was used to obtain surface representations of the caudate, putamen, and globus pallidus. Surfaces were derived from transformations of anatomic templates, and shapes were analyzed using reduced-dimensional measures of surface variability (i.e., principal components and canonical analysis). Canonical functions were derived using schizophrenia and control groups and were then used to compare shapes in the sibling groups. To visualize shape differences, maps of the estimated surface displacement between groups were created. RESULTS In the caudate, putamen, and globus pallidus, the degree of shape abnormality observed in the siblings of the schizophrenia subjects was intermediate between the schizophrenia and control subjects. In the schizophrenia subjects, significant correlations were observed between measures of caudate, putamen, and globus pallidus structure and the selected measures of lifetime psychopathology. CONCLUSIONS Attenuated abnormalities of basal ganglia structure are present in the unaffected siblings of schizophrenia subjects. This finding implies that basal ganglia structural abnormalities observed in subjects with schizophrenia are at least in part an intrinsic feature of the illness.
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Rubia K, Russell T, Bullmore ET, Soni W, Brammer MJ, Simmons A, Taylor E, Andrew C, Giampietro V, Sharma T. An fMRI study of reduced left prefrontal activation in schizophrenia during normal inhibitory function. Schizophr Res 2001; 52:47-55. [PMID: 11595391 DOI: 10.1016/s0920-9964(00)00173-0] [Citation(s) in RCA: 136] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Functional magnetic resonance imaging (fMRI) was used to investigate the hypothesis that schizophrenia is associated with a dysfunction of prefrontal brain regions during motor response inhibition. Generic brain activation of six male medicated patients with schizophrenia was compared to that of seven healthy comparison subjects matched for sex, age, and education level while performing 'stop' and 'go-no-go' tasks. No group differences were observed in task performance. Patients, however, showed reduced BOLD signal response in left anterior cingulate during both inhibition tasks and reduced left rostral dorsolateral prefrontal and increased thalamus and putamen BOLD signal response during stop task performance. Despite good task performance, patients with schizophrenia thus showed abnormal neural network patterns of reduced left prefrontal activation and increased subcortical activation when challenged with motor response inhibition.
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Affiliation(s)
- K Rubia
- Department of Child Psychiatry, Psychological Medicine, and Neurology, Institute of Psychiatry, King's College, De Crespigny Park, SE5 8AF, London, UK.
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Myles-Worsley M, Coon H, McDowell J, Brenner C, Hoff M, Lind B, Bennett P, Freedman R, Clementz B, Byerley W. Linkage of a composite inhibitory phenotype to a chromosome 22q locus in eight Utah families. ACTA ACUST UNITED AC 1999. [DOI: 10.1002/(sici)1096-8628(19991015)88:5<544::aid-ajmg20>3.0.co;2-v] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Manor BR, Gordon E, Williams LM, Rennie CJ, Bahramali H, Latimer CR, Barry RJ, Meares RA. Eye movements reflect impaired face processing in patients with schizophrenia. Biol Psychiatry 1999; 46:963-9. [PMID: 10509179 DOI: 10.1016/s0006-3223(99)00038-4] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Impaired processing of faces in patients with schizophrenia may underlie aspects of disturbance in their social interaction. This study examined patterns of eye fixation in subjects with schizophrenia and non-psychiatric controls, while processing a high resolution picture of a neutral face and a nonbiological complex geometric stimulus. METHODS Ten-second sequences of eye movement were recorded video-oculographically (50 samples/sec) while subjects were "free-viewing" the stimuli. An essential element of the study was customized software that ensured stimulus presentation on a video display only after subjects were fixated upon a centre-screen cue, so that all subjects began stimulus processing from the same point. RESULTS Compared with the control group, subjects with schizophrenia exhibited reduced scanpath lengths and a tendency toward fewer fixations for the face stimulus. They also showed an initial relative right spatial hemineglect (for the first voluntary fixation) when viewing the Rey figure, but not when viewing the face stimulus. Overall, there were no significant differences between the schizophrenia and control groups in the lateral distribution of subsequent fixations for either stimulus. CONCLUSIONS Disturbed spatial and temporal patterns of eye movement in some people with schizophrenia may reflect sub-optimal processing of face stimuli, that may predispose these individuals to dysfunctional interpretation of facial communication cues.
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Affiliation(s)
- B R Manor
- Department of Psychiatry, Westmead Hospital, Australia
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Arolt V, Teichert HM, Steege D, Lencer R, Heide W. Distinguishing schizophrenic patients from healthy controls by quantitative measurement of eye movement parameters. Biol Psychiatry 1998; 44:448-58. [PMID: 9777176 DOI: 10.1016/s0006-3223(97)00479-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Eye tracking dysfunction is a putative trait marker for susceptibility to schizophrenia; however, it cannot be recommended as an additional tool for the diagnosis of schizophrenia, due to low sensitivity and specificity. METHODS To assess the diagnostic potentials of combinations of eye movement paradigms, four smooth pursuit experiments (1: constant velocity of 15 degrees/sec; 2 and 3: combination with either visual or auditory distractors; 4: constant velocity of 30 degrees/sec) and two saccadic eye movement experiments (1: reflexive saccades; 2: voluntary saccades) were conducted. Fourteen patients with residual schizophrenia and 17 healthy controls were studied. Two sets of discriminant analyses (each with the resubstitution and with the "leaving one out" method) were calculated. RESULTS In the first set, all 10 characteristic variables were included, whereas for the second set, the three most powerful parameters were selected (two from smooth pursuit tasks and one from a voluntary saccade experiment). This procedure provided the best classification results, regarding concordance between clinical diagnoses and eye movement dysfunction (kappa = .67-.80). CONCLUSIONS Schizophrenic patients of the residual subtype can be differentiated from healthy individuals with considerable criterion validity on the basis of paradigms from two different ocular motor systems.
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Affiliation(s)
- V Arolt
- Department of Psychiatry, University of Luebeck School of Medicine, Germany
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Abstract
The nature of saccadic abnormalities in schizophrenia was investigated in three different paradigms: (1) the visually guided saccade; (2) the antisaccade; and (3) the remembered saccade paradigm. Subjects comprised 14 schizophrenic patients and 14 normal volunteers. Deficits in the schizophrenic group were observed in the antisaccade and remembered saccade tasks, both of which were characterized by increased latency and reduced gain. Moreover, in the antisaccade task, schizophrenic patients showed an increased number of errors compared with control subjects. Saccadic abnormalities in the patients were correlated with impaired performance on the Wisconsin Card Sorting Test. These data suggest that schizophrenic patients have difficulty in inhibiting reflexive saccades and in producing voluntary saccades. The implications of these findings for a prefrontal cortex dysfunction involved in oculomotor control in schizophrenia are discussed.
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Affiliation(s)
- B Karoumi
- Institut de Psychopathologie Cognitive et Neurobiologique, Jeune Equipe 1882 (Université Lyon I), Hôpital du Vinatier, Lyon-Bron, France
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Schreiber H, Stolz-Born G, Born J, Rothmeier J, Rothenberger A, Jürgens R, Becker W, Kornhuber HH. Visually-guided saccadic eye movements in adolescents at genetic risk for schizophrenia. Schizophr Res 1997; 25:97-109. [PMID: 9187008 DOI: 10.1016/s0920-9964(97)00011-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Visually-guided saccades of 21 offspring of schizophrenic parents and 21 individually matched controls were compared with regard to the frequency of occurrence of saccadic hypometria and hypermetria, non-fixations, and omissions of target jumps. Target steps ranged from 10 to 60 degrees, and interstimulus intervals averaged 2.5 s; subjects were promised financial reward depending on performance. Recordings were carried out at the subjects' homes. To screen for cognitive abilities and psychopathological behavior, subjects were tested by means of an intelligence scale and a behavioral checklist. With large target steps (40-60 degrees), the high-risk group made significantly more grossly hypometric saccades (gain < or = 0.8) than the control group; responses to small target steps (10-30 degrees) exhibited a similar, albeit statistically not significant, trend. There were no significant differences with regard to the occurrence of hypermetria. Non-fixations scored marginally higher in the high-risks as compared to controls, but this was again not a significant difference. The incidence of omissions of saccades was very low in both groups. The results of the study suggest that subjects at genetic risk for schizophrenia may differ from controls by an increased incidence of conspicuously hypometric saccades. Clearly, this difference is not caused by a deficit of the saccadic motor circuitry proper; comparison to control data obtained with a similar experimental protocol suggests that it probably reflects an impaired internal control of saccades in the presence of distraction and stress. The relevance of saccades as indicators of a possible schizophrenic vulnerability is discussed.
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Affiliation(s)
- H Schreiber
- University of Ulm, RKU Hospital, Department of Neurology, Germany
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Fischer B, Biscaldi M, Gezeck S. On the development of voluntary and reflexive components in human saccade generation. Brain Res 1997; 754:285-97. [PMID: 9134986 DOI: 10.1016/s0006-8993(97)00094-2] [Citation(s) in RCA: 205] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The saccadic performance of a large number (n = 281) of subjects of different ages (8-70 years) was studied applying two saccade tasks: the prosaccade overlap (PO) task and the antisaccade gap (AG) task. From the PO task, the mean reaction times and the percentage of express saccades were determined for each subject. From the AG task, the mean reaction time of the correct antisaccades and of the erratic prosaccades were measured. In addition, we determined the error rate and the mean correction time, i.e. the time between the end of the first erratic prosaccade and the following corrective antisaccade. These variables were measured separately for stimuli presented (in random order) at the right or left side. While strong correlations were seen between variables for the right and left sides, considerable side asymmetries were obtained from many subjects. A factor analysis revealed that the seven variables (six eye movement variables plus age) were mainly determined by only two factors, V and F. The V factor was dominated by the variables from the AG task (reaction time, correction time, error rate) the F factor by variables from the PO task (reaction time, percentage express saccades) and the reaction time of the errors (prosaccades!) from the AG task. The relationship between the percentage number of express saccades and the percentage number of errors was completely asymmetric: high numbers of express saccades were accompanied by high numbers of errors but not vice versa. Only the variables in the V factor covaried with age. A fast decrease of the antisaccade reaction time (by 50 ms), of the correction times (by 70 ms) and of the error rate (from 60 to 22%) was observed between age 9 and 15 years, followed by a further period of slower decrease until age 25 years. The mean time a subject needed to reach the side opposite to the stimulus as required by the antisaccade task decreased from approximately 350 to 250 ms until age 15 years and decreased further by 20 ms before it increased again to approximately 280 ms. At higher ages, there was a slight indication for a return development. Subjects with high error rates had long antisaccade latencies and needed a long time to reach the opposite side on error trials. The variables obtained from the PO task varied also significantly with age but by smaller amounts. The results are discussed in relation to the subsystems controlling saccade generation: a voluntary and a reflex component the latter being suppressed by active fixation. Both systems seem to develop differentially. The data offer a detailed baseline for clinical studies using the pro- and antisaccade tasks as an indication of functional impairments, circumscribed brain lesions, neurological and psychiatric diseases and cognitive deficits.
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Affiliation(s)
- B Fischer
- Brain Research Unit, Institute of Biophysics, University of Freiburg, Germany.
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Farber RH, Clementz BA, Swerdlow NR. Characteristics of open- and closed-loop smooth pursuit responses among obsessive-compulsive disorder, schizophrenia, and nonpsychiatric individuals. Psychophysiology 1997; 34:157-62. [PMID: 9090264 DOI: 10.1111/j.1469-8986.1997.tb02126.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Twenty obsessive-compulsive disorder patients and comparison samples of 20 schizophrenia and 20 nonpsychiatric individuals were presented with (a) a step-ramp task designed to measure smooth pursuit initiation and (b) a regular ramp task designed to measure steady-state tracking performance. Obsessive-compulsive disorder and non-psychiatric individuals had statistically similar pursuit reaction time and average eye accelerations during the open-loop interval. They also had similar closed-loop performance. Schizophrenia patients, however, had delayed pursuit reaction times and reduced eye acceleration during the last 60 ms of the open-loop interval. These findings suggest that brain regions supporting smooth pursuit performance are unimpaired among obsessive-compulsive disorder patients. Furthermore, the deficits found in the schizophrenia patients replicate and extend the results of previous smooth pursuit studies.
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Affiliation(s)
- R H Farber
- Department of Psychology, University of California-San Diego, La Jolla 92093-0109, USA
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19
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Rosenberg DR, Sweeney JA, Squires-Wheeler E, Keshavan MS, Cornblatt BA, Erlenmeyer-Kimling L. Eye-tracking dysfunction in offspring from the New York High-Risk Project: diagnostic specificity and the role of attention. Psychiatry Res 1997; 66:121-30. [PMID: 9075276 DOI: 10.1016/s0165-1781(96)02975-7] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Eye tracking abnormalities were studied in the offspring of schizophrenic, unipolar depressed and bipolar probands from the New York High-Risk Project to examine their familial specificity. Offspring of schizophrenic and depressed probands both had significant global performance deficits based on spectral purity measurements, but only the offspring of schizophrenic probands had an increased rate of intrusive anticipatory saccades. The greater specificity of high anticipatory saccade rate than global performance impairment suggests that this eye movement abnormality may provide a more specific biological marker of risk for schizophrenia than the global measure of eye tracking performance used in this study. Attention facilitation effectively normalized all performance deficits in the offspring of schizophrenic patients, suggesting that a problem sustaining focused visual attention may contribute to eye tracking deficits observed in the relatives of schizophrenic probands.
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Affiliation(s)
- D R Rosenberg
- Western Psychiatric Institute and Clinic, University of Pittsburgh Medical Center, PA 15213-2593, USA
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20
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Jacobsen LK, Hommer DW, Hong WL, Castellanos FX, Frazier JA, Giedd JN, Rapoport JL. Blink rate in childhood-onset schizophrenia: comparison with normal and attention-deficit hyperactivity disorder controls. Biol Psychiatry 1996; 40:1222-9. [PMID: 8959287 DOI: 10.1016/0006-3223(95)00625-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Several lines of evidence have implicated central dopaminergic pathways in the modulation of blink rate. In the present study, blink rate during smooth pursuit was examined in 17 children with childhood-onset schizophrenia, on and off of clozapine, and compared to that of age-matched normal children and unmedicated children with attention-deficit hyperactivity disorder (ADHD). As has been observed in adolescent and adult schizophrenics, blink rate was significantly higher in schizophrenic children relative to normal and ADHD controls. Within the schizophrenic group, blink rate did not significantly change with the introduction of clozapine and was not related to clinical variables. Blink rate was positively correlated with deterioration in smooth pursuit in normal subjects.
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Affiliation(s)
- L K Jacobsen
- Child Psychiatry Branch, National Institute of Mental Health, Bethesda, Maryland 20892, USA
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21
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Jacobsen LK, Hong WL, Hommer DW, Hamburger SD, Castellanos FX, Frazier JA, Giedd JN, Gordon CT, Karp BI, McKenna K, Rapoport JL. Smooth pursuit eye movements in childhood-onset schizophrenia: comparison with attention-deficit hyperactivity disorder and normal controls. Biol Psychiatry 1996; 40:1144-54. [PMID: 8931918 DOI: 10.1016/s0006-3223(95)00630-3] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Abnormalities of the smooth pursuit eye movements of adults with schizophrenia have been well described. We examined smooth pursuit eye movements in schizophrenic children, contrasting them with normal and attention-deficit hyperactivity disorder (ADHD) subjects, to determine whether there is continuity of eye movement dysfunction between childhood- and adult-onset forms of schizophrenia. Seventeen schizophrenic children with onset of illness by age 12, 18 ADHD children, and 22 normal children were studied while engaged in a smooth pursuit eye tracking task. Eye tracking variables were compared across the three groups. Schizophrenic children exhibited significantly greater smooth pursuit impairments than either normal or ADHD subjects. Within the schizophrenic group, there were no significant relationships between eye tracking variables and clinical variables, or ventricular/brain ratio. Childhood-onset schizophrenia is associated with a similar pattern of smooth pursuit abnormalities to that seen in later-onset schizophrenia.
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Affiliation(s)
- L K Jacobsen
- Child Psychiatry Branch, National Institute of Mental Health, Bethesda, Maryland 20892, USA
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22
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Ross DE, Ochs AL, Pandurangi AK, Thacker LR, Kendler KS. Mixture analysis of smooth pursuit eye movements in schizophrenia. Psychophysiology 1996; 33:390-7. [PMID: 8753939 DOI: 10.1111/j.1469-8986.1996.tb01064.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The goal of this study was to replicate and extend previous findings indicating that the eye movement data of schizophrenic patients is best represented by the mixture of two groups, one of which has distinctly poor performance. Forty-nine schizophrenic patients and 32 normal controls had their smooth pursuit eye movements quantified by calculating the root mean square (RMS) deviation between the target and eye waveforms. Based on the finding of mixture in the distribution of RMS error, the patients were divided into low (better tracking) and high (worse tracking) RMS error subgroups. The high RMS error patients had abnormally decreased gain. Both patient subgroups had abnormally increased frequency of catch-up saccades and increased phase lag. Distinguishing between these two subgroups may be useful in clarifying the pathophysiology of abnormal pursuit and its relationship to heterogeneity in schizophrenia.
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Affiliation(s)
- D E Ross
- Department of Psychiatry, Medical College of Virginia-Virginia Commonwealth University, Richmond, USA.
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23
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McDowell JE, Clementz BA, Wixted JT. Timing and amplitude of saccades during predictive saccadic tracking in schizophrenia. Psychophysiology 1996; 33:93-101. [PMID: 8570799 DOI: 10.1111/j.1469-8986.1996.tb02112.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Schizophrenia patients have ocular motor abnormalities. It has been hypothesized that these abnormalities are associated with frontal eye field pathology. If so, schizophrenia patients should have difficulties decreasing saccadic reaction times in response to predictably moving targets. To evaluate the frontal eye field hypothesis, 25 schizophrenic and 26 nonpsychiatric subjects completed predictive saccadic tracking tasks. The groups demonstrated equivalent decreases in saccadic reaction times over consecutive trials. Schizophrenia patients, however, had faster reaction times and shorter amplitude saccades than nonpsychiatric subjects. The shorter amplitude saccades were made regardless of reaction time, perhaps an antipsychotic medication effect. The reaction time results are unlikely to be an effect of treatment with antipsychotic medication and are inconsistent with the hypothesis that schizophrenia patients have frontal eye field pathology.
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Affiliation(s)
- J E McDowell
- Department of Psychology, University of California, San Diego, La Jolla 92092-0109, USA
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24
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Arolt V, Lencer R, Nolte A, Pinnow M, Schwinger E. Eye tracking dysfunction in families with multiple cases of schizophrenia. Eur Arch Psychiatry Clin Neurosci 1996; 246:175-81. [PMID: 8832194 DOI: 10.1007/bf02188950] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
There is increasing evidence that the genetic predisposition for schizophrenia in families affects more individuals than those fulfilling the criteria for schizophrenia. This finding is supposed to be one of the major problems in molecular genetic schizophrenia research, especially when linkage studies are employed. Eye-tracking dysfunction (ETD), which is conceived as a possible phenotypic marker for genetic liability to schizophrenia, may offer considerable advantages. However, there is only little information from families with multiple occurrence of schizophrenia. It is still unclear whether in these families ETD aggregates with diagnoses from the schizophrenia spectrum. This first report from an ongoing study presents the results of 48 individuals from 6 multiplex families. Smooth-pursuit eye movements were recorded by infrared reflectometry and assessed by quantitative measurement techniques. Along with the high degree of psychiatric morbidity in these families, in 56.3% of the individuals ETD was assessed. Reduced mean pursuit gain was present in 39.6%. The distribution of eye-tracking dysfunction resembles the distribution of schizophrenia-related psychiatry morbidity.
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Affiliation(s)
- V Arolt
- Department of Psychiatry, University of Lübeck School of Medicine, Germany
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25
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Abstract
A countermanding paradigm was utilized to investigate the regulation of saccade initiation. Two rhesus monkeys were instructed to generate a saccade to a peripheral target; however, on a fraction of trials after a delay, the monkeys were signaled to inhibit saccade initiation. With short delays between the presentation of the target and the signal to inhibit saccade generation, monkeys withheld saccades to the peripheral target. As the delay of the stop signal increased, monkeys increasingly failed to withhold the saccade. The hypothesis that the generation of the saccade is determined by a race between a go and a stop process provides three explicit means of estimating the covert latency of response to the stop signal. This latency, known as stop signal reaction time, was estimated to be on average 82 ms for both monkeys. Because the stop signal latency represents the time required to exert inhibitory control over saccade production, the countermanding paradigm will be useful for studying neural mechanisms that regulate saccade initiation.
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Affiliation(s)
- D P Hanes
- Department of Psychology, Vanderbilt University, Nashville, TN 37240, USA
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26
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Schreiber H, Rothmeier J, Becker W, Jürgens R, Born J, Stolz-Born G, Westphal KP, Kornhuber HH. Comparative assessment of saccadic eye movements, psychomotor and cognitive performance in schizophrenics, their first-degree relatives and control subjects. Acta Psychiatr Scand 1995; 91:195-201. [PMID: 7625195 DOI: 10.1111/j.1600-0447.1995.tb09766.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
This study is aimed at detecting biological markers for schizophrenia. For this purpose, a total of 70 subjects (21 schizophrenic patients, 27 first-degree relatives and 22 controls) performed a series of tests assessing various attentional, psychomotor and cognitive functions and saccadic eye movements. The schizophrenics performed significantly poorer than both high-risk and control subjects in most of the tests demanding attention, concentration and psychomotor speed (d2 concentration test, reaction times and Stroop test of perceptual interference) as well as cognition (Wechsler intelligence scales). On the other hand, these tests did not differentiate between the high-risk and control subjects. This distinction, however, could be made by two other parameters: hypometria score of saccadic eye movements and ratio of verbal to performance intelligence scores. Both parameters were significantly increased in both the schizophrenic and the high-risk group, distinguishing both from the control group. The relevance of these findings in indicating a schizophrenic disposition is discussed.
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Affiliation(s)
- H Schreiber
- Department of Neurology, University of Ulm, RKU Hospital, Germany
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27
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Friedman L, Jesberger JA, Siever LJ, Thompson P, Mohs R, Meltzer HY. Smooth pursuit performance in patients with affective disorders or schizophrenia and normal controls: analysis with specific oculomotor measures, RMS error and qualitative ratings. Psychol Med 1995; 25:387-403. [PMID: 7675926 DOI: 10.1017/s003329170003628x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Smooth pursuit performance in schizophrenia and affective disorders has generally been found to be abnormal using a variety of measures. The purpose of this study was to assess patients with these disorders and normal controls in order to compare the different measures across diagnoses. Smooth pursuit was assessed using quantitative specific measures (gain, catch-up saccade rate and amplitude, square-wave jerk rate, number of anticipatory saccades and total time scored), as well as two global measures: root mean-square error (RMS) and qualitative rating. As previously reported, patients with schizophrenia had low gain, increased catch-up saccade rate and spent less time engaged in scoreable smooth pursuit than normal controls. Patients with affective disorders were not statistically different from controls on any of these measures, and had significantly higher gain than patients with schizophrenia. RMS error and qualitative rating measures were highly correlated (r = 0.87). In linear regression analyses, the quantitative specific measures were highly significant predictors of both RMS error and qualitative ratings (P < 0.0001). Linear regression analyses and a modelling study indicated that one quantitative specific measure, the percent of time engaged in scoreable smooth pursuit (total time scored), was most related to global ratings. However, RMS error and qualitative ratings were less sensitive than total time scored to the difference between controls and patients with schizophrenia. These data indicate two smooth pursuit performance deficits in schizophrenia: patients spend less time engaged in scoreable smooth pursuit and have low gain (accompanied by increased compensatory saccades) when the smooth pursuit is engaged.
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Affiliation(s)
- L Friedman
- Laboratory of Biological Psychiatry, Case Western Reserve University, University Hospitals of Cleveland, Ohio 44106, USA
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28
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Van Gelder P, Lebedev S, Liu PM, Tsui WH. Anticipatory saccades in smooth pursuit: task effects and pursuit vector after saccades. Vision Res 1995; 35:667-78. [PMID: 7900305 DOI: 10.1016/0042-6989(94)00161-e] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The dramatic improvement in smooth pursuit performance seen while analyzing the pursuit target has been ascribed to attention enhancement. With a periodic constant velocity target trajectory we ran a concurrent listening condition instead, to see if this mild distraction would degrade performance. Performance improved somewhat with the listening task, suggesting that displacing attentional effort from pursuit accuracy, rather than increasing it, brings better pursuit performance. Catch-up saccades were evenly distributed across tracking, listening, and target analysis conditions, but anticipatory and overshooting saccades were almost eliminated with target analysis. Thus the poor pursuit seems to have been caused by anticipatory and overshooting saccades, produced erroneously in the attempt to perform purposive smooth pursuit. Pursuit velocity immediately following anticipatory saccades was reduced such that the target would catch up with the point of gaze when it reached the endpoint of its trajectory, indicating a predictive goal other than instantaneous target foveation and velocity match.
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Affiliation(s)
- P Van Gelder
- Nathan S. Kline Institute for Psychiatric Research, Orangeburg, NY 10962
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29
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MacAvoy MG, Bruce CJ. Comparison of the smooth eye tracking disorder of schizophrenics with that of nonhuman primates with specific brain lesions. Int J Neurosci 1995; 80:117-51. [PMID: 7775044 DOI: 10.3109/00207459508986097] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The smooth pursuit eye tracking deficit (ETD) often associated with schizophrenia has generated enormous interest over the last 20 years. The deficit is observed in about 80% of schizophrenics and in half of their first degree relatives. It is not affected by neuroleptic medication and is not due to inattention. A review of 52 studies (and actual records when available) on ETD in schizophrenia reveals that the deficit can consistently be described as low gain pursuit augmented with catch-up saccades and often peppered with intrusive saccades. A review of the brain areas that have been shown to be involved in pursuit provides the necessary background for the subsequent section which details the nature of the smooth tracking deficits following experimental lesions. This section reveals that the ETD following lesions of the frontal lobe is unique in that it closely resembles the ETD of schizophrenics. This finding lends further support for frontal lobe theories of schizophrenia.
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Affiliation(s)
- M G MacAvoy
- Section of Neurobiology, Yale University School of Medicine, New Haven, Connecticut 06520-8001, USA
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30
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Schwartz BD, Evans WJ, Pena JM, Winstead DK. Visible persistence decay rates for schizophrenics and substance abusers. Biol Psychiatry 1994; 36:662-9. [PMID: 7880935 DOI: 10.1016/0006-3223(94)91175-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Information-processing deficits are consistently reported for schizophrenics. The findings from the majority of psychophysical tasks indicate that the deficit is specific to schizophrenics and thus may represent a marker for schizophrenia. The present study evaluated for specificity of impairment by including controls using methadone. A two-pulsed forced choice information-processing task that required the detection of a line or a blank-field during an interstimulus interval (ISI) indexed efficiency of processing (i.e., visible persistence). There were 19 schizophrenic, 9 schizoaffective, 8 depressed, 12 on methadone, and 12 normal subjects. The visual stimuli were low and high spatial frequency gratings. Either a line of equivalent width to those of the gratings or a blank field was presented during the ISI. The gratings were presented for 150 msec prior to and following an ISI of 30, 60, 90, 120, 150, and 350 msec. The results support previous findings for impaired processing during a 90-150 msec interval for schizophrenics. Also, the methadone-using controls were not significantly different from schizophrenics. Normal and depressed controls' profiles did not differ from each other, however, they were significantly different from the other groups. The results support an early information-processing deficit in schizophrenic individuals and may implicate dysregulation of dopaminergic neuromodulation.
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Affiliation(s)
- B D Schwartz
- Department of Psychiatry, Tulane University Medical Center, New Orleans, LA 70112
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