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Bansal S. Object Recognition in Psychosis: Altered Connectivity Between Levels of the Visual Perceptual Hierarchy. BIOLOGICAL PSYCHIATRY. COGNITIVE NEUROSCIENCE AND NEUROIMAGING 2021; 6:1122-1124. [PMID: 34887081 DOI: 10.1016/j.bpsc.2021.08.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Accepted: 08/11/2021] [Indexed: 06/13/2023]
Affiliation(s)
- Sonia Bansal
- Maryland Psychiatric Research Center, University of Maryland School of Medicine, Catonsville, Maryland.
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Major depressive disorder and schizophrenia are associated with a disturbed experience of temporal memory. JOURNAL OF AFFECTIVE DISORDERS REPORTS 2020. [DOI: 10.1016/j.jadr.2020.100049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Spencer JMY, Sekuler AB, Bennett PJ, Christensen BK. Contribution of coherent motion to the perception of biological motion among persons with Schizophrenia. Front Psychol 2013; 4:507. [PMID: 23964253 PMCID: PMC3741574 DOI: 10.3389/fpsyg.2013.00507] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Accepted: 07/17/2013] [Indexed: 12/01/2022] Open
Abstract
People with schizophrenia (SCZ) are impaired in several domains of visual processing, including the discrimination and detection of biological motion. However, the mechanisms underlying SCZ-related biological motion processing deficits are unknown. Moreover, whether these impairments are specific to biological motion or represent a more widespread visual motion processing deficit is unclear. In the current study, three experiments were conducted to investigate the contribution of global coherent motion processing to biological motion perception among patients with SCZ. In Experiments 1 and 2, participants with SCZ (n = 33) and healthy controls (n = 33) were asked to discriminate the direction of motion from upright and inverted point-light walkers in the presence and absence of a noise mask. Additionally, participants discriminated the direction of non-biological global coherent motion. In Experiment 3, participants discriminated the direction of motion from upright scrambled walkers (which contained only local motion information) and upright random position walkers (which contained only global form information). Consistent with previous research, results from Experiment 1 and 2 showed that people with SCZ exhibited deficits in the direction discrimination of point-light walkers; however, this impairment was accounted for by decreased performance in the coherent motion control task. Furthermore, results from Experiment 3 demonstrated similar performance in the discrimination of scrambled and random position point-light walkers.
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Affiliation(s)
- Justine M. Y. Spencer
- Department of Psychology, Neuroscience and Behaviour, McMaster UniversityHamilton, ON, Canada
| | - Allison B. Sekuler
- Department of Psychology, Neuroscience and Behaviour, McMaster UniversityHamilton, ON, Canada
| | - Patrick J. Bennett
- Department of Psychology, Neuroscience and Behaviour, McMaster UniversityHamilton, ON, Canada
| | - Bruce K. Christensen
- Department of Psychiatry and Behavioural Neurosciences, McMaster UniversityHamilton, ON, Canada
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Butler PD, Abeles IY, Silverstein SM, Dias EC, Weiskopf NG, Calderone DJ, Sehatpour P. An event-related potential examination of contour integration deficits in schizophrenia. Front Psychol 2013; 4:132. [PMID: 23519476 PMCID: PMC3604636 DOI: 10.3389/fpsyg.2013.00132] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Accepted: 03/03/2013] [Indexed: 11/23/2022] Open
Abstract
Perceptual organization, which refers to the ability to integrate fragments of stimuli to form a representation of a whole edge, part, or object, is impaired in schizophrenia. A contour integration paradigm, involving detection of a set of Gabor patches forming an oval contour pointing to the right or left embedded in a field of randomly oriented Gabors, has been developed for use in clinical trials of schizophrenia. The purpose of the present study was to assess contributions of early and later stages of processing to deficits in contour integration, as well as to develop an event-related potential (ERP) analog of this task. Twenty-one patients with schizophrenia and 28 controls participated. The Gabor elements forming the contours were given a low or high degree of orientational jitter, making it either easy or difficult to identify the direction in which the contour was pointing. ERP results showed greater negative peaks at ~165 (N1 component) and ~270 ms for the low-jitter versus the high-jitter contours, with a much greater difference between jitter conditions at 270 ms. This later ERP component was previously termed Ncl for closure negativity. Source localization identified the Ncl in the lateral occipital object recognition area. Patients showed a significant decrease in the Ncl, but not N1, compared to controls, and this was associated with impaired behavioral ability to identify contours. In addition, an earlier negative peak was found at ~120 ms (termed N120) that differentiated jitter conditions, had a dorsal stream source, and differed between patients and controls. Patients also showed a deficit in the dorsal stream sensory P1 component. These results are in accord with impairments in distributed circuitry contributing to perceptual organization deficits and provide an ERP analog to the behavioral contour integration task.
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Affiliation(s)
- Pamela D Butler
- Schizophrenia Research Division, Nathan S. Kline Institute for Psychiatric Research Orangeburg, NY, USA ; Department of Psychiatry, NYU School of Medicine New York, NY, USA ; Department of Psychology, City University of New York New York, NY, USA
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Kim J, Park S, Blake R. Perception of biological motion in schizophrenia and healthy individuals: a behavioral and FMRI study. PLoS One 2011; 6:e19971. [PMID: 21625492 PMCID: PMC3098848 DOI: 10.1371/journal.pone.0019971] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2010] [Accepted: 04/19/2011] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Anomalous visual perception is a common feature of schizophrenia plausibly associated with impaired social cognition that, in turn, could affect social behavior. Past research suggests impairment in biological motion perception in schizophrenia. Behavioral and functional magnetic resonance imaging (fMRI) experiments were conducted to verify the existence of this impairment, to clarify its perceptual basis, and to identify accompanying neural concomitants of those deficits. METHODOLOGY/FINDINGS In Experiment 1, we measured ability to detect biological motion portrayed by point-light animations embedded within masking noise. Experiment 2 measured discrimination accuracy for pairs of point-light biological motion sequences differing in the degree of perturbation of the kinematics portrayed in those sequences. Experiment 3 measured BOLD signals using event-related fMRI during a biological motion categorization task. Compared to healthy individuals, schizophrenia patients performed significantly worse on both the detection (Experiment 1) and discrimination (Experiment 2) tasks. Consistent with the behavioral results, the fMRI study revealed that healthy individuals exhibited strong activation to biological motion, but not to scrambled motion in the posterior portion of the superior temporal sulcus (STSp). Interestingly, strong STSp activation was also observed for scrambled or partially scrambled motion when the healthy participants perceived it as normal biological motion. On the other hand, STSp activation in schizophrenia patients was not selective to biological or scrambled motion. CONCLUSION Schizophrenia is accompanied by difficulties discriminating biological from non-biological motion, and associated with those difficulties are altered patterns of neural responses within brain area STSp. The perceptual deficits exhibited by schizophrenia patients may be an exaggerated manifestation of neural events within STSp associated with perceptual errors made by healthy observers on these same tasks. The present findings fit within the context of theories of delusion involving perceptual and cognitive processes.
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Affiliation(s)
- Jejoong Kim
- Department of Brain and Cognitive Sciences, Seoul National University, Seoul, Korea.
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Ventura J, Thames AD, Wood RC, Guzik LH, Hellemann GS. Disorganization and reality distortion in schizophrenia: a meta-analysis of the relationship between positive symptoms and neurocognitive deficits. Schizophr Res 2010; 121:1-14. [PMID: 20579855 PMCID: PMC3160271 DOI: 10.1016/j.schres.2010.05.033] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2009] [Revised: 05/23/2010] [Accepted: 05/26/2010] [Indexed: 11/22/2022]
Abstract
BACKGROUND Factor analytic studies have shown that in schizophrenia patients, disorganization (e.g., conceptual disorganization and bizarre behavior) is a separate dimension from other types of positive symptoms such as reality distortion (delusions and hallucinations). Although some studies have found that disorganization is more strongly linked to neurocognitive deficits and poor functional outcomes than reality distortion, the findings are not always consistent. METHODS A meta-analysis of 104 studies (combined n=8015) was conducted to determine the magnitude of the relationship between neurocognition and disorganization as compared to reality distortion. Additional analyses were conducted to determine whether the strength of these relationships differed depending on the neurocognitive domain under investigation. RESULTS The relationship between reality distortion and neurocognition was weak (r=-.04; p=.03) as compared to the moderate association between disorganization and neurocognition (r=-.23; p<.01). In each of the six neurocognitive domains that were examined, disorganization was more strongly related to neurocognition (r's range from -.20 to -.26) than to reality distortion (r's range from .01 to -.12). CONCLUSIONS The effect size of the relationship between neurocognition and disorganization was significantly larger than the effect size of the relationship between neurocognition and reality distortion. These results hold across several neurocognitive domains. These findings support a dimensional view of positive symptoms distinguishing disorganization from reality distortion.
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Affiliation(s)
- Joseph Ventura
- UCLA Department of Psychiatry, 300 Medical Plaza, Room 2243, Los Angeles CA 90095-6968, United States.
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Silverstein SM, Berten S, Essex B, Kovács I, Susmaras T, Little DM. An fMRI examination of visual integration in schizophrenia. J Integr Neurosci 2009; 8:175-202. [PMID: 19618486 DOI: 10.1142/s0219635209002113] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2009] [Accepted: 04/02/2009] [Indexed: 11/18/2022] Open
Abstract
Behavioral and electrophysiological studies of schizophrenia have consistently demonstrated impairments in the integration of visual features into unified perceptual representations. Specific brain regions involved in this dysfunction, however, remain to be clarified. This study used functional Magnetic Resonance Imaging (fMRI) to examine the relative involvement of visual cortex areas (involved in form perception) and parietal and frontal regions (involved in attention), in the visual integration impairment in schizophrenia. Fourteen patients with schizophrenia and 14 healthy controls were compared on behavioral performance and data acquired via fMRI while completing a contour integration task that had previously been used to identify a visual integration deficit in schizophrenia. The schizophrenia patients demonstrated poorer visual integration than controls. Analyses of peak signal change indicated that while the groups were equivalent in area V1, the schizophrenia group demonstrated reduced signal in areas V2-V4, which are the earliest regions sensitive to global configurations of stimuli. Moreover, whereas the control group demonstrated greater recruitment of prefrontal and parietal areas during perception of integrated forms compared to random stimuli, the schizophrenia group demonstrated greater recruitment of frontal regions during perception of random stimuli. The two groups differed on brain regions involved in form perception even when they were matched on accuracy levels. The visual integration disturbance in schizophrenia involves both deficient basic visual processes (beginning as early as occipital region V2), as well as reduced feedback from visual attention regions that normally serves to amplify relevant visual representations relative to irrelevant information.
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Cocchi L, Schenk F, Volken H, Bovet P, Parnas J, Vianin P. Visuo-spatial processing in a dynamic and a static working memory paradigm in schizophrenia. Psychiatry Res 2007; 152:129-42. [PMID: 17512986 DOI: 10.1016/j.psychres.2006.02.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2005] [Revised: 12/23/2005] [Accepted: 02/05/2006] [Indexed: 10/23/2022]
Abstract
Recent findings suggest that the visuo-spatial sketchpad (VSSP) may be divided into two sub-components processing dynamic or static visual information. This model may be useful to elucidate the confusion of data concerning the functioning of the VSSP in schizophrenia. The present study examined patients with schizophrenia and matched controls in a new working memory paradigm involving dynamic (the Ball Flight Task - BFT) or static (the Static Pattern Task - SPT) visual stimuli. In the BFT, the responses of the patients were apparently based on the retention of the last set of segments of the perceived trajectory, whereas control subjects relied on a more global strategy. We assume that the patients' performances are the result of a reduced capacity in chunking visual information since they relied mainly on the retention of the last set of segments. This assumption is confirmed by the poor performance of the patients in the static task (SPT), which requires a combination of stimulus components into object representations. We assume that the static/dynamic distinction may help us to understand the VSSP deficits in schizophrenia. This distinction also raises questions about the hypothesis that visuo-spatial working memory can simply be dissociated into visual and spatial sub-components.
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Affiliation(s)
- Luca Cocchi
- Institute of Sport science and physical education, Lausanne, Switzerland.
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Uhlhaas PJ, Phillips WA, Mitchell G, Silverstein SM. Perceptual grouping in disorganized schizophrenia. Psychiatry Res 2006; 145:105-17. [PMID: 17081620 DOI: 10.1016/j.psychres.2005.10.016] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2004] [Revised: 01/19/2005] [Accepted: 10/17/2005] [Indexed: 11/24/2022]
Abstract
This study evaluated visual perceptual grouping in schizophrenia to test the hypothesis that the disorganization syndrome in schizophrenia is related to a deficit in cognitive coordination. Perceptual grouping was examined with three psychophysically well-controlled tasks in patients with disorganized schizophrenia (n=11), non-disorganized schizophrenia (n=24), psychotic disorders other than schizophrenia (n=31) and non-psychotic psychiatric disorders (n=35). These measures assessed processing of both concurrent and preceding stimulus context. Deficits in perceptual grouping were observed on all three tasks in disorganized schizophrenia patients. Dysfunctional perceptual grouping mechanisms produced both enhanced and impaired task performance suggesting that the pattern of performance observed was the result of a specific deficit in the grouping of stimulus elements. We interpret these data as further support for the hypothesis that the disorganization syndrome in schizophrenia reflects a widespread deficit in the cognitive coordination of contextually related stimuli, leading to dysfunctional grouping of stimulus features in vision, thought and language.
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Affiliation(s)
- Peter J Uhlhaas
- Department of Neurophysiology, Max-Planck Institute for Brain Research, Deutschordenstr. 46, Frankfurt am Main, 60528, Germany.
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Kozma-Wiebe P, Silverstein SM, Fehér A, Kovács I, Ulhaas P, Wilkniss SM. Development of a world-wide web based contour integration test. COMPUTERS IN HUMAN BEHAVIOR 2006. [DOI: 10.1016/j.chb.2004.03.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Silverstein SM, Hatashita-Wong M, Schenkel LS, Wilkniss S, Kovács I, Fehér A, Smith T, Goicochea C, Uhlhaas P, Carpiniello K, Savitz A. Reduced top-down influences in contour detection in schizophrenia. Cogn Neuropsychiatry 2006; 11:112-32. [PMID: 16537237 DOI: 10.1080/13546800444000209] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
INTRODUCTION Chronic schizophrenia patients have previously demonstrated performance deficits in contour integration tasks. The purpose of this study was to investigate whether schizophrenia patients, spanning a range of illness severity, would demonstrate responsiveness to manipulations that recruit top-down processing strategies involving learning and sequencing effects in a contour integration task. METHODS We administered a contour integration test over four consecutive days and in two different presentation conditions each day. In one condition, the stimuli were administered in order of increasing difficulty, and in the other they were presented in random order. The order in which these two conditions were presented was counterbalanced across days and participants. In addition, a nonschizophrenia psychotic disorders control group was included to determine if past findings of a contour integration deficit in schizophrenia could be replicated in the presence of a symptomatically similar control group. RESULTS All groups demonstrated similar learning curves across the four days and generally similar overall levels of performance, with the exception of the group of the most chronic schizophrenia patients. In addition, the order in which the stimuli were presented to subjects affected their performance, with higher scores achieved for all groups in the condition where the stimuli were presented in increasing order of difficulty. Interaction effects revealed that the effects of order presentation were greater for nonpatient than for psychotic patients. CONCLUSIONS These data are further evidence that perceptual organization impairments in schizophrenia are illness severity-related, and that schizophrenia patients as a whole are less sensitive to top-down manipulations in this type of task.
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Quelen F, Grainger J, Raymondet P. An investigation of semantic priming in schizophrenia using a new priming paradigm. Schizophr Res 2005; 80:173-83. [PMID: 16140505 DOI: 10.1016/j.schres.2005.07.020] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2005] [Revised: 07/11/2005] [Accepted: 07/14/2005] [Indexed: 11/26/2022]
Abstract
In the present study, twenty schizophrenic patients and twenty healthy controls were tested in a new priming paradigm that allows a clear distinction to be made between automatic, perceptual priming effects and effects related to decision bias. Participants had to identify briefly presented masked target words preceded by clearly visible primes that were semantically related to the target or not. Target presentation duration corresponded to a pre-determined perceptual threshold for each participant, and a two-alternative forced-choice methodology was used. Equivalent amounts of semantic priming were found in schizophrenic patients compared with healthy controls. However, for the schizophrenic patients, a positive correlation was found between the size of automatic perceptual priming effects and formal thought disorders, as measured by Andreasen's Thought, Language and Communication (TLC) scale. The new paradigm tested in the present study overcomes some of the limitations of prior research on semantic priming in schizophrenia, and provides further evidence suggesting that an increased spreading of activation in the semantic network could partly underlie formal thought disorders in schizophrenia.
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Affiliation(s)
- Florence Quelen
- Laboratoire de Psychologie Cognitive, CNRS et Université de Provence, Centre St Charles, Bâtiment 9, Case D, 3 place Victor Hugo, 13331 Marseille Cedex 3, France
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Uhlhaas PJ, Silverstein SM. Perceptual Organization in Schizophrenia Spectrum Disorders: Empirical Research and Theoretical Implications. Psychol Bull 2005; 131:618-632. [PMID: 16060805 DOI: 10.1037/0033-2909.131.4.618] [Citation(s) in RCA: 178] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The research into perceptual organization in schizophrenia spectrum disorders has found evidence for and against a perceptual organization deficit and has interpreted the data from within several different theoretical frameworks. A synthesis of this evidence, however, reveals that this body of work has produced reliable evidence for deficits in schizophrenia, as well as for the clinical, stimulus, and task parameters associated with normal and abnormal performance. Recent models of cognition have also advanced understanding of the underlying pathophysiological processes of perceptual organization dysfunction in schizophrenia spectrum disorders. These suggest that deficits in perceptual organization may be one manifestation of a wider disturbance in the integration of contextually related information across space and time.
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Zalla T, Verlut I, Franck N, Puzenat D, Sirigu A. Perception of dynamic action in patients with schizophrenia. Psychiatry Res 2004; 128:39-51. [PMID: 15450913 DOI: 10.1016/j.psychres.2003.12.026] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2003] [Revised: 09/30/2003] [Accepted: 12/22/2003] [Indexed: 11/23/2022]
Abstract
Neuropsychological studies have revealed that schizophrenic (SZ) patients have severe impairments in the cognitive integration of static and moving perceptual stimuli. Research on knowledge structures has shown that sequences of continuous actions are represented in memory as clusters of goal-directed events in a hierarchical manner. In the present study, we investigated the ability to segment familiar sequences of dynamic goal-directed actions into small and large meaningful units in a group of patients with schizophrenia (N = 16) and a group of healthy control subjects (N = 17). While viewing two videotaped movies, participants were requested to detect the transitions between component events at both low and high levels of the action categorical structure. Both groups detected significantly more events under the small-oriented condition as compared to the large-oriented condition. Differently from normal controls, patients recalled the event scenes in a detailed and fragmentary manner and showed considerable difficulties in detecting large action units. Moreover, low performance on action boundary detection significantly correlated with higher levels of disorganisation symptoms in patients with schizophrenia. A defective conceptual organisation of perceptive action knowledge would help to explain the severe everyday difficulties of these patients both in monitoring their own actions and in understanding others' intentions.
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Affiliation(s)
- Tiziana Zalla
- Institut des Sciences Cognitives, 67, boulevard Pinel, 69675 Bron Cedex, France.
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Abstract
AbstractN-methyl-d-aspartate receptor (NMDAR) dysfunction plays a crucial role in schizophrenia, leading to impairments in cognitive coordination. NMDAR agonists (e.g., glycine) ameliorate negative and cognitive symptoms, consistent with NMDAR models. However, not all types of cognitive coordination use NMDAR. Further, not all aspects of cognitive coordination are impaired in schizophrenia, suggesting the need for specificity in applying the cognitive coordination construct.
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Abstract
AbstractPhillips & Silverstein's focus on schizophrenia as a failure of “cognitive coordination” is welcome. They note that a simple hypothesis of reduced Gamma synchronisation subserving impaired coordination does not fully account for recent observations. We suggest that schizophrenia reflects a dynamic compensation to a core deficit of coordination, expressed either as hyper- or hyposynchronisation, with neurotransmitter systems and arousal as modulatory mechanisms.
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Abstract
AbstractNumerous searches have failed to identify a single co-occurrence of total blindness and schizophrenia. Evidence that blindness causes loss of certain NMDA-receptor functions is balanced by reports of compensatory gains. Connections between visual and anterior cingulate NMDA-receptor systems may help to explain how blindness could protect against schizophrenia.
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Setting domain boundaries for convergence of biological and psychological perspectives on cognitive coordination in schizophrenia. Behav Brain Sci 2003. [DOI: 10.1017/s0140525x0328002x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
AbstractThe claim that the disorganized subtype of schizophrenia results from glutamate hypofunction is enhanced by consideration of current subtypology of schizophrenia, symptom definition, interdependence of neurotransmitters, and the nature of the data needed to support the hypothesis. Careful specification clarifies the clinical reality of disorganization as a feature of schizophrenia and increases the utility of the subtype.
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Abstract
AbstractAlthough context-processing deficits may be core features of schizophrenia, context remains a poorly defined concept. To test Phillips & Silverstein's model, we need to operationalize context more precisely. We offer several useful ways of framing context and discuss enhancing or facilitating schizophrenic patients' performance under different contextual situations. Furthermore, creativity may be a byproduct of cognitive uncoordination.
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Abstract
AbstractImpairments in cognitive coordination in schizophrenia are supported by phenomenological data that suggest deficits in the processing of visual context. Although the target article is sympathetic to such a phenomenological perspective, we argue that the relevance of phenomenological data for a wider understanding of consciousness in schizophrenia is not sufficiently addressed by the authors.
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Guarding against over-inclusive notions of “context”: Psycholinguistic and electrophysiological studies of specific context functions in schizophrenia. Behav Brain Sci 2003. [DOI: 10.1017/s0140525x03470027] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractPhillips & Silverstein offer an exciting synthesis of ongoing efforts to link the clinical and cognitive manifestations of schizophrenia with cellular accounts of its pathophysiology. We applaud their efforts but wonder whether the highly inclusive notion of “context” adequately captures some important details regarding schizophrenia and NMDA/glutamate function that are suggested by work on language processing and cognitive electrophysiology.
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Abstract
AbstractMechanisms that contribute to perceptual processing dysfunction in schizophrenia were examined by Phillips & Silverstein, and formulated as involving disruptions in both local and higher-level coordination of signals. We agree that dysfunction in the coordination of cognitive functions (disconnection) is also indicated for many of the linguistic processing deficits documented for schizophrenia. We suggest, however, that it may be necessary to add a timing mechanism to the theoretical account.
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Abstract
AbstractSchizophrenics exhibit a deficit in theory of mind (ToM), but an intact theory of biology (ToB). One explanation is that ToM relies on an independent module that is selectively damaged. Phillips & Silverstein's analyses suggest an alternative: ToM requires the type of coordination that is impaired in schizophrenia, whereas ToB is spared because this type of coordination is not involved.
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Abstract
AbstractThe additional arguments and evidence supplied by the commentaries strengthen the hypothesis that underactivity of NMDA receptors produces impaired cognitive coordination in schizophrenia. This encourages the hope that though the distance from molecules to mind is great, it can nevertheless be traversed. We therefore predict that in this decade or the next molecular psychology will be seen to be as fundamental to our understanding of mind as molecular biology is to our understanding of life.
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Abstract
AbstractIt is proposed that cortical activity is normally coordinated across synaptically connected areas and that this coordination supports cognitive coherence relations. This view is consistent with the NMDA- hypoactivity hypothesis of the target article in regarding disorganization symptoms in schizophrenia as arising from disruption of normal interareal coordination. This disruption may produce abnormal contextual effects in the cortex that lead to anomalous cognitive coherence relations.
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Abstract
AbstractThis commentary compares clinical aspects of ketamine with the amphetamine model of schizophrenia. Hallucinations and loss of insight, associated with amphetamine, seem more schizophrenia-like. Flat affect encountered with ketamine is closer to the clinical presentation in schizophrenia. We argue that flat affect is not a sign of schizophrenia, but rather, arisk factorfor chronic schizophrenia.
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Cortical connectivity in high-frequency beta-rhythm in schizophrenics with positive and negative symptoms. Behav Brain Sci 2003. [DOI: 10.1017/s0140525x03440028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
AbstractIn chronic schizophrenic patients with both positive and negative symptoms (see Table 1), interhemispheric connections at the high frequency beta2-rhythm are absent during cognitive tasks, in contrast to normal controls, who have many interhemispheric connections at this frequency in the same situation. Connectivity is a fundamental brain feature, evidently greatly promoted by the NMDA system. It is a more reliable measure of brain function than the spectral power of this rhythm.
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Bressler SL. Cortical coordination dynamics and the disorganization syndrome in schizophrenia. Neuropsychopharmacology 2003; 28 Suppl 1:S35-9. [PMID: 12827142 DOI: 10.1038/sj.npp.1300145] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
There has been a long history of investigation in the fields of neuropsychology and cognitive psychology into the question of functional integration in the brain. Each of the several dominant themes in that history can be interpreted as representing an important feature of a unitary general mechanism that integrates distributed processes in the cerebral cortex. This mechanism must allow local areas to function within the large-scale anatomical structure of the cortex so as to satisfy competing requirements for stability and flexibility. Each specialized cortical area must perform a unique role by expressing its own form of information, yet must have its performance constrained by interactions with other areas to which it is connected. In order to generate adaptive behavior within changing and not fully predictable environments, the cortex as a whole must be able to rapidly coordinate the activities of variable assemblages of areas that can collectively express consensual information that is appropriate for the functional requirements engendered by each successive stage of behavioral performance. This paper proposes that the phase synchronization of neuronal population activity from different cortical areas may serve a role in large-scale coordination. Theoretical studies suggest that the cortex normally operates in a metastable dynamic regime in which groups of areas are able to coordinate rapidly and reversibly their activities through changes in their degree of phase synchronization. A disruption of phase synchronization, leading to an excess of local information expression by cortical areas, is proposed as a contributing factor to the disorganization syndrome in schizophrenia.
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Affiliation(s)
- Steven L Bressler
- Center for Complex Systems & Brain Sciences, Florida Atlantic University, 777 Glades Road, Boca Raton, FL 33431, USA.
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Where the rubber meets the road: The importance of implementation. Behav Brain Sci 2003. [DOI: 10.1017/s0140525x03230028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractPhillips & Silverstein argue that a range of cognitive disturbances in schizophrenia result from a deficit in cognitive coordination attributable to NMDA receptor dysfunction. We suggest that the viability of this hypothesis would be further supported by explicit implementation in a computational framework that can produce quantitative estimates of the behavior of both healthy individuals and individuals with schizophrenia.
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Context, connection, and coordination: The need to switch. Behav Brain Sci 2003. [DOI: 10.1017/s0140525x03370025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractContext, connection, and coordination (CCC) describe well where the problems that apply to thought-disordered patients with schizophrenia lie. But they may be part of the experience of those with other symptom constellations. Switching is an important mechanism to allow context to be applied appropriately to changing circumstances. In some cases, NMDA-voltage modulations may be central, but gain and shift are also functions that monoaminergic systems express in CCC.
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31
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Synchronous dynamics for cognitive coordination: But how? Behav Brain Sci 2003. [DOI: 10.1017/s0140525x03450024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractAlthough interesting, the hypotheses proposed by Phillips & Silverstein lack unifying structure both in specific mechanisms and in cited evidence. They provide little to support the notion that low-level sensory processing and high-level cognitive coordination share dynamic grouping by synchrony as a common processing mechanism. We suggest that more realistic large-scale modeling at multiple levels is needed to address these issues.
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32
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A wide-spectrum coordination model of schizophrenia. Behav Brain Sci 2003. [DOI: 10.1017/s0140525x03240024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractThe target article presents a model for schizophrenia extending four levels of abstraction: molecules, cells, cognition, and syndrome. An important notion in the model is that of coordination, applicable to both the level of cells and of cognition. The molecular level provides an “implementation” of the coordination at the cellular level, which in turn underlies the coordination at the cognitive level, giving rise to the clinical symptoms.
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Abstract
AbstractTo understand schizophrenia, a linking hypothesis is needed that shows how brain mechanisms lead to behavioral functions in normals, and also how breakdowns in these mechanisms lead to behavioral symptoms of schizophrenia. Such a linking hypothesis is now available that complements the discussion offered by Phillips & Silverstein (P&S).
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Spatial integration in perception and cognition: An empirical approach to the pathophysiology of schizophrenia. Behav Brain Sci 2003. [DOI: 10.1017/s0140525x03260027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractEvidence for a dysfunction in cognitive coordination in schizophrenia is emerging, but it is not specific enough to prove (or disprove) this long-standing hypothesis. Many aspects of the external world are spatially mapped in the brain. A comprehensive internal representation relies on integration of information across space. Focus on spatial integration in the perceptual and cognitive processes will generate empirical data that shed light on the pathophysiology of schizophrenia.
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35
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Inferring contextual field interactions from scalp EEG. Behav Brain Sci 2003. [DOI: 10.1017/s0140525x03390028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractThis commentary highlights methods for using scalp EEG to make inferences about contextual field interactions, which, in view of the target article, may be specially relevant to the study of schizophrenia. Although scalp EEG has limited spatial resolution, prior knowledge combined with experimental manipulations may be used to strengthen inferences about underlying brain processes. Both spatial and temporal context are discussed within the framework of nonlinear interactions. Finally, results from a visual contour integration EEG pilot study are summarized in view of a hypothesis that relates receptive field and contextual field processing to evoked and induced activity, respectively.
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Reconciling schizophrenic deficits in top-down and bottom-up processes: Not yet. Behav Brain Sci 2003. [DOI: 10.1017/s0140525x03360029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractThis commentary challenges the authors to use their computational modeling techniques to support one of their central claims: that schizophrenic deficits in bottom-up (Gestalt-type tasks) and top-down (cognitive control tasks) context processing tasks arise from the same dysfunction. Further clarification about the limits of cognitive coordination would also strengthen the hypothesis.
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37
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Cognitive coordination deficits: A necessary but not sufficient factor in the development of schizophrenia. Behav Brain Sci 2003. [DOI: 10.1017/s0140525x03290026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractThe Phillips & Silverstein model of NMDA-mediated coordination deficits provides a useful heuristic for the study of schizophrenic cognition. However, the model does not specifically account for the development of schizophrenia-spectrum disorders. The P&S model is compared to Meehl's seminal model of schizotaxia, schizotypy, and schizophrenia, as well as the model of schizophrenic cognitive dysfunction posited by McCarley and colleagues.
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38
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NMDA-receptor hypofunction versus excessive synaptic elimination as models of schizophrenia. Behav Brain Sci 2003. [DOI: 10.1017/s0140525x03320023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractWe propose that the primary cause of schizophrenia is a pathological extension of synaptic pruning involving local connectivity that unfolds ordinarily during adolescence. Computer simulations suggest that this pathology provides reasonable accounts of a range of symptoms in schizophrenia, and is consistent with recent postmortem and genetic studies. NMDA-receptors play a regulatory role in maintaining and/or eliminating cortical synapses, and therefore may play a pathophysiological role.
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Is sensory gating a form of cognitive coordination? Behav Brain Sci 2003. [DOI: 10.1017/s0140525x03340026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractNeurophysiological investigations of the past two decades have consistently demonstrated a deficit in sensory gating associated with schizophrenia. Phillips & Silverstein interpret this impairment as being consistent with cognitive coordination dysfunction. However, the physiological mechanisms that underlie sensory gating have not been shown to involve gamma-band oscillations or NMDA-receptors, both of which are critical neural elements in the cognitive coordination model.
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Why do schizophrenic patients hallucinate? Behav Brain Sci 2003. [DOI: 10.1017/s0140525x03410029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractPhillips & Silverstein argue that schizophrenia is a result of a deficit of the contextual coordination of neuronal responses. The authors propose that NMDA-receptors control these modulatory effects. However, hallucinations, which are among the principle symptoms of schizophrenia, imply a flaw in the interactions between neurons that is more fundamental than just a general weakness of contextual modulation.
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Schizophrenic cognition: Taken out of context? Behav Brain Sci 2003. [DOI: 10.1017/s0140525x03310027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
AbstractThis commentary addresses: (a) the problems of definition which have been prominent in the use of the term context in schizophrenia research; (b) potentially useful distinctions and links with other theories of schizophrenic cognition; and (c) possible pathways to schizophrenic symptoms. It is suggested that at least two major aspects of the operation of context may be distinguished and that both may be impaired in schizophrenia.
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NMDA synapses can bias competition between object representations and mediate attentional selection. Behav Brain Sci 2003. [DOI: 10.1017/s0140525x03400022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
AbstractPhillips & Silverstein emphasize the gain-control properties of NMDA synapses in cognitive coordination. We endorse their view and suggest that NMDA synapses play a crucial role in biased attentional competition and (visual) working memory. Our simulations show that NMDA synapses can control the storage rate of visual objects. We discuss specific predictions of our model about cognitive effects of NMDA-antagonists and schizophrenia.
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Combating fuzziness with computational modeling. Behav Brain Sci 2003. [DOI: 10.1017/s0140525x03460020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractPhillips & Silverstein's ambitious link between receptor abnormalities and the symptoms of schizophrenia involves a certain amount of fuzziness: No detailed mechanism is suggested through which the proposed abnormality would lead to psychological traits. We propose that detailed simulation of brain regions, using model neural networks, can aid in understanding the relation between biological abnormality and psychological dysfunction in schizophrenia.
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