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Jayakumar S, Ahmed AO, Butler PD, Silverstein SM, Thompson JL, Seitz AR. Performance on a contour integration task as a function of contour shape in schizophrenia and controls. Vision Res 2024; 219:108394. [PMID: 38579407 DOI: 10.1016/j.visres.2024.108394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 03/21/2024] [Accepted: 03/21/2024] [Indexed: 04/07/2024]
Abstract
Contour Integration (CI) is the ability to integrate elemental features into objects and is a basic visual process essential for object perception and recognition, and for functioning in visual environments. It is now well documented that people with schizophrenia (SZ), in addition to having cognitive impairments, also have several visual perceptual deficits, including in CI. Here, we retrospectively characterize the performance of both SZ and neurotypical individuals (NT) on a series of contour shapes, made up of Gabor elements, that varied in terms of closure and curvature. Participants in both groups performed a CI training task that included 7 different families of shapes (Lines, Ellipse, Blobs, Squiggles, Spiral, Circle and Letters) for up to 40 sessions. Two parameters were manipulated in the training task: Orientation Jitter (OJ, i.e., orientation deviations of individual Gabor elements from ideal for each shape) and Inducer Number (IN, i.e., number of Gabor elements defining the shape). Results show that both OJ and IN thresholds significantly differed between the groups, with higher (OJ) and lower (IN) thresholds observed in the controls. Furthermore, we found significant effects as a function of the contour shapes, with differences between groups emerging with contours that were considered more complex, e.g., due to having a higher degree of curvature (Blobs, Spiral, Letters). These data can inform future work that aims to characterize visual integration impairments in schizophrenia.
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Affiliation(s)
- Samyukta Jayakumar
- Department of Psychology, University of California, Riverside, United States.
| | - Anthony O Ahmed
- Department of Psychiatry, Weill Cornell Medicine, United States.
| | - Pamela D Butler
- Nathan S. Kline Institute for Psychiatric Research, United States.
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Li J, Zhong BL, Zhou D, Fu Y, Huang X, Chen L, Liu H, Zheng J, Tang E, Li Y, Guan C, Shen M, Chen H. The dynamic process of hyperfocusing and hyperfiltering in schizophrenia. NATURE MENTAL HEALTH 2024; 2:367-378. [DOI: 10.1038/s44220-024-00211-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Accepted: 01/24/2024] [Indexed: 08/01/2024]
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The spatial extent of focused attention modulates attentional disengagement. PSYCHOLOGICAL RESEARCH 2022; 87:1520-1536. [PMID: 36264511 DOI: 10.1007/s00426-022-01747-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 09/22/2022] [Indexed: 10/24/2022]
Abstract
Attention can be flexibly changed to optimize visual processing: it can be oriented, resized, or even divided. Although much is known about these processes individually, much less is known about how they interact with one another. In the present study we examined how the spatial extent of the attentional focus modulates the efficiency of the first component of attentional orienting, the disengagement of attention. To this end, we used abrupt-onset stimuli of different sizes to trigger the reflexive resizing of the attentional focus (Castiello and Umiltà in Acta Psychol 73:195-209, 1990), combined with a gap task to assess the efficiency of attentional disengagement (Mackeben and Nakayama in Vis Res 33:85-90, 1993). The results of five experiments showed that the magnitude of the gap effect is significantly greater when the scope of attention is small than when it is large, indicating that disengaging attention is delayed when attention is highly focused. Furthermore, these findings highlight that different aspects of attentional control interact with one another, emphasizing the importance of studying them in conjunction.
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Abstract
Working memory (WM) refers to the ability to maintain a small number of representations in an activated, easily accessible state for a short period of time in the service of ongoing cognitive processing and behavior. Because WM is a resource critical for multiple forms of complex cognition and executive control of behavior, it is of central interest in the study of disorders such as schizophrenia that involve a broad compromise of cognitive function and in the regulation of goal-directed behavior. There is now robust evidence that WM impairment is characteristic of people with schizophrenia. The impairment includes both elementary storage capacity as well as more complex forms of WM that involve the manipulation and updating of WM representations. These impairments appear to underlie a substantial portion of the generalized cognitive deficit in schizophrenia. Neuroimaging studies have implicated widespread abnormalities in the broad neural system that subserves WM performance, consistent with the evidence of broad cognitive impairment seen in PSZ.
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Affiliation(s)
- James M Gold
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA.
| | - Steven J Luck
- Center for Mind & Brain and Department of Psychology, University of California, Davis, CA, USA
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Abstract
Attention is clearly a core area of cognitive dysfunction in schizophrenia, but the concept of "attention" is complex and multifaceted. This chapter focuses on three different aspects of attentional function that are of particular interest in schizophrenia. First, we discuss the evidence that schizophrenia involves a reduction in global alertness, leading to an inward focusing of attention and a neglect of external stimuli and tasks. Second, we discuss the control of attention, the set of processes that allow general goals to be translated into shifts of attention toward task-relevant information. When a goal is adequately represented, people with schizophrenia often show no deficit in using the goal to direct attention in the visual modality unless challenged by stimuli that strongly activate the magnocellular processing pathway. Finally, we discuss the implementation of selection, the processes that boost relevant information and suppress distractors once attention has been directed to a given source of information. Although early evidence indicated an impairment in selection, more recent evidence indicating that people with schizophrenia actually focus their attention more narrowly and more intensely that healthy individuals (hyperfocusing). However, this hyperfocused attention may be directed toward goal-irrelevant information, creating the appearance of impaired attentional filtering.
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Affiliation(s)
- Steven J Luck
- Department of Psychology, Center for Mind and Brain, University of California, Davis, CA, USA.
| | - James M Gold
- Department of Psychiatry, Maryland Psychiatric Research Center, University of Maryland School of Medicine, Baltimore, MD, USA
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Cross-species evidence that nicotine widens the attentional window. Psychopharmacology (Berl) 2021; 238:3559-3568. [PMID: 34618202 PMCID: PMC8629923 DOI: 10.1007/s00213-021-05972-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 08/23/2021] [Indexed: 10/20/2022]
Abstract
RATIONALE The ability to spread attention over items or locations is as important for everyday functioning as the ability to focus narrowly. Little is known about neuronal processes involved in broad monitoring, but indirect evidence suggests a role of nicotinic acetylcholine receptors (nAChRs). OBJECTIVE The present study tested whether the prototypical nAChR agonist nicotine enhances the ability of humans and rodents to maintain a broad attentional window. METHODS Fifty-three never-smokers wearing a nicotine (7 mg/24 h) or placebo patch performed an attention task requiring detection of stimuli presented randomly in one of four peripheral locations, with a central cue predicting the target location or indicating the need to spread attention over all locations. Nineteen rats performed the 5-choice serial reaction time task requiring detection of stimuli presented randomly in a horizontal array of five locations. Performance after nicotine (0.1 and 0.2 mg/kg) or vehicle administration was analyzed as a function of target location eccentricity. RESULTS In human subjects, nicotine caused greater reaction time reduction when all locations were monitored than when a single location was cued. In rats, nicotine attenuated the decline in stimulus detections and the increase in omission errors with greater target location eccentricity. CONCLUSIONS The findings represent cross-species evidence that nAChR agonism facilitates the ability to spread attention broadly. This suggests that nAChR hypofunction may be central to broad monitoring deficits as seen, for example, in schizophrenia. The homology of findings between the rodent and the human paradigm contributes to validating a translational strategy for treatment development.
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Linton SR, Popa AM, Luck SJ, Bolden K, Angkustsiri K, Carter CS, Niendam TA, Simon TJ. Atypical attentional filtering of visual information in youth with chromosome 22q11.2 deletion syndrome as indexed by event-related potentials. Neuroimage Clin 2021; 32:102877. [PMID: 34773799 PMCID: PMC8592928 DOI: 10.1016/j.nicl.2021.102877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 11/04/2021] [Accepted: 11/05/2021] [Indexed: 11/27/2022]
Abstract
BACKGROUND Youth with chromosome 22q11.2 deletion syndrome (22q) face one of the highest genetic risk factors for the development of schizophrenia. Previous research suggests impairments in attentional control and potential interactions with elevated anxiety and reduced adaptive functioning may increase the risk for developing psychosis in this population. Here, we examined how variations in attentional control relate to the presence or severity of psychosis-proneness symptoms in these individuals. METHODS To achieve this, we measured attentional control in youth (12-18 years) with 22q (N = 35) compared to a typically developing group (N = 45), using a flanker task (the Distractor Target task) while measuring neural activity with event-related potentials. RESULTS Similar to previous findings observed in people with schizophrenia, greater attentional capture by, and reduced suppression of, non-target flanker stimuli characterized participants with 22q and was indexed by the N2pc (N2-posterior-contralateral) and PD (distractor positivity) components. Although we observed no relationships between these components and measures of psychosis-proneness in youth with 22q, these individuals endorsed a relatively low incidence of positive symptoms overall. CONCLUSIONS Our results provide neural evidence of an attentional control impairment in youth with 22q that suggests these individuals experience sustained attentional focus on irrelevant information and reduced suppression of distracting stimuli in their environment. Impairments in attentional control might be a valid biomarker of the potential to develop attenuated positive symptoms or frank psychosis in high-risk individuals long before the age at which such symptoms typically arise. The evaluation of such a hypothesis, and the preventive potential for the putative biomarker, should be the focus of future studies.
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Affiliation(s)
- S R Linton
- Department of Psychiatry and Behavioral Sciences, UC Davis, 2230 Stockton Blvd, Sacramento, CA 95817, USA; MIND Institute, UC Davis, 2825 50(th) Street, Sacramento, CA 95817, USA.
| | - A M Popa
- Department of Psychiatry and Behavioral Sciences, UC Davis, 2230 Stockton Blvd, Sacramento, CA 95817, USA; MIND Institute, UC Davis, 2825 50(th) Street, Sacramento, CA 95817, USA
| | - S J Luck
- Center for Mind and Brain and Department of Psychology, UC Davis, 267 Cousteau Place, Davis, CA 95618, USA
| | - K Bolden
- Department of Psychiatry and Behavioral Sciences, UC Davis, 2230 Stockton Blvd, Sacramento, CA 95817, USA; Imaging Research Center, UC Davis, 4701 X Street, Sacramento, CA 95817, USA
| | - K Angkustsiri
- Department of Psychiatry and Behavioral Sciences, UC Davis, 2230 Stockton Blvd, Sacramento, CA 95817, USA; Department of Pediatrics, UC Davis, 2516 Stockton Blvd, Sacramento, CA 95817, USA
| | - C S Carter
- Department of Psychiatry and Behavioral Sciences, UC Davis, 2230 Stockton Blvd, Sacramento, CA 95817, USA; Imaging Research Center, UC Davis, 4701 X Street, Sacramento, CA 95817, USA
| | - T A Niendam
- Department of Psychiatry and Behavioral Sciences, UC Davis, 2230 Stockton Blvd, Sacramento, CA 95817, USA; Imaging Research Center, UC Davis, 4701 X Street, Sacramento, CA 95817, USA
| | - T J Simon
- Department of Psychiatry and Behavioral Sciences, UC Davis, 2230 Stockton Blvd, Sacramento, CA 95817, USA; MIND Institute, UC Davis, 2825 50(th) Street, Sacramento, CA 95817, USA
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Hahn B, Robinson BM, Kiat JE, Geng J, Bansal S, Luck SJ, Gold JM. Impaired Filtering and Hyperfocusing: Neural Evidence for Distinct Selective Attention Abnormalities in People with Schizophrenia. Cereb Cortex 2021; 32:1950-1964. [PMID: 34546344 DOI: 10.1093/cercor/bhab327] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Although schizophrenia is classically thought to involve impaired attentional filtering, people with schizophrenia (PSZ) exhibit a more intense and more exclusive attentional focus than healthy control subjects (HCS) in many tasks. To resolve this contradiction, this functional magnetic resonance imaging study tested the impact of attentional control demands on the modulation of stimulus-induced activation in the fusiform face area and parahippocampal place area when participants (43 PSZ and 43 HCS) were looking for a target face versus house. Stimuli were presented individually, or as face-house overlays that challenged attentional control. Responses were slower for house than face stimuli and when prioritizing houses over faces in overlays, suggesting a difference in salience. Blood-oxygen-level-dependent activity reflected poorer attentional selectivity in PSZ than HCS when attentional control was challenged most, that is, when stimuli were overlaid and the task required detecting the lower-salience house target. By contrast, attentional selectivity was exaggerated in PSZ when control was challenged least, that is, when stimuli were presented sequentially and the task required detecting the higher-salience face target. These findings are consistent with 2 distinct attentional abnormalities in schizophrenia leading to impaired and exaggerated selection under different conditions: attentional control deficits, and hyperfocusing once attention has been directed toward a stimulus.
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Affiliation(s)
- Britta Hahn
- University of Maryland School of Medicine, Maryland Psychiatric Research Center, Baltimore, MD 21228, USA
| | - Benjamin M Robinson
- University of Maryland School of Medicine, Maryland Psychiatric Research Center, Baltimore, MD 21228, USA
| | - John E Kiat
- University of California Davis, Center for Mind and Brain, Davis, CA 95618, USA
| | - Joy Geng
- University of California Davis, Center for Mind and Brain, Davis, CA 95618, USA
| | - Sonia Bansal
- University of Maryland School of Medicine, Maryland Psychiatric Research Center, Baltimore, MD 21228, USA
| | - Steven J Luck
- University of California Davis, Center for Mind and Brain, Davis, CA 95618, USA
| | - James M Gold
- University of Maryland School of Medicine, Maryland Psychiatric Research Center, Baltimore, MD 21228, USA
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Leroux E, Poirel N, Dollfus S. Anatomical Connectivity of the Visuospatial Attentional Network in Schizophrenia: A Diffusion Tensor Imaging Tractography Study. J Neuropsychiatry Clin Neurosci 2021; 32:266-273. [PMID: 31948322 DOI: 10.1176/appi.neuropsych.19040101] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
OBJECTIVE In healthy individuals, the visuospatial attentional network consists of frontoparietal bundles; however, the anatomical organization of this network in persons with schizophrenia remains largely unknown. Using diffusion tensor imaging-based tractography, the authors investigated the white matter integrity and volume of frontoparietal and frontotemporo-occipital bundles in the right and left hemispheres and studied their structural asymmetry in persons with schizophrenia and in healthy individuals. METHODS This study included 34 participants with schizophrenia and 69 healthy individuals. Integrity parameters and volume were calculated in the three branches of the superior longitudinal fasciculus (SLF I, II, and III), the inferior longitudinal fasciculus, and the inferior fronto-occipital fasciculus in both hemispheres. RESULTS In the SLF II and SLF III of the right hemisphere, healthy individuals showed greater integrity, compared with participants with schizophrenia. Both groups presented increased integrity in the SLF III of the right hemisphere, compared with the SLF III of the left hemisphere, but only healthy individuals had this pattern regarding the SLF II. Bundle volumes did not differ between groups. CONCLUSIONS This study is the first to describe the structural hemispheric lateralization and organization of the visuospatial attentional network in persons with schizophrenia. The main findings indicate loss of integrity in the SLF II, associated with loss of asymmetry in participants with schizophrenia, compared with healthy individuals, suggesting a potential substrate of attentional deficits.
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Affiliation(s)
- Elise Leroux
- The Department of Psychiatry, Université de Caen Normandie, Caen, France (Leroux, Dollfus); Université de Paris, LaPsyDÉ, UMR 8240, CNRS, Paris (Poirel); Institut Universitaire de France, Paris (Poirel); Service de Psychiatrie Adulte, Centre Hospitalier Universitaire de Caen, Caen, France (Dollfus); and the Department of Psychiatry, UFR de Médecine, Université de Caen Normandie, Caen, France (Dollfus)
| | - Nicolas Poirel
- The Department of Psychiatry, Université de Caen Normandie, Caen, France (Leroux, Dollfus); Université de Paris, LaPsyDÉ, UMR 8240, CNRS, Paris (Poirel); Institut Universitaire de France, Paris (Poirel); Service de Psychiatrie Adulte, Centre Hospitalier Universitaire de Caen, Caen, France (Dollfus); and the Department of Psychiatry, UFR de Médecine, Université de Caen Normandie, Caen, France (Dollfus)
| | - Sonia Dollfus
- The Department of Psychiatry, Université de Caen Normandie, Caen, France (Leroux, Dollfus); Université de Paris, LaPsyDÉ, UMR 8240, CNRS, Paris (Poirel); Institut Universitaire de France, Paris (Poirel); Service de Psychiatrie Adulte, Centre Hospitalier Universitaire de Caen, Caen, France (Dollfus); and the Department of Psychiatry, UFR de Médecine, Université de Caen Normandie, Caen, France (Dollfus)
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Ashinoff BK, Abu-Akel A. Hyperfocus: the forgotten frontier of attention. PSYCHOLOGICAL RESEARCH 2021; 85:1-19. [PMID: 31541305 PMCID: PMC7851038 DOI: 10.1007/s00426-019-01245-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Accepted: 09/09/2019] [Indexed: 01/20/2023]
Abstract
'Hyperfocus' is a phenomenon that reflects one's complete absorption in a task, to a point where a person appears to completely ignore or 'tune out' everything else. Hyperfocus is most often mentioned in the context of autism, schizophrenia, and attention deficit hyperactivity disorder, but research into its effect on cognitive and neural functioning is limited. We propose that hyperfocus is a critically important aspect of cognition, particularly with regard to clinical populations, and that it warrants significant investigation. Hyperfocus, though ostensibly self-explanatory, is poorly defined within the literature. In many cases, hyperfocus goes undefined, relying on the assumption that the reader inherently knows what it entails. Thus, there is no single consensus to what constitutes hyperfocus. Moreover, some studies do not refer to hyperfocus by name, but describe processes that may be related. In this paper, we review how hyperfocus (as well as possibly related phenomena) has been defined and measured, the challenges associated with hyperfocus research, and assess how hyperfocus affects both neurotypical and clinical populations. Using this foundation, we provide constructive criticism about previously used methods and analyses. We also propose an operational definition of hyperfocus for researchers to use moving forward.
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Affiliation(s)
- Brandon K Ashinoff
- Department of Psychiatry, Columbia University, 1051 Riverside Dr, New York, NY, 10032, USA.
- Centre for Human Brain Health (CHBH), School of Psychology, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
| | - Ahmad Abu-Akel
- Institute of Psychology, University of Lausanne, Quartier UNIL-Mouline, Geopolis, Lausanne, 1015, Switzerland
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Griffiths O, Balzan R. Schizotypy is associated with difficulty maintaining multiple hypotheses. Q J Exp Psychol (Hove) 2021; 74:1153-1163. [PMID: 33283637 DOI: 10.1177/1747021820982256] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Among neurocognitive accounts of delusions, there is a growing consensus that it is the certainty with which delusions are held, rather than their content that defines some beliefs as delusional. On a continuum model of psychosis, this inappropriate certainty ought to be present (albeit in an attenuated form) in healthy adults who score highly in schizotypy. It was hypothesised that this might be most evident in circumstances where the environment provides incomplete or probabilistic information, which thereby forces the participant to hold two imperfectly supported, concurrent hypotheses in mind. A cued visual search task was used to measure people's capacity to use partially predictive information (i.e., a cue that predicted the target may occur in one of the two locations) to facilitate speeded responding. As hypothesised, people's performance on the trials that required holding two hypotheses in mind concurrently was significantly and specifically associated with the positive components of schizotypy. This finding is consistent with a hyperfocusing of attention in schizophrenia, and may help explain why delusion-prone individuals have a tendency to "jump to conclusions" or be resistant to disconfirming information when faced with multiple, partially supported hypotheses.
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Affiliation(s)
- Oren Griffiths
- Discipline of Psychology, Flinders University, Adelaide, SA, Australia
| | - Ryan Balzan
- Discipline of Psychology, Flinders University, Adelaide, SA, Australia
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12
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Coffman BA, Murphy TK, Haas G, Olson C, Cho R, Ghuman AS, Salisbury DF. Lateralized evoked responses in parietal cortex demonstrate visual short-term memory deficits in first-episode schizophrenia. J Psychiatr Res 2020; 130:292-299. [PMID: 32866678 PMCID: PMC7554220 DOI: 10.1016/j.jpsychires.2020.07.036] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 07/25/2020] [Accepted: 07/25/2020] [Indexed: 11/19/2022]
Abstract
Working memory dysfunction may be central to neurocognitive deficits in schizophrenia. Maintenance of visual information in working memory, or visual short-term memory (vSTM), is linked to general cognitive dysfunction and predicts functional outcome. Lateralized change-detection tasks afford investigation of the contralateral delay activity (CDA), a useful tool for investigating vSTM dysfunction. Previous work suggests "hyperfocusing" of attention in schizophrenia, such that CDA is increased when a single item is maintained in vSTM but reduced for multiple items. If observed early in the disease, vSTM dysfunction may be a key feature of schizophrenia or target for intervention. We investigated CDA during lateralized vSTM of one versus three items using sensor-level electroencephalography and source-level magnetoencephalography in 26 individuals at their first episode of schizophrenia-spectrum psychosis (FESz) and 26 matched healthy controls. FESz were unable to modulate CDA with increased memory load - high-load CDA was reduced and low-load CDA was increased compared to controls. Further, sources of CDA in posterior parietal cortex were reduced in FESz and indices of working memory were correlated with neurocognitive deficits and symptom severity. These results support working memory maintenance dysfunction as a central and early component to the disorder. Targeted intervention focusing on vSTM deficits may be warranted to alleviate downstream effects of this disability.
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Affiliation(s)
- Brian A Coffman
- Clinical Neurophysiology Research Laboratory, Western Psychiatric Hospital of UPMC, Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Tim K Murphy
- Clinical Neurophysiology Research Laboratory, Western Psychiatric Hospital of UPMC, Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Gretchen Haas
- Western Psychiatric Hospital of UPMC, Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Carl Olson
- Center for Neural Basis of Cognition, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Raymond Cho
- Western Psychiatric Hospital of UPMC, Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA; Department of Psychiatry and Behavioral Sciences, Baylor College of Medicine, Houston, TX, USA; Michael E. DeBakey Houston VA Medical Center, Houston, TX, USA
| | - Avniel Singh Ghuman
- Laboratory of Cognitive Neurodynamics, Department of Neurosurgery, Presbyterian Hospital, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Dean F Salisbury
- Clinical Neurophysiology Research Laboratory, Western Psychiatric Hospital of UPMC, Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
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13
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Abstract
It is now well documented that schizophrenia is associated with impairments in visual processing at all levels of vision, and that these disturbances are related to deficits in multiple higher-level cognitive and social cognitive functions. Visual remediation methods have been slow to appear in the literature as a potential treatment strategy to target these impairments, however, in contrast to interventions that aim to improve auditory and higher cognitive functions in schizophrenia. In this report, we describe a National Institute of Mental Health (NIMH)-funded R61/R33 grant that uses a phased approach to optimize and evaluate a novel visual remediation intervention for people with schizophrenia. The goals of this project are: (1) in the R61 phase, to establish the optimal components and dose (number of sessions) of a visual remediation intervention from among two specific visual training strategies (and their combination) for improving low and mid-level visual functions in schizophrenia; and (2) in the R33 phase, to determine the extent to which the optimal intervention improves not only visual processing but also higher-level cognitive and role functions. Here we present the scientific background for and innovation of the study, along with our methods, hypotheses, and preliminary data. The results of this study will help determine the utility of this novel intervention approach for targeting visual perceptual, cognitive, and functional impairments in schizophrenia.
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Coffman BA, Haas G, Olson C, Cho R, Ghuman AS, Salisbury DF. Reduced Dorsal Visual Oscillatory Activity During Working Memory Maintenance in the First-Episode Schizophrenia Spectrum. Front Psychiatry 2020; 11:743. [PMID: 32848922 PMCID: PMC7417606 DOI: 10.3389/fpsyt.2020.00743] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 07/16/2020] [Indexed: 11/17/2022] Open
Abstract
Cognitive deficits in people with schizophrenia are among the hardest to treat and strongly predict functional outcome. The ability to maintain sensory precepts in memory over a short delay is impacted early in the progression of schizophrenia and has been linked to reliable neurophysiological markers. Yet, little is known about the mechanisms of these deficits. Here, we investigated possible neurophysiological mechanisms of impaired visual short-term memory (vSTM, aka working memory maintenance) in the first-episode schizophrenia spectrum (FESz) using magnetoencephalography (MEG). Twenty-eight FESz and 25 matched controls performed a lateralized change detection task where they were cued to selectively attend and remember colors of circles presented in either the left or right peripheral visual field over a 1 s delay. Contralateral alpha suppression (CAS) during the delay period was used to assess selective attention to cued visual hemifields held in vSTM. Delay-period CAS was compared between FESz and controls and between trials presenting one vs three items per visual hemifield. CAS in dorsal visual cortex was reduced in FESz compared to controls in high-load trials, but not low-load trials. Group differences in CAS were found beginning 100 ms after the disappearance of the memory set, suggesting deficits were not due to the initial deployment of attention to the cued visual hemifield prior to stimulus presentation. CAS was not greater for high-load vs low-load trials in FESz subjects, although this effect was prominent in controls. Further, lateralized gamma (34-40 Hz) power emerged in dorsal visual cortex prior to the onset of CAS in controls but not FESz. Gamma power in this cluster differed between groups at both high and low load. CAS deficits observed in FESz were correlated with change detection accuracy, working memory function, estimated IQ, and negative symptoms. Our results implicate deficits in CAS in trials requiring broad, but not narrow, focus of attention to spatially distributed objects maintained in vSTM in FESz, possibly due to reduced ability to broadly distribute visuospatial attention (alpha) or disruption of object-location binding (gamma) during encoding/consolidation. This early pathophysiology may shed light upon mechanisms of emerging working memory deficits that are intrinsic to schizophrenia.
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Affiliation(s)
- Brian A. Coffman
- Clinical Neurophysiology Research Laboratory, Western Psychiatric Hospital of UPMC, Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
| | - Gretchen Haas
- Western Psychiatric Hospital of UPMC, Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
| | - Carl Olson
- Center for Neural Basis of Cognition, Carnegie Mellon University, Pittsburgh, PA, United States
| | - Raymond Cho
- Western Psychiatric Hospital of UPMC, Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
- Department of Psychiatry and Behavioral Sciences, Baylor College of Medicine, Houston, TX, United States
| | - Avniel Singh Ghuman
- Laboratory of Cognitive Neurodynamics, Department of Neurosurgery, Presbyterian Hospital, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
| | - Dean F. Salisbury
- Clinical Neurophysiology Research Laboratory, Western Psychiatric Hospital of UPMC, Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
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15
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Cortical hyperactivation at low working memory load: A primary processing abnormality in people with schizophrenia? NEUROIMAGE-CLINICAL 2020; 26:102270. [PMID: 32388334 PMCID: PMC7210598 DOI: 10.1016/j.nicl.2020.102270] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 04/01/2020] [Accepted: 04/20/2020] [Indexed: 11/20/2022]
Abstract
A frequent finding when studying substrates of working memory (WM) deficits in people with schizophrenia (PSZ) is task-induced hyperactivation relative to healthy control subjects (HCS) when WM load is low. Hyperactivation accompanying similar performance is commonly attributed to cognitive deficits rendering relatively easy operations more resource-consuming. To test if hyperactivation at low load really is secondary to cognitive impairment in PSZ, we re-analyzed functional MRI data showing left posterior parietal cortex (PPC) hyperactivation in PSZ when holding a single color-item in WM. In subgroups matched for the number of items successfully stored in WM (K) by excluding the highest-performing HCS and lowest-performing PSZ, performance was almost identical across all set sizes (1-7). While BOLD activation at the larger set sizes did not differ between groups, PSZ still robustly hyperactivated left PPC when a single item had to be maintained. The same pattern was observed in subgroups matched for model-based estimates of WM capacity or attentional lapse rate. Given that in the K-matched subsamples PSZ performed as well as HCS even in the most challenging load conditions and that no BOLD signal difference was seen at high loads, it is implausible that PSZ over-recruited WM-related neural structures because they were more challenged by maintaining a single item in WM. Instead, the findings are consistent with a primary schizophrenia-related processing abnormality as proposed by the hyperfocusing hypothesis, which suggests that an abnormally narrow but intense focusing of processing resources is central to many aspects of impaired cognition in PSZ.
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Leonard CJ, Robinson BM, Hahn B, Gold JM, Luck SJ. Increased influence of a previously attended feature in people with schizophrenia. JOURNAL OF ABNORMAL PSYCHOLOGY 2020; 129:305-311. [PMID: 32212750 DOI: 10.1037/abn0000511] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Everyday functioning requires the appropriate allocation of visual attention, which is achieved through multiple mechanisms of attentional guidance. Traditional theories have focused on top-down and bottom-up factors, but implicit learning from recent experience ("selection history") also has a substantial impact on attentional allocation. The present experiment examined the influence of intertrial priming on attentional guidance in people with schizophrenia and matched control subjects. Participants searched for a color pop-out target, which switched randomly between a red target among blue distractors and a blue target among red distractors. We found that performance on the current trial was more influenced by the previous-trial target color in people with schizophrenia than in control subjects. Moreover, this implicit priming effect was greater in individuals with lower working memory capacity (as measured in a separate task). These results suggest that intertrial priming has an exaggerated impact on attentional guidance in people with schizophrenia and that this is associated with other aspects of impaired cognition. Overall, these results are consistent with the hyperfocusing hypothesis, which proposes that a single underlying attentional abnormality may explain a range of atypical effects across perception, attention, and cognition in schizophrenia. (PsycInfo Database Record (c) 2020 APA, all rights reserved).
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Affiliation(s)
| | - Benjamin M Robinson
- Maryland Psychiatric Research Center, University of Maryland School of Medicine
| | - Britta Hahn
- Maryland Psychiatric Research Center, University of Maryland School of Medicine
| | - James M Gold
- Maryland Psychiatric Research Center, University of Maryland School of Medicine
| | - Steven J Luck
- Center for Mind and Brain and Department of Psychology, University of California, Davis
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Favorable effects of omega-3 polyunsaturated fatty acids in attentional control and conversion rate to psychosis in 22q11.2 deletion syndrome. Neuropharmacology 2020; 168:107995. [PMID: 32057798 DOI: 10.1016/j.neuropharm.2020.107995] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 02/05/2020] [Accepted: 02/06/2020] [Indexed: 12/13/2022]
Abstract
Omega-3-polyunsaturated-fatty-acids were suggested against cognitive dysfunctions and conversion to psychosis. However, a recent multicenter trial found no effect in reducing conversion rates in individuals at risk of developing schizophrenia. Patients' genetic heterogeneity and the timing of treatment might influence omega-3 efficacy. Here, we addressed the impact of omega-3 early treatment in both mice and human subjects with a 22q11.2 genetic hemi-deletion (22q11DS), characterized by cognitive dysfunctions and high penetrance of schizophrenia. We first tested the behavioural and cognitive consequences of adolescent exposure to normal or omega-3-enriched diets in wild-type and 22q11DS (LgDel/+) mice. We then contrasted mouse data with those gathered from sixty-two patients with 22q11DS exposed to a normal diet or supplemented with omega-3 during pre-adolescence/adolescence. Adolescent omega-3 exposure had no effects in wild-type mice. However, this treatment ameliorated distractibility deficits revealed in LgDel/+ mice by the Five Choice Serial Reaction Time Task (5CSRTT). The omega-3 improvement in LgDel/+ mice was selective, as no other generalized cognitive and non-cognitive effects were evident. Similarly, omega-3-exposed 22q11DS patients showed long-lasting improvements on distractibility as revealed by the continuous performance test (CPT). Moreover, omega-3-exposed 22q11DS patients showed less risk of developing an Ultra High Risk status and lower conversion rate to psychosis. Our convergent mouse-human findings represent a first analysis on the effects of omega-3 early treatment in 22q11DS. The beneficial effects in attentional control and transition to psychosis could support the early use of omega-3 supplementation in the 22q11DS population.
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Bae GY, Leonard CJ, Hahn B, Gold JM, Luck SJ. Assessing the information content of ERP signals in schizophrenia using multivariate decoding methods. NEUROIMAGE-CLINICAL 2020; 25:102179. [PMID: 31954988 PMCID: PMC6965722 DOI: 10.1016/j.nicl.2020.102179] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 12/22/2019] [Accepted: 01/13/2020] [Indexed: 02/01/2023]
Abstract
This study took multivariate decoding methods that are widely used to assess the nature of neural representations in neurotypical people and applied them to a comparison of people with schizophrenia and matched control subjects. Participants performed a visual working memory task that required remembering 1–5 items from one side of the display and ignoring an equal number of items on the other side of the display. We attempted to decode which side was being held in working memory from the scalp distribution of the ERP activity during the delay period of the working memory task, and we found greater decoding accuracy in people with schizophrenia than in control subjects when a single item was being held in memory. These results support the hyperfocusing hypothesis of cognitive dysfunction in schizophrenia, and they provide an important proof of concept for applying multivariate decoding methods to comparisons of neural representations in psychiatric and non-psychiatric populations.
Multivariate pattern classification (decoding) methods are commonly employed to study mechanisms of neurocognitive processing in typical individuals, where they can be used to quantify the information that is present in single-participant neural signals. These decoding methods are also potentially valuable in determining how the representation of information differs between psychiatric and non-psychiatric populations. Here, we examined ERPs from people with schizophrenia (PSZ) and healthy control subjects (HCS) in a working memory task that involved remembering 1, 3, or 5 items from one side of the display and ignoring the other side. We used the spatial pattern of ERPs to decode which side of the display was being held in working memory. One might expect that decoding accuracy would be inevitably lower in PSZ as a result of increased noise (i.e., greater trial-to-trial variability). However, we found that decoding accuracy was greater in PSZ than in HCS at memory load 1, consistent with previous research in which memory-related ERP signals were larger in PSZ than in HCS at memory load 1. We also observed that decoding accuracy was strongly related to the ratio of the memory-related ERP activity and the noise level. In addition, we found similar noise levels in PSZ and HCS, counter to the expectation that PSZ would exhibit greater trial-to-trial variability. Together, these results demonstrate that multivariate decoding methods can be validly applied at the individual-participant level to understand the nature of impaired cognitive function in a psychiatric population.
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Affiliation(s)
- Gi-Yeul Bae
- Department of Psychology, Arizona State University, 950 S. McAllister Ave, Tempe, AZ 85287, USA.
| | - Carly J Leonard
- Department of Psychology, University of Colorado - Denver, USA
| | - Britta Hahn
- Maryland Psychiatric Research Center and School of Medicine, University of Maryland, USA
| | - James M Gold
- Maryland Psychiatric Research Center and School of Medicine, University of Maryland, USA
| | - Steven J Luck
- Center for Mind & Brain and Department of Psychology, University of California - Davis, USA
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Luck SJ, Hahn B, Leonard CJ, Gold JM. The Hyperfocusing Hypothesis: A New Account of Cognitive Dysfunction in Schizophrenia. Schizophr Bull 2019; 45:991-1000. [PMID: 31317191 PMCID: PMC6737469 DOI: 10.1093/schbul/sbz063] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Impairments in basic cognitive processes such as attention and working memory are commonly observed in people with schizophrenia and are predictive of long-term outcome. In this review, we describe a new theory-the hyperfocusing hypothesis-which provides a unified account of many aspects of impaired cognition in schizophrenia. This hypothesis proposes that schizophrenia involves an abnormally narrow but intense focusing of processing resources. This hyperfocusing impairs the ability of people with schizophrenia to distribute attention among multiple locations, decreases the number of representations that can simultaneously be maintained in working memory, and causes attention to be abnormally captured by irrelevant inputs that share features with active representations. Evidence supporting the hyperfocusing hypothesis comes from a variety of laboratory tasks and from both behavioral and electrophysiological measures of processing. In many of these tasks, people with schizophrenia exhibit supranormal effects of task manipulations, which cannot be explained by a generalized cognitive deficit or by nonspecific factors such as reduced motivation or poor task comprehension. In addition, the degree of hyperfocusing in these tasks is often correlated with the degree of impairment in measures of broad cognitive function, which are known to be related to long-term outcome. Thus, the mechanisms underlying hyperfocusing may be a good target for new treatments targeting cognitive deficits in schizophrenia.
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Affiliation(s)
- Steven J Luck
- Center for Mind and Brain, University of California, Davis, CA
| | - Britta Hahn
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD
| | - Carly J Leonard
- Department of Psychology, University of Colorado Denver, Denver, CO
| | - James M Gold
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD
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Abstract
Recent evidence suggests that schizophrenia involves hyperfocusing, an unusually narrow but intense focusing of processing resources. This appears to contradict the classic idea that schizophrenia involves an impairment in the ability to focus on relevant information and filter irrelevant information. Here, we review one set of studies suggesting that attentional filtering is impaired in people with schizophrenia and another set of studies suggesting that attentional filtering is unimpaired or even enhanced in these individuals. Considerable evidence supports both conclusions, and we propose 3 potential ways of reconciling the conflicting evidence. First, impaired attentional filtering may occur primarily during periods of active psychosis, with hyperfocusing being a part of the broad pattern of cognitive impairment that persists independent of the level of positive symptoms. Second, schizophrenia may involve hyperfocusing in the visual modality and impaired attentional filtering in the auditory modality. Third, attention may be directed toward irrelevant inputs as a result of impaired executive control, and hyperfocusing on those inputs may be functionally equivalent to a failure of attentional filtering. Given the widespread clinical observations and first-person reports of impaired attentional filtering in schizophrenia, it will be important for future research to test these possibilities.
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Affiliation(s)
- Steven J Luck
- Center for Mind & Brain, University of California, Davis, Davis, CA,To whom correspondence should be addressed; tel: 530-297-4424, fax: 530-754-4500, e-mail:
| | - Carly J Leonard
- Department of Psychology, University of Colorado, Denver, CO
| | - Britta Hahn
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD
| | - James M Gold
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD
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Leonard CJ, Robinson BM, Hahn B, Luck SJ, Gold JM. Altered spatial profile of distraction in people with schizophrenia. JOURNAL OF ABNORMAL PSYCHOLOGY 2019; 126:1077-1086. [PMID: 29154568 DOI: 10.1037/abn0000314] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Attention is critical for effective processing of incoming information and has long been identified as a potential area of dysfunction in people with schizophrenia (PSZ). In the realm of visual processing, both spatial attention and feature-based attention are involved in biasing selection toward task-relevant stimuli and avoiding distraction. Evidence from multiple paradigms has suggested that PSZ may hyperfocus and have a narrower "spotlight" of spatial attention. In contrast, feature-based attention seems largely preserved, with some suggestion of increased processing of stimuli sharing the target-defining feature. In the current study, we examined the spatial profile of feature-based distraction using a task in which participants searched for a particular color target and attempted to ignore distractors that varied in distance from the target location and either matched or mismatched the target color. PSZ differed from healthy controls in terms of interference from peripheral distractors that shared the target-color presented 200 ms before a central target. Specifically, PSZ showed an amplified gradient of spatial attention, with increased distraction to near distractors and less interference to far distractors. Moreover, consistent with hyperfocusing, individual differences in this spatial profile were correlated with positive symptoms, such that those with greater positive symptoms showed less distraction by target-colored distractors near the task-relevant location. (PsycINFO Database Record
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Affiliation(s)
| | - Benjamin M Robinson
- Maryland Psychiatric Research Center, University of Maryland School of Medicine
| | - Britta Hahn
- Maryland Psychiatric Research Center, University of Maryland School of Medicine
| | - Steven J Luck
- Center for Mind & Brain and Department of Psychology, University of California, Davis
| | - James M Gold
- Maryland Psychiatric Research Center, University of Maryland School of Medicine
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Diametric effects of autism tendencies and psychosis proneness on attention control irrespective of task demands. Sci Rep 2018; 8:8478. [PMID: 29855492 PMCID: PMC5981437 DOI: 10.1038/s41598-018-26821-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Accepted: 05/15/2018] [Indexed: 11/09/2022] Open
Abstract
Our capacity to attend a target while ignoring irrelevant distraction impacts our ability to successfully interact with our environment. Previous reports have sometimes identified excessive distractor interference in both autism and schizophrenia spectrum disorders and in neurotypical individuals with high subclinical expressions of these conditions. Independent of task, we show that the direction of the effect of autism or psychosis traits on the suppression or rejection of a non-target item is diametrical. In Study 1, in which the presence of a salient non-target item hindered performance, higher autism traits were associated with better performance, while higher psychosis traits were associated with worse performance. In Study 2, in which the presence of a salient non-target item facilitated performance, a complete reversal of effects was observed. Future clinical interventions may be informed by the context-specific advantages we observed for the autism and psychosis spectra, and by the need to consider the diametric effects they yield.
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Bismark AW, Thomas ML, Tarasenko M, Shiluk AL, Rackelmann SY, Young JW, Light GA. Reverse translated and gold standard continuous performance tests predict global cognitive performance in schizophrenia. Transl Psychiatry 2018; 8:80. [PMID: 29643355 PMCID: PMC5895589 DOI: 10.1038/s41398-018-0127-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Revised: 10/24/2017] [Accepted: 11/13/2017] [Indexed: 12/27/2022] Open
Abstract
Attentional dysfunction contributes to functional impairments in schizophrenia (SZ). Sustained attention is typically assessed via continuous performance tasks (CPTs), though many CPTs have limited cross-species translational validity and place demands on additional cognitive domains. A reverse-translated 5-Choice Continuous Performance Task (5C-CPT) for human testing-originally developed for use in rodents-was designed to minimize demands on perceptual, visual learning, processing speed, or working memory functions. To-date, no studies have validated the 5C-CPT against gold standard attentional measures nor evaluated how 5C-CPT scores relate to cognition in SZ. Here we examined the relationship between the 5C-CPT and the CPT-Identical Pairs (CPT-IP), an established and psychometrically robust measure of vigilance from the MATRICS Consensus Cognitive Battery (MCCB) in a sample of SZ patients (n = 35). Relationships to global and individual subdomains of cognition were also assessed. 5C-CPT and CPT-IP measures of performance (d-prime) were strongly correlated (r = 0.60). In a regression model, the 5C-CPT and CPT-IP collectively accounted for 54% of the total variance in MCCB total scores, and 27.6% of overall cognitive variance was shared between the 5C-CPT and CPT-IP. These results indicate that the reverse translated 5C-CPT and the gold standard CPT-IP index a common attentional construct that also significantly overlaps with variance in general cognitive performance. The use of simple, cross-species validated behavioral indices of attentional/cognitive functioning such as the 5C-CPT could accelerate the development of novel generalized pro-cognitive therapeutics for SZ and related neuropsychiatric disorders.
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Affiliation(s)
- Andrew W. Bismark
- 0000 0004 0419 2708grid.410371.0VISN-22 Mental Illness Research Education and Clinical Center (MIRECC), VA San Diego Healthcare System, San Diego, USA ,0000 0001 2107 4242grid.266100.3Department of Psychiatry, University of California, San Diego, USA
| | - Michael L. Thomas
- 0000 0001 2107 4242grid.266100.3Department of Psychiatry, University of California, San Diego, USA
| | - Melissa Tarasenko
- 0000 0004 0419 2708grid.410371.0VISN-22 Mental Illness Research Education and Clinical Center (MIRECC), VA San Diego Healthcare System, San Diego, USA
| | - Alexandra L. Shiluk
- 0000 0001 2107 4242grid.266100.3Department of Psychiatry, University of California, San Diego, USA
| | - Sonia Y. Rackelmann
- 0000 0001 2107 4242grid.266100.3Department of Psychiatry, University of California, San Diego, USA
| | - Jared W. Young
- 0000 0004 0419 2708grid.410371.0VISN-22 Mental Illness Research Education and Clinical Center (MIRECC), VA San Diego Healthcare System, San Diego, USA ,0000 0001 2107 4242grid.266100.3Department of Psychiatry, University of California, San Diego, USA
| | - Gregory A. Light
- 0000 0004 0419 2708grid.410371.0VISN-22 Mental Illness Research Education and Clinical Center (MIRECC), VA San Diego Healthcare System, San Diego, USA ,0000 0001 2107 4242grid.266100.3Department of Psychiatry, University of California, San Diego, USA
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Berkovitch L, Del Cul A, Maheu M, Dehaene S. Impaired conscious access and abnormal attentional amplification in schizophrenia. NEUROIMAGE-CLINICAL 2018; 18:835-848. [PMID: 29876269 PMCID: PMC5988039 DOI: 10.1016/j.nicl.2018.03.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/09/2017] [Revised: 03/09/2018] [Accepted: 03/13/2018] [Indexed: 11/25/2022]
Abstract
Previous research suggests that the conscious perception of a masked stimulus is impaired in schizophrenia, while unconscious bottom-up processing of the same stimulus, as assessed by subliminal priming, can be preserved. Here, we test this postulated dissociation between intact bottom-up and impaired top-down processing and evaluate its brain mechanisms using high-density recordings of event-related potentials. Sixteen patients with schizophrenia and sixteen controls were exposed to peripheral digits with various degrees of visibility, under conditions of either focused attention or distraction by another task. In the distraction condition, the brain activity evoked by masked digits was drastically reduced in both groups, but early bottom-up visual activation could still be detected and did not differ between patients and controls. By contrast, under focused top-down attention, a major impairment was observed: in patients, contrary to controls, the late non-linear ignition associated with the P3 component was reduced. Interestingly, the patients showed an essentially normal attentional amplification of the P1 and N2 components. These results suggest that some but not all top-down attentional amplification processes are impaired in schizophrenia, while bottom-up processing seems to be preserved. An elevated consciousness threshold is observed in schizophrenia. Under unattended conditions, brain activity was similarly reduced in schizophrenic patients and controls. Under attended conditions, the late ignition associated with the P3 component is impaired in patients. In schizophrenia, top-down attentional amplification is abnormal while bottom-up processing is essentially spared.
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Affiliation(s)
- L Berkovitch
- Cognitive Neuroimaging Unit, CEA DSV/I2BM, INSERM, Université Paris-Sud, Université Paris-Saclay, NeuroSpin Center, 91191 Gif-sur-Yvette, France; Sorbonne Universités, UPMC Univ Paris 06, IFD, 4 place Jussieu, 75252 Paris Cedex 05, France.
| | - A Del Cul
- AP-HP, Groupe Hospitalier Pitié-Salpêtrière, Service de Psychiatrie d'Adultes, 75013 Paris, France; Inserm, CNRS, APHP, Institut du Cerveau et de la Moelle (ICM), Hôpital Pitié-Salpêtrière, Sorbonne Universités, UPMC Univ Paris 06, 75013 Paris, France
| | - M Maheu
- Cognitive Neuroimaging Unit, CEA DSV/I2BM, INSERM, Université Paris-Sud, Université Paris-Saclay, NeuroSpin Center, 91191 Gif-sur-Yvette, France; Université Paris Descartes, Sorbonne Paris Cité, 75006 Paris, France
| | - S Dehaene
- Cognitive Neuroimaging Unit, CEA DSV/I2BM, INSERM, Université Paris-Sud, Université Paris-Saclay, NeuroSpin Center, 91191 Gif-sur-Yvette, France; Collège de France, 11 Place Marcelin Berthelot, 75005 Paris, France
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Hahn B, Reneski CH, Pocivavsek A, Schwarcz R. Prenatal kynurenine treatment in rats causes schizophrenia-like broad monitoring deficits in adulthood. Psychopharmacology (Berl) 2018; 235:651-661. [PMID: 29128872 PMCID: PMC5823752 DOI: 10.1007/s00213-017-4780-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 11/01/2017] [Indexed: 12/12/2022]
Abstract
RATIONALE Elevated brain kynurenic acid (KYNA) levels are implicated in the pathology and neurodevelopmental pathogenesis of schizophrenia. In rats, embryonic treatment with kynurenine (EKyn) causes elevated brain KYNA levels in adulthood and cognitive deficits reminiscent of schizophrenia. OBJECTIVES Growing evidence suggests that people with schizophrenia have a narrowed attentional focus, and we aimed at establishing whether these abnormalities may be related to KYNA dysregulation. METHODS To test whether EKyn rats display broad monitoring deficits, kynurenine was added to the chow of pregnant Wistar dams on embryonic days 15-22. As adults, 20 EKyn and 20 control rats were trained to stable performance on the five-choice serial reaction time task, requiring the localization of 1-s light stimuli presented randomly across five apertures horizontally arranged along a curved wall, equating the locomotor demands of reaching each hole. RESULTS EKyn rats displayed elevated omission errors and reduced anticipatory responses relative to control rats, indicative of a lower response rate, and showed reduced locomotor activity. The ability to spread attention broadly was measured by parsing performance by stimulus location. Both groups displayed poorer stimulus detection with greater target location eccentricity, but this effect was significantly more pronounced in the EKyn group. Specifically, the groups differed in the spatial distribution of correct but not incorrect responses. This pattern cannot be explained by differences in response rate and is indicative of a narrowed attentional focus. CONCLUSIONS The findings suggest a potential etiology of broad monitoring deficits in schizophrenia, which may constitute a core cognitive deficit.
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Affiliation(s)
- Britta Hahn
- Maryland Psychiatric Research Center, University of Maryland School of Medicine, P.O. Box 21247, Baltimore, MD, 21228, USA.
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Attentional Control in Adolescent Mice Assessed with a Modified Five Choice Serial Reaction Time Task. Sci Rep 2017; 7:9936. [PMID: 28855580 PMCID: PMC5577211 DOI: 10.1038/s41598-017-10112-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 08/04/2017] [Indexed: 12/30/2022] Open
Abstract
Adolescence is a critical period for the development of higher-order cognitive functions. Unlike in humans, very limited tools are available to assess such cognitive abilities in adolescent rodents. We implemented a modified 5-Choice Serial Reaction Time Task (5CSRTT) to selectively measure attentiveness, impulsivity, broad monitoring, processing speed and distractibility in adolescent mice. 21-day old C57BL/6J mice reliably acquired this task with no sex-dependent differences in 10–12 days. A protocol previously used in adults was less effective to assess impulsiveness in adolescents, but revealed increased vulnerability in females. Next, we distinctively assessed selective, divided and broad monitoring attention modeling the human Spatial Attentional Resource Allocation Task (SARAT). Finally, we measured susceptibility to distractions using non-predictive cues that selectively disrupted attention. These paradigms were also applied to two genetically modified lines: the dopamine transporter (DAT) and catechol-O-methyltransferase (COMT) heterozygous. Adolescent DAT hypo-functioning mice showed attentional deficits and higher impulsivity as found in adults. In contrast to adults, adolescent COMT hypo-functioning mice showed decreased impulsivity and attentional resilience to distractors. These paradigms open new avenues to study the establishment of higher-order cognitive functions in mice, as well as an effective tool for drug-testing and genetic screenings focused on adolescence.
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Huang H, Guadagna S, Mereu M, Ciampoli M, Pruzzo G, Ballard T, Papaleo F. A schizophrenia relevant 5-Choice Serial Reaction Time Task for mice assessing broad monitoring, distractibility and impulsivity. Psychopharmacology (Berl) 2017; 234:2047-2062. [PMID: 28378204 DOI: 10.1007/s00213-017-4611-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 03/19/2017] [Indexed: 02/06/2023]
Abstract
The 5-Choice Serial Reaction Time Task (5-CSRTT) is an automated test for rodents allowing the assessment of multiple cognitive measures. Originally designed to assess cognitive deficits relevant to attention deficit hyperactivity disorder, it has been widely used in the investigation of neural systems of attention. In the current study, we have set up a modified version, which reduced the training phase to only 8-9 days with minimal food deprivation and without single-housing. Furthermore, based on evidence that patients with schizophrenia are more impaired in broad monitoring abilities than in sustained attention, we successfully developed a protocol replicating the Spatial Attentional Resource Allocation Task (SARAT), used in humans to assess broad monitoring. During this task, when the target appeared at a single pre-cued location, mice selectively responded faster. Instead, increasing the number of validly cued locations proportionately decreased accuracy. We then validated a protocol which is relevant for neuropsychiatric disorders in which additional irrelevant pre-cue lights selectively disrupted attention (distractibility). Finally, we improved previously used protocols changing inter-trial intervals from 5 to 7 s by randomly presenting this shift only in 20% of the trials. This resulted in a selective effect on premature responses (impulsivity), with important implications for schizophrenia as well as for other mental disorders. Therefore, this revised 5-CSRTT reduced training and stress on the animals while selectively measuring different cognitive functions with translational validity to schizophrenia and other psychiatric disorders.
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Affiliation(s)
- Huiping Huang
- Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, via Morego, 30, 16163, Genova, Italy
| | - Simone Guadagna
- Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, via Morego, 30, 16163, Genova, Italy
| | - Maddalena Mereu
- Dipartimento di Scienze del Farmaco, Università degli Studi di Padova, Largo Meneghetti, 2, 35131, Padova, Italy
| | - Mariasole Ciampoli
- Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, via Morego, 30, 16163, Genova, Italy
| | - Giacomo Pruzzo
- Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, via Morego, 30, 16163, Genova, Italy
| | - Theresa Ballard
- Neuroscience, Ophthalmology and Rare Diseases, Roche Pharma Research and Early Development, Roche Innovation Center, Basel, Switzerland
| | - Francesco Papaleo
- Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, via Morego, 30, 16163, Genova, Italy.
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Mereu M, Contarini G, Buonaguro EF, Latte G, Managò F, Iasevoli F, de Bartolomeis A, Papaleo F. Dopamine transporter (DAT) genetic hypofunction in mice produces alterations consistent with ADHD but not schizophrenia or bipolar disorder. Neuropharmacology 2017; 121:179-194. [PMID: 28454982 DOI: 10.1016/j.neuropharm.2017.04.037] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Revised: 03/13/2017] [Accepted: 04/24/2017] [Indexed: 01/02/2023]
Abstract
ADHD, schizophrenia and bipolar disorder are psychiatric diseases with a strong genetic component which share dopaminergic alterations. Dopamine transporter (DAT) genetics might be potentially implicated in all these disorders. However, in contrast to DAT absence, the effects of DAT hypofunction especially in developmental trajectories have been scarcely addressed. Thus, we comprehensively studied DAT hypofunctional mice (DAT+/-) from adolescence to adulthood to disentangle DAT-dependent alterations in the development of psychiatric-relevant phenotypes. From pre-adolescence onward, DAT+/- displayed a hyperactive phenotype, while responses to external stimuli and sensorimotor gating abilities were unaltered. General cognitive impairments in adolescent DAT+/- were partially ameliorated during adulthood in males but not in females. Despite this, attentional and impulsivity deficits were evident in DAT+/- adult males. At the molecular level, DAT+/- mice showed a reduced expression of Homer1a in the prefrontal cortex, while other brain regions as well as Arc and Homer1b expression were mostly unaffected. Amphetamine treatments reverted DAT+/- hyperactivity and rescued cognitive deficits. Moreover, amphetamine shifted DAT-dependent Homer1a altered expression from prefrontal cortex to striatal regions. These behavioral and molecular phenotypes indicate that a genetic-driven DAT hypofunction alters neurodevelopmental trajectories consistent with ADHD, but not with schizophrenia and bipolar disorders.
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Affiliation(s)
- M Mereu
- Department of Pharmaceutical Science, University of Padua, Padua, Italy
| | - G Contarini
- Department of Pharmaceutical Science, University of Padua, Padua, Italy
| | - E F Buonaguro
- Section of Psychiatry. Department of Neuroscience, Reproductive and Odontostomatological Science, University School of Medicine "Federico II", Naples, Italy
| | - G Latte
- Section of Psychiatry. Department of Neuroscience, Reproductive and Odontostomatological Science, University School of Medicine "Federico II", Naples, Italy
| | - F Managò
- Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
| | - F Iasevoli
- Section of Psychiatry. Department of Neuroscience, Reproductive and Odontostomatological Science, University School of Medicine "Federico II", Naples, Italy
| | - A de Bartolomeis
- Section of Psychiatry. Department of Neuroscience, Reproductive and Odontostomatological Science, University School of Medicine "Federico II", Naples, Italy
| | - F Papaleo
- Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy.
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Electrophysiological Evidence for Hyperfocusing of Spatial Attention in Schizophrenia. J Neurosci 2017; 37:3813-3823. [PMID: 28283557 DOI: 10.1523/jneurosci.3221-16.2017] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2016] [Revised: 01/25/2017] [Accepted: 02/10/2017] [Indexed: 11/21/2022] Open
Abstract
A recently proposed hyperfocusing hypothesis of cognitive dysfunction in schizophrenia proposes that people with schizophrenia (PSZ) tend to concentrate processing resources more narrowly but more intensely than healthy control subjects (HCS). The present study tests a key prediction of this hypothesis, namely, that PSZ will hyperfocus on information presented at the center of gaze. This should lead to greater filtering of peripheral stimuli when the task requires focusing centrally but reduced filtering of central stimuli when the task requires attending broadly in the periphery. These predictions were tested in a double oddball paradigm, in which frequent standard stimuli and rare oddball stimuli were presented at central and peripheral locations while event-related potentials were recorded. Participants were instructed to discriminate between the standard and oddball stimuli at either the central location or at the peripheral locations. PSZ and HCS showed opposite patterns of spatial bias at the level of early sensory processing, as assessed with the P1 component: PSZ exhibited stronger sensory suppression of peripheral stimuli when the task required attending narrowly to the central location, whereas HCS exhibited stronger sensory suppression of central stimuli when the task required attending broadly to the peripheral locations. Moreover, PSZ exhibited a stronger stimulus categorization response than HCS, as assessed with the P3b component, for central stimuli when the task required attending to the peripheral region. These results provide strong evidence of hyperfocusing in PSZ, which may provide a unified mechanistic account of multiple aspects of cognitive dysfunction in schizophrenia.SIGNIFICANCE STATEMENT Schizophrenia clearly involves impaired attention, but attention is complex, and delineating the precise nature of attentional dysfunction in schizophrenia has been difficult. The present study tests a new hyperfocusing hypothesis, which proposes that people with schizophrenia (PSZ) tend to concentrate processing resources more intensely but more narrowly than healthy control subjects (HCS). Using electrophysiological measures of sensory and cognitive processing, we found that PSZ were actually superior to HCS in focusing attention at the point of gaze and filtering out peripheral distractors when the task required a narrow focusing of attention. This finding of superior filtering in PSZ supports the hyperfocusing hypothesis, which may provide the mechanism underlying a broad range of cognitive impairments in schizophrenia.
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Yuille MB, Olmstead CK, Wells AK, Hahn B. A test of the cognitive-enhancing potential of low-dose mecamylamine in healthy non-smokers. Psychopharmacology (Berl) 2017; 234:109-116. [PMID: 27678550 PMCID: PMC5209795 DOI: 10.1007/s00213-016-4443-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Accepted: 09/16/2016] [Indexed: 11/30/2022]
Abstract
RATIONALE The beneficial effects of nicotinic acetylcholine receptor (nAChR) agonists on cognitive performance have been widely shown. Paradoxically, recent preclinical studies employing extremely low doses of nAChR antagonists have also found cognitive enhancement, perhaps pointing to a novel treatment mechanism for cognitive deficits. OBJECTIVES The aim was to test whether low doses of the nAChR antagonist mecamylamine would benefit performance in human volunteers. METHODS The study employed a double-blind within-subject design. Over four separate days, healthy adult non-smokers (n = 23) were tested with placebo and three trace doses of mecamylamine (0.25-1 mg, p.o.), adjusted for body weight. Participants performed three computerized tasks: a task of spatial selective attention and stimulus detection, the rapid visual information processing task (RVIPT) taxing sustained attention and working memory, and a change detection short-term memory task. Subjective state and vital signs were assessed repeatedly. RESULTS Mecamylamine did not improve performance in any of the tasks. Any trends that were observed instead pointed toward performance impairment. Mecamylamine also had no effects on subjective state or vital signs. CONCLUSIONS The present results do not support the hypothesized cognitive-enhancing potential of low doses of mecamylamine. Contrary to preclinical reports, these findings speak against low-dose nAChR antagonism as a novel avenue for treating cognitive deficits.
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Affiliation(s)
| | | | | | - Britta Hahn
- Maryland Psychiatric Research Center, University of Maryland School of Medicine, P.O. Box 21247, Baltimore, MD, 21228, USA.
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López-Luengo B, González-Andrade A, García-Cobo M. Not All Differences between Patients with Schizophrenia and Healthy Subjects Are Pathological: Performance on the Conners' Continuous Performance Test. Arch Clin Neuropsychol 2016; 31:983-995. [PMID: 27620627 DOI: 10.1093/arclin/acw075] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/17/2016] [Indexed: 11/14/2022] Open
Abstract
OBJECTIVE This study analyzed attentional performance in patients with schizophrenia during a continuous performance task requiring a high response rate. METHOD The Conners' Continuous Performance Test-II (CPT-II) was administered to 64 patients with schizophrenia and 64 healthy comparison subjects. A cross-sectional design was used in order to allow analysis of the means between patients and healthy subjects. Differences in performance were assessed for significance using ANCOVA. Percentiles were also analyzed in order to determine whether a participant showed normal or pathological performance. Pearson's correlation was used to detect possible relationships between attentional performance and psychopathology. RESULTS Of the 12 CPT-II measures, response style and slowing of reaction time (RT) between targets increased to similar extents between patients and healthy comparison subjects. Patients performed significantly less well than non-patient group on all other measures. Nevertheless, patient's performance on four of these measures remained within the normal range, and patient's performance on the remaining measures qualified as pathological only in the case of variability in hit RT. No significant correlations between attention performance and symptoms were found. CONCLUSIONS These results suggest that although patients may show lower attentional functioning than non-patients on tasks requiring a high response rate, their attentional performance remains within the normal range on most dimensions.
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Sawaki R, Kreither J, Leonard CJ, Kaiser ST, Hahn B, Gold JM, Luck SJ. Hyperfocusing of attention on goal-related information in schizophrenia: Evidence from electrophysiology. JOURNAL OF ABNORMAL PSYCHOLOGY 2016; 126:106-116. [PMID: 27709980 DOI: 10.1037/abn0000209] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Schizophrenia clearly involves impairments of attention, but the precise nature of these impairments has been difficult to determine. One possibility is that the deficit in attention is a secondary consequence of a deficit in goal maintenance. However, recent research suggests that people with schizophrenia (PSZ) actually focus attention more strongly on objects containing goal-relevant features. To test these competing hypotheses, we recorded event-related potentials (ERPs) from PSZ (N = 20) and healthy control subjects (HCS; N = 20) while they looked for a particular target color at fixation and tried to ignore lateral distractors that sometimes matched the target color (target-color distractors). Goal maintenance was made trivially easy by the continual presentation of a goal reminder. We found that HCS were able to successfully suppress target-color distractors (leading to a distractor positivity ERP component), whereas PSZ focused attention on these items (leading to an N2-posterior-contralateral ERP component). This suggests that, when maintaining a task set, PSZ engage in aberrant focusing of attention, or hyperfocusing, on goal-relevant features. (PsycINFO Database Record
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Affiliation(s)
- Risa Sawaki
- Center for Mind and Brain, University of California, Davis
| | | | | | - Samuel T Kaiser
- Maryland Psychiatric Research Center, University of Maryland School of Medicine
| | - Britta Hahn
- Maryland Psychiatric Research Center, University of Maryland School of Medicine
| | - James M Gold
- Maryland Psychiatric Research Center, University of Maryland School of Medicine
| | - Steven J Luck
- Center for Mind and Brain, University of California, Davis
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Hahn B, Harvey AN, Gold JM, Fischer BA, Keller WR, Ross TJ, Stein EA. Hyperdeactivation of the Default Mode Network in People With Schizophrenia When Focusing Attention in Space. Schizophr Bull 2016; 42:1158-66. [PMID: 26926831 PMCID: PMC4988736 DOI: 10.1093/schbul/sbw019] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
When studying selective attention in people with schizophrenia (PSZ), a counterintuitive but replicated finding has been that PSZ display larger performance benefits than healthy control subjects (HCS) by cues that predicts the location of a target stimulus relative to non-predictive cues. Possible explanations are that PSZ hyperfocus attention in response to predictive cues, or that an inability to maintain a broad attentional window impairs performance when the cue is non-predictive. Over-recruitment of regions involved in top-down focusing of spatial attention in response to predictive cues would support the former possibility, and an inappropriate recruitment of these regions in response to non-predictive cues the latter. We probed regions of the dorsal attention network while PSZ (N = 20) and HCS (N = 20) performed a visuospatial attention task. A central cue either predicted at which of 4 peripheral locations a target signal would appear, or it gave no information about the target location. As observed previously, PSZ displayed a larger reaction time difference between predictive and non-predictive cue trials than HCS. Activity in frontoparietal and occipital regions was greater for predictive than non-predictive cues. This effect was almost identical between PSZ and HCS. There was no sign of over-recruitment when the cue was predictive, or of inappropriate recruitment when the cue was non-predictive. However, PSZ differed from HCS in their cue-dependent deactivation of the default mode network. Unexpectedly, PSZ displayed significantly greater deactivation than HCS in predictive cue trials, which may reflect a tendency to expend more processing resources when focusing attention in space.
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Affiliation(s)
- Britta Hahn
- Maryland Psychiatric Research Center, University of Maryland School of Medicine, Baltimore, MD;
| | - Alexander N. Harvey
- Maryland Psychiatric Research Center, University of Maryland School of Medicine, Baltimore, MD
| | - James M. Gold
- Maryland Psychiatric Research Center, University of Maryland School of Medicine, Baltimore, MD
| | - Bernard A. Fischer
- Maryland Psychiatric Research Center, University of Maryland School of Medicine, Baltimore, MD
| | - William R. Keller
- Maryland Psychiatric Research Center, University of Maryland School of Medicine, Baltimore, MD
| | - Thomas J. Ross
- Neuroimaging Research Branch, National Institute on Drug Abuse—Intramural Research Program, Baltimore, MD
| | - Elliot A. Stein
- Neuroimaging Research Branch, National Institute on Drug Abuse—Intramural Research Program, Baltimore, MD
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Tang Y, Li Y, Zhuo K, Wang Y, Liao L, Song Z, Li H, Fan X, Goff DC, Wang J, Xu Y, Liu D. Neural correlates of the preserved inhibition of return in schizophrenia. PLoS One 2015; 10:e0119521. [PMID: 25875486 PMCID: PMC4395298 DOI: 10.1371/journal.pone.0119521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Accepted: 01/30/2015] [Indexed: 11/19/2022] Open
Abstract
Inhibition of return (IOR) is an attentional mechanism that previously has been reported to be either intact or blunted in subjects with schizophrenia (SCZ). In the present study, we explored the neural mechanism of IOR in SCZ by comparing the target-locked N1 and P1 activity evoked by valid-cued trials with that evoked by invalid-cued trials. Twenty-seven schizophrenia patients and nineteen healthy controls participated in a task involving covert orienting of attention with two stimulus onset asynchronies (SOAs: 700 ms and 1200 ms) during which 64-channel EEG data were recorded. Behavioral reaction times (RTs) were longer in response to valid-cued trials than to invalid-cued ones, suggesting an intact IOR in SCZ. However, reduced N1 amplitude elicited by valid-cued trials suggested a stronger inhibition of attention from being oriented to a previously cued location, and therefore a relative inhibition of perceptual processing at that location in SCZ. These results indicate that altered N1 activity is associated with the preservation of IOR in SCZ and could be a sensitive marker to track the IOR effect.
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Affiliation(s)
- Yingying Tang
- First-episode Schizophrenia and Early Psychosis Program, Division of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yan Li
- First-episode Schizophrenia and Early Psychosis Program, Division of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Kaiming Zhuo
- First-episode Schizophrenia and Early Psychosis Program, Division of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yan Wang
- Department of Psychology, East China Normal University, Shanghai, China
| | - Liwei Liao
- First-episode Schizophrenia and Early Psychosis Program, Division of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Zhenhua Song
- First-episode Schizophrenia and Early Psychosis Program, Division of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Hui Li
- First-episode Schizophrenia and Early Psychosis Program, Division of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xiaoduo Fan
- Nathan Kline Institute for Psychiatric Research, New York University Medical Center, New York, New York, United States of America
| | - Donald C. Goff
- Psychotic Disorders Program, UMass Memorial Medical Center, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Jijun Wang
- First-episode Schizophrenia and Early Psychosis Program, Division of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yifeng Xu
- First-episode Schizophrenia and Early Psychosis Program, Division of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- * E-mail: (YX); (DL)
| | - Dengtang Liu
- First-episode Schizophrenia and Early Psychosis Program, Division of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- * E-mail: (YX); (DL)
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35
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Erickson MA, Hahn B, Leonard CJ, Robinson B, Gray B, Luck SJ, Gold J. Impaired working memory capacity is not caused by failures of selective attention in schizophrenia. Schizophr Bull 2015; 41:366-73. [PMID: 25031223 PMCID: PMC4332943 DOI: 10.1093/schbul/sbu101] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The cognitive impairments associated with schizophrenia have long been known to involve deficits in working memory (WM) capacity. To date, however, the causes of WM capacity deficits remain unknown. The present study examined selective attention impairments as a putative contributor to observed capacity deficits in this population. To test this hypothesis, we used an experimental paradigm that assesses the role of selective attention in WM encoding and has been shown to involve the prefrontal cortex and the basal ganglia. In experiment 1, participants were required to remember the locations of 3 or 5 target items (red circles). In another condition, 3-target items were accompanied by 2 distractor items (yellow circles), which participants were instructed to ignore. People with schizophrenia (PSZ) exhibited significant impairment in memory for the locations of target items, consistent with reduced WM capacity, but PSZ and healthy control subjects did not differ in their ability to filter the distractors. This pattern was replicated in experiment 2 for distractors that were more salient. Taken together, these results demonstrate that reduced WM capacity in PSZ is not attributable to a failure of filtering irrelevant distractors.
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Affiliation(s)
- Molly A. Erickson
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Catonsville, MD;,*To whom correspondence should be addressed; Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, 55 Wade Avenue, Catonsville, MD 21228, US; tel: 402-410-6898, fax: 410-788-3837, e-mail:
| | - Britta Hahn
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Catonsville, MD
| | - Carly J. Leonard
- University of California Davis, Center for Mind and Brain, Davis, CA
| | - Benjamin Robinson
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Catonsville, MD
| | - Brad Gray
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Catonsville, MD
| | - Steven J. Luck
- University of California Davis, Center for Mind and Brain, Davis, CA
| | - James Gold
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Catonsville, MD
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36
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Young JW, Geyer MA. Developing treatments for cognitive deficits in schizophrenia: the challenge of translation. J Psychopharmacol 2015; 29:178-96. [PMID: 25516372 PMCID: PMC4670265 DOI: 10.1177/0269881114555252] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Schizophrenia is a life-long debilitating mental disorder affecting tens of millions of people worldwide. The serendipitous discovery of antipsychotics focused pharmaceutical research on developing a better antipsychotic. Our understanding of the disorder has advanced however, with the knowledge that cognitive enhancers are required for patients in order to improve their everyday lives. While antipsychotics treat psychosis, they do not enhance cognition and hence are not antischizophrenics. Developing pro-cognitive therapeutics has been extremely difficult, however, especially when no approved treatment exists. In lieu of stumbling on an efficacious treatment, developing targeted compounds can be facilitated by understanding the neural mechanisms underlying altered cognitive functioning in patients. Equally importantly, these cognitive domains will need to be measured similarly in animals and humans so that novel targets can be tested prior to conducting expensive clinical trials. To date, the limited similarity of testing across species has resulted in a translational bottleneck. In this review, we emphasize that schizophrenia is a disorder characterized by abnormal cognitive behavior. Quantifying these abnormalities using tasks having cross-species validity would enable the quantification of comparable processes in rodents. This approach would increase the likelihood that the neural substrates underlying relevant behaviors will be conserved across species. Hence, we detail cross-species tasks which can be used to test the effects of manipulations relevant to schizophrenia and putative therapeutics. Such tasks offer the hope of providing a bridge between non-clinical and clinical testing that will eventually lead to treatments developed specifically for patients with deficient cognition.
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Affiliation(s)
- JW Young
- Department of Psychiatry, University of California San Diego, La Jolla, CA, USA
| | - MA Geyer
- Research Service, VA San Diego Healthcare System, San Diego, CA, USA
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37
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Elshaikh AA, Sponheim SR, Chafee MV, MacDonald AW. Spatial attentional control is not impaired in schizophrenia: Dissociating specific deficits from generalized impairments. JOURNAL OF ABNORMAL PSYCHOLOGY 2014; 124:302-308. [PMID: 25546021 DOI: 10.1037/a0038537] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A large literature has established that people with schizophrenia are impaired on tasks that require attentional control. However, evidence is mixed as to whether these impairments are specific deficits (Oltmanns & Neale, 1975) or merely reflect a generalized impairment (Dickinson & Harvey, 2009). Recent evidence also suggests visual attentional control for encoding into working memory may be selectively spared in people with schizophrenia (Gold et al., 2006). The current study used a cued backward masking task to investigate 23 people with schizophrenia and 27 healthy controls. People with schizophrenia were hypothesized to perform better on invalidly cued trials when making a simple identification or location judgment. However, we found schizophrenia impaired performance on both valid and invalid cues to the same degree whether the cue was a stored representation (top-down) or presented at the location of the stimulus (bottom-up). In contrast to a large neuropsychological literature, these findings suggest that people with schizophrenia show no specific spatial attentional control deficit. The errors that they make on such task may be consistent with a generalized impairment.
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38
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Gray BE, Hahn B, Robinson B, Harvey A, Leonard CJ, Luck SJ, Gold JM. Relationships between divided attention and working memory impairment in people with schizophrenia. Schizophr Bull 2014; 40:1462-71. [PMID: 24748559 PMCID: PMC4193709 DOI: 10.1093/schbul/sbu015] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Recent studies suggest that people with schizophrenia (PSZ) have difficulty distributing their attention broadly. Other research suggests that PSZ have reduced working memory (WM) capacity. This study tested whether these findings reflect a common underlying deficit. We measured the ability to distribute attention by means of the Useful Field of View (UFOV) task, in which participants must distribute attention so that they can discriminate a foveal target and simultaneously localize a peripheral target. Participants included 50 PSZ and 52 healthy control subjects. We found that PSZ exhibited severe impairments in UFOV performance, that UFOV performance was highly correlated with WM capacity in PSZ (r = -.61), and that UFOV impairments could not be explained by either impaired low-level processing or a generalized deficit. These results suggest that a common mechanism explains deficits in the ability to distribute attention broadly, reduced WM capacity, and other aspects of impaired cognition in schizophrenia. We hypothesize that this mechanism may involve abnormal local circuit dynamics that cause a hyperfocusing of resources onto a small number of internal representations.
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Affiliation(s)
- Bradley E. Gray
- Department of Psychiatry, Maryland Psychiatric Research Center, University of Maryland School of Medicine, Baltimore, Maryland;,*To whom correspondence should be addressed; Department of Psychiatry, Maryland Psychiatric Research Center, University of Maryland School of Medicine, PO Box 21247, Baltimore, Maryland 21228, US; tel: +141-040-27879, fax: +1-410-402-7198, e-mail:
| | - Britta Hahn
- Department of Psychiatry, Maryland Psychiatric Research Center, University of Maryland School of Medicine, Baltimore, Maryland
| | - Benjamin Robinson
- Department of Psychiatry, Maryland Psychiatric Research Center, University of Maryland School of Medicine, Baltimore, Maryland
| | - Alex Harvey
- Department of Psychiatry, Maryland Psychiatric Research Center, University of Maryland School of Medicine, Baltimore, Maryland
| | - Carly J. Leonard
- Department of Psychology and Center for Mind & Brain, University of California, Davis
| | - Steven J. Luck
- Department of Psychology and Center for Mind & Brain, University of California, Davis
| | - James M. Gold
- Department of Psychiatry, Maryland Psychiatric Research Center, University of Maryland School of Medicine, Baltimore, Maryland
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Luck SJ, McClenon C, Beck VM, Hollingworth A, Leonard CJ, Hahn B, Robinson BM, Gold JM. Hyperfocusing in schizophrenia: Evidence from interactions between working memory and eye movements. JOURNAL OF ABNORMAL PSYCHOLOGY 2014; 123:783-95. [PMID: 25089655 PMCID: PMC4227934 DOI: 10.1037/abn0000003] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Recent research suggests that processing resources are focused more narrowly but more intensely in people with schizophrenia (PSZ) than in healthy control subjects (HCS), possibly reflecting local cortical circuit abnormalities. This hyperfocusing hypothesis leads to the counterintuitive prediction that, although PSZ cannot store as much information in working memory as HCS, the working memory representations that are present in PSZ may be more intense than those in HCS. To test this hypothesis, we used a task in which participants make a saccadic eye movement to a peripheral target and avoid a parafoveal nontarget while they are holding a color in working memory. Previous research with this task has shown that the parafoveal nontarget is more distracting when it matches the color being held in working memory. This effect should be enhanced in PSZ if their working memory representations are more intense. Consistent with this prediction, we found that the effect of a match between the distractor color and the memory color was larger in PSZ than in HCS. We also observed evidence that PSZ hyperfocused spatially on the region surrounding the fixation point. These results provide further evidence that some aspects of cognitive dysfunction in schizophrenia may be a result of a narrower and more intense focusing of processing resources.
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Affiliation(s)
- Steven J. Luck
- University of California, Davis, Center for Mind & Brain and Department of Psychology, 267 Cousteau Place, Davis, CA 95618, USA
| | - Clara McClenon
- University of California, Davis, Center for Mind & Brain and Department of Psychology, 267 Cousteau Place, Davis, CA 95618, USA
| | - Valerie M. Beck
- University of Iowa, Department of Psychology, 11 Seashore Hall E, Iowa City, IA 52242, USA
- University of California, Davis, Center for Mind & Brain and Department of Psychology, 267 Cousteau Place, Davis, CA 95618, USA
| | - Andrew Hollingworth
- University of Iowa, Department of Psychology, 11 Seashore Hall E, Iowa City, IA 52242, USA
| | - Carly J. Leonard
- University of California, Davis, Center for Mind & Brain and Department of Psychology, 267 Cousteau Place, Davis, CA 95618, USA
| | - Britta Hahn
- University of Maryland School of Medicine, Maryland Psychiatric Research Center, P.O. box 21247, Baltimore, MD 21228, USA
| | - Benjamin M. Robinson
- University of Maryland School of Medicine, Maryland Psychiatric Research Center, P.O. box 21247, Baltimore, MD 21228, USA
| | - James M. Gold
- University of Maryland School of Medicine, Maryland Psychiatric Research Center, P.O. box 21247, Baltimore, MD 21228, USA
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Leonard CJ, Robinson BM, Hahn B, Gold JM, Luck SJ. Enhanced distraction by magnocellular salience signals in schizophrenia. Neuropsychologia 2014; 56:359-66. [PMID: 24561035 DOI: 10.1016/j.neuropsychologia.2014.02.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 02/06/2014] [Accepted: 02/11/2014] [Indexed: 11/16/2022]
Abstract
Research on schizophrenia has provided evidence of both impaired attentional control and dysfunctional magnocellular sensory processing. The present study tested the hypothesis that these impairments may be related, such that people with schizophrenia would be differentially distracted by stimuli that strongly activate the magnocellular pathway. To accomplish this, we used a visual attention paradigm from the basic cognitive neuroscience literature designed to assess the capture of attention by salient but irrelevant stimuli. Participants searched for a target shape in an array of non-target shapes. On some trials, a salient distractor was presented that either selectively activated the parvocellular system (parvo-biased distractors) or activated both the magnocellular and parvocellular systems (magno+parvo distractors). For both manual reaction times and eye movement measures, the magno+parvo distractors captured attention more strongly than the parvo-biased distractors in people with schizophrenia, but the opposite pattern was observed in matched healthy control participants. These results indicate that attentional control deficits in schizophrenia may arise, at least in part, by means of an interaction with magnocellular sensory dysfunction.
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Affiliation(s)
- Carly J Leonard
- Center for Mind & Brain and Department of Psychology, University of California, Davis, CA 95618, United States.
| | - Benjamin M Robinson
- University of Maryland School of Medicine, Maryland Psychiatric Research Center, Baltimore, MD, United States
| | - Britta Hahn
- University of Maryland School of Medicine, Maryland Psychiatric Research Center, Baltimore, MD, United States
| | - James M Gold
- University of Maryland School of Medicine, Maryland Psychiatric Research Center, Baltimore, MD, United States
| | - Steven J Luck
- Center for Mind & Brain and Department of Psychology, University of California, Davis, CA 95618, United States
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Hahn B, Harvey AN, Concheiro-Guisan M, Huestis MA, Holcomb HH, Gold JM. A test of the cognitive self-medication hypothesis of tobacco smoking in schizophrenia. Biol Psychiatry 2013; 74:436-43. [PMID: 23660272 PMCID: PMC3755590 DOI: 10.1016/j.biopsych.2013.03.017] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2013] [Revised: 02/22/2013] [Accepted: 03/15/2013] [Indexed: 12/15/2022]
Abstract
BACKGROUND Heavier tobacco smoking among people with schizophrenia (SCZ) has been suggested to reflect self-medication of cognitive deficits. The idea that cognitive-enhancing effects of nicotine are a primary motivator of tobacco consumption in SCZ and that abstinence would deprive SCZ of such beneficial effects might explain hesitation among providers to pursue smoking cessation in SCZ. This study tested predictions of the cognitive self-medication hypothesis. METHODS In three counterbalanced sessions, 17 SCZ and 17 healthy control subjects (HCS), all smokers, were tested under ad libitum smoking or 3.5 hours after abstaining and receiving a nicotine (14 mg/24 hours) or placebo patch. RESULTS Attention task performance was improved by transdermal nicotine relative to placebo, with intermediate performance by ad libitum smoking. These effects were of similar size in SCZ and HCS and did not reflect remediation of functions disproportionately impaired in SCZ. Although more SCZ reported that the need to concentrate influenced their smoking, this was not reflected by the actual behavior of these patients. Self-reported ability to concentrate changed with nicotine status in HCS but not SCZ, suggesting insensitivity of SCZ to nicotine-derived performance benefits. Nicotine plasma concentrations after ad libitum smoking were not associated with performance benefits but instead with the propensity to experience nicotine withdrawal upon abstinence. This association was seen selectively in SCZ, suggesting a possible reason for heavier smoking. CONCLUSIONS These findings suggest that subjective or objective attentional benefits are unlikely the primary driving force of tobacco consumption in SCZ and should not discourage providers from supporting quit attempts.
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Affiliation(s)
- Britta Hahn
- Maryland Psychiatric Research Center, University of Maryland School of Medicine, Baltimore, MD 21228, USA.
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Badgaiyan RD. Nonconscious processing and a novel target for schizophrenia research. OPEN JOURNAL OF PSYCHIATRY 2012; 2. [PMID: 24404419 DOI: 10.4236/ojpsych.2012.224047] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Analysis of the pattern of altered cognition observed in schizophrenia provides better insight into neurocognitive deficits. It reveals a potential novel target for schizophrenia research. To understand this target we reviewed the findings of neuroimaging studies on implicit [nonconscious] memory. These studies have consistently reported attenuated activity in the area V3A of the extrastriate cortex during retrieval of studied items. It was suggested that the attenuation limits the pool of information available for further cognitive processing. Therefore, if V3A is functionally damaged, individuals will have access to a larger pool of information for cognitive processing. Since cognitive tasks that are not dependent on attention [attention independent] process a larger pool of information more efficiently, performance in these tasks is likely to improve after V3A is damaged. Conversely, tasks that are dependent on attentional resources are more efficient in processing smaller pool of information. Performance in these tasks therefore is expected to deteriorate if a large pool of information is made available following V3A damage. A review of cognitive performance in schizophrenia suggests that patients perform at above normal level in attention independent priming tasks and perform at subnormal level in attention dependent episodic and working memory tasks. These findings indicate possible impairment of V3A activity. It could therefore be a potentially important unstudied target for schizophrenia research, particularly because a number of investigators have reported that the activity in this area is altered in schizophrenia.
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Affiliation(s)
- Rajendra D Badgaiyan
- Department of Psychiatry; State University of New York at Buffalo, New York, USA ; Department of Psychiatry, VA Medical Center, Buffalo, New York, USA
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Leonard CJ, Kaiser ST, Robinson BM, Kappenman ES, Hahn B, Gold JM, Luck SJ. Toward the neural mechanisms of reduced working memory capacity in schizophrenia. Cereb Cortex 2012; 23:1582-92. [PMID: 22661407 DOI: 10.1093/cercor/bhs148] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
People with schizophrenia (PSZ) demonstrate reliable reductions in working memory (WM) capacity (i.e., the number of objects that can be held in memory). The present study asked whether WM impairments in PSZ can be explained by the same neural mechanisms that underlie individual differences in WM capacity among healthy individuals. Specifically, we examined event-related potentials in PSZ and healthy matched controls during a change detection task that required the storage of multiple objects in WM. The amplitude of contralateral delay activity (CDA), which correlates with WM capacity in healthy individuals, was larger in controls than in PSZ for memory loads of 3 and 5 objects, but larger in PSZ than in controls for a memory load of 1. This same pattern was found in the subgroups of PSZ and controls with an equivalent WM capacity. Moreover, the increase in CDA amplitude was correlated with individual differences in capacity in controls, but not in PSZ. These results demonstrate that WM impairment in PSZ is not associated with the same patterns of neural activity that characterize low WM capacity in healthy individuals. We propose that WM impairment in PSZ instead reflects a specific impairment in the ability to distribute attention broadly.
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Affiliation(s)
- Carly J Leonard
- Department of Psychology, Center for Mind and Brain, University of California, Davis, CA 95618, USA.
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Hahn B, Hollingworth A, Robinson BM, Kaiser ST, Leonard CJ, Beck VM, Kappenman ES, Luck SJ, Gold JM. Control of working memory content in schizophrenia. Schizophr Res 2012; 134:70-5. [PMID: 22079944 PMCID: PMC3275350 DOI: 10.1016/j.schres.2011.10.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Revised: 10/14/2011] [Accepted: 10/17/2011] [Indexed: 11/19/2022]
Abstract
People with schizophrenia (PSZ) exhibit signs of reduced working memory (WM) capacity. However, this may reflect an impairment in managing its content, e.g. preventing irrelevant information from taking up available storage space, rather than a true capacity reduction. We tested the ability to eliminate and update WM content in 38 PSZ and 30 healthy control subjects (HCS). Images of real-world objects were presented consecutively, and a tone cued the item most likely to be tested for memory. On half the trials, randomly intermixed, a second tone occurred. Participants were informed that the item cued by the second tone was now the most likely to be tested, and the item cued by the first tone now the least likely, providing incentive to eliminate the first cued item from WM. Both HCS and PSZ displayed a robust performance advantage for cued items. Unexpectedly, PSZ more efficiently removed the no-longer-essential item from WM than HCS. The magnitude of the WM clearance of this first cued item correlated with memory performance for the newly prioritized second cued item in PSZ, indicating that it was adaptive. However, WM clearance was not associated with WM capacity, ruling out the need to budget limited resources as an explanation for greater clearance in PSZ. A robust correlation between WM clearance and poverty of speech in PSZ instead suggests that the propensity to rapidly clear non-essential information and minimize the number of items in WM may be the reflection of a negative symptom trait. This finding may reflect a more general tendency of PSZ to focus processing more narrowly than HCS.
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Affiliation(s)
- Britta Hahn
- University of Maryland School of Medicine, Maryland Psychiatric Research Center, P.O. box 21247, Baltimore, MD 21228, USA
- Corresponding author: , Tel: 001-410-402-6112, Fax: 001-410-402-7198
| | - Andrew Hollingworth
- University of Iowa, Department of Psychology, 11 Seashore Hall E, Iowa City, IA 52242, USA
| | - Benjamin M. Robinson
- University of Maryland School of Medicine, Maryland Psychiatric Research Center, P.O. box 21247, Baltimore, MD 21228, USA
| | - Samuel T. Kaiser
- University of Maryland School of Medicine, Maryland Psychiatric Research Center, P.O. box 21247, Baltimore, MD 21228, USA
| | - Carly J. Leonard
- University of California, Davis, Center for Mind & Brain and Department of Psychology, 267 Cousteau Place, Davis, CA 95618, USA
| | - Valerie M. Beck
- University of California, Davis, Center for Mind & Brain and Department of Psychology, 267 Cousteau Place, Davis, CA 95618, USA
| | - Emily S. Kappenman
- University of California, Davis, Center for Mind & Brain and Department of Psychology, 267 Cousteau Place, Davis, CA 95618, USA
| | - Steven J. Luck
- University of California, Davis, Center for Mind & Brain and Department of Psychology, 267 Cousteau Place, Davis, CA 95618, USA
| | - James M. Gold
- University of Maryland School of Medicine, Maryland Psychiatric Research Center, P.O. box 21247, Baltimore, MD 21228, USA
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