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Yao B, Rolfs M, Slate R, Roberts D, Fattal J, Achtyes ED, Tso IF, Diwadkar VA, Kashy D, Bao J, Thakkar KN. Abnormal Oculomotor Corollary Discharge Signaling as a Trans-diagnostic Mechanism of Psychosis. Schizophr Bull 2024; 50:631-641. [PMID: 38245499 PMCID: PMC11059795 DOI: 10.1093/schbul/sbad180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2024]
Abstract
BACKGROUND AND HYPOTHESIS Corollary discharge (CD) signals are "copies" of motor signals sent to sensory areas to predict the corresponding input. They are a posited mechanism enabling one to distinguish actions generated by oneself vs external forces. Consequently, altered CD is a hypothesized mechanism for agency disturbances in psychosis. Previous studies have shown a decreased influence of CD signals on visual perception in individuals with schizophrenia-particularly in those with more severe positive symptoms. We therefore hypothesized that altered CD may be a trans-diagnostic mechanism of psychosis. STUDY DESIGN We examined oculomotor CD (using the blanking task) in 49 participants with schizophrenia or schizoaffective disorder (SZ), 36 bipolar participants with psychosis (BPP), and 40 healthy controls (HC). Participants made a saccade to a visual target. Upon saccade initiation, the target disappeared and reappeared at a horizontally displaced position. Participants indicated the direction of displacement. With intact CD, participants can make accurate perceptual judgements. Otherwise, participants may use saccade landing site as a proxy of pre-saccadic target to inform perception. Thus, multi-level modeling was used to examine the influence of target displacement and saccade landing site on displacement judgements. STUDY RESULTS SZ and BPP were equally less sensitive to target displacement than HC. Moreover, regardless of diagnosis, SZ and BPP with more severe positive symptoms were more likely to rely on saccade landing site. CONCLUSIONS These results suggest that altered CD may be a trans-diagnostic mechanism of psychosis.
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Affiliation(s)
- Beier Yao
- Schizophrenia and Bipolar Disorder Program, McLean Hospital, Belmont, MA, USA
- Department of Psychiatry, Harvard Medical School, Boston, MA, USA
- Department of Psychology, Michigan State University, East Lansing, MI, USA
| | - Martin Rolfs
- Department of Psychology, Humboldt University, Berlin, Germany
| | - Rachael Slate
- Department of Psychology, Brigham Young University, Provo, UT, USA
| | - Dominic Roberts
- Department of Psychology, Michigan State University, East Lansing, MI, USA
| | - Jessica Fattal
- Department of Psychology, Northwestern University, Evanston, IL, USA
| | - Eric D Achtyes
- Cherry Health, Grand Rapids, MI, USA
- Department of Psychiatry, Western Michigan University Homer Stryker M.D. School of Medicine, Kalamazoo, MI, USA
| | - Ivy F Tso
- Department of Psychiatry and Behavioral Health, The Ohio State University, Columbus, OH, USA
| | - Vaibhav A Diwadkar
- Department of Psychiatry and Behavioral Neuroscience, Wayne State University, Detroit, MI, USA
| | - Deborah Kashy
- Department of Psychology, Michigan State University, East Lansing, MI, USA
| | - Jacqueline Bao
- Department of Psychology, Michigan State University, East Lansing, MI, USA
- Department of Psychology & Neuroscience, Duke University, Durham, NC, USA
| | - Katharine N Thakkar
- Department of Psychology, Michigan State University, East Lansing, MI, USA
- Department of Psychiatry and Behavioral Medicine, Michigan State University College of Human Medicine, Grand Rapids, MI, USA
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2
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Lehet M, Rolfs M, Bao J, Fattal J, Thakkar KN. Pre-saccadic shifts of attention in individuals diagnosed with schizophrenia. Brain Behav 2024; 14:e3466. [PMID: 38450916 PMCID: PMC10918725 DOI: 10.1002/brb3.3466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 02/15/2024] [Accepted: 02/18/2024] [Indexed: 03/08/2024] Open
Abstract
INTRODUCTION Pathophysiological theories of schizophrenia (SZ) symptoms posit an abnormality in using predictions to guide behavior. One such prediction is based on imminent movements, via corollary discharge signals (CD) that relay information about planned movement kinematics to sensory brain regions. Empirical evidence suggests a reduced influence of sensorimotor predictions in individuals with SZ within multiple sensory systems, including in the visual system. One function of CD in the visual system is to selectively enhance visual sensitivity at the location of planned eye movements (pre-saccadic attention), thus enabling a prediction of the to-be-foveated stimulus. We expected pre-saccadic attention shifts to be less pronounced in individuals with SZ than in healthy controls (HC), resulting in unexpected sensory consequences of eye movements, which may relate to symptoms than can be explained in the context of altered allocation of attention. METHODS We examined this question by testing 30 SZ and 30 HC on a pre-saccadic attention task. On each trial participants made a saccade to a cued location in an array of four stimuli. A discrimination target that was either congruent or incongruent with the cued location was briefly presented after the cue, during saccade preparation. Pre-saccadic attention was quantified by comparing accuracy on congruent trials to incongruent trials within the interval preceding the saccade. RESULTS Although SZs were less accurate overall, the magnitude of the pre-saccadic attention effect generally did not differ across groups nor show a convincing relationship with symptom severity. We did, however, observe that SZ had reduced pre-saccadic attention effects when the discrimination target (probe) was presented at early stages of saccade planning, when pre-saccadic attention effects first emerged in HC. CONCLUSION These findings suggest generally intact pre-saccadic shifts of attention in SZ, albeit slightly delayed. Results contribute to our understanding of altered sensory predictions in people with schizophrenia.
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Affiliation(s)
- Matthew Lehet
- Department of PsychologyMichigan State UniversityEast LansingMichiganUSA
| | - Martin Rolfs
- Department of PsychologyHumboldt UniversityBerlinGermany
| | - Jacqueline Bao
- Department of PsychologyMichigan State UniversityEast LansingMichiganUSA
| | - Jessica Fattal
- Department of PsychologyNorthwestern UniversityEvanstonIllinoisUSA
| | - Katharine N. Thakkar
- Department of PsychologyMichigan State UniversityEast LansingMichiganUSA
- Psychiatry and Behavioral MedicineMichigan State University College of Human MedicineEast LansingMichiganUSA
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3
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Rummell BP, Bikas S, Babl SS, Gogos JA, Sigurdsson T. Altered corollary discharge signaling in the auditory cortex of a mouse model of schizophrenia predisposition. Nat Commun 2023; 14:7388. [PMID: 37968289 PMCID: PMC10651874 DOI: 10.1038/s41467-023-42964-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 10/27/2023] [Indexed: 11/17/2023] Open
Abstract
The ability to distinguish sensations that are self-generated from those caused by external events is disrupted in schizophrenia patients. However, the neural circuit abnormalities underlying this sensory impairment and its relationship to the risk factors for the disease is not well understood. To address this, we examined the processing of self-generated sounds in male Df(16)A+/- mice, which model one of the largest genetic risk factors for schizophrenia, the 22q11.2 microdeletion. We find that auditory cortical neurons in Df(16)A+/- mice fail to attenuate their responses to self-generated sounds, recapitulating deficits seen in schizophrenia patients. Notably, the auditory cortex of Df(16)A+/- mice displayed weaker motor-related signals and received fewer inputs from the motor cortex, suggesting an anatomical basis underlying the sensory deficit. These results provide insights into the mechanisms by which a major genetic risk factor for schizophrenia disrupts the top-down processing of sensory information.
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Affiliation(s)
- Brian P Rummell
- Institute of Neurophysiology, Goethe University, Theodor-Stern Kai 7, 60590, Frankfurt, Germany
- Ernst Strüngmann Institute (ESI) for Neuroscience in Cooperation with Max Planck Society, 60528, Frankfurt am Main, Germany
| | - Solmaz Bikas
- Institute of Neurophysiology, Goethe University, Theodor-Stern Kai 7, 60590, Frankfurt, Germany
| | - Susanne S Babl
- Institute of Neurophysiology, Goethe University, Theodor-Stern Kai 7, 60590, Frankfurt, Germany
| | - Joseph A Gogos
- Mortimer B. Zuckerman Mind Brain and Behavior Institute, Columbia University, New York, NY, 10027, USA
- Departments of Physiology, Neuroscience and Psychiatry, Vagelos College of Physicians & Surgeons, Columbia University, New York, NY, 10032, USA
| | - Torfi Sigurdsson
- Institute of Neurophysiology, Goethe University, Theodor-Stern Kai 7, 60590, Frankfurt, Germany.
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4
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Hua L, Adams RA, Grent-'t-Jong T, Gajwani R, Gross J, Gumley AI, Krishnadas R, Lawrie SM, Schultze-Lutter F, Schwannauer M, Uhlhaas PJ. Thalamo-cortical circuits during sensory attenuation in emerging psychosis: a combined magnetoencephalography and dynamic causal modelling study. SCHIZOPHRENIA (HEIDELBERG, GERMANY) 2023; 9:25. [PMID: 37117187 PMCID: PMC10147678 DOI: 10.1038/s41537-023-00341-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 02/28/2023] [Indexed: 04/30/2023]
Abstract
Evidence suggests that schizophrenia (ScZ) involves impairments in sensory attenuation. It is currently unclear, however, whether such deficits are present during early-stage psychosis as well as the underlying network and the potential as a biomarker. To address these questions, Magnetoencephalography (MEG) was used in combination with computational modeling to examine M100 responses that involved a "passive" condition during which tones were binaurally presented, while in an "active" condition participants were asked to generate a tone via a button press. MEG data were obtained from 109 clinical high-risk for psychosis (CHR-P) participants, 23 people with a first-episode psychosis (FEP), and 48 healthy controls (HC). M100 responses at sensor and source level in the left and right thalamus (THA), Heschl's gyrus (HES), superior temporal gyrus (STG) and right inferior parietal cortex (IPL) were examined and dynamic causal modeling (DCM) was performed. Furthermore, the relationship between sensory attenuation and persistence of attenuated psychotic symptoms (APS) and transition to psychosis was investigated in CHR-P participants. Sensory attenuation was impaired in left HES, left STG and left THA in FEP patients, while in the CHR-P group deficits were observed only in right HES. DCM results revealed that CHR-P participants showed reduced top-down modulation from the right IPL to the right HES. Importantly, deficits in sensory attenuation did not predict clinical outcomes in the CHR-P group. Our results show that early-stage psychosis involves impaired sensory attenuation in auditory and thalamic regions but may not predict clinical outcomes in CHR-P participants.
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Affiliation(s)
- Lingling Hua
- Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, UK
- Department of Psychiatry, The Affiliated Brain Hospital of Nanjing Medical University, 264 Guangzhou Road, Nanjing, 210029, China
| | - Rick A Adams
- Centre for Medical Image Computing and AI, University College London, 90 High Holborn, London, WC1V 6LJ, UK
- Max Planck-UCL Centre for Computational Psychiatry and Ageing Research, 10-12 Russell Square, London, WC1B 5EH, UK
| | - Tineke Grent-'t-Jong
- Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, UK
- Department of Child and Adolescent Psychiatry, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt- Universität zu Berlin, Berlin, Germany
| | - Ruchika Gajwani
- Institute of Health and Wellbeing, University of Glasgow, Glasgow, UK
| | - Joachim Gross
- Institute for Biomagnetism and Biosignalanalysis, University of Muenster, Muenster, Germany
| | - Andrew I Gumley
- Institute of Health and Wellbeing, University of Glasgow, Glasgow, UK
| | - Rajeev Krishnadas
- Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, UK
| | - Stephen M Lawrie
- Department of Psychiatry, University of Edinburgh, Edinburgh, UK
| | - Frauke Schultze-Lutter
- Department of Psychiatry and Psychotherapy, Medical Faculty, Heinrich Heine University, Düsseldorf, Germany
- Department of Psychology, Faculty of Psychology, Airlangga University, Surabaya, Indonesia
- University Hospital of Child and Adolescent Psychiatry and Psychotherapy, University of Bern, Bern, Switzerland
| | | | - Peter J Uhlhaas
- Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, UK.
- Department of Child and Adolescent Psychiatry, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt- Universität zu Berlin, Berlin, Germany.
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5
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Deane G. Consciousness in active inference: Deep self-models, other minds, and the challenge of psychedelic-induced ego-dissolution. Neurosci Conscious 2021; 2021:niab024. [PMID: 34484808 PMCID: PMC8408766 DOI: 10.1093/nc/niab024] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 07/26/2021] [Accepted: 08/02/2021] [Indexed: 11/16/2022] Open
Abstract
Predictive processing approaches to brain function are increasingly delivering promise for illuminating the computational underpinnings of a wide range of phenomenological states. It remains unclear, however, whether predictive processing is equipped to accommodate a theory of consciousness itself. Furthermore, objectors have argued that without specification of the core computational mechanisms of consciousness, predictive processing is unable to inform the attribution of consciousness to other non-human (biological and artificial) systems. In this paper, I argue that an account of consciousness in the predictive brain is within reach via recent accounts of phenomenal self-modelling in the active inference framework. The central claim here is that phenomenal consciousness is underpinned by 'subjective valuation'-a deep inference about the precision or 'predictability' of the self-evidencing ('fitness-promoting') outcomes of action. Based on this account, I argue that this approach can critically inform the distribution of experience in other systems, paying particular attention to the complex sensory attenuation mechanisms associated with deep self-models. I then consider an objection to the account: several recent papers argue that theories of consciousness that invoke self-consciousness as constitutive or necessary for consciousness are undermined by states (or traits) of 'selflessness'; in particular the 'totally selfless' states of ego-dissolution occasioned by psychedelic drugs. Drawing on existing work that accounts for psychedelic-induced ego-dissolution in the active inference framework, I argue that these states do not threaten to undermine an active inference theory of consciousness. Instead, these accounts corroborate the view that subjective valuation is the constitutive facet of experience, and they highlight the potential of psychedelic research to inform consciousness science, computational psychiatry and computational phenomenology.
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Affiliation(s)
- George Deane
- School of Philosophy, Psychology and Language Sciences, The University of Edinburgh, 3 Charles Street, Edinburgh EH8 9AD, UK
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6
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Yao B, Rolfs M, McLaughlin C, Isenstein EL, Guillory SB, Grosman H, Kashy DA, Foss-Feig JH, Thakkar KN. Oculomotor corollary discharge signaling is related to repetitive behavior in children with autism spectrum disorder. J Vis 2021; 21:9. [PMID: 34351395 PMCID: PMC8354038 DOI: 10.1167/jov.21.8.9] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 07/08/2021] [Indexed: 12/25/2022] Open
Abstract
Corollary discharge (CD) signals are "copies" of motor signals sent to sensory regions that allow animals to adjust sensory consequences of self-generated actions. Autism spectrum disorder (ASD) is characterized by sensory and motor deficits, which may be underpinned by altered CD signaling. We evaluated oculomotor CD using the blanking task, which measures the influence of saccades on visual perception, in 30 children with ASD and 35 typically developing (TD) children. Participants were instructed to make a saccade to a visual target. Upon saccade initiation, the presaccadic target disappeared and reappeared to the left or right of the original position. Participants indicated the direction of the jump. With intact CD, participants can make accurate perceptual judgements. Otherwise, participants may use saccade landing site as a proxy of the presaccadic target and use it to inform perception. We used multilevel modeling to examine the influence of saccade landing site on trans-saccadic perceptual judgements. We found that, compared with TD participants, children with ASD were more sensitive to target displacement and less reliant on saccade landing site when spatial uncertainty of the post-saccadic target was high. This pattern was driven by ASD participants with less severe restricted and repetitive behaviors. These results suggest a relationship between altered CD signaling and core ASD symptoms.
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Affiliation(s)
- Beier Yao
- Department of Psychology, Michigan State University, East Lansing, MI, USA
| | - Martin Rolfs
- Department of Psychology, Humboldt-Universität zu Berlin, Germany
| | - Christopher McLaughlin
- Seaver Autism Center, Icahn School of Medicine at Mount Sinai Hospital, New York, NY, USA
| | - Emily L Isenstein
- Department of Brain and Cognitive Sciences, University of Rochester, Rochester, NY, USA
| | - Sylvia B Guillory
- Seaver Autism Center, Icahn School of Medicine at Mount Sinai Hospital, New York, NY, USA
| | - Hannah Grosman
- Seaver Autism Center, Icahn School of Medicine at Mount Sinai Hospital, New York, NY, USA
| | - Deborah A Kashy
- Department of Psychology, Michigan State University, East Lansing, MI, USA
| | - Jennifer H Foss-Feig
- Seaver Autism Center, Icahn School of Medicine at Mount Sinai Hospital, New York, NY, USA
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai Hospital, New York, NY, USA
| | - Katharine N Thakkar
- Department of Psychology, Michigan State University, East Lansing, MI, USA
- Division of Psychiatry and Behavioral Medicine, Michigan State University, Grand Rapids, MI, USA
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7
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Masselink J, Lappe M. Visuomotor learning from postdictive motor error. eLife 2021; 10:64278. [PMID: 33687328 PMCID: PMC8057815 DOI: 10.7554/elife.64278] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 03/04/2021] [Indexed: 01/02/2023] Open
Abstract
Sensorimotor learning adapts motor output to maintain movement accuracy. For saccadic eye movements, learning also alters space perception, suggesting a dissociation between the performed saccade and its internal representation derived from corollary discharge (CD). This is critical since learning is commonly believed to be driven by CD-based visual prediction error. We estimate the internal saccade representation through pre- and trans-saccadic target localization, showing that it decouples from the actual saccade during learning. We present a model that explains motor and perceptual changes by collective plasticity of spatial target percept, motor command, and a forward dynamics model that transforms CD from motor into visuospatial coordinates. We show that learning does not follow visual prediction error but instead a postdictive update of space after saccade landing. We conclude that trans-saccadic space perception guides motor learning via CD-based postdiction of motor error under the assumption of a stable world.
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Affiliation(s)
- Jana Masselink
- Institute for Psychology and Otto Creutzfeldt Center for Cognitive and Behavioral Neuroscience, University of Muenster, Münster, Germany
| | - Markus Lappe
- Institute for Psychology and Otto Creutzfeldt Center for Cognitive and Behavioral Neuroscience, University of Muenster, Münster, Germany
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8
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Towards assessing extra-retinal uncertainty: A reply to M. Lisi (2020). Cortex 2020; 130:444-448. [PMID: 32641212 DOI: 10.1016/j.cortex.2020.05.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 05/27/2020] [Accepted: 05/27/2020] [Indexed: 11/23/2022]
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9
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Thakkar KN, Rolfs M. Disrupted Corollary Discharge in Schizophrenia: Evidence From the Oculomotor System. BIOLOGICAL PSYCHIATRY. COGNITIVE NEUROSCIENCE AND NEUROIMAGING 2019; 4:773-781. [PMID: 31105039 PMCID: PMC6733648 DOI: 10.1016/j.bpsc.2019.03.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2019] [Revised: 03/04/2019] [Accepted: 03/22/2019] [Indexed: 01/18/2023]
Abstract
Corollary discharge (CD) signals are motor-related signals that exert an influence on sensory processing. They allow mobile organisms to predict the sensory consequences of their imminent actions. Among the many functions of CD is to provide a means by which we can distinguish sensory experiences caused by our own actions from those with external causes. In this way, they contribute to a subjective sense of agency. A disruption in the sense of agency is central to many of the clinical symptoms of schizophrenia, and abnormalities in CD signaling have been theorized to underpin particularly those agency-related psychotic symptoms of the illness. Characterizing abnormal CD associated with eye movements in schizophrenia and their resulting influence on visual processing and subsequent action plans may have advantages over other sensory and motor systems. That is because the most robust psychophysiological and neurophysiological data regarding the dynamics and influence of CD as well as the neural circuitry implicated in CD generation and transmission comes from the study of eye movements in humans and nonhuman primates. We review studies of oculomotor CD signaling in the schizophrenia spectrum and possible neurobiological correlates of CD disturbances. We conclude by speculating on the ways in which oculomotor CD dysfunction, specifically, may invoke specific experiences, clinical symptoms, and cognitive impairments. These speculations lay the groundwork for empirical study, and we conclude by outlining potentially fruitful research directions.
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Affiliation(s)
- Katharine N Thakkar
- Department of Psychology, Michigan State University, East Lansing, Michigan; Division of Psychiatry and Behavioral Medicine, Michigan State University, East Lansing, Michigan.
| | - Martin Rolfs
- Department of Psychology, Humboldt-Universität zu Berlin, Berlin, Germany; Bernstein Center for Computational Neuroscience, Berlin, Germany
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10
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Cassanello CR, Ostendorf F, Rolfs M. A generative learning model for saccade adaptation. PLoS Comput Biol 2019; 15:e1006695. [PMID: 31398185 PMCID: PMC6703699 DOI: 10.1371/journal.pcbi.1006695] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2018] [Revised: 08/21/2019] [Accepted: 06/19/2019] [Indexed: 11/19/2022] Open
Abstract
Plasticity in the oculomotor system ensures that saccadic eye movements reliably meet their visual goals-to bring regions of interest into foveal, high-acuity vision. Here, we present a comprehensive description of sensorimotor learning in saccades. We induced continuous adaptation of saccade amplitudes using a double-step paradigm, in which participants saccade to a peripheral target stimulus, which then undergoes a surreptitious, intra-saccadic shift (ISS) as the eyes are in flight. In our experiments, the ISS followed a systematic variation, increasing or decreasing from one saccade to the next as a sinusoidal function of the trial number. Over a large range of frequencies, we confirm that adaptation gain shows (1) a periodic response, reflecting the frequency of the ISS with a delay of a number of trials, and (2) a simultaneous drift towards lower saccade gains. We then show that state-space-based linear time-invariant systems (LTIS) represent suitable generative models for this evolution of saccade gain over time. This state-equation algorithm computes the prediction of an internal (or hidden state-) variable by learning from recent feedback errors, and it can be compared to experimentally observed adaptation gain. The algorithm also includes a forgetting rate that quantifies per-trial leaks in the adaptation gain, as well as a systematic, non-error-based bias. Finally, we study how the parameters of the generative models depend on features of the ISS. Driven by a sinusoidal disturbance, the state-equation admits an exact analytical solution that expresses the parameters of the phenomenological description as functions of those of the generative model. Together with statistical model selection criteria, we use these correspondences to characterize and refine the structure of compatible state-equation models. We discuss the relation of these findings to established results and suggest that they may guide further design of experimental research across domains of sensorimotor adaptation.
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Affiliation(s)
- Carlos R. Cassanello
- Department of Psychology, Humboldt-Universität zu Berlin, Berlin, Germany
- Bernstein Center for Computational Neuroscience, Humboldt-Universität zu Berlin, Berlin, Germany
- * E-mail: (CRC); (MR)
| | - Florian Ostendorf
- Department of Neurology, Charité – University Medicine Berlin, Berlin, Germany
| | - Martin Rolfs
- Department of Psychology, Humboldt-Universität zu Berlin, Berlin, Germany
- Bernstein Center for Computational Neuroscience, Humboldt-Universität zu Berlin, Berlin, Germany
- * E-mail: (CRC); (MR)
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11
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Császár N, Kapócs G, Bókkon I. A possible key role of vision in the development of schizophrenia. Rev Neurosci 2019; 30:359-379. [PMID: 30244235 DOI: 10.1515/revneuro-2018-0022] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 08/01/2018] [Indexed: 12/12/2022]
Abstract
Based on a brief overview of the various aspects of schizophrenia reported by numerous studies, here we hypothesize that schizophrenia may originate (and in part be performed) from visual areas. In other words, it seems that a normal visual system or at least an evanescent visual perception may be an essential prerequisite for the development of schizophrenia as well as of various types of hallucinations. Our study focuses on auditory and visual hallucinations, as they are the most prominent features of schizophrenic hallucinations (and also the most studied types of hallucinations). Here, we evaluate the possible key role of the visual system in the development of schizophrenia.
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Affiliation(s)
- Noemi Császár
- Gaspar Karoly University Psychological Institute, H-1091 Budapest, Hungary.,Psychoszomatic Outpatient Department, H-1037 Budapest, Hungary
| | - Gabor Kapócs
- Buda Family Centred Mental Health Centre, Department of Psychiatry and Psychiatric Rehabilitation, St. John Hospital, Budapest, Hungary
| | - István Bókkon
- Psychoszomatic Outpatient Department, H-1037 Budapest, Hungary.,Vision Research Institute, Neuroscience and Consciousness Research Department, 25 Rita Street, Lowell, MA 01854, USA
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12
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Abstract
Our vision depends upon shifting our high-resolution fovea to objects of interest in the visual field. Each saccade displaces the image on the retina, which should produce a chaotic scene with jerks occurring several times per second. It does not. This review examines how an internal signal in the primate brain (a corollary discharge) contributes to visual continuity across saccades. The article begins with a review of evidence for a corollary discharge in the monkey and evidence from inactivation experiments that it contributes to perception. The next section examines a specific neuronal mechanism for visual continuity, based on corollary discharge that is referred to as visual remapping. Both the basic characteristics of this anticipatory remapping and the factors that control it are enumerated. The last section considers hypotheses relating remapping to the perceived visual continuity across saccades, including remapping's contribution to perceived visual stability across saccades.
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Affiliation(s)
- Robert H Wurtz
- Laboratory of Sensorimotor Research, National Eye Institute, National Institutes of Health, Bethesda, Maryland 20892-4435, USA;
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13
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Prediction, Psychosis, and the Cerebellum. BIOLOGICAL PSYCHIATRY: COGNITIVE NEUROSCIENCE AND NEUROIMAGING 2019; 4:820-831. [PMID: 31495402 DOI: 10.1016/j.bpsc.2019.06.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 05/30/2019] [Accepted: 06/01/2019] [Indexed: 12/19/2022]
Abstract
An increasingly influential hypothesis posits that many of the diverse symptoms of psychosis can be viewed as reflecting dysfunctional predictive mechanisms. Indeed, to perceive something is to take a sensory input and make a prediction of the external source of that signal; thus, prediction is perhaps the most fundamental neural computation. Given the ubiquity of prediction, a more challenging problem is to specify the unique predictive role or capability of a particular brain structure. This question is relevant when considering recent claims that one aspect of the predictive deficits observed in psychotic disorders might be related to cerebellar dysfunction, a subcortical structure known to play a critical role in predictive sensorimotor control and perhaps higher-level cognitive function. Here, we review evidence bearing on this question. We first focus on clinical, behavioral, and neuroimaging findings suggesting cerebellar involvement in psychosis and, specifically, schizophrenia. We then review a relatively novel line of research exploring whether computational models of cerebellar motor function can also account for cerebellar involvement in higher-order human cognition, and in particular, language function. We end the review by highlighting some key gaps in these literatures, limitations that currently preclude strong conclusions regarding cerebellar involvement in psychosis.
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Whitford TJ. Speaking-Induced Suppression of the Auditory Cortex in Humans and Its Relevance to Schizophrenia. BIOLOGICAL PSYCHIATRY: COGNITIVE NEUROSCIENCE AND NEUROIMAGING 2019; 4:791-804. [PMID: 31399393 DOI: 10.1016/j.bpsc.2019.05.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 05/21/2019] [Accepted: 05/22/2019] [Indexed: 01/13/2023]
Abstract
Speaking-induced suppression (SIS) is the phenomenon that the sounds one generates by overt speech elicit a smaller neurophysiological response in the auditory cortex than comparable sounds that are externally generated. SIS is a specific example of the more general phenomenon of self-suppression. SIS has been well established in nonhuman animals and is believed to involve the action of corollary discharges. This review summarizes, first, the evidence for SIS in heathy human participants, where it has been most commonly assessed with electroencephalography and/or magnetoencephalography using an experimental paradigm known as "Talk-Listen"; and second, the growing number of Talk-Listen studies that have reported subnormal levels of SIS in patients with schizophrenia. This result is theoretically significant, as it provides a plausible explanation for some of the most distinctive and characteristic symptoms of schizophrenia, namely the first-rank symptoms. In particular, while the failure to suppress the neural consequences of self-generated movements (such as those associated with overt speech) provides a prima facie explanation for delusions of control, the failure to suppress the neural consequences of self-generated inner speech provides a plausible explanation for certain classes of auditory-verbal hallucinations, such as audible thoughts. While the empirical evidence for a relationship between SIS and the first-rank symptoms is currently limited, I predict that future studies with more sensitive experimental designs will confirm its existence. Establishing the existence of a causal, mechanistic relationship would represent a major step forward in our understanding of schizophrenia, which is a necessary precursor to the development of novel treatments.
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Affiliation(s)
- Thomas J Whitford
- School of Psychology, The University of New South Wales, Sydney, New South Wales, Australia.
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15
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Corlett PR, Horga G, Fletcher PC, Alderson-Day B, Schmack K, Powers AR. Hallucinations and Strong Priors. Trends Cogn Sci 2019; 23:114-127. [PMID: 30583945 PMCID: PMC6368358 DOI: 10.1016/j.tics.2018.12.001] [Citation(s) in RCA: 263] [Impact Index Per Article: 52.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 12/01/2018] [Accepted: 12/04/2018] [Indexed: 01/25/2023]
Abstract
Hallucinations, perceptions in the absence of objectively identifiable stimuli, illustrate the constructive nature of perception. Here, we highlight the role of prior beliefs as a critical elicitor of hallucinations. Recent empirical work from independent laboratories shows strong, overly precise priors can engender hallucinations in healthy subjects and that individuals who hallucinate in the real world are more susceptible to these laboratory phenomena. We consider these observations in light of work demonstrating apparently weak, or imprecise, priors in psychosis. Appreciating the interactions within and between hierarchies of inference can reconcile this apparent disconnect. Data from neural networks, human behavior, and neuroimaging support this contention. This work underlines the continuum from normal to aberrant perception, encouraging a more empathic approach to clinical hallucinations.
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Affiliation(s)
| | - Guillermo Horga
- Department of Psychiatry, Columbia University, New York, NY, USA
| | - Paul C Fletcher
- Department of Psychiatry, University of Cambridge, Cambridge, UK; The Cambridgeshire and Peteborough NHS Foundation Trust, Elizabeth House, Fulbourn Hospital, Cambridge, UK
| | | | | | - Albert R Powers
- Department of Psychiatry, Yale University, New Haven, CT, USA
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16
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Structural Thalamofrontal Hypoconnectivity Is Related to Oculomotor Corollary Discharge Dysfunction in Schizophrenia. J Neurosci 2019; 39:2102-2113. [PMID: 30630882 DOI: 10.1523/jneurosci.1473-18.2019] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2018] [Revised: 11/30/2018] [Accepted: 01/02/2019] [Indexed: 11/21/2022] Open
Abstract
By predicting sensory consequences of actions, humans can distinguish self-generated sensory inputs from those that are elicited externally. This is one mechanism by which we achieve a subjective sense of agency over our actions. Corollary discharge (CD) signals-"copies" of motor signals sent to sensory areas-permit such predictions, and CD abnormalities are a hypothesized mechanism for the agency disruptions in schizophrenia that characterize a subset of symptoms. Indeed, behavioral evidence of altered CD, including in the oculomotor system, has been observed in schizophrenia patients. A pathway projecting from the superior colliculus to the frontal eye fields (FEFs) via the mediodorsal thalamus (MD) conveys oculomotor CD associated with saccadic eye movements in nonhuman primates. This animal work provides a promising translational framework in which to investigate CD abnormalities in clinical populations. In the current study, we examined whether structural connectivity of this MD-FEF pathway relates to oculomotor CD functioning in schizophrenia. Twenty-two schizophrenia patients and 24 healthy control participants of both sexes underwent diffusion tensor imaging, and a large subset performed a trans-saccadic perceptual task that yields measures of CD. Using probabilistic tractography, we identified anatomical connections between FEF and MD and extracted indices of microstructural integrity. Patients exhibited compromised microstructural integrity in the MD-FEF pathway, which was correlated with greater oculomotor CD abnormalities and more severe psychotic symptoms. These data reinforce the role of the MD-FEF pathway in transmitting oculomotor CD signals and suggest that disturbances in this pathway may relate to psychotic symptom manifestation in patients.SIGNIFICANCE STATEMENT People with schizophrenia sometimes experience abnormalities in a sense of agency, which may stem from abnormal sensory predictions about their own actions. Consistent with this notion, the current study found reduced structural connectivity in patients with schizophrenia in a specific brain pathway found to transmit such sensorimotor prediction signals in nonhuman primates. Reduced structural connectivity was correlated with behavioral evidence for impaired sensorimotor predictions and psychotic symptoms.
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17
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Bansal S, Ford JM, Spering M. The function and failure of sensory predictions. Ann N Y Acad Sci 2018; 1426:199-220. [PMID: 29683518 DOI: 10.1111/nyas.13686] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 02/26/2018] [Accepted: 02/27/2018] [Indexed: 01/24/2023]
Abstract
Humans and other primates are equipped with neural mechanisms that allow them to automatically make predictions about future events, facilitating processing of expected sensations and actions. Prediction-driven control and monitoring of perceptual and motor acts are vital to normal cognitive functioning. This review provides an overview of corollary discharge mechanisms involved in predictions across sensory modalities and discusses consequences of predictive coding for cognition and behavior. Converging evidence now links impairments in corollary discharge mechanisms to neuropsychiatric symptoms such as hallucinations and delusions. We review studies supporting a prediction-failure hypothesis of perceptual and cognitive disturbances. We also outline neural correlates underlying prediction function and failure, highlighting similarities across the visual, auditory, and somatosensory systems. In linking basic psychophysical and psychophysiological evidence of visual, auditory, and somatosensory prediction failures to neuropsychiatric symptoms, our review furthers our understanding of disease mechanisms.
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Affiliation(s)
- Sonia Bansal
- Maryland Psychiatric Research Center, University of Maryland, Catonsville, Maryland
| | - Judith M Ford
- University of California and Veterans Affairs Medical Center, San Francisco, California
| | - Miriam Spering
- Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, British Columbia, Canada
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18
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Giersch A. Saccadic Eye Movement System and Agency Disorders: Yes, They Are Related! BIOLOGICAL PSYCHIATRY: COGNITIVE NEUROSCIENCE AND NEUROIMAGING 2018. [PMID: 29529403 DOI: 10.1016/j.bpsc.2017.12.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Anne Giersch
- Institut National de la Santé et de la Recherche Médicale U1114, Pôle de Psychiatrie, Fédération de Médecine Translationnelle de Strasbourg, Centre Hospitalier Régional Universitaire of Strasbourg, Université de Strasbourg, Strasbourg, France.
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Bansal S, Bray LCJ, Schwartz BL, Joiner WM. Transsaccadic Perception Deficits in Schizophrenia Reflect the Improper Internal Monitoring of Eye Movement Rather Than Abnormal Sensory Processing. BIOLOGICAL PSYCHIATRY: COGNITIVE NEUROSCIENCE AND NEUROIMAGING 2017. [PMID: 29529412 DOI: 10.1016/j.bpsc.2017.06.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
BACKGROUND Symptoms of psychosis in schizophrenia reflect disturbances in sense of agency-difficulty distinguishing internally from externally generated sensory and perceptual experiences. One theory attributes these anomalies to a disruption in corollary discharge (CD), an internal copy of generated motor commands used to distinguish self-movement-generated sensations from externally generated stimulation. METHODS We used a transsaccadic shift detection paradigm to examine possible deficits in CD and sense of agency based on the ability to perceive visual changes in 31 schizophrenia patients (SZPs) and 31 healthy control subjects. We derived perceptual measures based on manual responses indicating the transsaccadic target shift direction. We also developed a distance-from-unity-line measure to quantify use of CD versus purely sensory (visual) information in evaluating visual changes in the environment after an eye movement. RESULTS SZPs had higher perceptual thresholds in detecting shift of target location than healthy control subjects, regardless of movement direction or amplitude. Despite producing similar hypometric saccades, healthy control subjects overestimated target location, whereas SZPs relied more on the experienced visual error and consequently underestimated the target position. We show that in SZPs the postsaccadic judgment of the initial target location was largely aligned with the measure based only on visual error, suggesting a deficit in the use of CD. This CD deficit also correlated with positive schizophrenia symptoms and disturbances in sense of agency. CONCLUSIONS These results provide a novel approach in quantifying abnormal use of CD in SZPs and provide a framework to distinguish deficits in sensory processing versus defects in the internal CD-based monitoring of movement.
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Affiliation(s)
- Sonia Bansal
- Department of Neuroscience, George Mason University, Fairfax, Virginia; Mental Health Service Line, Washington DC Veterans Affairs Medical Center, Washington, DC
| | | | - Barbara L Schwartz
- Mental Health Service Line, Washington DC Veterans Affairs Medical Center, Washington, DC; Department of Psychiatry, Georgetown University School of Medicine, Washington, DC
| | - Wilsaan M Joiner
- Department of Neuroscience, George Mason University, Fairfax, Virginia; Department of Bioengineering, George Mason University, Fairfax, Virginia; Krasnow Institute for Advanced Study, George Mason University, Fairfax, Virginia.
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Thakkar KN, Diwadkar VA, Rolfs M. Oculomotor Prediction: A Window into the Psychotic Mind. Trends Cogn Sci 2017; 21:344-356. [PMID: 28292639 PMCID: PMC5401650 DOI: 10.1016/j.tics.2017.02.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2016] [Revised: 01/29/2017] [Accepted: 02/01/2017] [Indexed: 12/27/2022]
Abstract
Psychosis - an impaired contact with reality - is a hallmark of schizophrenia. Many psychotic symptoms are associated with disruptions in agency - the sense that 'I' cause my actions. A failure to predict sensory consequences of one's own actions may underlie agency disturbances. Such predictions rely on corollary discharge (CD) signals, 'copies' of movement commands sent to sensory regions prior to action execution. Here, we make a case that the oculomotor system is a promising model for understanding CD in psychosis, building on advances in our understanding of the behavioral and neurophysiological correlates of CD associated with eye movements. In this opinion article, we provide an overview of recent evidence for disturbed oculomotor CD in schizophrenia, potentially linking bizarre and disturbing psychotic experiences with basic physiological processes.
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Affiliation(s)
| | - Vaibhav A Diwadkar
- Department of Psychiatry and Behavioral Neurosciences, Brain Imaging Research Division, Wayne State University, Detroit, MI, USA
| | - Martin Rolfs
- Bernstein Center for Computational Neuroscience and Department of Psychology, Humboldt Universität, 10099 Berlin, Germany
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22
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Giraldo-Chica M, Woodward ND. Review of thalamocortical resting-state fMRI studies in schizophrenia. Schizophr Res 2017; 180:58-63. [PMID: 27531067 PMCID: PMC5297399 DOI: 10.1016/j.schres.2016.08.005] [Citation(s) in RCA: 140] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Revised: 08/03/2016] [Accepted: 08/06/2016] [Indexed: 12/19/2022]
Abstract
Brain circuitry underlying cognition, emotion, and perception is abnormal in schizophrenia. There is considerable evidence that the neuropathology of schizophrenia includes the thalamus, a key hub of cortical-subcortical circuitry and an important regulator of cortical activity. However, the thalamus is a heterogeneous structure composed of several nuclei with distinct inputs and cortical connections. Limitations of conventional neuroimaging methods and conflicting findings from post-mortem investigations have made it difficult to determine if thalamic pathology in schizophrenia is widespread or limited to specific thalamocortical circuits. Resting-state fMRI has proven invaluable for understanding the large-scale functional organization of the brain and investigating neural circuitry relevant to psychiatric disorders. This article summarizes resting-state fMRI investigations of thalamocortical functional connectivity in schizophrenia. Particular attention is paid to the course, diagnostic specificity, and clinical correlates of thalamocortical network dysfunction.
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Kotchoubey B, Tretter F, Braun HA, Buchheim T, Draguhn A, Fuchs T, Hasler F, Hastedt H, Hinterberger T, Northoff G, Rentschler I, Schleim S, Sellmaier S, Tebartz Van Elst L, Tschacher W. Methodological Problems on the Way to Integrative Human Neuroscience. Front Integr Neurosci 2016; 10:41. [PMID: 27965548 PMCID: PMC5126073 DOI: 10.3389/fnint.2016.00041] [Citation(s) in RCA: 98] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 11/15/2016] [Indexed: 12/21/2022] Open
Abstract
Neuroscience is a multidisciplinary effort to understand the structures and functions of the brain and brain-mind relations. This effort results in an increasing amount of data, generated by sophisticated technologies. However, these data enhance our descriptive knowledge, rather than improve our understanding of brain functions. This is caused by methodological gaps both within and between subdisciplines constituting neuroscience, and the atomistic approach that limits the study of macro- and mesoscopic issues. Whole-brain measurement technologies do not resolve these issues, but rather aggravate them by the complexity problem. The present article is devoted to methodological and epistemic problems that obstruct the development of human neuroscience. We neither discuss ontological questions (e.g., the nature of the mind) nor review data, except when it is necessary to demonstrate a methodological issue. As regards intradisciplinary methodological problems, we concentrate on those within neurobiology (e.g., the gap between electrical and chemical approaches to neurophysiological processes) and psychology (missing theoretical concepts). As regards interdisciplinary problems, we suggest that core disciplines of neuroscience can be integrated using systemic concepts that also entail human-environment relations. We emphasize the necessity of a meta-discussion that should entail a closer cooperation with philosophy as a discipline of systematic reflection. The atomistic reduction should be complemented by the explicit consideration of the embodiedness of the brain and the embeddedness of humans. The discussion is aimed at the development of an explicit methodology of integrative human neuroscience, which will not only link different fields and levels, but also help in understanding clinical phenomena.
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Affiliation(s)
- Boris Kotchoubey
- Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen Tübingen, Germany
| | - Felix Tretter
- Bertalanffy Centre for the Study of Systems ScienceVienna, Austria; Bavarian Academy for Addiction and Health Issues (BAS)Munich, Germany
| | - Hans A Braun
- AG Neurodynamics, Institute of Physiology and Pathophysiology, Philipps University of Marburg Marburg, Germany
| | - Thomas Buchheim
- Department of Philosophy I, Ludwig Maximilian University of Munich Munich, Germany
| | - Andreas Draguhn
- Institute of Physiology and Pathophysiology, Faculty of Medicine, University of Heidelberg Heidelberg, Germany
| | - Thomas Fuchs
- Department of General Psychiatry, Centre of Psychosocial Medicine, University of Heidelberg Heidelberg, Germany
| | - Felix Hasler
- Berlin School of Mind and Brain, Humboldt University of Berlin Berlin, Germany
| | - Heiner Hastedt
- Institute of Philosophy, University of Rostock Rostock, Germany
| | - Thilo Hinterberger
- Department of Psychosomatic Medicine, University Clinic of Regensburg Regensburg, Germany
| | - Georg Northoff
- Institute of Mental Health Research: Mind, Brain Imaging and Neuroethics, University of Ottawa Ottawa, ON, Canada
| | - Ingo Rentschler
- Institute of Medical Psychology, Ludwig Maximilian University of Munich Munich, Germany
| | - Stephan Schleim
- Department of Theory and History of Psychology, Faculty of Behavioral and Social Sciences, University of Groningen Groningen, Netherlands
| | - Stephan Sellmaier
- Research Centre Neurophilosophy and Ethics of Neuroscience, Ludwig Maximilian University of Munich Munich, Germany
| | - Ludger Tebartz Van Elst
- Section of Neuropsychiatry, Department of Psychiatry and Psychotherapy, University of Freiburg Freiburg, Germany
| | - Wolfgang Tschacher
- Experimental Psychology, University Hospital of Psychiatry and Psychotherapy, University of Bern Bern, Switzerland
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Heinzle J, Aponte EA, Stephan KE. Computational models of eye movements and their application to schizophrenia. Curr Opin Behav Sci 2016. [DOI: 10.1016/j.cobeha.2016.03.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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25
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Cassanello CR, Ohl S, Rolfs M. Saccadic adaptation to a systematically varying disturbance. J Neurophysiol 2016; 116:336-50. [PMID: 27098027 DOI: 10.1152/jn.00206.2016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 04/18/2016] [Indexed: 01/01/2023] Open
Abstract
Saccadic adaptation maintains the correct mapping between eye movements and their targets, yet the dynamics of saccadic gain changes in the presence of systematically varying disturbances has not been extensively studied. Here we assessed changes in the gain of saccade amplitudes induced by continuous and periodic postsaccadic visual feedback. Observers made saccades following a sequence of target steps either along the horizontal meridian (Two-way adaptation) or with unconstrained saccade directions (Global adaptation). An intrasaccadic step-following a sinusoidal variation as a function of the trial number (with 3 different frequencies tested in separate blocks)-consistently displaced the target along its vector. The oculomotor system responded to the resulting feedback error by modifying saccade amplitudes in a periodic fashion with similar frequency of variation but lagging the disturbance by a few tens of trials. This periodic response was superimposed on a drift toward stronger hypometria with similar asymptotes and decay rates across stimulus conditions. The magnitude of the periodic response decreased with increasing frequency and was smaller and more delayed for Global than Two-way adaptation. These results suggest that-in addition to the well-characterized return-to-baseline response observed in protocols using constant visual feedback-the oculomotor system attempts to minimize the feedback error by integrating its variation across trials. This process resembles a convolution with an internal response function, whose structure would be determined by coefficients of the learning model. Our protocol reveals this fast learning process in single short experimental sessions, qualifying it for the study of sensorimotor learning in health and disease.
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Affiliation(s)
- Carlos R Cassanello
- Department of Psychology and Bernstein Center for Computational Neuroscience, Humboldt Universität zu Berlin, Berlin, Germany
| | - Sven Ohl
- Department of Psychology and Bernstein Center for Computational Neuroscience, Humboldt Universität zu Berlin, Berlin, Germany
| | - Martin Rolfs
- Department of Psychology and Bernstein Center for Computational Neuroscience, Humboldt Universität zu Berlin, Berlin, Germany
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Abstract
UNLABELLED Saccadic eye movements direct the high-resolution foveae of our retinas toward objects of interest. With each saccade, the image jumps on the retina, causing a discontinuity in visual input. Our visual perception, however, remains stable. Philosophers and scientists over centuries have proposed that visual stability depends upon an internal neuronal signal that is a copy of the neuronal signal driving the eye movement, now referred to as a corollary discharge (CD) or efference copy. In the old world monkey, such a CD circuit for saccades has been identified extending from superior colliculus through MD thalamus to frontal cortex, but there is little evidence that this circuit actually contributes to visual perception. We tested the influence of this CD circuit on visual perception by first training macaque monkeys to report their perceived eye direction, and then reversibly inactivating the CD as it passes through the thalamus. We found that the monkey's perception changed; during CD inactivation, there was a difference between where the monkey perceived its eyes to be directed and where they were actually directed. Perception and saccade were decoupled. We established that the perceived eye direction at the end of the saccade was not derived from proprioceptive input from eye muscles, and was not altered by contextual visual information. We conclude that the CD provides internal information contributing to the brain's creation of perceived visual stability. More specifically, the CD might provide the internal saccade vector used to unite separate retinal images into a stable visual scene. SIGNIFICANCE STATEMENT Visual stability is one of the most remarkable aspects of human vision. The eyes move rapidly several times per second, displacing the retinal image each time. The brain compensates for this disruption, keeping our visual perception stable. A major hypothesis explaining this stability invokes a signal within the brain, a corollary discharge, that informs visual regions of the brain when and where the eyes are about to move. Such a corollary discharge circuit for eye movements has been identified in macaque monkey. We now show that selectively inactivating this brain circuit alters the monkey's visual perception. We conclude that this corollary discharge provides a critical signal that can be used to unite jumping retinal images into a consistent visual scene.
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27
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Jayet Bray LC, Bansal S, Joiner WM. Quantifying the spatial extent of the corollary discharge benefit to transsaccadic visual perception. J Neurophysiol 2015; 115:1132-45. [PMID: 26683070 DOI: 10.1152/jn.00657.2015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 12/16/2015] [Indexed: 01/20/2023] Open
Abstract
Extraretinal information, such as corollary discharge (CD), is hypothesized to help compensate for saccade-induced visual input disruptions. However, support for this hypothesis is largely for one-dimensional transsaccadic visual changes, with little comprehensive information on the spatial characteristics. Here we systematically mapped the two-dimensional extent of this compensation by quantifying the insensitivity to different displacement metrics. Human subjects made saccades to targets positioned at different amplitudes (4° or 8°) and directions (rightward, oblique, or upward). After the saccade the initial target disappeared and, after a blank period, reappeared at a shifted location-a collinear, diagonal, or orthogonal displacement. Subjects reported the perceived shift direction, and we determined the displacement detection based on the perceptual judgments. The two-dimensional insensitivity fields resulting from the perceptual thresholds had spatial features similar to the saccadic eye movement variability: 1) scaled with movement amplitude, 2) oriented (less sensitive to the change) along the saccade vector, and 3) approximately constant in shape when normalized by movement amplitude. In addition, comparing the postsaccadic perceptual estimate of the presaccadic target location to that based solely on the postsaccade visual error showed that overall the perceptual estimate was approximately 50% more accurate and 35% less variable than estimates based solely on this visual information. However, this relationship was not uniform: The benefit of extraretinal information was observed largely for displacements with a component parallel to the saccade vector. These results suggest a graded use of extraretinal information when forming the postsaccadic perceptual evaluation of transsaccadic environmental changes.
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Affiliation(s)
| | - Sonia Bansal
- Department of Neuroscience, George Mason University, Fairfax, Virginia; and
| | - Wilsaan M Joiner
- Department of Bioengineering, George Mason University, Fairfax, Virginia; Department of Neuroscience, George Mason University, Fairfax, Virginia; and Krasnow Institute for Advanced Study, Sensorimotor Integration Laboratory, George Mason University, Fairfax, Virginia
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