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Zanker J, Hüser D, Savy A, Lázaro-Petri S, Hammer EM, Schwarzer C, Heilbronn R. Evaluation of the SH-SY5Y cell line as an in vitro model for potency testing of a neuropeptide-expressing AAV vector. Front Mol Neurosci 2023; 16:1280556. [PMID: 38098942 PMCID: PMC10720649 DOI: 10.3389/fnmol.2023.1280556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2023] [Accepted: 10/23/2023] [Indexed: 12/17/2023] Open
Abstract
Viral vectors have become important tools for basic research and clinical gene therapy over the past years. However, in vitro testing of vector-derived transgene function can be challenging when specific post-translational modifications are needed for biological activity. Similarly, neuropeptide precursors need to be processed to yield mature neuropeptides. SH-SY5Y is a human neuroblastoma cell line commonly used due to its ability to differentiate into specific neuronal subtypes. In this study, we evaluate the suitability of SH-SY5Y cells in a potency assay for neuropeptide-expressing adeno-associated virus (AAV) vectors. We looked at the impact of neuronal differentiation and compared single-stranded (ss) AAV and self-complementary (sc) AAV transduction at increasing MOIs, RNA transcription kinetics, as well as protein expression and mature neuropeptide production. SH-SY5Y cells proved highly transducible with AAV1 already at low MOIs in the undifferentiated state and even better after neuronal differentiation. Readouts were GFP or neuropeptide mRNA expression. Production of mature neuropeptides was poor in undifferentiated cells. By contrast, differentiated cells produced and sequestered mature neuropeptides into the medium in a MOI-dependent manner.
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Affiliation(s)
- Jeanette Zanker
- Department of Neurology, AG Gene Therapy, Berlin Institute of Health, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Daniela Hüser
- Department of Neurology, AG Gene Therapy, Berlin Institute of Health, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Adrien Savy
- Department of Neurology, AG Gene Therapy, Berlin Institute of Health, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Sara Lázaro-Petri
- Department of Neurology, AG Gene Therapy, Berlin Institute of Health, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Eva-Maria Hammer
- Department of Neurology, AG Gene Therapy, Berlin Institute of Health, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Christoph Schwarzer
- Institute of Pharmacology, Medical University of Innsbruck, Innsbruck, Austria
| | - Regine Heilbronn
- Department of Neurology, AG Gene Therapy, Berlin Institute of Health, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
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Heise V, Holman C, Lo H, Lyras EM, Adkins MC, Aquino MRJ, Bougioukas KI, Bray KO, Gajos M, Guo X, Hartling C, Huerta-Gutierrez R, Jindrová M, Kenney JPM, Kępińska AP, Kneller L, Lopez-Rodriguez E, Mühlensiepen F, Richards A, Richards G, Siebert M, Smith JA, Smith N, Stransky N, Tarvainen S, Valdes DS, Warrington KL, Wilpert NM, Witkowska D, Zaneva M, Zanker J, Weissgerber TL. Ten simple rules for implementing open and reproducible research practices after attending a training course. PLoS Comput Biol 2023; 19:e1010750. [PMID: 36602968 PMCID: PMC9815586 DOI: 10.1371/journal.pcbi.1010750] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Open, reproducible, and replicable research practices are a fundamental part of science. Training is often organized on a grassroots level, offered by early career researchers, for early career researchers. Buffet style courses that cover many topics can inspire participants to try new things; however, they can also be overwhelming. Participants who want to implement new practices may not know where to start once they return to their research team. We describe ten simple rules to guide participants of relevant training courses in implementing robust research practices in their own projects, once they return to their research group. This includes (1) prioritizing and planning which practices to implement, which involves obtaining support and convincing others involved in the research project of the added value of implementing new practices; (2) managing problems that arise during implementation; and (3) making reproducible research and open science practices an integral part of a future research career. We also outline strategies that course organizers can use to prepare participants for implementation and support them during this process.
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Affiliation(s)
- Verena Heise
- Freelance Open Science researcher, Gladbeck, Germany
| | - Constance Holman
- QUEST Center for Responsible Research, Berlin Institute of Health at Charité–Universitätsmedizin Berlin, Berlin, Germany
| | - Hung Lo
- Einstein Center for Neurosciences Berlin, Charité–Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
- Neuroscience Research Center (NWFZ), Charité–Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - Ekaterini Maria Lyras
- Charité–Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | | | - Maria Raisa Jessica Aquino
- Population Health Sciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle Upon Tyne, United Kingdom
| | - Konstantinos I. Bougioukas
- Department of Hygiene, Social-Preventive Medicine & Medical Statistics, School of Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, University Campus, Thessaloniki, Greece
| | - Katherine O. Bray
- Melbourne Neuropsychiatry Centre (MNC), Department of Psychiatry, The University of Melbourne & Melbourne Health, Melbourne, Australia, and Melbourne School of Psychological Sciences, University of Melbourne, Melbourne, Australia
| | - Martyna Gajos
- Department of Mathematics and Computer Science, Freie Universität Berlin, Berlin, Germany
| | - Xuanzong Guo
- Einstein Center for Neurosciences Berlin, Charité–Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - Corinna Hartling
- Department of Psychiatry and Psychotherapy, Charité–Universitätsmedizin Berlin, Berlin, Germany
| | | | - Miroslava Jindrová
- Department of Psychosomatic Medicine and Psychotherapy, Central Institute of Mental Health Mannheim, Medical Faculty Mannheim / Heidelberg University, Mannheim, Germany
| | | | - Adrianna P. Kępińska
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
- Seaver Autism Center for Research and Treatment, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Laura Kneller
- Division of Pulmonary Inflammation, Charité–Universitätsmedizin Berlin, Berlin, Germany
| | - Elena Lopez-Rodriguez
- Institute of Functional Anatomy, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Felix Mühlensiepen
- Center for Health Services Research, Brandenburg Medical School Theodor Fontane, Faculty of Health Sciences Brandenburg, Ruedersdorf, Germany
| | | | - Gareth Richards
- School of Psychology, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Maximilian Siebert
- Meta-Research Innovation Center at Stanford (METRICS), Stanford University, Stanford, California, United States of America
| | - James A. Smith
- Botnar Research Centre and Centre for Statistics in Medicine, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, United Kingdom
| | - Natalie Smith
- Department of Psychology, School of Education, Language and Psychology, York St John University, New York, United Kingdom
| | - Nicolai Stransky
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Sirpa Tarvainen
- Department of Psychology and Logopedics, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Daniela Sofia Valdes
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany
- Experimental and Clinical Research Center Charité–Universitätsmedizin Berlin, Berlin, Germany
| | | | - Nina-Maria Wilpert
- Department of Neuropediatrics, Charité–Universitätsmedizin Berlin, Berlin, Germany
| | - Disa Witkowska
- Division of Psychology and Language Sciences, University College London, London, United Kingdom
| | - Mirela Zaneva
- Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom
| | - Jeanette Zanker
- Einstein Center for Neurosciences Berlin, Charité–Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - Tracey L. Weissgerber
- QUEST Center for Responsible Research, Berlin Institute of Health at Charité–Universitätsmedizin Berlin, Berlin, Germany
- * E-mail:
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Daly RM, Iuliano S, Fyfe JJ, Scott D, Kirk B, Thompson MQ, Dent E, Fetterplace K, Wright ORL, Lynch GS, Zanker J, Yu S, Kurrle S, Visvanathan R, Maier AB. Screening, Diagnosis and Management of Sarcopenia and Frailty in Hospitalized Older Adults: Recommendations from the Australian and New Zealand Society for Sarcopenia and Frailty Research (ANZSSFR) Expert Working Group. J Nutr Health Aging 2022; 26:637-651. [PMID: 35718874 DOI: 10.1007/s12603-022-1801-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Sarcopenia and frailty are highly prevalent conditions in older hospitalized patients, which are associated with a myriad of adverse clinical outcomes. This paper, prepared by a multidisciplinary expert working group from the Australian and New Zealand Society for Sarcopenia and Frailty Research (ANZSSFR), provides an up-to-date overview of current evidence and recommendations based on a narrative review of the literature for the screening, diagnosis, and management of sarcopenia and frailty in older patients within the hospital setting. It also includes suggestions on potential pathways to implement change to encourage widespread adoption of these evidence-informed recommendations within hospital settings. The expert working group concluded there was insufficient evidence to support any specific screening tool for sarcopenia and recommends an assessment of probable sarcopenia/sarcopenia using established criteria for all older (≥65 years) hospitalized patients or in younger patients with conditions (e.g., comorbidities) that may increase their risk of sarcopenia. Diagnosis of probable sarcopenia should be based on an assessment of low muscle strength (grip strength or five times sit-to-stand) with sarcopenia diagnosis including low muscle mass quantified from dual energy X-ray absorptiometry, bioelectrical impedance analysis or in the absence of diagnostic devices, calf circumference as a proxy measure. Severe sarcopenia is represented by the addition of impaired physical performance (slow gait speed). All patients with probable sarcopenia or sarcopenia should be investigated for causes (e.g., chronic/acute disease or malnutrition), and treated accordingly. For frailty, it is recommended that all hospitalized patients aged 70 years and older be screened using a validated tool [Clinical Frailty Scale (CFS), Hospital Frailty Risk Score, the FRAIL scale or the Frailty Index]. Patients screened as positive for frailty should undergo further clinical assessment using the Frailty Phenotype, Frailty Index or information collected from a Comprehensive Geriatric Assessment (CGA). All patients identified as frail should receive follow up by a health practitioner(s) for an individualized care plan. To treat older hospitalized patients with probable sarcopenia, sarcopenia, or frailty, it is recommended that a structured and supervised multi-component exercise program incorporating elements of resistance (muscle strengthening), challenging balance, and functional mobility training be prescribed as early as possible combined with nutritional support to optimize energy and protein intake and correct any deficiencies. There is insufficient evidence to recommend pharmacological agents for the treatment of sarcopenia or frailty. Finally, to facilitate integration of these recommendations into hospital settings organization-wide approaches are needed, with the Spread and Sustain framework recommended to facilitate organizational culture change, with the help of 'champions' to drive these changes. A multidisciplinary team approach incorporating awareness and education initiatives for healthcare professionals is recommended to ensure that screening, diagnosis and management approaches for sarcopenia and frailty are embedded and sustained within hospital settings. Finally, patients and caregivers' education should be integrated into the care pathway to facilitate adherence to prescribed management approaches for sarcopenia and frailty.
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Affiliation(s)
- R M Daly
- Professor Robin M. Daly, Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, 221 Burwood Highway, Burwood, Melbourne, Victoria, Australia 3125, Phone: +61 3 9244 6040, , ORCID ID: 0000-0002-9897-1598
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Zanker J, Lázaro-Petri S, Hüser D, Heilbronn R, Savy A. Insight & Development of Advanced rAAV Analysis Tools Exploiting Single Particle Quantification by Multidimensional ddPCR. Hum Gene Ther 2021; 33:977-989. [PMID: 34937401 PMCID: PMC10112877 DOI: 10.1089/hum.2021.182] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Recombinant Adeno-Associated Virus (rAAV) has become the most widely used vector in the gene therapy field with hundreds of clinical trials ongoing and already several products on the market. AAV's physico-chemical stability, and the various natural and engineered serotypes allow for targeting a broad range of cell types and tissue by diverse routes of administration. Progressing from early clinical studies to eventual market approval, many critical quality attributes (CQAs) have to be defined and reproducibly quantified, such as AAV stability, purity, aggregates, empty/full particles ratio and rAAV genome titration. Droplet digital PCR (ddPCR) is becoming the tool of choice to perform absolute quantification of rAAV genomes. In the present study, we have identified critical parameters that could impact AAV titration and characterization accuracy, such as Poisson distribution confidence interval, primers/probe position and potential aggregates. Our work presents how ddPCR can help to better characterize AAV vectors on the single particle level and highlights challenges that we are facing today in term of AAV titration.
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Affiliation(s)
- Jeanette Zanker
- Charité Universitätsmedizin Berlin Campus Benjamin Franklin, 9164, Institute of Health, Department of Neurology, AG Gene Therapy, Berlin, Berlin, Germany;
| | - Sara Lázaro-Petri
- Charité Universitätsmedizin Berlin Campus Benjamin Franklin, 9164, Institute of Health, Department of Neurology, AG Gene Therapy, Berlin, Berlin, Germany;
| | - Daniela Hüser
- Charité Universitätsmedizin Berlin Campus Benjamin Franklin, 9164, Institute of Health, Department of Neurology, AG Gene Therapy, Berlin, Berlin, Germany;
| | - Regine Heilbronn
- Charité Universitätsmedizin Berlin Campus Benjamin Franklin, 9164, Institute of Health, Department of Neurology, AG Gene Therapy, Berlin, Berlin, Germany;
| | - Adrien Savy
- Charité Universitätsmedizin Berlin Campus Benjamin Franklin, 9164, Institute of Health, Department of Neurology, AG Gene Therapy, Berlin, Berlin, Germany.,Kolibri, BioProcess, Paris, France;
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Oktaviana J, Zanker J, Vogrin S, Duque G. The Effect of β-hydroxy-β-methylbutyrate (HMB) on Sarcopenia and Functional Frailty in Older Persons: A Systematic Review. J Nutr Health Aging 2019; 23:145-150. [PMID: 30697623 DOI: 10.1007/s12603-018-1153-y] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
BACKGROUND Beta-hydroxy-beta-methylbutyrate (HMB) has been shown to be effective and superior to other types of protein supplements to attenuate loss of muscle mass, strength and function, however, its benefits in sarcopenic and frail older people remain unclear. OBJECTIVE We seek to determine the effect of HMB on muscle mass, strength and function in older people with sarcopenia or frailty by reviewing results from available randomized controlled trials (RCTs). DESIGN This review was registered at PROSPERO (University of York) with registration number CRD42018088462 and conducted according to the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines. Using a pre-determined e-search strategy, we searched PubMed, Medline, EMBASE, CINAHL, LILACS, Web of Science, Cochrane and Scopus databases. Our inclusion criteria were RCTs that assessed the effect of HMB on muscle mass, strength and function in older people with sarcopenia and frailty aged ≥60 years. The main outcomes were lean body mass, handgrip, leg press strength, and Short Physical Performance Battery (SPPB) score. RESULTS Three studies matched our eligibility criteria which enrolled 203 subjects through a variety of definitions of sarcopenia or frailty. Lean body mass increased and muscle strength and function were preserved following HMB supplementation. CONCLUSION HMB improves lean muscle mass and preserves muscle strength and function in older people with sarcopenia or frailty.
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Affiliation(s)
- J Oktaviana
- Prof. Gustavo Duque, MD, Ph.D., FRACP, FGSA, Australian Institute for Musculoskeletal Science (AIMSS), The University of Melbourne and Western Health, 176 Furlong Road, St. Albans, VIC, Australia 3021,Tel: +61 3 8395 8121,
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Zanker J, Scott D, Reijnierse EM, Brennan-Olsen SL, Daly RM, Girgis CM, Grossmann M, Hayes A, Henwood T, Hirani V, Inderjeeth CA, Iuliano S, Keogh JWL, Lewis JR, Maier AB, Pasco JA, Phu S, Sanders KM, Sim M, Visvanathan R, Waters DL, Yu SCY, Duque G. Establishing an Operational Definition of Sarcopenia in Australia and New Zealand: Delphi Method Based Consensus Statement. J Nutr Health Aging 2019; 23:105-110. [PMID: 30569078 DOI: 10.1007/s12603-018-1113-6] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
BACKGROUND Globally there are several operational definitions for sarcopenia, complicating clinical and research applications. OBJECTIVE The objective of the Australian and New Zealand Society for Sarcopenia and Frailty Research (ANZSSFR) Task Force on Diagnostic Criteria for Sarcopenia was to reach consensus on the operational definition of sarcopenia for regional use by clinicians and researchers. METHOD A four-Phase modified Delphi process was undertaken in which 24 individuals with expertise or a recognised interest in sarcopenia from different fields across Australia and New Zealand were invited to be Task Force members. An initial face-to-face meeting was held in Adelaide, South Australia, in November 2017, followed by two subsequent online Phases conducted by electronic surveys. A final Phase was used to approve the final statements. Responses were analysed using a pre-specified strategy. The level of agreement required for consensus was 80%. RESULTS In Phase 2, 94.1% of Task Force respondents voted in favour of adopting an existing operational definition of sarcopenia. In Phase 3, 94.4% of respondents voted in favour of adopting the European Working Group on Sarcopenia in Older People (EWGSOP) definition as the operational definition for sarcopenia in Australia and New Zealand. CONCLUSION With consensus achieved, the ANZSSFR will adopt, promote and validate the EWGSOP operational definition of sarcopenia for use by clinicians and researchers in Australia and New Zealand.
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Affiliation(s)
- J Zanker
- Prof. Gustavo Duque, MD, PhD, FRACP, FGSA, Australian Institute for Musculoskeletal Science (AIMSS), 176 Furlong Road, St. Albans, VIC, Australia 3021, e-mail: , phone: +61 8395 8121
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Braun D, Fahle M, Schönle P, Zanker J. Deficits and Recovery of First-Order and Second-Order Motion Perception in Patients with Unilateral Posterior Parietal Lesions. Perception 2016. [DOI: 10.1068/v96l0206] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Our aim was to test whether unilateral posterior parietal lesions degrade first-order and second-order motion differentially, and to investigate the time course of any potential recovery. We tested ten patients with circumscribed parietal lesions. Thresholds were measured for the discrimination of the direction of motion of stimuli presented 5.5° peripherally in the ipsilesional and contralesional visual hemifields. Subjects had to indicate whether a rectangular region (1.6 deg × 3 deg) embedded in dynamic random noise background moved up or down. The region contained moving (signal) and flickering (background) dots and moved for 1 s at 2.36 deg s−1. Signal dots were either (a) coherently moving in the same direction as the region (first-order), (b) stationary (second-order), or (c) coherently moving in the opposite direction (theta). Thresholds were defined as percentage of signal dots within the region yielding 75% correct responses. All patients had higher thresholds for second-order than for first-order motion. When contralesional and ipsilesional thresholds were compared, three patients showed proportional threshold elevations for all three types of motion stimuli in the contralesional hemifield. Two of these three patients were tested again five months later. Both showed considerable recovery: in one patient, the contralesional deficit was no longer present; in the other, it was reduced by about half. None of our patients had lesions affecting first-order or second-order motion differentially; lesions always affected first-order and second-order motion similarly. Owing to recovery, these deficits might be detectable only for a short time.
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Rowland E, Zanker J, Durant S. Simple duration detectors for encoding event time. J Vis 2014. [DOI: 10.1167/14.10.1144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Ayhan I, Doyle E, Zanker J. Measuring image distortions using an Iterative Amsler Grid (IAG) in patients with age-related macular degeneration. J Vis 2014. [DOI: 10.1167/14.10.1360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Zanker J, Targher S, Durant S. A new Barbers Pole configuration to study the integration of local motion information. J Vis 2010. [DOI: 10.1167/7.9.979] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Durant S, Zanker J. Comparing image structure with local motion structure in real life optic flow. J Vis 2010. [DOI: 10.1167/9.8.1043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Abstract
When a sinewave grating is moving within a cross-shaped aperture, a strongly multi-stable phenomenon is perceived. The percept switches between the coherence of an extended surface moving in a single direction and the segregation of two patterned strips sliding across each other in directions parallel to the branches of the cross. We studied how the balance between these two percepts is affected by the length of the arms and by the shape of their ends. We report here that human observers report the segregation into two surfaces more often when the branches of the cross are extended, and when the small sides of the arms are oriented parallel to the grating. Two kinds of early motion signals interact in the crossed barber-pole stimulus: (a) the signals extracted in the middle of the bars are ambiguous with regard to their direction, and usually would be interpreted as motion normal to the grating orientation; (b) the signals from regions where the grating is intersected by the borders of the aperture convey motion signals in direction of the border. Our results show that the global appearance of our display can be dramatically influenced by the reliability of motion signals located in small regions that may be separated by large distances. To explain this long-range effect, we tentatively propose the existence of a representation level situated between the extraction of low-level local signals and the final global percept. The postulated processing level is concerned with the segmenting of the entire image into surfaces that are likely to belong to the same object, even if they are not contiguous in space. This hypothetical mechanism involves the construction of coarse-scale 'patches' from the local motion signal distributions, each carrying a single velocity associated with a certain degree of reliability. Our experiments indicate that the probability of grouping together similar patches depends on their respective reliabilities.
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Affiliation(s)
- E Castet
- Centre de Recherche en Neurosciences Cognitives, VPR 9012 du CNRS, Marseille, France.
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Abstract
In the first part of this review a basic mechanism of motion perception was illustrated. The elementary motion detector (EMD) of the correlation type can account for the detection of "Fourier" motion stimuli in which the spatial intensity distribution on the retina is shifted over time. In recent years, novel classes of stimuli such as "drift-balanced" or "theta" motion (in which the picture elements carrying luminance contrast do not move, or move in the opposite direction to the traveling object defined by such element motion) were introduced into psychophysics. Such stimuli may play an important role in the understanding of "higher" visual processing which goes beyond the pure detection of motion. Thus, in the second part of the review, the question will be addressed as to what further processing steps, or more sophisticated mechanisms than the EMD, have to be assumed in order to understand more complex aspects of human motion perception.
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Affiliation(s)
- J Zanker
- Max-Planck-Institut für biologische Kybernetik, Tübingen
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Abstract
Motion perception is one of the most prominent tasks of the visual system and therefore has been extensively investigated both experimentally and theoretically. A classical model describing the mechanism of motion detection originally developed in the context of insect orientation behavior, the elementary motion detector (EMD) of the correlation type, turned out to be very powerful in explaining many basic aspects of human motion perception. For more complex visual tasks, like the discrimination of a figure from its background by relative motion, on the other hand, further processing of motion information is required. In the first part of this review it will be illustrated by means of a few examples, what kind of motion information can be derived from the mere correlation-type model, and what perceptual phenomena can be accounted for by the EMD. In the second part, more recently developed stimuli will be introduced to answer the question what further processing steps, or more sophisticated mechanisms than the EMD, have to be assumed in order to understand "higher" aspects of human motion perception.
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Affiliation(s)
- J Zanker
- Max-Planck-Institut für biologische Kybernetik, Tübingen
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Abstract
Vernier acuity, i.e. the detection of a small misalignment between lines, is about one order of magnitude finer than the resolution of periodic gratings in adult humans. This hyperacuity is generally attributed to cortical mechanisms, and the time-course of its development seems to differ from the development of grating resolution that probably is limited by retinal factors. We investigated 271 human infants and children between 2 months and 8 yr of age with essentially identical stimuli and experimental procedures. Vernier thresholds for Vernier targets were compared to grating resolution. The preferential looking experiments led to the following results: (i) Vernier acuity starts below grating resolution. (ii) Like grating resolution, Vernier acuity develops gradually, but more rapidly and longer; at the age of 5 yr performance becomes comparable to that of adults. (iii) Flanking borders without offset, added to the Vernier targets at various distances, did not affect thresholds consistently across distances and age groups.
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Affiliation(s)
- J Zanker
- Max-Planck-Institute for Biological Cybernetics, Tübingen, Fed. Rep. Germany
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