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Hayashi S, Caron BA, Heinsfeld AS, Vinci-Booher S, McPherson B, Bullock DN, Bertò G, Niso G, Hanekamp S, Levitas D, Ray K, MacKenzie A, Avesani P, Kitchell L, Leong JK, Nascimento-Silva F, Koudoro S, Willis H, Jolly JK, Pisner D, Zuidema TR, Kurzawski JW, Mikellidou K, Bussalb A, Chaumon M, George N, Rorden C, Victory C, Bhatia D, Aydogan DB, Yeh FCF, Delogu F, Guaje J, Veraart J, Fischer J, Faskowitz J, Fabrega R, Hunt D, McKee S, Brown ST, Heyman S, Iacovella V, Mejia AF, Marinazzo D, Craddock RC, Olivetti E, Hanson JL, Garyfallidis E, Stanzione D, Carson J, Henschel R, Hancock DY, Stewart CA, Schnyer D, Eke DO, Poldrack RA, Bollman S, Stewart A, Bridge H, Sani I, Freiwald WA, Puce A, Port NL, Pestilli F. brainlife.io: a decentralized and open-source cloud platform to support neuroscience research. Nat Methods 2024:10.1038/s41592-024-02237-2. [PMID: 38605111 DOI: 10.1038/s41592-024-02237-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Accepted: 03/05/2024] [Indexed: 04/13/2024]
Abstract
Neuroscience is advancing standardization and tool development to support rigor and transparency. Consequently, data pipeline complexity has increased, hindering FAIR (findable, accessible, interoperable and reusable) access. brainlife.io was developed to democratize neuroimaging research. The platform provides data standardization, management, visualization and processing and automatically tracks the provenance history of thousands of data objects. Here, brainlife.io is described and evaluated for validity, reliability, reproducibility, replicability and scientific utility using four data modalities and 3,200 participants.
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Affiliation(s)
| | - Bradley A Caron
- Indiana University, Bloomington, IN, USA
- The University of Texas, Austin, TX, USA
| | | | - Sophia Vinci-Booher
- Indiana University, Bloomington, IN, USA
- Vanderbilt University, Nashville, TN, USA
| | - Brent McPherson
- Indiana University, Bloomington, IN, USA
- McGill University, Montréal, Quebec, Canada
| | | | | | - Guiomar Niso
- Indiana University, Bloomington, IN, USA
- Cajal Institute, CSIC, Madrid, Spain
| | | | - Daniel Levitas
- Indiana University, Bloomington, IN, USA
- The University of Texas, Austin, TX, USA
| | | | | | | | - Lindsey Kitchell
- Indiana University, Bloomington, IN, USA
- Applied Physics Laboratory, Johns Hopkins University, Laurel, MD, USA
| | - Josiah K Leong
- Indiana University, Bloomington, IN, USA
- University of Arkansas, Fayetteville, AR, USA
| | | | | | | | | | | | | | | | - Kyriaki Mikellidou
- University of Limassol, Nicosia, Cyprus
- University of Cyprus, Nicosia, Cyprus
| | - Aurore Bussalb
- Institut du Cerveau, CNRS, Sorbonne Université, Paris, France
| | | | - Nathalie George
- Institut du Cerveau, CNRS, Sorbonne Université, Paris, France
| | | | | | | | - Dogu Baran Aydogan
- University of Eastern Finland, Kuopio, Finland
- Aalto University School of Science, Espoo, Finland
| | | | - Franco Delogu
- Lawrence Technological University, Southfield, MI, USA
| | | | | | | | | | | | - David Hunt
- Indiana University, Bloomington, IN, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Ashley Stewart
- University of Queensland, St Lucia, Queensland, Australia
| | | | - Ilaria Sani
- The Rockefeller University, New York, NY, USA
- University of Geneva, Geneva, Switzerland
| | | | - Aina Puce
- Indiana University, Bloomington, IN, USA
| | | | - Franco Pestilli
- Indiana University, Bloomington, IN, USA.
- The University of Texas, Austin, TX, USA.
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Keeler JM, Listman JB, Hite MJ, Heeger DJ, Tourula E, Port NL, Schlader ZJ. Arterial oxygen desaturation during moderate hypoxia hinders sensorimotor performance. PLoS One 2024; 19:e0297486. [PMID: 38394255 PMCID: PMC10889874 DOI: 10.1371/journal.pone.0297486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Accepted: 01/06/2024] [Indexed: 02/25/2024] Open
Abstract
INTRODUCTION Moderate hypoxia may impact cognitive and sensorimotor performance prior to self-recognized impairments. Therefore, rapid and objective assessment tools to identify people at risk of impaired function during moderate hypoxia is needed. PURPOSE Test the hypothesis that reductions in arterial oxygen saturation during moderate normobaric hypoxia (FiO2 = 14%) decreases gamified sensorimotor performance as measured by alterations of motor acuity. METHODS Following three consecutive days of practice, thirty healthy adults (25 ± 5 y, 10 females) completed three bouts of the tablet-based gamified assessment (Statespace Labs, Inc.) of motor acuity at Baseline and 60 and 90 min after exposure to 13.8 ± 0.2% (hypoxia) and 20.1 ± 0.4% (normoxia) oxygen. The gamified assessment involved moving the tablet to aim and shoot at targets. Both conditions were completed on the same day and were administered in a single-blind, block randomized manner. Performance metrics included shot time and shot variability. Arterial oxyhemoglobin saturation estimated via forehead pulse oximetry (SpO2). Data were analyzed using linear mixed effects models. RESULTS Compared to normoxia (99±1%), SpO2 was lower (p<0.001) at 60 (89±3%) and 90 (90±2%) min of hypoxia. Shot time was unaffected by decreases in SpO2 (0.012, p = 0.19). Nor was shot time affected by the interaction between SpO2 decrease and baseline performance (0.006, p = 0.46). Shot variability was greater (i.e., less precision, worse performance) with decreases in SpO2 (0.023, p = 0.02) and depended on the interaction between SpO2 decrease and baseline performance (0.029, p< 0.01). CONCLUSION Decreases in SpO2 during moderate hypoxic exposure hinders sensorimotor performance via decreased motor acuity, i.e., greater variability (less precision) with no change in speed with differing decreases in SpO2. Thus, personnel who are exposed to moderate hypoxia and have greater decreases in SpO2 exhibit lower motor acuity, i.e., less precise movements even though decision time and movement speed are unaffected.
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Affiliation(s)
- Jason M. Keeler
- Department of Kinesiology, H.H. Morris Human Performance Laboratories, School of Public Health-Bloomington, Indiana University, Bloomington, IN, United States of America
| | | | - M. Jo Hite
- Department of Kinesiology, H.H. Morris Human Performance Laboratories, School of Public Health-Bloomington, Indiana University, Bloomington, IN, United States of America
| | - David J. Heeger
- Statespace Labs, Inc. New York, NY, United States of America
| | - Erica Tourula
- Department of Kinesiology, H.H. Morris Human Performance Laboratories, School of Public Health-Bloomington, Indiana University, Bloomington, IN, United States of America
| | - Nicholas L. Port
- School of Optometry, Indiana University, Bloomington, IN, United States of America
| | - Zachary J. Schlader
- Department of Kinesiology, H.H. Morris Human Performance Laboratories, School of Public Health-Bloomington, Indiana University, Bloomington, IN, United States of America
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Hayashi S, Caron BA, Heinsfeld AS, Vinci-Booher S, McPherson B, Bullock DN, Bertò G, Niso G, Hanekamp S, Levitas D, Ray K, MacKenzie A, Kitchell L, Leong JK, Nascimento-Silva F, Koudoro S, Willis H, Jolly JK, Pisner D, Zuidema TR, Kurzawski JW, Mikellidou K, Bussalb A, Rorden C, Victory C, Bhatia D, Baran Aydogan D, Yeh FCF, Delogu F, Guaje J, Veraart J, Bollman S, Stewart A, Fischer J, Faskowitz J, Chaumon M, Fabrega R, Hunt D, McKee S, Brown ST, Heyman S, Iacovella V, Mejia AF, Marinazzo D, Craddock RC, Olivetti E, Hanson JL, Avesani P, Garyfallidis E, Stanzione D, Carson J, Henschel R, Hancock DY, Stewart CA, Schnyer D, Eke DO, Poldrack RA, George N, Bridge H, Sani I, Freiwald WA, Puce A, Port NL, Pestilli F. brainlife.io: A decentralized and open source cloud platform to support neuroscience research. ArXiv 2023:arXiv:2306.02183v3. [PMID: 37332566 PMCID: PMC10274934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
Neuroscience research has expanded dramatically over the past 30 years by advancing standardization and tool development to support rigor and transparency. Consequently, the complexity of the data pipeline has also increased, hindering access to FAIR data analysis to portions of the worldwide research community. brainlife.io was developed to reduce these burdens and democratize modern neuroscience research across institutions and career levels. Using community software and hardware infrastructure, the platform provides open-source data standardization, management, visualization, and processing and simplifies the data pipeline. brainlife.io automatically tracks the provenance history of thousands of data objects, supporting simplicity, efficiency, and transparency in neuroscience research. Here brainlife.io's technology and data services are described and evaluated for validity, reliability, reproducibility, replicability, and scientific utility. Using data from 4 modalities and 3,200 participants, we demonstrate that brainlife.io's services produce outputs that adhere to best practices in modern neuroscience research.
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Keeler JM, Tourula E, Hite MJ, Listman JB, Heeger DJ, Port NL, Schlader ZJ. Gamified assessment of cognitive performance during moderate hypoxia. PLoS One 2023; 18:e0288201. [PMID: 37459310 PMCID: PMC10351691 DOI: 10.1371/journal.pone.0288201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Accepted: 06/21/2023] [Indexed: 07/20/2023] Open
Abstract
INTRODUCTION There is a need for rapid and objective assessment tools to identify people at risk of impaired cognitive function during hypoxia. PURPOSE To test the hypotheses that performance on gamified cognitive tests examining the cognitive domains of executive function (Gridshot), working memory (Capacity) and spatial tracking (Multitracker) will be reduced during normobaric exposure to moderate normobaric hypoxia. METHODS Following three consecutive days of practice, twenty-one healthy adults (27 ± 5 y, 9 females) completed five 1-min rounds of the tablet-based games Gridshot, Capacity, and Multitracker (Statespace Labs, Inc.) at Baseline and 60 and 90 min after exposure to 14.0 ± 0.2% (hypoxia) and 20.6 ± 0.3% (normoxia) oxygen. Both conditions were completed on the same day and were administered in a single-blind, block randomized manner. Arterial oxyhemoglobin saturation was estimated via forehead pulse oximetry (SpO2). Data were analyzed using ANCOVA with a covariate of Baseline. RESULTS Compared to normoxia (98 ± 1%), SpO2 was lower (p < 0.001) at 60 (91 ± 3%) and 90 (91 ± 2%) min of hypoxia. No condition x time interaction effects were identified for any gamified cognitive tests (p ≥ 0.32). A main effect of condition was identified for Capacity (p = 0.05) and Multitracker (p = 0.04), but not Gridshot (p = 0.33). Post hoc analyses of the composite scores for both Capacity (p = 0.11) and Multitracker (p = 0.73) demonstrated no difference between conditions. CONCLUSION Performance on gamified cognitive tests was not consistently affected by acute normobaric moderate hypoxic exposure.
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Affiliation(s)
- Jason M. Keeler
- Department of Kinesiology, H.H. Morris Human Performance Laboratories, School of Public Health, Indiana University, Bloomington, Indiana, United States of America
| | - Erica Tourula
- Department of Kinesiology, H.H. Morris Human Performance Laboratories, School of Public Health, Indiana University, Bloomington, Indiana, United States of America
| | - M. Jo Hite
- Department of Kinesiology, H.H. Morris Human Performance Laboratories, School of Public Health, Indiana University, Bloomington, Indiana, United States of America
| | | | - David J. Heeger
- Statespace Labs, Inc. New York, New York, United States of America
| | - Nicholas L. Port
- School of Optometry, Indiana University, Bloomington, Indiana, United States of America
| | - Zachary J. Schlader
- Department of Kinesiology, H.H. Morris Human Performance Laboratories, School of Public Health, Indiana University, Bloomington, Indiana, United States of America
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Ferris LM, Kontos AP, Eagle SR, Elbin RJ, Clugston JR, Ortega J, Port NL. Optimizing VOMS for identifying acute concussion in collegiate athletes: Findings from the NCAA-DoD CARE consortium. Vision Res 2022; 200:108081. [PMID: 35926346 DOI: 10.1016/j.visres.2022.108081] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 03/07/2022] [Accepted: 06/07/2022] [Indexed: 01/25/2023]
Abstract
The Vestibular/Ocular-Motor Screening (VOMS), an important component in acute (<72 h) sport-related concussion (SRC) assessment, is increasingly used alongside the Sport Concussion Assessment Tool (SCAT) and as part of the Military Acute Concussion Evaluation 2 (MACE2). VOMS demonstrates clinically useful diagnostic accuracy for acute SRC and improves the overall utility when added to the SCAT3. However, potential overlap among VOMS's vestibular and oculomotor items suggests the possibility of a more efficient version. VOMS and SCAT3 scores were analyzed for 3,958 preseason (47.8% female) and 496 acute-SRC (37.5% female) NCAA-DoD Concussion Assessment, Research, and Education (CARE) consortium collegiate athlete evaluations. Analyses revealed very large effect sizes (d = 2.39-2.45) and high correlations (rho = 0.95-0.99) among all VOMS items except near point of convergence distance (d = 0.79, rho ≤ 0.341). Receiver operating characteristic (ROC) curve analyses showed clinically useful discriminative utility for VOMS Total (AUC = 0.85) and the VOMS Total change score, where pretest symptoms were incorporated (AUC = 0.81). A modified VOMS (mVOMS) consisting of four items (smooth pursuits, horizontal saccades, horizontal vestibulo-ocular reflex, visual motion sensitivity) yielded identical AUCs to VOMS Total. Integer cutoff analyses suggest a score of ≥4 for VOMS Total and ≥4 for mVOMS Total optimizes concussion identification. Incorporating VOMS or mVOMS into SCAT3 (AUC = 0.79) significantly improved the combined tool's acute utility for acute concussion identification by a maximum of 4% (SCAT3+VOMS AUC = 0.84, SCAT3+mVOMS AUC = 0.83). Future versions of SCAT or MACE may want to consider incorporating a more parsimonious VOMS for the purpose of identifying acute concussion.
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Affiliation(s)
| | | | | | - R J Elbin
- University of Arkansas, United States
| | | | - Justus Ortega
- Humboldt State University Kinesiology and Recreation Administration, United States
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Hite MJ, Keeler JM, Tourula E, Kerr PM, Baker TB, Port NL, Schlader ZJ. Moderate hypoxia decreases selective attention performance as assessed via a domain‐specific gamified assessment. FASEB J 2022. [DOI: 10.1096/fasebj.2022.36.s1.l7956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- M. J. Hite
- KinesiologyIndiana UniversityBloomingtonIN
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Ferris LM, Kontos AP, Eagle SR, Elbin RJ, Collins MW, Mucha A, McAllister TW, Broglio SP, McCrea M, Pasquina PF, Port NL. Utility of VOMS, SCAT3, and ImPACT Baseline Evaluations for Acute Concussion Identification in Collegiate Athletes: Findings From the NCAA-DoD Concussion Assessment, Research and Education (CARE) Consortium. Am J Sports Med 2022; 50:1106-1119. [PMID: 35179972 DOI: 10.1177/03635465211072261] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
BACKGROUND The Vestibular/Ocular-Motor Screening (VOMS) is a valuable component of acute (<72 hours) sports-related concussion (SRC) assessments and is increasingly used with the Immediate Post-concussion Assessment and Cognitive Testing (ImPACT) instrument and the third edition of the Sport Concussion Assessment Tool (SCAT3). Research has suggested that VOMS acute postinjury scores are useful in identifying acute concussion. However, the utility of preseason baseline measurements to improve diagnostic accuracy remains ambiguous. To this end, there is a need to determine how reliable VOMS baseline assessments are across years and whether incorporating individuals' baseline performance improves diagnostic yield for acute concussions. PURPOSE To analyze VOMS, SCAT3, and ImPACT to evaluate the test-retest reliability of consecutive-year preseason baseline assessments to directly compare the diagnostic utility of these tools when incorporating baseline assessments versus using postinjury data alone to identify acute SRC. STUDY DESIGN Cohort study (diagnosis); Level of evidence, 2. METHODS Preseason and postinjury VOMS, SCAT3, ImPACT Post-Concussion Symptom Scale (PCSS), and ImPACT composite scores were analyzed for 3958 preseason (47.7% female) and 496 acute (≤48 hours) SRC (37.5% female) collegiate athlete evaluations in the National Collegiate Athletic Association-Department of Defense Concussion Assessment Research and Education Consortium. Descriptive statistics, Kolmogorov-Smirnov significance, and Cohen d effect size were calculated. Consecutive-year baseline reliability was evaluated for a subset of 447 athlete encounters using Pearson r, Cohen κ, Cohen d, and 2-way mixed intraclass correlation coefficients (ICCs). Wilcoxon signed rank tests were used to determine the statistical significance between population performances, and the 90% reliable change index (RCI) was calculated from the test-retest results. Preseason to postinjury change scores were then calculated from each tool's RCI. Finally, receiver operating characteristic (ROC) curve analyses were conducted, and DeLong method was used to compare the area under the curve (AUC) of raw postinjury scores versus change scores from preseason baseline assessments. Potential effects of sex, medical history (learning disorders or attention-deficit/hyperactivity disorder), and outlier data were also explored. RESULTS Effect sizes were large, and overall predictive utilities were clinically useful for postinjury VOMS Total (d = 2.44; AUC = 0.85), the SCAT3 Symptom Evaluation total severity score (d = 1.74; AUC = 0.82), and the ImPACT PCSS total severity score (d = 1.67; AUC = 0.80). Comparatively, effect sizes were small and predictive utilities were poor for Standardized Assessment of Concussion (SAC), modified Balance Error Scoring System (mBESS), and all ImPACT composites (d = 0.11-0.46; AUC = 0.48-0.59). Preseason baseline test-retest reliability was poor to moderate (r = 0.23-0.52; κ = 0.32-0.36; ICC = 0.36-0.68) for all assessments except ImPACT Visual Motion Sensitivity (r = 0.73; ICC = 0.85). Incorporating baseline scores for VOMS Total, SCAT3 (Symptom Evaluation, SAC, mBESS), ImPACT PCSS, or ImPACT composites did not significantly improve AUCs. CONCLUSION VOMS Total and symptom severity (SCAT3, PCSS) total scores had large effect sizes and clinically useful AUCs for identifying acute concussion. However, all tools demonstrated high within-patient test-retest variability, resulting in poor reliability. The findings in this sample of collegiate athletes suggest that incorporating baseline assessments does not significantly increase diagnostic yield for acute concussion.
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Affiliation(s)
- Lyndsey M Ferris
- Indiana University School of Optometry, Bloomington, Indiana, USA
| | | | - Shawn R Eagle
- University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - R J Elbin
- University of Arkansas, Fayetteville, Arkansas, USA
| | | | - Anne Mucha
- UPMC Centers for Rehab Services, Pittsburg, Pennsylvania, USA
| | - Thomas W McAllister
- Department of Psychiatry, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Steven P Broglio
- Michigan Concussion Center, University of Michigan, Ann Arbor, Michigan, USA
| | - Michael McCrea
- Neurosurgery, Medical College of Wisconsin, Millwauke, Wisconsin, USA
| | - Paul F Pasquina
- Department of Physical Medicine and Rehabilitation, Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA
| | - Nicholas L Port
- Indiana University School of Optometry, Bloomington, Indiana, USA
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Greenshields JT, Goodwin SM, Bento AI, Port NL, Carter SJ, Johnson BD, Hipskind AS, Schlader ZJ, Rink LD. Positive SARS-CoV-2 Diagnosis Has Modest Effects On Resting Indices Of Cardiac Conduction And Repolarization In Division-I NCAA Athletes. Med Sci Sports Exerc 2021. [DOI: 10.1249/01.mss.0000759928.49127.13] [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: 11/21/2022]
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Ferris LM, Kontos AP, Eagle SR, Elbin RJ, Collins MW, Mucha A, Clugston JR, Port NL. Predictive Accuracy of the Sport Concussion Assessment Tool 3 and Vestibular/Ocular-Motor Screening, Individually and In Combination: A National Collegiate Athletic Association-Department of Defense Concussion Assessment, Research and Education Consortium Analysis. Am J Sports Med 2021; 49:1040-1048. [PMID: 33600216 DOI: 10.1177/0363546520988098] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
BACKGROUND Vestibular and ocular symptoms in sport-related concussions are common. The Vestibular/Ocular-Motor Screening (VOMS) tool is a rapid, free, pen-and-paper tool that directly assesses these symptoms and shows consistent utility in concussion identification, prognosis, and management. However, a VOMS validation study in the acute concussion period of a large sample is lacking. PURPOSE To examine VOMS validity among collegiate student-athletes, concussed and nonconcussed, from the multisite National Collegiate Athletic Association-Department of Defense Concussion Assessment, Research and Education (CARE) Consortium. A secondary aim was to utilize multidimensional machine learning pattern classifiers to deduce the additive power of the VOMS in relation to components of the Sport Concussion Assessment Tool 3 (SCAT3). STUDY DESIGN Cohort study (diagnosis); Level of evidence, 3. METHODS Preseason and acute concussion assessments were analyzed for 419 student-athletes. Variables in the analysis included the VOMS, Balance Error Scoring System, Standardized Assessment of Concussion, and SCAT3 symptom evaluation score. Descriptive statistics were calculated for all tools, including Kolmogorov-Smirnov significance and Cohen d effect size. Correlations between tools were analyzed with Spearman r, and predictive accuracy was evaluated through an Ada Boosted Tree machine learning model's generated receiver operating characteristic curves. RESULTS Total VOMS scores and SCAT3 symptom scores demonstrated significant increases in the acute concussion time frame (Cohen d = 1.23 and 1.06; P < .0001), whereas the Balance Error Scoring System lacked clinical significance (Cohen d = 0.17). Incorporation of VOMS into the full SCAT3 significantly boosted overall diagnostic ability by 4.4% to an area under the curve of 0.848 (P < .0001) and produced a 9% improvement in test sensitivity over the existing SCAT3 battery. CONCLUSION The results from this study highlight the relevance of the vestibular and oculomotor systems to concussion and the utility of the VOMS tool. Given the 3.8 million sports-related and 45,121 military-related concussions per year, the addition of VOMS to the SCAT3 is poised to identify up to an additional 304,000 athletes and 3610 servicemembers annually who are concussed, thereby improving concussion assessment and diagnostic rates. Health care providers should consider the addition of VOMS to their concussion assessment toolkits, as its use can positively affect assessment and management of concussions, which may ultimately improve outcomes for this complex and common injury.
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Affiliation(s)
- Lyndsey M Ferris
- Indiana University School of Optometry, Bloomington, Indiana, USA
| | | | - Shawn R Eagle
- University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - R J Elbin
- University of Arkansas, Fayatteville, Arkansas, USA
| | | | - Anne Mucha
- UPMC Centers for Rehab Services, Pittsburgh, Pennsylvania, USA
| | | | - Nicholas L Port
- Indiana University School of Optometry, Bloomington, Indiana, USA
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Abstract
The relationship between gaze stability, retinal image quality, and visual perception is complex. Gaze instability related to pathology in adults can cause a reduction in visual acuity (e.g., Chung, LaFrance, & Bedell, 2011). Conversely, poor retinal image quality and spatial vision may be a contributing factor to gaze instability (e.g., Ukwade & Bedell, 1993). Though much is known about the immaturities in spatial vision of human infants, little is currently understood about their gaze stability. To characterize the gaze stability of young infants, adult participants and 4- to 10-week-old infants were shown a dynamic random-noise stimulus for 30-s intervals while their eye positions were recorded binocularly. After removing adultlike saccades, we used 5-s epochs of stable intersaccade gaze to estimate bivariate contour ellipse area and standard deviations of vergence. The geometric means (with standard deviations) for infants' bivariate contour ellipse area were left eye = -0.697 ± 0.534 log(°2), right eye = -0.471 ± 0.367 log(°2). For binocular vergence stability, the infant geometric means (with standard deviations) were horizontal = -1.057 ± 0.743 log(°), vertical = -1.257 ± 0.573 log(°). These values were all not significantly different from those of the adult comparison sample, suggesting that gaze instability is not a significant limiting factor in retinal image quality and spatial vision during early postnatal development.
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Affiliation(s)
| | - Nicholas L Port
- Indiana University School of Optometry, Bloomington, IN, USA
| | - T Rowan Candy
- Indiana University School of Optometry, Bloomington, IN, USA
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Kellar D, Newman S, Pestilli F, Cheng H, Port NL. Comparing fMRI activation during smooth pursuit eye movements among contact sport athletes, non-contact sport athletes, and non-athletes. Neuroimage Clin 2018. [PMID: 29541575 PMCID: PMC5849867 DOI: 10.1016/j.nicl.2018.01.025] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Objectives Though sub-concussive impacts are common during contact sports, there is little consensus whether repeat blows affect brain function. Using a "lifetime exposure" rather than acute exposure approach, we examined oculomotor performance and brain activation among collegiate football players and two control groups. Our analysis examined whether there are group differences in eye movement behavioral performance and in brain activation during smooth pursuit. Methods Data from 21 off-season Division I football "starters" were compared with a) 19 collegiate cross-country runners, and b) 11 non-athlete college students who were SES matched to the football player group (total N = 51). Visual smooth pursuit was performed while undergoing fMRI imaging via a 3 Tesla scanner. Smooth pursuit eye movements to three stimulus difficulty levels were measured with regard to RMS error, gain, and lag. Results No meaningful differences were found for any of the standard analyses used to assess smooth pursuit eye movements. For fMRI, greater activation was seen in the oculomotor region of the cerebellar vermis and areas of the FEF for football players as compared to either control group, who did not differ on any measure. Conclusion Greater cerebellar activity among football players while performing an oculomotor task could indicate that they are working harder to compensate for some subtle, long-term subconcussive deficits. Alternatively, top athletes in a sport requiring high visual motor skill could have more of their cerebellum and FEF devoted to oculomotor task performance regardless of subconcussive history. Overall, these results provide little firm support for an effect of accumulated subconcussion exposure on brain function.
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Affiliation(s)
- Derek Kellar
- Department of Psychological and Brain Sciences, Indiana University, 1101 E 10th St., Bloomington, IN, United States
| | - Sharlene Newman
- Department of Psychological and Brain Sciences, Indiana University, 1101 E 10th St., Bloomington, IN, United States
| | - Franco Pestilli
- Department of Psychological and Brain Sciences, Indiana University, 1101 E 10th St., Bloomington, IN, United States
| | - Hu Cheng
- Department of Psychological and Brain Sciences, Indiana University, 1101 E 10th St., Bloomington, IN, United States
| | - Nicholas L Port
- Department of Psychological and Brain Sciences, Indiana University, 1101 E 10th St., Bloomington, IN, United States.
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Port NL, Trimberger J, Hitzeman S, Redick B, Beckerman S. Micro and regular saccades across the lifespan during a visual search of "Where's Waldo" puzzles. Vision Res 2015; 118:144-57. [PMID: 26049037 DOI: 10.1016/j.visres.2015.05.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Revised: 05/01/2015] [Accepted: 05/18/2015] [Indexed: 11/30/2022]
Abstract
Despite the fact that different aspects of visual-motor control mature at different rates and aging is associated with declines in both sensory and motor function, little is known about the relationship between microsaccades and either development or aging. Using a sample of 343 individuals ranging in age from 4 to 66 and a task that has been shown to elicit a high frequency of microsaccades (solving Where's Waldo puzzles), we explored microsaccade frequency and kinematics (main sequence curves) as a function of age. Taking advantage of the large size of our dataset (183,893 saccades), we also address (a) the saccade amplitude limit at which video eye trackers are able to accurately measure microsaccades and (b) the degree and consistency of saccade kinematics at varying amplitudes and directions. Using a modification of the Engbert-Mergenthaler saccade detector, we found that even the smallest amplitude movements (0.25-0.5°) demonstrate basic saccade kinematics. With regard to development and aging, both microsaccade and regular saccade frequency exhibited a very small increase across the life span. Visual search ability, as per many other aspects of visual performance, exhibited a U-shaped function over the lifespan. Finally, both large horizontal and moderate vertical directional biases were detected for all saccade sizes.
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Affiliation(s)
- Nicholas L Port
- School of Optometry, Indiana University, 800 E Atwater Ave, Bloomington, IN 47405, United States; Program in Neuroscience, Department of Psychological and Brain Sciences, Cognitive Science Program, Indiana University, United States.
| | - Jane Trimberger
- School of Optometry, Indiana University, 800 E Atwater Ave, Bloomington, IN 47405, United States; Illinois College of Optometry, 3241 South Michigan Avenue, Chicago, IL 60616, United States
| | - Steve Hitzeman
- School of Optometry, Indiana University, 800 E Atwater Ave, Bloomington, IN 47405, United States
| | - Bryan Redick
- School of Optometry, Indiana University, 800 E Atwater Ave, Bloomington, IN 47405, United States
| | - Stephen Beckerman
- Illinois College of Optometry, 3241 South Michigan Avenue, Chicago, IL 60616, United States
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Abstract
The visual world presents multiple potential targets that can be brought to the fovea by saccadic eye movements. These targets produce activity at multiple sites on a movement map in the superior colliculus (SC), an area of the brain related to saccade generation. The saccade made must result from competition between the populations of neurons representing these many saccadic goals, and in the present experiments we used multiple moveable microelectrodes to follow this competition. We recorded simultaneously from two sites on the SC map where each site was related to a different saccade target. The two targets appeared in rapid sequence, and the monkey was rewarded for making a saccade toward the one appearing first. Our study concentrated on trials in which the monkey made strongly curved saccades that were directed first toward one target and then toward the other. These curved saccades activated both sites on the SC map as they veered from one target to the other. The major finding was that the strongly curved saccades were preceded by sequential activity in the two neurons as indicated by three observations: the firing rate for the neuron related to the first target reached its peak earlier than did the rate of the neuron for the second target; the timing of the peak activity of the two neurons was related to the beginning and end of the saccade curvature; a weighted vector-average model based on the activity of the two neurons predicted the timing of saccade curvature. Straight averaging saccades ended between the targets so that they did not go to either target, and they were accompanied by simultaneous rather than sequential activation of the two neurons. Thus when multiple populations of neurons are active on the SC movement map, the resulting saccade is determined by the relative timing of the activity in the populations as well as their magnitude. In contrast, SC activity at the two sites did not predict the final direction of the saccade, and several control experiments found insufficient activity at other sites on the SC map to account for that final direction. We conclude that the SC neuronal activity predicts the timing of the saccade curvature, but not the final direction of the trajectory. These observations are consistent with SC activity being critical in selecting the goal of the saccade, but not in determining the exact trajectory.
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Affiliation(s)
- Nicholas L Port
- Laboratory of Sensorimotor Research, National Eye Institute, National Institutes of Health, Bethesda, Maryland 20982-4435, USA.
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Abstract
Animals control contact with surfaces when locomoting, catching prey, etc. This requires sensorily guiding the rate of closure of gaps between effectors such as the hands, feet or jaws and destinations such as a ball, the ground and a prey. Control is generally rapid, reliable and robust, even with small nervous systems: the sensorimotor processes are therefore probably rather simple. We tested a hypothesis, based on general tau theory, that closing two gaps simultaneously, as required in many actions, might be achieved simply by keeping the taus of the gaps coupled in constant ratio. tau of a changing gap is defined as the time-to-closure of the gap at the current closure-rate. General tau theory shows that tau of a gap could, in principle, be directly sensed without needing to sense either the gap size or its rate of closure. In our experiment, subjects moved an effector (computer cursor) to a destination zone indicated on the computer monitor, to stop in the zone just as a moving target cursor reached it. The results indicated the subjects achieved the task by keeping tau of the gap between effector and target coupled to tau of the gap between the effector and the destination zone. Evidence of tau-coupling has also been found, for example, in bats guiding landing using echolocation. Thus, it appears that a sensorimotor process used by different species for coordinating the closure of two or more gaps between effectors and destinations entails constantly sensing the taus of the gaps and moving so as to keep the taus coupled in constant ratio.
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Affiliation(s)
- D N Lee
- Department of Psychology, University of Edinburgh, Scotland.
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Abstract
Abstract
Two rhesus monkeys were trained to intercept a moving target at a fixed location with a feedback cursor controlled bya 2-D manipulandum. The direction from which the target appeared, the time from the target onset to its arrival at the interception point, and the target acceleration were randomized for each trial, thus requiring the animal to adjust its movement according to the visual input on a trail-by-trail basis. The two animals adopted different strategies, similar to those identified previously in human subjects. Single-cell activity was recorded from the arm area of the primary motor cortex in these two animals, and the neurons were classified based on the temporal patterns in their activity, using a nonhierarchical cluster analysis. Results of this analysis revealed differences in the complexity and diversity of motor cortical activity between the two animals that paralleled those of behavioral strategies. Most clusters displayed activity closedly related to the kinematics of hand movements. In addition, some clusters displayed patterns of activation that conveyed additional information necessary for successful performance of the task, such as the initial target velocity and the interval between successive submovements, suggesting that such information is represented in selective subpopulations of neurons in the primary motor cortex. These results also suggest that conversion of information about target motion into movement-related signals takes place in a broad network of cortical areas including the primary motor cortex.
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Affiliation(s)
- D Lee
- Veteran Affairs Medical Center, Minneapolis, MN 55417, USA
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Abstract
Abstract
The single-unit activity of 831 cells was recorded in the arm area of the motor cortex of tow monkeys while the monkeys intercepted a moving visual stimulus (interception task) or remained immobile during presentation of the same moving stimulus (no-go task). The moving target traveled on an oblique path from either lower corner of a screen toward the vertical meridian, and its movement time (0.5,1.0, or 1.5 sec) and velocity profile (accelerating, decelerating, or constant velocity) were pseudorandomly varied. The moving target had to be intercepted within 130 msec of target arrival at an interception point. By comparing motor cortical activity at the single-neuron tasks, we tested whether information about parameters of moving target is represented in the primary motor cortex to generate appropriate motor responses. A substantial number of neurons displayed modulation of their activity during the no-go task, and this activity was often affected by the stimulus parameters. These results suggest a role of motor cortex in specifying the timing of movement initiation based on information about target motion. In addition, there was a lack of systematic relation between the onset times of neural activity in the interception and no-go task, suggesting that processing of information concerning target motion and generation of hand movement occurs in parallel. Finally, the activity in the most motor cortical neurons was modulated according to an estimate of the time-to-target interception, raising the possibility that time-to-interception may be coded in the motor cortical activity.
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Affiliation(s)
- N L Port
- Veterans Affairs Medical Center, Minneapolis, MN 55417, USA
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Abstract
The monkey superior colliculus (SC) has maps for both visual input and movement output in the superficial and intermediate layers, respectively, and activity on these maps is generally related to visual stimuli only in one part of the visual field and/or to a restricted range of saccadic eye movements to those stimuli. For some neurons within these maps, however, activity has been reported to spread from the caudal SC to the rostral SC during the course of a saccade. This spread of activity was inferred from averages of recordings at different sites on the SC movement map during saccades of different amplitudes and even in different monkeys. In the present experiments, SC activity was recorded simultaneously in pairs of neurons to observe the spread of activity during individual saccades. Two electrodes were positioned along the rostral-caudal axis of the SC with one being more caudal than the other, and 60 neuron pairs whose movement fields were large enough to see a spread of activity were studied. During individual saccades, the relative time of discharge of the two neurons was compared using 1) the time difference between peak discharge of the two neurons, 2) the difference between the "median activation time" of the two neurons, and 3) the shift required to align the two discharge patterns using cross-correlation. All three analysis methods gave comparable results. Many pairs of neurons were activated in sequence during saccade generation, and the order of activation was most frequently caudal to rostral. Such a sequence of activation was not observed in every neuron pair, but over the sample of neuron pairs studied, the spread was statistically significant. When we compared the time of neuronal activity to the time of saccade onset, we found that the caudal neuronal activity was more likely to be before the saccade, whereas the rostral neuronal activity was more likely to be during the saccade. These results demonstrate that when individual pairs of neurons are examined during single saccades there is evidence of a caudal to rostral spread of activity within the monkey SC, and they confirm the previous inferences of a spread of activity drawn from observations on averaged neuronal activity during multiple saccades. The functional contribution of this spread of activity remains to be determined.
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Affiliation(s)
- N L Port
- Laboratory of Sensorimotor Research, National Eye Institute, National Institutes of Health, Bethesda, Maryland 20982-4435, USA.
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Lee D, Port NL, Kruse W, Georgopoulos AP. Variability and correlated noise in the discharge of neurons in motor and parietal areas of the primate cortex. J Neurosci 1998; 18:1161-70. [PMID: 9437036 PMCID: PMC6792758] [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] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
We analyzed the magnitude and interneuronal correlation of the variability in the activity of single neurons that were recorded simultaneously using a multielectrode array in the primary motor cortex and parietal areas 2/5 in rhesus monkeys. The animals were trained to move their arms in one of eight directions as instructed by a visual target. The relationship between variability (SD) and mean of the discharge rate was described by a power function with a similar exponent ( approximately 0.57), regardless of the cortical area or the behavioral condition. We examined whether the deviation from mean activity between target onset and the end of the movement was correlated on a trial-by-trial basis with variability in activity during the hold period before target onset. In both cortical areas, for about a quarter of the neurons, the neuronal noise of these two periods was positively correlated, whereas significant negative correlations were seldom observed. Overall, neurons with higher signal correlation (i.e., similar directional pattern) showed higher noise correlation in both cortical areas. On the other hand, when the data were divided according to the distance between the electrode tips from which the neurons were recorded, a consistent relationship between the signal and noise correlations was found only for pairs of neurons recorded through the same electrode. These results suggest that nearby neurons with similar directional tuning carry primarily redundant messages, whereas neurons in separate cortical columns perform more independent processing.
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Affiliation(s)
- D Lee
- Brain Sciences Center, Veterans Administration Medical Center, Minneapolis, Minnesota 55417, USA
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Abstract
We studied the kinematic characteristics of arm movements and their relation to a stimulus moving with a wide range of velocity and acceleration. The target traveled at constant acceleration, constant deceleration, or constant velocity for 0.5-2.0 s, until it arrived at a location where it was required to be intercepted. For fast moving targets, subjects produced single movements with symmetrical, bell-shaped velocity profiles. In contrast, for slowly moving targets, hand velocity profiles displayed multiple peaks, which suggests a control mechanism that produces a series of discrete submovements according to characteristics of target motion. To analyze how temporal and spatial aspects of these submovements are influenced by target motion, we decomposed the vertical hand velocity profiles into bell-shaped velocity pulses according to the minimum-jerk model. The number of submovements was roughly proportional to the movement time, resulting in a relatively constant submovement frequency (approximately 2.5 Hz). On the other hand, the submovement onset asynchrony showed significantly more variability than the intersubmovement interval, indicating that the submovement onset was delayed more following a submovement with a longer duration. Examination of submovement amplitude and its relation to target motion revealed that the subjects achieved interception mainly by producing a series of submovements that would keep the displacement of the hand proportional to the first-order estimate of target position at the end of each submovement along the axis of hand movement. Finally, we did not find any evidence that information regarding target acceleration is properly utilized in the production of submovements.
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Affiliation(s)
- D Lee
- Brain Sciences Center (11B), Veterans Affairs Medical Center, Minneapolis, MN 55417, USA.
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Abstract
We investigated the capacities of human subjects to intercept moving targets in a two-dimensional (2D) space. Subjects were instructed to intercept moving targets on a computer screen using a cursor controlled by an articulated 2D manipulandum. A target was presented in 1 of 18 combinations of three acceleration types (constant acceleration, constant deceleration, and constant velocity) and six target motion times, from 0.5 to 2.0 s. First, subjects held the cursor in a start zone located at the bottom of the screen along the vertical meridian. After a pseudorandom hold period, the target appeared in the lower left or right corner of the screen and traveled at 45 degrees toward an interception zone located on the vertical meridian 12.5 cm above the start zone. For a trial to be considered successful, the subject's cursor had to enter the interception zone within 100 ms of the target's arrival at the center of the interception zone and stay inside a slightly larger hold zone. Trials in which the cursor arrived more than 100 ms before the target were classified as "early errors," whereas trials in which the cursor arrived more than 100 ms after the target were classified as "late errors." Given the criteria above, the task proved to be difficult for the subjects. Only 41.3% (1080 out of 2614) of the movements were successful, whereas the remaining 58.7% were temporal (i.e., early or late) errors. A large majority of the early errors occurred in trials with decelerating targets, and their percentage tended to increase with longer target motion times. In contrast, late errors occurred in relation to all three target acceleration types, and their percentage tended to decrease with longer target motion times. Three models of movement initiation were investigated. First, the threshold-distance model, originally proposed for optokinetic eye movements to constant-velocity visual stimuli, maintains that response time is composed of two parts, a constant processing time and the time required for the stimulus to travel a threshold distance. This model only partially fit our data. Second, the threshold-tau model, originally proposed as a strategy for movement initiation, assumes that the subject uses the first-order estimate of time-to-contact (tau) to determine when to initiate the interception movement. Similar to the threshold distance model, the threshold-tau model only partially fit the data. Finally, a dual-strategy model was developed which allowed for the adoption of either of the two strategies for movement initiation; namely, a strategy based on the threshold-distance model ("reactive" strategy) and another based on the threshold-tau model ("predictive" strategy). This model provided a good fit to the data. In fact, individual subjects preferred to use one or the other strategy. This preference was allowed to be manifested at long target motion times, whereas shorter target motion times (i.e., 0.5 s and 0.8 s) forced the subjects to use only the reactive strategy.
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Affiliation(s)
- N L Port
- Brain Sciences Center (11B), Veterans Affairs Medical Center, Minneapolis, MN 55417, USA.
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Kettner RE, Marcario JK, Port NL. Control of remembered reaching sequences in monkey. II. Storage and preparation before movement in motor and premotor cortex. Exp Brain Res 1996; 112:347-58. [PMID: 9007537 DOI: 10.1007/bf00227941] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Single-neuron responses in motor and premotor cortex were recorded during a movement-sequence delay task. On each trial the monkey viewed a randomly selected sequence of target lights arrayed in two-dimensional space, remembered the sequence during a delay period, and then generated a coordinated sequence of movements to the remembered targets. Of 307 neurons studied, 25% were tuned specifically for either the first or the second target, but not both. In particular, for neurons tuned during both target presentations, tuned activity related to a particular first target direction were maintained during the presentation of a second target in a different direction. During the delay period, 32% of the neurons were tuned for upcoming movement in a single direction. These delay period responses often reflected activity patterns that first developed during target presentations and may therefore act to maintain target period information during the delay. Neurons with tuned activity during both the delay and movement periods exhibited two patterns: the first exhibited tuned responses during the delay that were correlated with the tuning of first-movement responses, while the second pattern showed delay-period tuning that was better correlated with tuned responses during second movements. This indicates that, before movement, distinct neural populations are correlated with specific movements in a sequence. About half the neurons studied were not directionally tuned during the initiation, target, or delay periods, but did show systematic changes in activity during task performance. Some (34%) were exclusively tuned during movement and appear to be involved in the direct control of movement. Others (17%) showed changes in firing rate from period to period within a trial but showed no directional preference for a particular direction of movement. Population analyses of tuned activity during the target and delay periods indicated that accurate directional information about both first and second movements was available in the neuronal ensemble well before reaching began. These results extend the idea that both motor and premotor cortex play a role in reaching behavior other than the direct control of muscles. While some early neural responses resembled muscle activation patterns involved in maintaining fixed postures before movement, others probably relate to the sensory-to-motor transformations, information storage in short-term memory, and movement preparation required to generate accurate reaching to remembered locations in space.
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Affiliation(s)
- R E Kettner
- Northwestern University Medical School, Department of Physiology, Chicago, IL 60611, USA.
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Abstract
Human subjects were instructed to intercept with a cursor real and apparent motion targets presented on a computer screen. Targets traveled counterclockwise (CCW) in a circle at one of five angular velocities (180, 300, 420, 480 and 540 deg/s), either smoothly (real motion) or in path-guided apparent motion. Subjects operated a computer mouse and were instructed to intercept targets at the 12 o'clock position; there were no constraints on when to initiate the response, which was a movement from the center of the screen towards and past 12 o'clock. We found the following: (a) for both motion conditions and all target velocities, subjects were late in intercepting the target, especially at higher target velocities; (b) for both motion conditions, the directional variability of the response increased as a linear function of the target velocity; (c) the directional variability of the response was systematically higher for the apparent than the real motion condition; there was no significant interaction between target velocity and target motion type; (d) the response time did not vary significantly with velocity, but was consistently longer for apparent than real motion targets; (e) the movement time was very similar for different target velocities; and (f) the moment of initiation of the interception movement was delayed appreciably at higher target velocities, relative to that dictated for perfect interception at a given target velocity. This delay was greater for the apparent motion target. These results demonstrated the following: (a) for both target motion conditions, interception was not fully predictive but lagged the target in spite of the constant target velocity and the unconstrained time allowed for initiating the interception movement; (b) subjects can intercept an apparent motion target but, compared with real motion, the performance is somewhat degraded overall; (c) the similarities in performance between the two target motion conditions, and the fact that target velocity influenced performance in a similar fashion, suggest that the motor system can access the visual information provided by the moving target; and (d) since movement time was similar for different target velocities, the strategy for interception relied on controlling the moment of initiation of the interception movement. This was successful for low target velocities but became unsuccessful at higher target velocities.
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Affiliation(s)
- N L Port
- Brain Sciences Center, Veterans Affairs Medical Center, Minneapolis, MN 55417, USA.
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