1
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Seidler R, Tays G, Hupfeld K, McGregor H, Beltran N, de Dios Y, Mulder E, Bloomberg J, Mulavara A, Wood S. Daily Artificial Gravity Partially Mitigates Vestibular Processing Changes Associated with Head-down Tilt Bedrest. Res Sq 2023:rs.3.rs-3157785. [PMID: 37502989 PMCID: PMC10371135 DOI: 10.21203/rs.3.rs-3157785/v1] [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] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Microgravity alters vestibular signaling and reduces body loading, driving sensory reweighting and adaptation. The unloading effects can be modelled using head down tilt bedrest (HDT). Artificial gravity (AG) has been hypothesized to serve as an integrated countermeasure for the physiological declines associated with HDT and spaceflight. Here, we examined the efficacy of 30 minutes of daily AG to counteract brain and behavior changes that arise from 60 days of HDT. One group of participants received 30 minutes of AG daily (AG; n = 16) while in HDT, and another group served as controls, spending 60 days in HDT bedrest with no AG (CTRL; n = 8). We examined how HDT and AG affect vestibular processing by collecting fMRI scans from participants as they received vestibular stimulation. We collected these data prior to, during (2x), and post HDT. We assessed brain activation initially in 10 regions of interest (ROIs) and then conducted an exploratory whole brain analysis. The AG group showed no changes in brain activation during vestibular stimulation in a cerebellar ROI, whereas the CTRL group showed decreased cerebellar activation specific to the HDT phase. Additionally, those that received AG and showed little pre- to post-bed rest changes in left OP2 activation during HDT had better post-HDT balance performance. Exploratory whole brain analyses identified increased pre- to during-HDT activation in the CTRL group in the right precentral gyrus and the right inferior frontal gyrus specific to HDT, where the AG group maintained pre-HDT activation levels. Together, these results indicate that AG could mitigate brain activation changes in vestibular processing in a manner that is associated with better balance performance after HDT.
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2
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Noohi F, Kinnaird C, De Dios Y, Kofman IS, Wood SJ, Bloomberg J, Mulavara A, Sienko KH, Polk TA, Seidler RD. Age Differences in Vestibular Brain Connectivity Are Associated With Balance Performance. Front Aging Neurosci 2020; 12:566331. [PMID: 33312123 PMCID: PMC7703342 DOI: 10.3389/fnagi.2020.566331] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 10/27/2020] [Indexed: 11/26/2022] Open
Abstract
Visual and auditory brain network connectivity decline with age, but less is known about age effects on vestibular functional connectivity and its association with behavior. We assessed age differences in the connectivity of the vestibular cortex with other sensory brain regions, both during rest and during vestibular stimulation. We then assessed the relationship between vestibular connectivity and postural stability. A sample of seventeen young and fifteen older adults participated in our study. We assessed the amount of body sway in performing the Romberg balance task, with degraded somatosensory and visual inputs. The results showed no significant difference in balance performance between age groups. However, functional connectivity analyses revealed a main effect of age and condition, suggesting that vestibular connectivity was higher in young adults than older adults, and vestibular connectivity increased from resting state to stimulation trials. Surprisingly, young adults who exhibited higher connectivity during stimulation also had greater body sway. This suggests that young adults who exhibit better balance are those who respond more selectively to vestibular inputs. This correlation is non-significant in older adults, suggesting that the relationship between vestibular functional connectivity and postural stability differs with age.
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Affiliation(s)
- Fatemeh Noohi
- Department of Kinesiology, University of Michigan, Ann Arbor, MI, United States.,Department of Psychology, University of Michigan, Ann Arbor, MI, United States
| | - Catherine Kinnaird
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States
| | | | | | - Scott J Wood
- NASA Johnson Space Center, Houston, TX, United States
| | | | | | - Kathleen H Sienko
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States
| | - Thad A Polk
- Department of Psychology, University of Michigan, Ann Arbor, MI, United States
| | - Rachael D Seidler
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, United States
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3
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Yuan P, Koppelmans V, Reuter-Lorenz P, De Dios Y, Gadd N, Wood S, Riascos R, Kofman I, Bloomberg J, Mulavara A, Seidler R. Vestibular brain changes within 70 days of head down bed rest. Hum Brain Mapp 2018. [PMID: 29528169 DOI: 10.1002/hbm.24037] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Head-down-tilt bed rest (HDBR) is frequently utilized as a spaceflight analog research environment to study the effects of axial body unloading and fluid shifts that are associated with spaceflight in the absence of gravitational modifications. HDBR has been shown to result in balance changes, presumably due to sensory reweighting and adaptation processes. Here, we examined whether HDBR results in changes in the neural correlates of vestibular processing. Thirteen men participated in a 70-day HDBR intervention; we measured balance, functional mobility, and functional brain activity in response to vestibular stimulation at 7 time points before, during, and after HDBR. Vestibular stimulation was administered by means of skull taps, resulting in activation of the vestibular cortex and deactivation of the cerebellar, motor, and somatosensory cortices. Activation in the bilateral insular cortex, part of the vestibular network, gradually increased across the course of HDBR, suggesting an upregulation of vestibular inputs in response to the reduced somatosensory inputs experienced during bed rest. Furthermore, greater increase of activation in multiple frontal, parietal, and occipital regions in response to vestibular stimulation during HDBR was associated with greater decrements in balance and mobility from before to after HDBR, suggesting reduced neural efficiency. These findings shed light on neuroplastic changes occurring with conditions of altered sensory inputs, and reveal the potential for central vestibular-somatosensory convergence and reweighting with bed rest.
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Affiliation(s)
- Peng Yuan
- School of Kinesiology, University of Michigan, Ann Arbor, Michigan
| | | | | | - Yiri De Dios
- Wyle Science, Technology & Engineering Group, Houston, Texas
| | - Nichole Gadd
- Wyle Science, Technology & Engineering Group, Houston, Texas
| | - Scott Wood
- Department of Psychology, Azusa Pacific University, Azusa, California
| | - Roy Riascos
- The University of Texas Health Science Center, Houston, Texas
| | - Igor Kofman
- Wyle Science, Technology & Engineering Group, Houston, Texas
| | | | - Ajitkumar Mulavara
- NASA Johnson Space Center, Houston, Texas.,Universities Space Research Association, Houston, Texas
| | - Rachael Seidler
- School of Kinesiology, University of Michigan, Ann Arbor, Michigan.,Department of Applied Physiology & Kinesiology, University of Florida, Gainesville, Florida
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4
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Yuan P, Koppelmans V, Reuter-Lorenz P, De Dios Y, Gadd N, Riascos R, Kofman I, Bloomberg J, Mulavara A, Seidler RD. Change of cortical foot activation following 70 days of head-down bed rest. J Neurophysiol 2018; 119:2145-2152. [PMID: 29488843 DOI: 10.1152/jn.00693.2017] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Head-down tilt bed rest (HDBR) has been used as a spaceflight analog to study some of the effects of microgravity on human physiology, cognition, and sensorimotor functions. Previous studies have reported declines in balance control and functional mobility after spaceflight and HDBR. In this study we investigated how the brain activation for foot movement changed with HDBR. Eighteen healthy men participated in the current HDBR study. They were in a 6° head-down tilt position continuously for 70 days. Functional MRI scans were acquired to estimate brain activation for foot movement before, during, and after HDBR. Another 11 healthy men who did not undergo HDBR participated as control subjects and were scanned at four time points. In the HDBR subjects, the cerebellum, fusiform gyrus, hippocampus, and middle occipital gyrus exhibited HDBR-related increases in activation for foot tapping, whereas no HDBR-associated activation decreases were found. For the control subjects, activation for foot tapping decreased across sessions in a couple of cerebellar regions, whereas no activation increase with session was found. Furthermore, we observed that less HDBR-related decline in functional mobility and balance control was associated with greater pre-to-post HDBR increases in brain activation for foot movement in several cerebral and cerebellar regions. Our results suggest that more neural control is needed for foot movement as a result of HDBR. NEW & NOTEWORTHY Long-duration head-down bed rest serves as a spaceflight analog research environment. We show that brain activity in the cerebellum and visual areas during foot movement increases from pre- to post-bed rest and then shows subsequent recovery. Greater increases were seen for individuals who exhibited less decline in functional mobility and balance control, suggestive of adaptive changes in neural control with long-duration bed rest.
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Affiliation(s)
- Peng Yuan
- School of Kinesiology, University of Michigan , Ann Arbor, Michigan
| | - Vincent Koppelmans
- School of Kinesiology, University of Michigan , Ann Arbor, Michigan.,Department of Psychiatry, University of Utah , Salt Lake City, Utah
| | | | | | | | - Roy Riascos
- The University of Texas Health Science Center , Houston, Texas
| | | | | | | | - Rachael D Seidler
- School of Kinesiology, University of Michigan , Ann Arbor, Michigan.,Department of Applied Physiology & Kinesiology, University of Florida , Gainesville, Florida
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5
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Cassady K, Ruitenberg M, Koppelmans V, Reuter-Lorenz P, De Dios Y, Gadd N, Wood S, Riascos Castenada R, Kofman I, Bloomberg J, Mulavara A, Seidler R. Neural predictors of sensorimotor adaptation rate and savings. Hum Brain Mapp 2017; 39:1516-1531. [PMID: 29274105 DOI: 10.1002/hbm.23924] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [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: 08/29/2017] [Revised: 11/07/2017] [Accepted: 12/07/2017] [Indexed: 01/07/2023] Open
Abstract
In this study, we investigate whether individual variability in the rate of visuomotor adaptation and multiday savings is associated with differences in regional gray matter volume and resting-state functional connectivity. Thirty-four participants performed a manual adaptation task during two separate test sessions, on average 9 days apart. Functional connectivity strength between sensorimotor, dorsal cingulate, and temporoparietal regions of the brain was found to predict the rate of learning during the early phase of the adaptation task. In contrast, default mode network connectivity strength was found to predict both the rate of learning during the late adaptation phase and savings. As for structural predictors, greater gray matter volume in temporoparietal and occipital regions predicted faster early learning, whereas greater gray matter volume in superior posterior regions of the cerebellum predicted faster late learning. These findings suggest that the offline neural predictors of early adaptation may facilitate the cognitive aspects of sensorimotor adaptation, supported by the involvement of temporoparietal and cingulate networks. The offline neural predictors of late adaptation and savings, including the default mode network and the cerebellum, likely support the storage and modification of newly acquired sensorimotor representations.
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Affiliation(s)
- Kaitlin Cassady
- Department of Psychology, University of Michigan, Ann Arbor, Michigan
| | - Marit Ruitenberg
- School of Kinesiology, University of Michigan, Ann Arbor, MIichigan
| | | | | | - Yiri De Dios
- KBRwyle Science, Technology, and Engineering Group, Houston, Texas
| | - Nichole Gadd
- KBRwyle Science, Technology, and Engineering Group, Houston, Texas
| | - Scott Wood
- NASA Johnson Space Center, Houston, Texas
| | | | - Igor Kofman
- KBRwyle Science, Technology, and Engineering Group, Houston, Texas
| | | | | | - Rachael Seidler
- Department of Psychology, University of Michigan, Ann Arbor, Michigan.,School of Kinesiology, University of Michigan, Ann Arbor, MIichigan.,Neuroscience Graduate Program, University of Michigan, Ann Arbor, Michigan
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6
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Noohi F, Kinnaird C, DeDios Y, Kofman IS, Wood S, Bloomberg J, Mulavara A, Seidler R. Functional Brain Activation in Response to a Clinical Vestibular Test Correlates with Balance. Front Syst Neurosci 2017; 11:11. [PMID: 28344549 PMCID: PMC5344901 DOI: 10.3389/fnsys.2017.00011] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Accepted: 02/21/2017] [Indexed: 11/16/2022] Open
Abstract
The current study characterizes brain fMRI activation in response to two modes of vestibular stimulation: Skull tap and auditory tone burst. The auditory tone burst has been used in previous studies to elicit either a vestibulo-spinal reflex [saccular-mediated colic Vestibular Evoked Myogenic Potentials (cVEMP)], or an ocular muscle response [utricle-mediated ocular VEMP (oVEMP)]. Research suggests that the skull tap elicits both saccular and utricle-mediated VEMPs, while being faster and less irritating for subjects than the high decibel tones required to elicit VEMPs. However, it is not clear whether the skull tap and auditory tone burst elicit the same pattern of brain activity. Previous imaging studies have documented activity in the anterior and posterior insula, superior temporal gyrus, inferior parietal lobule, inferior frontal gyrus, and the anterior cingulate cortex in response to different modes of vestibular stimulation. Here we hypothesized that pneumatically powered skull taps would elicit a similar pattern of brain activity as shown in previous studies. Our results provide the first evidence of using pneumatically powered skull taps to elicit vestibular activity inside the MRI scanner. A conjunction analysis revealed that skull taps elicit overlapping activation with auditory tone bursts in the canonical vestibular cortical regions. Further, our postural control assessments revealed that greater amplitude of brain activation in response to vestibular stimulation was associated with better balance control for both techniques. Additionally, we found that skull taps elicit more robust vestibular activity compared to auditory tone bursts, with less reported aversive effects, highlighting the utility of this approach for future clinical and basic science research.
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Affiliation(s)
- Fatemeh Noohi
- School of Kinesiology, University of MichiganAnn Arbor, MI, USA; Department of Psychology, University of MichiganAnn Arbor, MI, USA
| | - Catherine Kinnaird
- Department of Mechanical Engineering, University of Michigan Ann Arbor, MI, USA
| | | | | | - Scott Wood
- NASA Johnson Space Center Houston, TX, USA
| | | | | | - Rachael Seidler
- School of Kinesiology, University of MichiganAnn Arbor, MI, USA; Department of Psychology, University of MichiganAnn Arbor, MI, USA
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7
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Hides J, Lambrecht G, Ramdharry G, Cusack R, Bloomberg J, Stokes M. Parallels between astronauts and terrestrial patients - Taking physiotherapy rehabilitation "To infinity and beyond". Musculoskelet Sci Pract 2017; 27 Suppl 1:S32-S37. [PMID: 28279266 DOI: 10.1016/j.msksp.2016.12.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [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] [Received: 08/15/2016] [Revised: 09/29/2016] [Accepted: 11/06/2016] [Indexed: 12/31/2022]
Abstract
Exposure to the microgravity environment induces physiological changes in the cardiovascular, musculoskeletal and sensorimotor systems in healthy astronauts. As space agencies prepare for extended duration missions, it is difficult to predict the extent of the effects that prolonged exposure to microgravity will have on astronauts. Prolonged bed rest is a model used by space agencies to simulate the effects of spaceflight on the human body, and bed rest studies have provided some insights into the effects of immobilisation and inactivity. Whilst microgravity exposure is confined to a relatively small population, on return to Earth, the physiological changes seen in astronauts parallel many changes routinely seen by physiotherapists on Earth in people with low back pain (LBP), muscle wasting diseases, exposure to prolonged bed rest, elite athletes and critically ill patients in intensive care. The medical operations team at the European Space Agency are currently involved in preparing astronauts for spaceflight, advising on exercises whilst astronauts are on the International Space Station, and reconditioning astronauts following their return. There are a number of parallels between this role and contemporary roles performed by physiotherapists working with elite athletes and muscle wasting conditions. This clinical commentary will draw parallels between changes which occur to the neuromuscular system in the absence of gravity and conditions which occur on Earth. Implications for physiotherapy management of astronauts and terrestrial patients will be discussed.
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Affiliation(s)
- Julie Hides
- Centre for Musculoskeletal Research, Mary MacKillop Institute for Health Research, Australian Catholic University, Brisbane 4102, Australia; Mater/ACU Back Stability Research Clinic, Mater Health Services, South Brisbane, QLD 4101, Australia.
| | - Gunda Lambrecht
- European Space Agency Space-Medicine Office, European Astronaut Centre, Linder Hoehe, 51147 Cologne, Germany; Germany Praxis fur Physiotherapie und Osteopathische Techniken, Kaiserstrasse 34, 53721 Siegburg, Germany
| | - Gita Ramdharry
- Faculty of Health, Social Science and Education, Kingston University/St George's University of London, London SW17 0RE, UK
| | - Rebecca Cusack
- Critical Care Research Area, Southampton NIHR Respiratory Biomedical Research Unit, University Hospital NHS Foundation Trust, Southampton SO16 6YD, UK; Integrative Physiology and Critical Illness Group, Faculty of Medicine, University of Southampton, UK
| | - Jacob Bloomberg
- Neuroscience Laboratories, NASA/Johnson Space Center, Houston, TX, USA
| | - Maria Stokes
- Faculty of Health Sciences, University of Southampton Highfield Campus, Southampton, SO17 1BJ, UK; Arthritis Research UK Centre for Sport, Exercise and Osteoarthritis, UK
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8
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Cassady K, Koppelmans V, Reuter-Lorenz P, De Dios Y, Gadd N, Wood S, Castenada RR, Kofman I, Bloomberg J, Mulavara A, Seidler R. Effects of a spaceflight analog environment on brain connectivity and behavior. Neuroimage 2016; 141:18-30. [DOI: 10.1016/j.neuroimage.2016.07.029] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Revised: 06/22/2016] [Accepted: 07/12/2016] [Indexed: 01/25/2023] Open
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9
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English KL, Mulavara A, Bloomberg J, Ploutz-Snyder LL. Calf Strength Loss during Mechanical Unloading. Med Sci Sports Exerc 2016. [DOI: 10.1249/01.mss.0000486733.01498.8d] [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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10
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Bloomberg J, Jones GM, Segal B, McFarlane S, Soul J. Vestibular-contingent voluntary saccades based on cognitive estimates of remembered vestibular information. Adv Otorhinolaryngol 2015; 41:71-5. [PMID: 3265009 DOI: 10.1159/000416034] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- J Bloomberg
- Department of Physiology, McGill University, Montréal, Qué., Canada
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11
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Streeper T, Cavanagh PR, Hanson A, Carpenter RD, Saeed I, Kornak J, Frassetto L, Grodsinsky C, Funk J, Lee SM, Spiering B, Bloomberg J, Mulavara AP, Sibonga J, Lang T. Development Of An Integrated Countermeasure Device For Use In Long-duration Space Flight. Med Sci Sports Exerc 2011. [DOI: 10.1249/01.mss.0000402286.94289.35] [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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12
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Ploutz‐Snyder L, Ryder J, Buxton R, Redd E, Scott‐Pandorf M, Hackney K, Fiedler J, Ploutz‐Snyder R, Bloomberg J. Novel analog for muscle deconditioning. FASEB J 2011. [DOI: 10.1096/fasebj.25.1_supplement.668.8] [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)
- Lori Ploutz‐Snyder
- Exercise Physiology and CountermeasuresUniversities Space Research AssociationhoustonTX
| | - Jeff Ryder
- Exercise Physiology and CountermeasuresUniversities Space Research AssociationhoustonTX
| | - Roxanne Buxton
- Exercise Physiology and CountermeasuresUniversity of HoustonhoustonTX
| | - Elizabeth Redd
- Exercise Physiology and CountermeasuresUniversity of HoustonhoustonTX
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Brady R, Batson C, Peters B, Mulavara A, Bloomberg J. 154 SENSORY BIAS PREDICTS POSTURAL STABILITY, ANXIETY, AND COGNITIVE PERFORMANCE IN HEALTHY ADULTS WALKING IN NOVEL DISCORDANT CONDITIONS. Parkinsonism Relat Disord 2010. [DOI: 10.1016/s1353-8020(10)70155-3] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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14
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Batson C, Brady R, Peters B, Mulavara A, Bloomberg J. 216 GAIT TRAINING IMPROVES PERFORMANCE IN HEALTHY ADULTS EXPOSED TO NOVEL DISCORDANT CONDITIONS. Parkinsonism Relat Disord 2010. [DOI: 10.1016/s1353-8020(10)70217-0] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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15
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Mohamed N, Bloomberg J. Molecular Diagnosis of Common Viral Infectious Diseases Based on Real Time PCR. Int J Infect Dis 2008. [DOI: 10.1016/j.ijid.2008.05.1338] [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: 10/21/2022] Open
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16
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Rogers HL, Cromwell RL, Grady J, Weaver G, Layne C, Bloomberg J. ADAPTIVE BALANCE STRATEGIES EXHIBITED DURING GAIT BY OLDER AND YOUNGER ADULTS IN RESPONSE TO SENSORY CHALLENGES TO DYNAMIC BALANCE. J Geriatr Phys Ther 2006. [DOI: 10.1519/00139143-200612000-00038] [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: 11/08/2022]
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Abstract
The purpose of this study was to determine the accuracy, repeatability and resolution of a six-camera Motion Analysis system in a vertical split-volume configuration using a unique quasi-static methodology. The position of a reflective marker was recorded while it was moved quasi-statically over a range of 2.54 mm (0.100 inches) via a linearly-translating table. The table was placed at five different heights to cover both sub-volumes and the overlapping region. Data analysis showed that accuracy, repeatability and resolution values were consistent across all regions of the split-volume, including the overlapping section.
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Affiliation(s)
- Chris Miller
- Neurosciences Laboratories, Wyle Laboratories, Mail Code NL/37, 1290 Hercules Dr. Suite 120, Houston, TX 77058, USA.
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18
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Abstract
We investigated how sensorimotor adaptation acquired during one experimental session influenced the adaptation in a subsequent session. The subjects' task was to track a visual target using a joystick-controlled cursor, while the relationship between joystick and cursor position was manipulated to introduce a sensorimotor discordance. Each subject participated in two sessions, separated by a pause of 2 min to 1 month duration. We found that adaptation was achieved within minutes, and persisted in the memory for at least a month, with only a small decay (experiment A). When the discordances administered in the two sessions were in mutual conflict, we found evidence for task interference (experiment B). However, when the discordances were independent, we found facilitation rather than interference (experiment C); the latter finding could not be explained by the use of an "easier" discordance in the second session (experiment D). We conclude that interference is due to an incompatibility between task requirements, and not to a competition of tasks for short-term memory. We further conclude that the ability to adapt to a sensorimotor discordance can be improved by practicing with an unrelated discordance.
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Affiliation(s)
- O Bock
- Institute of Physiology, German Sport University, 50927 Köln, Germany.
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19
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Affiliation(s)
- L A Squires
- Department of Child Neurology, Massachusetts General Hospital, Harvard Medical School, Boston
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20
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Abstract
Ethical issues in child and adolescent psychiatry consultation arise frequently but seldom are discussed in a public setting. This case of an adolescent victim of a surgical accident illustrates many aspects of consultation psychiatry. The consult question itself, of behavior management, is not unusual, although in this case the question is complicated by the sequelae of trauma, psychosocial chaos, and the staff's angry feelings toward the patient. In addition, potential surgical wrongdoing at the referring hospital brings up the more difficult ethical questions of the consultant's responsibilities, which must be to the patient and his family, as well as to the attending and referring physicians.
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Affiliation(s)
- J Bloomberg
- Department of Child Psychiatry, Massachusetts General Hospital, Boston 02114
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21
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Abstract
Results from Bloomberg et al. (1991) led to the hypothesis that saccades which accompany the dark-tested vestibulo-ocular reflex (VOR) tend to move the eyes towards a vestibularly derived percept of an intended oculomotor goal: also that this is so even when that percept has been adaptively modified by suitably prolonged visual-vestibular conflict. The present experiments investigate these implications by comparing the combined VOR + saccade performance with a presumed "motor readout" of the normal and adaptively modified vestibular percept. The methods employed were similar to those of an earlier study Bloomberg et al. (1988) in which it was found that after cessation of a brief passive whole body rotation in the dark, a previously seen earth-fixed target can be accurately located by saccadic eye movements based on a vestibular memory of the preceding head rotation; the so-called "Vestibular Memory-Contingent Saccade" (VMCS) paradigm. The results showed that the vestibular perceptual response, as measured after rotation by means of the VMCS paradigm, was on average indistinguishable from the combined VOR + saccade response measured during rotation. Furthermore, this was so in both the normal and adapted states. We conclude that these findings substantiate the above hypothesis. The results incidentally reaffirm the adaptive modifiability of vestibular perception, emphasing the need for active maintenance of its proper calibration according to behavioural context.
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Affiliation(s)
- J Bloomberg
- Department of Physiology, McGill University, Montréal, Québec, Canada
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22
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Abstract
When a normal human subject is briefly turned in total darkness while trying to "look" at a spatially fixed target, the vestibulo-ocular reflex (VOR) produces slow-phase compensatory eye movements tending to hold the eyes on target. However, slow-phase compensation per se is generally inadequate in these circumstances. Nevertheless it has recently been found, that even in the dark, this inadequacy tends to be corrected by supplementary saccades usually acting in the compensatory direction. The present study further investigates this phenomenon by measuring the respective contributions of saccadic, slow-phase and overall net compensation in 9 subjects tested before and after 30% adaptive attenuation of VOR slow-phase gain. In each test series, subjects attempted to stabilize their gaze on a previously seen target during each of 40 brief (approximately 0.5 s) whole body rotations (40 degrees/s, 20 degrees amp) conducted in complete darkness. The adaptive experience comprised 2 h of full-field visual suppression of the VOR during sinusoidal rotation of subject and surround at 1/6 Hz and 40 degrees/s velocity amplitude. Before adaptation, the cumulative slow-phase and cumulative saccadic components produced on average 78% and 14% respectively of the ideal (100%) compensation, thus yielding an overall net compensation which was 92% of the desired value. After adaptation, the corresponding values in the same population were 53%, 18% and 71% respectively. Thus after adaptation, the combined saccadic-slow-phase response brought the final gaze position to a point in space that was systematically shifted in the direction of head rotation (i.e. undercompensation). Subjects re-exposed to 30 min of normal visual-vestibular interaction displayed a variety of recovery patterns using different combinations of slow and saccadic eye movements. However, there was a consistent "synergistic" tendency for saccadic eye movements to improve slow-phase performance, regardless of the subject's adaptive state. In one subject, compensatory saccadic eye movements corrected a consistent directional asymmetry in the slow-phase response. It is suggested that a conscious vestibular percept of self-rotation might underlie the combined saccadic-slow-phase response, and that the net under performance after adaptation might reflect attenuation of this percept relative to the actual rotational stimulus.
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Affiliation(s)
- J Bloomberg
- Department of Physiology, McGill University, Montréal, Quebéc, Canada
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Tropper J, Jones GM, Bloomberg J, Fadlallah H. Vestibular perceptual deficits in patients with parietal lobe lesions. A preliminary study. Acta Otolaryngol Suppl 1991; 481:528-33. [PMID: 1927462 DOI: 10.3109/00016489109131463] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- J Tropper
- Faculty of Medicine, Montreal Neurological Hospital, Canada
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Melvill Jones G, Segal B, Bloomberg J. The “cognitive connection” with reflex motor control: observations and speculations. J Neurosci Methods 1986. [DOI: 10.1016/0165-0270(86)90094-4] [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: 10/27/2022]
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