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Sample records for bildgebung vor minimalinvasiver

  1. Keine Panik vor Statistik!

    NASA Astrophysics Data System (ADS)

    Oestreich, Markus; Romberg, Oliver

    Die Statistik - unendliche Fragen. Sternzeit 0511;22: Wir schreiben das Jahr mit J wie "Juhu!", denn dies sind die Abenteuer der Doktorissimi Oestreich und Romberg, die mit Ihrem zusammen 281 Punkte zählenden IQ zwei Jahre lang unterwegs waren, um neue Statistik-Darstellungen zu erforschen, neue Formulierungen und neue Applikationen. Viele Lichtjahre von der faden Theorie entfernt, dringen die Autoren dabei in Galaxien vor, die nie ein Mensch zuvor so gesehen hat.

  2. Keine Panik vor Statistik!

    NASA Astrophysics Data System (ADS)

    Oestreich, Markus; Romberg, Oliver

    Die Statistik - unendliche Fragen. Sternzeit 0511,22: Wir schreiben das Jahr mit J wie "Juhu!" denn dies sind die Abenteuer der Doktorissimi Oestreich und Romberg, die mit Ihrem zusammen 28 Punkte zählenden IQ zwei Jahre lang unterwegs waren, um neue Statistik-Darstellungen zu erforschen, neue Formulierungen und neue Applikationen. Viele Lichtjahre von der faden Theorie entfernt, dringen die Autoren dabei in Phantasien vor, die nie ein Mensch zuvor so gehabt hat. Willkommen an Bord!

  3. VOR area navigation - Techniques and results

    NASA Technical Reports Server (NTRS)

    Ragsdale, W. A.

    1982-01-01

    Several methods for deriving position from VOR (without DME) have been developed and evaluated in this study. These methods permit navigation to arbitrary waypoints using either two VOR's or one VOR and a clock. These algorithms have been tested in computer simulations and in flight tests. The single VOR method appears to be the most practical and is a candidate for an automated light plane area navigation system, called VORNAV.

  4. Evaluation of the torsional VOR in weightlessness.

    PubMed

    Clarke, A H; Teiwes, W; Scherer, H

    1993-01-01

    The experimental concept and findings from a recent manned orbital spaceflight are described. Together with ongoing terrestrial and parabolic studies, the present experiment is intended to further our knowledge of the sensory integrative processing of information from the semicircular canals and the otolithic receptors, and to quantify the presumed otolithic adaptation to altered gravito-inertial force environments in a more reliable manner than to date. The experiment included measurement of the basic vestibulo-oculomotor response during active head rotation about each of the three orthogonal axes. Priority was given to the recording of ocular torsion, as elicited by head oscillation about the roll axis, and thus due to the concomitant stimulation of the semicircular canals and otolith receptors. Videooculography was employed for the measurement of eye movements; head movement was measured by three orthogonally arranged angular rate sensors and a triaxial linear accelerometer device. All signals were recorded synchronously on a video/data recorder. Preliminary results indicate alterations in the torsional VOR under zero-g conditions, suggesting an adaptive modification of the torsional VOR gain over the course of the 6-day orbital flight. In addition, the inflight test findings yielded discrepancies between intended and performed head movement, indicating impairment in sensorimotor coordination under prolonged microgravity conditions.

  5. 77 FR 64444 - VOR Federal Airway V-595; Oregon

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-22

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF TRANSPORTATION Federal Aviation Administration 14 CFR Part 71 RIN 2120-AA66 VOR Federal Airway V-595; Oregon AGENCY... action proposes to modify VHF omnidirectional range (VOR) Federal airway V-595 in Oregon. The FAA...

  6. Adaptation of VOR to Coriolis stimulation.

    PubMed

    Adenot, Sophie; Jarchow, Thomas; Young, Laurence R

    2005-04-01

    The vestibulo-ocular reflex (VOR) is normally characterized by the gain and phase of slow-phase velocity (SPV) relative to the stimulus velocity. Although this is perfectly satisfactory for steady-state sinusoidal oscillations about a single axis, it is less useful when applied to transient responses. The well-known decay of nystagmus following a step change of head velocity approximately follows a double exponential, with an initial amplitude (A), a long time constant (tau), and an adaptation time constant (tau(a)). We have developed a means of representing the transient response for a complex head velocity stimulus as experienced during high-speed artificial gravity (AG) experiments. When a subject, lying supine on a rotating horizontal platform, makes a yaw head movement of amplitude theta, the vertical semicircular canals experience a step in angular velocity. The pitch stimulus is equal to the change in the component of the centrifuge angular velocity (omega(c)) aligned with the interaural axis, and gives rise to a vertical VOR. The magnitude of the step change is omega(c) sin theta. The SPV is approximated by an exponential decay of amplitude A and single time constant tau, and then normalized relative to this stimulus step. MATLAB scripts filter the raw eye position data to remove noise, blinks, and saccades, differentiate the signal, and remove fast phases to obtain SPV. The amplitude of the fitted SPV exponential is divided by omega(c) sin theta to obtain the normalized SPV. A and tau are shown to behave differently as subjects adapt to repeated head movements of different amplitudes.

  7. 78 FR 41686 - Modification of VOR Federal Airway V-345 in the Vicinity of Ashland, WI

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-11

    ... Ashland, WI. The Ashland, WI, VOR Distance Measuring Equipment (VOR/DME) navigation aid, which forms the.../DME. DATES: Effective date 0901 UTC, October 17, 2013. The Director of the Federal Register approves... the Ashland, WI, VOR/DME. This action removes the airway segment between the Hayward, WI, VOR/DME...

  8. VHF Omnidirectional Radio Range (VOR) Electromagnetic Spectrum Measurements.

    DTIC Science & Technology

    1978-10-18

    EFFECTS IN SPECTRUM DISPLAYS 9-25 9.4 DOPPLER VOR ( DVOR ) 9-27 9.4.1 DVOR SPECTRUMS 9-28 9.4.2 DVOR SPECTRUM COMPONENT AMPLITUDES AS A FUNCTION OF...SPECTRUM ANALYZER BW 9-30 I 9.4.3 DIFFERENCES IN DVOR MODULATION PRODUCT AMPLITUDE ROLL-OFFS AT VARIOUS FACILITIES 9-32 9.4.4 SWITCHING TRANSIENTS 9-32 9.5...OF VOR AND DVOR EMISSIONS 9-40 9.7 IMPORTANCE OF RADIATED SPECTRUM MEASUREMENTS FOR ANALYTICAL AND ADJUSTMENT PURPOSES TO ASSIST INSTALLATION

  9. 77 FR 71493 - Amendment of VOR Federal Airway V-8 in the Vicinity of Rifle, CO

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-03

    ... amendment. SUMMARY: This action amends VHF Omnidirectional Range (VOR) Federal Airway V-8 in the vicinity of... realigned over the Rifle, CO, VHF Omnidirectional Range/Distance Measuring Equipment (VOR/DME)...

  10. 76 FR 82114 - Amendment of VOR Federal Airways V-320 and V-440; Alaska

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-30

    ... Federal Aviation Administration 14 CFR Part 71 RIN 2120-AA66 Amendment of VOR Federal Airways V-320 and V... action amends two VHF Omnidirectional Range (VOR) Federal airways in Alaska, V-320 and V-440, due to the... proposed rulemaking to amend VOR Federal airways V-320 and V-440 in Alaska, due to the relocation of...

  11. 77 FR 62468 - Proposed Amendment of VOR Federal Airway V-537, GA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-15

    ... to the scheduled decommissioning of the Moultrie, GA, VOR/DME facility which forms a point along the..., GA, VOR/DME, which forms a point along the route, is scheduled to be decommissioned, thus the route... would redefine the position of the Moultrie, GA, VOR/DME with a navigation fix formed by...

  12. Updating inertial navigation systems with VOR/DME information.

    NASA Technical Reports Server (NTRS)

    Bobick, J. C.; Bryson, A. E., Jr.

    1972-01-01

    Demonstration that updating an inertial navigation system (INS) with VOR/DME information (from one or two stations) by means of a maximum-likelihood filter results in substantial improvements in navigational accuracy over that obtained by the use of a single VOR/DME (current practice). When continuously updating, the use of a high-quality INS (0.01 deg/hr gyro drift) instead of a low-quality INS (1.0 deg/hr gyro drift) does not substantially improve position accuracy. In-flight alignment (or realignment) of an INS to an accuracy comparable to that of ground alignment can be accomplished by using two DMEs. Several reduced-order suboptimal filters were found to perform nearly optimally.

  13. Updating inertial navigation systems with VOR/DME information.

    NASA Technical Reports Server (NTRS)

    Bobick, J. C.; Bryson, A. E., Jr.

    1972-01-01

    Demonstration that updating an inertial navigation system (INS) with VOR/DME information (from one or two stations) by means of a maximum-likelihood filter results in substantial improvements in navigational accuracy over that obtained by the use of a single VOR/DME (current practice). When continuously updating, the use of a high-quality INS (0.01 deg/hr gyro drift) instead of a low-quality INS (1.0 deg/hr gyro drift) does not substantially improve position accuracy. In-flight alignment (or realignment) of an INS to an accuracy comparable to that of ground alignment can be accomplished by using two DMEs. Several reduced-order suboptimal filters were found to perform nearly optimally.

  14. Vertical and torsional VOR in posterior canal occlusion.

    PubMed

    Kanayama, R; Bronstein, A M; Gresty, M A; Brookes, G B

    1995-01-01

    The vertical and torsional vestibulo-ocular reflexes (VOR) were investigated in 3 patients with surgical occlusion of the posterior semicircular canal and 1 patient with singular neurectomy, for treatment of refractory paroxysmal positional vertigo. Stimuli comprised sinusoidal oscillation in the coronal ("roll") and sagittal ("pitch") plane as well as in two oblique planes intermediate between pitch in order to stimulate left anterior + right posterior (LARP) and right anterior + left posterior (RALP) canal pairs separately. One case with left side BPPV was investigated pre and post-operatively. Depression of the vertical and torsional VOR gain was seen 1 week postoperatively when the occluded canal was placed in the optimal plane for stimulation at 1 week postoperatively and subsequently gradually recovered. Recordings in other planes suggested that the contralateral posterior canal was also hypofunctioning, a finding which may explain some residual gait unsteadiness in this case. The other 3 cases who were investigated postoperatively all showed a decrease in downward VOR gain in the "on' direction of the operated canal. The data indicate the specificity of the test procedure and underline the prognostic value of comprehensive pre-operative vestibular assessment.

  15. VOR Gain Is Related to Compensatory Saccades in Healthy Older Adults.

    PubMed

    Anson, Eric R; Bigelow, Robin T; Carey, John P; Xue, Qian-Li; Studenski, Stephanie; Schubert, Michael C; Agrawal, Yuri

    2016-01-01

    Vestibulo-ocular reflex (VOR) gain is well-suited for identifying rotational vestibular dysfunction, but may miss partial progressive decline in age-related vestibular function. Since compensatory saccades might provide an alternative method for identifying subtle vestibular decline, we describe the relationship between VOR gain and compensatory saccades in healthy older adults. Horizontal VOR gain was measured in 243 subjects age 60 and older from the Baltimore Longitudinal Study of Aging using video head impulse testing (HIT). Saccades in each HIT were identified as either "compensatory" or "compensatory back-up," i.e., same or opposite direction as the VOR response respectively. Saccades were also classified as "covert" (occurring during head movement) and "overt" (occurring after head movement). The relationship between VOR gain and percentage of HITs with saccades, as well as the relationship between VOR gain and saccade latency and amplitude, were evaluated using regression analyses adjusting for age, gender, and race. In adjusted analyses, the percentage of HITs with compensatory saccades increased 4.5% for every 0.1 decrease in VOR gain (p < 0.0001). Overt compensatory saccade amplitude decreased 0.6° (p < 0.005) and latency increased 90 ms (p < 0.001) for every 0.1 increase in VOR gain. Covert back-up compensatory saccade amplitude increased 0.4° for every 0.1 increase in VOR gain. We observed significant relationships between VOR gain and compensatory saccades in healthy older adults. Lower VOR gain was associated with larger amplitude, shorter latency compensatory saccades. Compensatory saccades reflect underlying rotational vestibular hypofunction, and may be particularly useful at identifying partial vestibular deficits as occur in aging adults.

  16. VOR Gain Is Related to Compensatory Saccades in Healthy Older Adults

    PubMed Central

    Anson, Eric R.; Bigelow, Robin T.; Carey, John P.; Xue, Qian-Li; Studenski, Stephanie; Schubert, Michael C.; Agrawal, Yuri

    2016-01-01

    Objective: Vestibulo-ocular reflex (VOR) gain is well-suited for identifying rotational vestibular dysfunction, but may miss partial progressive decline in age-related vestibular function. Since compensatory saccades might provide an alternative method for identifying subtle vestibular decline, we describe the relationship between VOR gain and compensatory saccades in healthy older adults. Methods: Horizontal VOR gain was measured in 243 subjects age 60 and older from the Baltimore Longitudinal Study of Aging using video head impulse testing (HIT). Saccades in each HIT were identified as either “compensatory” or “compensatory back-up,” i.e., same or opposite direction as the VOR response respectively. Saccades were also classified as “covert” (occurring during head movement) and “overt” (occurring after head movement). The relationship between VOR gain and percentage of HITs with saccades, as well as the relationship between VOR gain and saccade latency and amplitude, were evaluated using regression analyses adjusting for age, gender, and race. Results: In adjusted analyses, the percentage of HITs with compensatory saccades increased 4.5% for every 0.1 decrease in VOR gain (p < 0.0001). Overt compensatory saccade amplitude decreased 0.6° (p < 0.005) and latency increased 90 ms (p < 0.001) for every 0.1 increase in VOR gain. Covert back-up compensatory saccade amplitude increased 0.4° for every 0.1 increase in VOR gain. Conclusion: We observed significant relationships between VOR gain and compensatory saccades in healthy older adults. Lower VOR gain was associated with larger amplitude, shorter latency compensatory saccades. Compensatory saccades reflect underlying rotational vestibular hypofunction, and may be particularly useful at identifying partial vestibular deficits as occur in aging adults. PMID:27445793

  17. 14 CFR 91.171 - VOR equipment check for IFR operations.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false VOR equipment check for IFR operations. 91... (CONTINUED) AIR TRAFFIC AND GENERAL OPERATING RULES GENERAL OPERATING AND FLIGHT RULES Flight Rules Instrument Flight Rules § 91.171 VOR equipment check for IFR operations. (a) No person may operate a...

  18. 78 FR 18232 - Amendment of VOR Federal Airway V-233, Springfield, IL

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-26

    ... Federal Aviation Administration 14 CFR Part 71 RIN 2120-AA66 Amendment of VOR Federal Airway V-233.... SUMMARY: This action amends VHF Omnidirectional Range (VOR) Federal Airway V-233 in the vicinity of Springfield, IL. The FAA is taking this action to correct the V-233 description contained in Part 71 to...

  19. 77 FR 26160 - Modification of VOR Federal Airway V-14; Missouri

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-03

    ... Federal Aviation Administration 14 CFR Part 71 Modification of VOR Federal Airway V-14; Missouri AGENCY... amends VOR Federal airway V-14 in the vicinity of St. Louis, MO. The FAA is taking this action to correct the V-14 description contained in Part 71 to ensure it matches the information contained in the...

  20. 76 FR 68674 - Proposed Amendment of VOR Federal Airways V-320 and V-440; Alaska

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-07

    ... Federal Airways V-320 and V-440; Alaska AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice... (VOR) Federal airways in Alaska, V-320 and V-440, due to the relocation of the Anchorage VOR navigation... that V-320 and V-440 did not have satisfactory signal reception coverage in the vicinity of...

  1. Effect of Spaceflight on Vestibulo-Ocular Reflexes (VORS) During Angular Head Motion

    NASA Technical Reports Server (NTRS)

    Tomko, David L.; Clifford, James O.; Hargens, Alan R. (Technical Monitor)

    1996-01-01

    Vestibulo-ocular reflexes (VORs) stabilize the eyes during head motion. During Earth-horizontal (E-H) pitch or roll rotations, canal and otolith stimuli occur together. In Earth-vertical (E-V) pitch or roll rotations, only canal signals occur. In cats and squirrel monkeys, pitch/roll VOR gains during E-H motion have been shown to be larger than during E-V motion, implying that otolith modulation plays a role in producing angular VORs (aVORs). The present experiments replicated this experiment in rhesus monkeys, and examined how spaceflight affected AVOR gain. During yaw, pitch and roll (0.5 - 1.0 Hz, 40-50 deg/s pk) motion, 3-d eye movements were recorded in four Rhesus monkeys using scleral search coils. Mean E-H and E-V pitch VOR gains were 0.85 and 0.71. Torsional VOR gains during E-H and E-V were 0.47 and 0.39. Gains are more compensatory during E-H pitch or roll. Two of the four monkeys flew for 11 days on the COSMOS 2229 Biosatellite. E-H pitch VOR gains were attenuated immediately (72 hrs) post-flight, with similar values to pre-flight E-V pitch gains. Horizontal yaw VOR gains were similar pre- and post-flight.

  2. 14 CFR 71.15 - Designation of jet routes and VOR Federal airways.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 2 2011-01-01 2011-01-01 false Designation of jet routes and VOR Federal airways. 71.15 Section 71.15 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF... ROUTES; AND REPORTING POINTS § 71.15 Designation of jet routes and VOR Federal airways. Unless otherwise...

  3. 14 CFR 71.15 - Designation of jet routes and VOR Federal airways.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Designation of jet routes and VOR Federal airways. 71.15 Section 71.15 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF... ROUTES; AND REPORTING POINTS § 71.15 Designation of jet routes and VOR Federal airways. Unless otherwise...

  4. Effect of Spaceflight on Vestibulo-Ocular Reflexes (VORS) During Angular Head Motion

    NASA Technical Reports Server (NTRS)

    Tomko, David L.; Clifford, James O.; Hargens, Alan R. (Technical Monitor)

    1996-01-01

    Vestibulo-ocular reflexes (VORs) stabilize the eyes during head motion. During Earth-horizontal (E-H) pitch or roll rotations, canal and otolith stimuli occur together. In Earth-vertical (E-V) pitch or roll rotations, only canal signals occur. In cats and squirrel monkeys, pitch/roll VOR gains during E-H motion have been shown to be larger than during E-V motion, implying that otolith modulation plays a role in producing angular VORs (aVORs). The present experiments replicated this experiment in rhesus monkeys, and examined how spaceflight affected AVOR gain. During yaw, pitch and roll (0.5 - 1.0 Hz, 40-50 deg/s pk) motion, 3-d eye movements were recorded in four Rhesus monkeys using scleral search coils. Mean E-H and E-V pitch VOR gains were 0.85 and 0.71. Torsional VOR gains during E-H and E-V were 0.47 and 0.39. Gains are more compensatory during E-H pitch or roll. Two of the four monkeys flew for 11 days on the COSMOS 2229 Biosatellite. E-H pitch VOR gains were attenuated immediately (72 hrs) post-flight, with similar values to pre-flight E-V pitch gains. Horizontal yaw VOR gains were similar pre- and post-flight.

  5. 14 CFR 71.15 - Designation of jet routes and VOR Federal airways.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 2 2013-01-01 2013-01-01 false Designation of jet routes and VOR Federal... ROUTES; AND REPORTING POINTS § 71.15 Designation of jet routes and VOR Federal airways. Unless otherwise specified, the place names appearing in the descriptions of airspace areas designated as jet routes...

  6. 14 CFR 71.15 - Designation of jet routes and VOR Federal airways.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 2 2012-01-01 2012-01-01 false Designation of jet routes and VOR Federal... ROUTES; AND REPORTING POINTS § 71.15 Designation of jet routes and VOR Federal airways. Unless otherwise specified, the place names appearing in the descriptions of airspace areas designated as jet routes...

  7. 14 CFR 71.15 - Designation of jet routes and VOR Federal airways.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 2 2014-01-01 2014-01-01 false Designation of jet routes and VOR Federal... ROUTES; AND REPORTING POINTS § 71.15 Designation of jet routes and VOR Federal airways. Unless otherwise specified, the place names appearing in the descriptions of airspace areas designated as jet routes...

  8. Vestibular Compensation in Unilateral Patients Often Causes Both Gain and Time Constant Asymmetries in the VOR

    PubMed Central

    Ranjbaran, Mina; Katsarkas, Athanasios; Galiana, Henrietta L.

    2016-01-01

    The vestibulo-ocular reflex (VOR) is essential in our daily life to stabilize retinal images during head movements. Balanced vestibular functionality secures optimal reflex performance which otherwise can be distorted by peripheral vestibular lesions. Luckily, vestibular compensation in different neuronal sites restores VOR function to some extent over time. Studying vestibular compensation gives insight into the possible mechanisms for plasticity in the brain. In this work, novel experimental analysis tools are employed to reevaluate the VOR characteristics following unilateral vestibular lesions and compensation. Our results suggest that following vestibular lesions, asymmetric performance of the VOR is not only limited to its gain. Vestibular compensation also causes asymmetric dynamics, i.e., different time constants for the VOR during leftward or rightward passive head rotation. Potential mechanisms for these experimental observations are provided using simulation studies. PMID:27065839

  9. Modeling learning in brain stem and cerebellar sites responsible for VOR plasticity

    NASA Technical Reports Server (NTRS)

    Quinn, K. J.; Didier, A. J.; Baker, J. F.; Peterson, B. W.

    1998-01-01

    A simple model of vestibuloocular reflex (VOR) function was used to analyze several hypotheses currently held concerning the characteristics of VOR plasticity. The network included a direct vestibular pathway and an indirect path via the cerebellum. An optimization analysis of this model suggests that regulation of brain stem sites is critical for the proper modification of VOR gain. A more physiologically plausible learning rule was also applied to this network. Analysis of these simulation results suggests that the preferred error correction signal controlling gain modification of the VOR is the direct output of the accessory optic system (AOS) to the vestibular nuclei vs. a signal relayed through the cerebellum via floccular Purkinje cells. The potential anatomical and physiological basis for this conclusion is discussed, in relation to our current understanding of the latency of the adapted VOR response.

  10. Modeling learning in brain stem and cerebellar sites responsible for VOR plasticity

    NASA Technical Reports Server (NTRS)

    Quinn, K. J.; Didier, A. J.; Baker, J. F.; Peterson, B. W.

    1998-01-01

    A simple model of vestibuloocular reflex (VOR) function was used to analyze several hypotheses currently held concerning the characteristics of VOR plasticity. The network included a direct vestibular pathway and an indirect path via the cerebellum. An optimization analysis of this model suggests that regulation of brain stem sites is critical for the proper modification of VOR gain. A more physiologically plausible learning rule was also applied to this network. Analysis of these simulation results suggests that the preferred error correction signal controlling gain modification of the VOR is the direct output of the accessory optic system (AOS) to the vestibular nuclei vs. a signal relayed through the cerebellum via floccular Purkinje cells. The potential anatomical and physiological basis for this conclusion is discussed, in relation to our current understanding of the latency of the adapted VOR response.

  11. 75 FR 12675 - Amendment of VOR Federal Airway V-422 in the Vicinity of Wolf Lake, IN

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-17

    ... Federal Aviation Administration 14 CFR Part 71 RIN 2120-AA66 Amendment of VOR Federal Airway V-422 in the...: This action amends the legal description of the VHF Omnidirectional Range (VOR) Federal Airway V-422 in... part of the V-422 route structure, is being renamed the Webster Lake VOR. DATES: Effective date...

  12. 76 FR 20835 - Amendment of VOR Federal Airways V-1, V-7, V-11 and V-20; Kona, HI

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-14

    ... Administration 14 CFR Part 71 Amendment of VOR Federal Airways V-1, V-7, V-11 and V-20; Kona, HI AGENCY: Federal... delays the effective date for the amendment of four VOR Federal airways in the vicinity of Kona, HI; V-1...), amends VOR Federal Airways V-1, V-7 V-11 and V-20; Kona, HI. These VHF Omnidirectional Range Federal...

  13. 78 FR 18271 - Proposed Modification of VOR Federal Airway V-345 in the Vicinity of Ashland, WI

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-26

    ... Measuring Equipment (VOR/ DME) navigation aid, which forms the northern most point of the airway, has been... service by the Ashland, WI, VOR/DME. DATES: Comments must be received on or before May 10, 2013. ADDRESSES... necessary because the Ashland, WI, VOR/DME, which serves as the northern endpoint of the airway, has...

  14. Assessment of VOR gain function and its test-retest reliability in normal hearing individuals.

    PubMed

    Bansal, Shalini; Sinha, Sujeet Kumar

    2016-10-01

    Video head impulse test (vHIT) aids to assess all three pairs of semi-circular canals (SCCs) separately and can be utilized to find out the exact site of lesion in any three SCCs by measuring vestibulo ocular reflex (VOR) gain. VOR gain value of vHIT has been used to diagnose different vestibular pathologies. Hence, it is important to establish the test-retest reliability of the VOR gain parameters before it could be administered to the patients. Therefore, the aim of the present study was to obtain VOR gain data, correlate all planes in both sides of head (right and left) and assess the test-retest reliability of VOR gain measure using vHIT in 25 normal young adult participants. Video head impulse test tests were carried out with prototype ICS impulse video goggles with a camera speed of 250 frames/s, recording motion of the right eye in all three planes (lateral, right anterior left posterior, left anterior right posterior) for all the participants. vHIT testing was repeated for all the participants after 15 days. Statistical analysis revealed that mean VOR gain for right horizontal canal was higher than the left horizontal canal; right anterior canal was higher than left anterior canal and left anterior was higher than right posterior canal. Horizontal canals have more gain compared to anterior and posterior canals. There was no significant difference between the VOR gain of session 1 and session 2 for each SCC.

  15. The cerebellum and VOR/OKR learning models.

    PubMed

    Kawato, M; Gomi, H

    1992-11-01

    Although one particular model of the cerebellum, as proposed by Marr and Albus, provides a formal framework for understanding how heterosynaptic plasticity of Purkinje cells might be used for motor learning, the physiological details remain largely an engima. Developments in computational neuroscience and artificial neural networks applied to real control problems are essential to understand fully how workspace errors associated with movement performances can be converted into motor-command errors, and how these errors can then be used as one kind of synaptic input by motor-learning algorithms that are based on biologically plausible rules involving heterosynaptic plasticity. These developments, as well as recent advances in the study of cellular mechanisms of synaptic plasticity, form the basis for the detailed computational models of cerebellar motor learning that have been proposed. These models provide hints toward resolving a long-standing controversy in the oculomotor literature regarding the sites of adaptive changes in the vestibuloocular reflex (VOR) and the optokinetic eye movement response (OKR), and suggest new experiments to elucidate general mechanisms of sensory motor learning.

  16. 78 FR 72005 - Amendment of VOR Federal Airway V-374, Northeastern United States

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-02

    ...) Domestic VOR Federal Airways * * * * * V-374 From Binghamton, NY; INT Binghamton 119 and Deer Park, NY, 308 radials; INT Deer Park 308 and Carmel, NY, 254 radials; Carmel; INT Carmel 099 and Calverton, NY,...

  17. 75 FR 54058 - Proposed Revocation of VOR Federal Airway V-284; New Jersey

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-03

    ... proposed rulemaking (NPRM). SUMMARY: This action proposes to remove VHF omnidirectional range (VOR) Federal airway V-284, which extends between the Sea Isle, NJ and Cedar Lake, NJ, VHF omnidirectional...

  18. 78 FR 2200 - Establishment of VOR Federal Airway V-629; Las Vegas, NV

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-10

    ... supplement the existing routes structure for aircraft navigating in an area of marginal radar coverage. This... aircraft navigating in an area of marginal radar coverage. VOR Federal airways are published in paragraph...

  19. 77 FR 54859 - Proposed Establishment of VOR Federal Airway V-629; Las Vegas, NV

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-06

    ... of marginal radar coverage. This would enhance the efficiency of the National Airspace System (NAS... navigating in an area of marginal radar coverage. VOR Federal airways are published in paragraph 6010 of FAA...

  20. 76 FR 12645 - Proposed Revocation of VOR Federal Airway V-284; New Jersey

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-08

    ...-284; New Jersey AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of proposed... Delaware-New Jersey-New York City-Philadelphia areas. For such aircraft, the VOR Federal airway...

  1. Dependence of the roll angular vestibuloocular reflex (aVOR) on gravity.

    PubMed

    Yakushin, Sergei B; Xiang, Yongqing; Cohen, Bernard; Raphan, Theodore

    2009-11-01

    Little is known about the dependence of the roll angular vestibuloocular reflex (aVOR) on gravity or its gravity-dependent adaptive properties. To study gravity-dependent characteristics of the roll aVOR, monkeys were oscillated about a naso-occipital axis in darkness while upright or tilted. Roll aVOR gains were largest in the upright position and decreased by 7-15% as animals were tilted from the upright. Thus the unadapted roll aVOR gain has substantial gravitational dependence. Roll gains were also decreased or increased by 0.25 Hz, in- or out-of-phase rotation of the head and the visual surround while animals were prone, supine, upright, or in side-down positions. Gain changes, determined as a function of head tilt, were fit with a sinusoid; the amplitudes represented the amount of the gravity-dependent gain change, and the bias, the gravity-independent gain change. Gravity-dependent gain changes were absent or substantially smaller in roll (approximately 5%) than in yaw (25%) or pitch (17%), whereas gravity-independent gain changes were similar for roll, pitch, and yaw (approximately 20%). Thus the high-frequency roll aVOR gain has an inherent dependence on head orientation re gravity in the unadapted state, which is different from the yaw/pitch aVORs. This inherent gravitational dependence may explain why the adaptive circuits are not active when the head is tilted re gravity during roll aVOR adaptation. These behavioral differences support the idea that there is a fundamental difference in the central organization of canal-otolith convergence of the roll and yaw/pitch aVORs.

  2. The under-compensatory roll aVOR does not affect dynamic visual acuity.

    PubMed

    Schubert, Michael C; Migliaccio, Americo A; Ng, Tammy W C; Shaikh, Aasef G; Zee, David S

    2012-08-01

    Rotations of the head evoke compensatory reflexive eye rotations in the orbit to stabilize images onto the fovea. In normal humans, the angular vestibulo-ocular reflex (aVOR) gain (eye/head velocity) changes depending on the head rotation plane. For pitch and yaw head rotations, the gain is near unity, but during roll head rotations, the aVOR gain is ∼ 0.7. The purpose of this study was to determine whether this physiological discrepancy affects dynamic visual acuity (DVA)--a functional measure of the aVOR that requires subjects to identify letters of varying acuities during head rotation. We used the scleral search coil technique to measure eye and head velocity during passive DVA testing in yaw, roll, and pitch head impulses in healthy controls and patients with unilateral vestibular hypofunction (UVH). For control subjects, the mean aVOR gain during roll impulses was significantly lower than the mean aVOR gain during yaw and pitch impulses; however, there was no difference in DVA between yaw, roll, or pitch. For subjects with UVH, only aVOR gain during head rotations toward the affected side (yaw) were asymmetric (ipsilesional, 0.32 ± 0.17, vs. contralesional, 0.95 ± 0.05), with no asymmetry during roll or pitch. Similarly, there was a large asymmetry for DVA only during yaw head rotations, with no asymmetry in roll or pitch. Interestingly, DVA during roll toward the affected ear was better than DVA during yaw toward the affected ear--even though the ipsilesional roll aVOR gain was 60 % lower. During roll, the axis of eye rotation remains nearly perpendicular to the fovea, resulting in minimal displacement between the fovea and fixation target image projected onto the back of the eye. For subjects with UVH, the DVA score during passive horizontal impulses is a better indicator of poor gaze stability than during passive roll or pitch.

  3. 78 FR 37103 - Amendment of VOR Federal Airways V-55 and V-169 in Eastern North Dakota

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-20

    ... September 15, 2012, which is incorporated by reference in 14 CFR 71.1. The VOR Federal airways listed in... August 8, 2012, and effective September 15, 2012, is amended as follows: Paragraph 6010 VOR Federal...; Gipper, MI; Keeler, MI; Pullman, MI; Muskegon, MI; INT Muskegon 327 and Green Bay, WI, 116 radials;...

  4. 78 FR 21856 - Proposed Amendment of VOR Federal Airway V-537; GA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-12

    ...-537 would extend between Palm Beach, FL, and Greenville, FL. Since this change expands the scope of... 15, 2012, is amended as follows: Paragraph 6010 Domestic VOR Federal Airways V-537 From Palm Beach, FL; INT Palm Beach 356 and Treasure, FL, 143 radials; Treasure; INT Treasure 318 and Orlando, FL,...

  5. 75 FR 39149 - Establishment of VOR Federal Airway V-625; Arizona

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-08

    ...; Arizona AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule. SUMMARY: This action... Arizona, (74 FR 17911). Interested parties were invited to participate in this rulemaking effort by... establishes a VOR Federal Airway in Arizona. Environmental Review The FAA has determined that this action...

  6. 78 FR 37105 - Modification of VOR Federal Airway V-537, GA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-20

    ... Federal Aviation Administration 14 CFR Part 71 RIN 2120-AA66 Modification of VOR Federal Airway V-537, GA AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule. SUMMARY: This action modifies VHF... Group, Office of Airspace Services, Federal Aviation Administration, 800 Independence Avenue SW...

  7. 78 FR 24346 - Modification of VOR Federal Airway V-595, Oregon

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-25

    ..., Oregon AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule. SUMMARY: This action modifies VHF omnidirectional range (VOR) Federal airway V-595 in Oregon due to the scheduled... FAA published in the Federal Register a notice of proposed rulemaking (NPRM) to modify V-595 in...

  8. Oxygen Compatibility and Challenge Testing of the PLSS Variable Oxygen Regulator (VOR) for the Advanced EMU

    NASA Technical Reports Server (NTRS)

    Campbell, Colin; Cox, Marlon; Meginnis, Carly; Falconi, Eric

    2017-01-01

    The Variable Oxygen Regulator (VOR), a stepper actuated two-stage mechanical regulator, is being developed for the purpose of serving as the Primary Oxygen Regulator (POR) and Secondary Oxygen Regulator (SOR) within the Advanced EMU PLSS, now referred to as the xEMU and xPLSS. Three prototype designs have been fabricated and tested as part of this development. Building upon the lessons learned from the 35 years of Shuttle/ISS EMU Program operation including the fleet-wide EMU Secondary Oxygen Pack (SOP) contamination failure that occurred in 2000, the VOR is being analyzed, designed, and tested for oxygen compatibility with controlled Non-Volatile Residue (NVR) and a representative worst-case hydro-carbon system contamination event (>100mg/sq ft dodecane). This paper discusses the steps taken in testing of VOR 2.0 with for oxygen compatibility and then discusses follow-on design changes implemented in the VOR 3.0 (3rd prototype) as a result.

  9. Horizontal Eye Position Affects Measured Vertical VOR Gain on the Video Head Impulse Test.

    PubMed

    McGarvie, Leigh A; Martinez-Lopez, Marta; Burgess, Ann M; MacDougall, Hamish G; Curthoys, Ian S

    2015-01-01

    With the video head impulse test (vHIT), the vertical VOR gain is defined as (vertical eye velocity/vertical head velocity), but compensatory eye movements to vertical canal stimulation usually have a torsional component. To minimize the contribution of torsion to the eye movement measurement, the horizontal gaze direction should be directed 40° from straight ahead so it is in the plane of the stimulated canal plane pair. as gaze is systematically moved horizontally away from canal plane alignment, the measured vertical VOR gain should decrease. Ten healthy subjects, with vHIT measuring vertical eye movement to head impulses in the plane of the left anterior-right posterior (LARP) canal plane, with gaze at one of five horizontal gaze positions [40°(aligned with the LARP plane), 20°, 0°, -20°, -40°]. Every head impulse was in the LARP plane. The compensatory eye movement was measured by the vHIT prototype system. The one operator delivered every impulse. The canal stimulus remained identical across trials, but the measured vertical VOR gain decreased as horizontal gaze angle was shifted away from alignment with the LARP canal plane. In measuring vertical VOR gain with vHIT the horizontal gaze angle should be aligned with the canal plane under test.

  10. Horizontal Eye Position Affects Measured Vertical VOR Gain on the Video Head Impulse Test

    PubMed Central

    McGarvie, Leigh A.; Martinez-Lopez, Marta; Burgess, Ann M.; MacDougall, Hamish G.; Curthoys, Ian S.

    2015-01-01

    Background/hypothesis: With the video head impulse test (vHIT), the vertical VOR gain is defined as (vertical eye velocity/vertical head velocity), but compensatory eye movements to vertical canal stimulation usually have a torsional component. To minimize the contribution of torsion to the eye movement measurement, the horizontal gaze direction should be directed 40° from straight ahead so it is in the plane of the stimulated canal plane pair. Hypothesis: as gaze is systematically moved horizontally away from canal plane alignment, the measured vertical VOR gain should decrease. Study design: Ten healthy subjects, with vHIT measuring vertical eye movement to head impulses in the plane of the left anterior-right posterior (LARP) canal plane, with gaze at one of five horizontal gaze positions [40°(aligned with the LARP plane), 20°, 0°, −20°, −40°]. Methods: Every head impulse was in the LARP plane. The compensatory eye movement was measured by the vHIT prototype system. The one operator delivered every impulse. Results: The canal stimulus remained identical across trials, but the measured vertical VOR gain decreased as horizontal gaze angle was shifted away from alignment with the LARP canal plane. Conclusion: In measuring vertical VOR gain with vHIT the horizontal gaze angle should be aligned with the canal plane under test. PMID:25852637

  11. 77 FR 42428 - Amendment of Jet Routes and VOR Federal Airways; Northeastern United States

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-19

    ... Federal Aviation Administration 14 CFR Part 71 Docket No. FAA-2012-0622; Airspace Docket No. 12-ANE-11 RIN 2120-AA66 Amendment of Jet Routes and VOR Federal Airways; Northeastern United States AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule; technical amendment. SUMMARY: This action amends...

  12. 76 FR 2800 - Amendment of VOR Federal Airways V-2 and V-21; Hawaii

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-18

    ...; Hawaii AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule. SUMMARY: This action amends two VHF Omnidirectional Range (VOR) Federal airway legal descriptions in the State of Hawaii. The... Federal Airways, V-2 and V-21, located in the State of Hawaii by removing all references to Restricted...

  13. 78 FR 72005 - Amendment of VOR Federal Airway V-45, North Carolina

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-02

    ..., and effective September 15, 2013, which is incorporated by reference in 14 CFR 71.1. The VOR Federal..., dated August 7, 2013, and effective September 15, 2013, is amended as follows: Paragraph 6010(a... and Jackson, MI, 166 radials; Jackson; Lansing, MI; Saginaw, MI; Alpena, MI; Sault Ste Marie, MI....

  14. Development of a VOR/DME model for an advanced concepts simulator

    NASA Technical Reports Server (NTRS)

    Steinmetz, G. G.; Bowles, R. L.

    1984-01-01

    The report presents a definition of a VOR/DME, airborne and ground systems simulation model. This description was drafted in response to a need in the creation of an advanced concepts simulation in which flight station design for the 1980 era can be postulated and examined. The simulation model described herein provides a reasonable representation of VOR/DME station in the continental United States including area coverage by type and noise errors. The detail in which the model has been cast provides the interested researcher with a moderate fidelity level simulator tool for conducting research and evaluation of navigator algorithms. Assumptions made within the development are listed and place certain responsibilities (data bases, communication with other simulation modules, uniform round earth, etc.) upon the researcher.

  15. An Investigation and Analysis of the Vestibulo-Ocular Reflex (VOR) in a Vibration Environment

    DTIC Science & Technology

    2013-03-01

    filtering and time-dependency,” Ergonomics , 613-626. Paddan, G. and M. Griffin (1988). “The transmission of translational seat vibration to the head...understand and describe the VOR in the presence of head slued imagery as a function of whole body low-frequency vibration. An experimental HMD was designed ...circuitry design to assisting with software coding. Finally, I would like to thank my beautiful fiancée for her love and support throughout the

  16. A New Tool for Investigating the Functional Testing of the VOR

    PubMed Central

    Colagiorgio, Paolo; Colnaghi, Silvia; Versino, Maurizio; Ramat, Stefano

    2013-01-01

    Peripheral vestibular function may be tested quantitatively, by measuring the gain of the angular vestibulo-ocular reflex (aVOR), or functionally, by assessing how well the aVOR performs with respect to its goal of stabilizing gaze in space and thus allow to acquire visual information during the head movement. In recent years, several groups have developed clinical and quantitative approaches to functional testing of the vestibular system based on the ability to identify an optotype briefly displayed on screen during head rotations. Although the proposed techniques differ in terms of the parameters controlling the testing paradigm, no study has thus far dealt with understanding the role of such choices in determining the effectiveness and reliability of the testing approach. Moreover, recent work has shown that peripheral vestibular patients may produce corrective saccades during the head movement (covert saccades), yet the role of these eye movements toward reading ability during head rotations is not yet understood. Finally, no study has thus far dealt with measuring the true performance of their experimental setups, which is nonetheless likely to be crucial information for understanding the effectiveness of functional testing approaches. Thus we propose a new software and hardware research tool allowing the combined measurement of eye and head movements, together with the timing of the optotype on screen, during functional testing of the vestibulo-ocular reflex (VOR) based on the Head Impulse Test. The goal of such tool is therefore that of allowing functional testing of the VOR while collecting the experimental data necessary to understand, for instance, (a) the effectiveness of the covert saccades strategy toward image stabilization, (b) which experimental parameters are crucial for optimizing the diagnostic power of the functional testing approach, and (c) which conditions lead to a successful reading or an error trial. PMID:24298265

  17. Horizontal angular VOR, nystagmus dumping, and sensation duration in spacelab SLS-1 crewmembers

    NASA Technical Reports Server (NTRS)

    Oman, C. M.; Balkwill, M. D.; Young, L. R. (Principal Investigator)

    1993-01-01

    In 1G, the apparent time constant (Td) of postrotatory SPV decay with the head tilted face down is 55% of that with head erect (Te). This phenomenon is called "nystagmus dumping" and has been attributed to G effects on VOR velocity storage. Similarly, postrotatory sensation duration with head tilted (Dd) is 32% of that when head erect (De). In parabolic flight, Te and De are 70% of 1-G values, but a pitch back dumping movement produces no further change. Te, Td, and Dd have not previously been measured in orbital flight. VOR and sensation duration was tested in 4 crewmembers in 4 preflight, 1 inflight (days 4 or 5) and 4 post flight sessions. Bitemporal EOG was recorded with eyes open in darkness. Instructions were to "gaze straight ahead," and indicate when "rotation sensation disappears or becomes ambiguous". Subjects were rotated CW and CCW head erect for 1 min at 120 degrees/s, stopped, and EOG was recorded for another 1 min. This procedure was then used to study dumping, except that immediately after chair stop, subjects pitched their head forward 90 degrees. SPV was calculated using order statistic filtering, and dropouts removed using an iterative model fitting method. Te and Td were determined by logarithmic linear regression of mean SPV for each subject. In orbit, 90 degrees pitch movement produced rapid subjective dumping, but not nystagmus dumping. Dd was noticeably shorter ("almost instantaneous") compared to preflight Dd. Te and Td in orbit were similar to preflight Te for 3/4 subjects (rather than to preflight Td as expected). No consistent VOR gain changes were seen in orbit. Although Te is known to decrease acutely in parabolic flight, a longer time constant was measured in 3/4 subjects after 4-5 days adaptation to weightlessness, suggesting a return of angular velocity storage.

  18. Horizontal angular VOR, nystagmus dumping, and sensation duration in spacelab SLS-1 crewmembers.

    PubMed

    Oman, C M; Balkwill, M D

    1993-01-01

    In 1G, the apparent time constant (Td) of postrotatory SPV decay with the head tilted face down is 55% of that with head erect (Te). This phenomenon is called "nystagmus dumping" and has been attributed to G effects on VOR velocity storage. Similarly, postrotatory sensation duration with head tilted (Dd) is 32% of that when head erect (De). In parabolic flight, Te and De are 70% of 1-G values, but a pitch back dumping movement produces no further change. Te, Td, and Dd have not previously been measured in orbital flight. VOR and sensation duration was tested in 4 crewmembers in 4 preflight, 1 inflight (days 4 or 5) and 4 post flight sessions. Bitemporal EOG was recorded with eyes open in darkness. Instructions were to "gaze straight ahead," and indicate when "rotation sensation disappears or becomes ambiguous". Subjects were rotated CW and CCW head erect for 1 min at 120 degrees/s, stopped, and EOG was recorded for another 1 min. This procedure was then used to study dumping, except that immediately after chair stop, subjects pitched their head forward 90 degrees. SPV was calculated using order statistic filtering, and dropouts removed using an iterative model fitting method. Te and Td were determined by logarithmic linear regression of mean SPV for each subject. In orbit, 90 degrees pitch movement produced rapid subjective dumping, but not nystagmus dumping. Dd was noticeably shorter ("almost instantaneous") compared to preflight Dd. Te and Td in orbit were similar to preflight Te for 3/4 subjects (rather than to preflight Td as expected). No consistent VOR gain changes were seen in orbit. Although Te is known to decrease acutely in parabolic flight, a longer time constant was measured in 3/4 subjects after 4-5 days adaptation to weightlessness, suggesting a return of angular velocity storage.

  19. Horizontal angular VOR, nystagmus dumping, and sensation duration in spacelab SLS-1 crewmembers

    NASA Technical Reports Server (NTRS)

    Oman, C. M.; Balkwill, M. D.; Young, L. R. (Principal Investigator)

    1993-01-01

    In 1G, the apparent time constant (Td) of postrotatory SPV decay with the head tilted face down is 55% of that with head erect (Te). This phenomenon is called "nystagmus dumping" and has been attributed to G effects on VOR velocity storage. Similarly, postrotatory sensation duration with head tilted (Dd) is 32% of that when head erect (De). In parabolic flight, Te and De are 70% of 1-G values, but a pitch back dumping movement produces no further change. Te, Td, and Dd have not previously been measured in orbital flight. VOR and sensation duration was tested in 4 crewmembers in 4 preflight, 1 inflight (days 4 or 5) and 4 post flight sessions. Bitemporal EOG was recorded with eyes open in darkness. Instructions were to "gaze straight ahead," and indicate when "rotation sensation disappears or becomes ambiguous". Subjects were rotated CW and CCW head erect for 1 min at 120 degrees/s, stopped, and EOG was recorded for another 1 min. This procedure was then used to study dumping, except that immediately after chair stop, subjects pitched their head forward 90 degrees. SPV was calculated using order statistic filtering, and dropouts removed using an iterative model fitting method. Te and Td were determined by logarithmic linear regression of mean SPV for each subject. In orbit, 90 degrees pitch movement produced rapid subjective dumping, but not nystagmus dumping. Dd was noticeably shorter ("almost instantaneous") compared to preflight Dd. Te and Td in orbit were similar to preflight Te for 3/4 subjects (rather than to preflight Td as expected). No consistent VOR gain changes were seen in orbit. Although Te is known to decrease acutely in parabolic flight, a longer time constant was measured in 3/4 subjects after 4-5 days adaptation to weightlessness, suggesting a return of angular velocity storage.

  20. Use of a visual guide to improve the quality of VOR responses evoked by high-velocity rotational stimuli

    PubMed Central

    Gianna-Poulin, C.C.; Peterka, R.J.

    2008-01-01

    High-velocity rotational stimuli have the potential to improve the diagnostic capabilities of clinical rotation testing by revealing nonlinear vestibulo-ocular reflex (VOR) responses that are indicative of asymmetric vestibular function. However, eye movements evoked by high-velocity rotations often are inconsistent over time and therefore do not yield reliable diagnostic measures. This study investigated whether use of a novel “visual guide” could improve the consistency and quality of VORs obtained during testing with pulse-step-sine (PSS) stimuli providing periodic high-velocity, horizontal-plane rotations with peak velocities up to 290 deg/s. The visual guide (narrow phosphorescent line spanning 180° field of view) was mounted horizontally on the rotation chair at the subject's eye level. Eight healthy human subjects were tested either in complete darkness while performing an alerting task, or while viewing the visual guide in an otherwise dark room. We found that the visual guide improved the quality of VOR responses as shown by an increased proportion of slow-phase velocity data segments retained for analysis, by a decreased variance of the processed eye velocity data, and by a reduction of outlying VOR response measures. We also found that the visual guide did not induce visual suppression because VOR gain measures were not diminished. PMID:18776595

  1. Short-term adaptation of the VOR: non-retinal-slip error signals and saccade substitution

    NASA Technical Reports Server (NTRS)

    Eggers, Sscott D Z.; De Pennington, Nick; Walker, Mark F.; Shelhamer, Mark; Zee, David S.

    2003-01-01

    We studied short-term (30 min) adaptation of the vestibulo-ocular reflex (VOR) in five normal humans using a "position error" stimulus without retinal image motion. Both before and after adaptation a velocity gain (peak slow-phase eye velocity/peak head velocity) and a position gain (total eye movement during chair rotation/amplitude of chair motion) were measured in darkness using search coils. The vestibular stimulus was a brief ( approximately 700 ms), 15 degrees chair rotation in darkness (peak velocity 43 degrees /s). To elicit adaptation, a straight-ahead fixation target disappeared during chair movement and when the chair stopped the target reappeared at a new location in front of the subject for gain-decrease (x0) adaptation, or 10 degrees opposite to chair motion for gain-increase (x1.67) adaptation. This position-error stimulus was effective at inducing VOR adaptation, though for gain-increase adaptation the primary strategy was to substitute augmenting saccades during rotation while for gain-decrease adaptation both corrective saccades and a decrease in slow-phase velocity occurred. Finally, the presence of the position-error signal alone, at the end of head rotation, without any attempt to fix upon it, was not sufficient to induce adaptation. Adaptation did occur, however, if the subject did make a saccade to the target after head rotation, or even if the subject paid attention to the new location of the target without actually looking at it.

  2. Short-term adaptation of the VOR: non-retinal-slip error signals and saccade substitution

    NASA Technical Reports Server (NTRS)

    Eggers, Sscott D Z.; De Pennington, Nick; Walker, Mark F.; Shelhamer, Mark; Zee, David S.

    2003-01-01

    We studied short-term (30 min) adaptation of the vestibulo-ocular reflex (VOR) in five normal humans using a "position error" stimulus without retinal image motion. Both before and after adaptation a velocity gain (peak slow-phase eye velocity/peak head velocity) and a position gain (total eye movement during chair rotation/amplitude of chair motion) were measured in darkness using search coils. The vestibular stimulus was a brief ( approximately 700 ms), 15 degrees chair rotation in darkness (peak velocity 43 degrees /s). To elicit adaptation, a straight-ahead fixation target disappeared during chair movement and when the chair stopped the target reappeared at a new location in front of the subject for gain-decrease (x0) adaptation, or 10 degrees opposite to chair motion for gain-increase (x1.67) adaptation. This position-error stimulus was effective at inducing VOR adaptation, though for gain-increase adaptation the primary strategy was to substitute augmenting saccades during rotation while for gain-decrease adaptation both corrective saccades and a decrease in slow-phase velocity occurred. Finally, the presence of the position-error signal alone, at the end of head rotation, without any attempt to fix upon it, was not sufficient to induce adaptation. Adaptation did occur, however, if the subject did make a saccade to the target after head rotation, or even if the subject paid attention to the new location of the target without actually looking at it.

  3. An Indirect System Identification Technique for Stable Estimation of Continuous-Time Parameters of the Vestibulo-Ocular Reflex (VOR)

    NASA Technical Reports Server (NTRS)

    Kukreja, Sunil L.; Wallin, Ragnar; Boyle, Richard D.

    2013-01-01

    The vestibulo-ocular reflex (VOR) is a well-known dual mode bifurcating system that consists of slow and fast modes associated with nystagmus and saccade, respectively. Estimation of continuous-time parameters of nystagmus and saccade models are known to be sensitive to estimation methodology, noise and sampling rate. The stable and accurate estimation of these parameters are critical for accurate disease modelling, clinical diagnosis, robotic control strategies, mission planning for space exploration and pilot safety, etc. This paper presents a novel indirect system identification method for the estimation of continuous-time parameters of VOR employing standardised least-squares with dual sampling rates in a sparse structure. This approach permits the stable and simultaneous estimation of both nystagmus and saccade data. The efficacy of this approach is demonstrated via simulation of a continuous-time model of VOR with typical parameters found in clinical studies and in the presence of output additive noise.

  4. Tuning of gravity-dependent and gravity-independent vertical angular VOR gain changes by frequency of adaptation.

    PubMed

    Yakushin, Sergei B

    2012-06-01

    The gain of the vertical angular vestibulo-ocular reflex (aVOR) was adaptively increased and decreased in a side-down head orientation for 4 h in two cynomolgus monkeys. Adaptation was performed at 0.25, 1, 2, or 4 Hz. The gravity-dependent and -independent gain changes were determined over a range of head orientations from left-side-down to right-side-down at frequencies from 0.25 to 10 Hz, before and after adaptation. Gain changes vs. frequency data were fit with a Gaussian to determine the frequency at which the peak gain change occurred, as well as the tuning width. The frequency at which the peak gravity-dependent gain change occurred was approximately equal to the frequency of adaptation, and the width increased monotonically with increases in the frequency of adaptation. The gravity-independent component was tuned to the adaptive frequency of 0.25 Hz but was uniformly distributed over all frequencies when the adaptation frequency was 1-4 Hz. The amplitude of the gravity-independent gain changes was larger after the aVOR gain decrease than after the gain increase across all tested frequencies. For the aVOR gain decrease, the phase lagged about 4° for frequencies below the adaptation frequency and led for frequencies above the adaptation frequency. For gain increases, the phase relationship as a function of frequency was inverted. This study demonstrates that the previously described dependence of aVOR gain adaptation on frequency is a property of the gravity-dependent component of the aVOR only. The gravity-independent component of the aVOR had a substantial tuning curve only at an adaptation frequency of 0.25 Hz.

  5. Tuning of gravity-dependent and gravity-independent vertical angular VOR gain changes by frequency of adaptation

    PubMed Central

    2012-01-01

    The gain of the vertical angular vestibulo-ocular reflex (aVOR) was adaptively increased and decreased in a side-down head orientation for 4 h in two cynomolgus monkeys. Adaptation was performed at 0.25, 1, 2, or 4 Hz. The gravity-dependent and -independent gain changes were determined over a range of head orientations from left-side-down to right-side-down at frequencies from 0.25 to 10 Hz, before and after adaptation. Gain changes vs. frequency data were fit with a Gaussian to determine the frequency at which the peak gain change occurred, as well as the tuning width. The frequency at which the peak gravity-dependent gain change occurred was approximately equal to the frequency of adaptation, and the width increased monotonically with increases in the frequency of adaptation. The gravity-independent component was tuned to the adaptive frequency of 0.25 Hz but was uniformly distributed over all frequencies when the adaptation frequency was 1–4 Hz. The amplitude of the gravity-independent gain changes was larger after the aVOR gain decrease than after the gain increase across all tested frequencies. For the aVOR gain decrease, the phase lagged about 4° for frequencies below the adaptation frequency and led for frequencies above the adaptation frequency. For gain increases, the phase relationship as a function of frequency was inverted. This study demonstrates that the previously described dependence of aVOR gain adaptation on frequency is a property of the gravity-dependent component of the aVOR only. The gravity-independent component of the aVOR had a substantial tuning curve only at an adaptation frequency of 0.25 Hz. PMID:22402654

  6. 76 FR 72093 - Amendment of VOR Federal Airways V-81, V-89, and V-169 in the Vicinity of Chadron, NE

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-22

    ...) Federal airways V-81, V-89, and V-169 in the vicinity of Chadron, Nebraska. The FAA is taking this action... confusion, and a potential flight safety issue, the Chadron VOR/DME is renamed the Toadstool VOR/DME and... criteria of the Regulatory Flexibility Act. The FAA's authority to issue rules regarding aviation safety is...

  7. 77 FR 42625 - Modification of VOR Federal Airways V-10, V-12, and V-508 in the Vicinity of Olathe, KS

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-20

    ... route structure due to the planned decommissioning of the Johnson County VOR navigation aid located on Johnson County Executive Airport, Olathe, KS. The establishment of the WETZL fix is canceled due to lack... reference to the decommissioning of the Distance Measuring Equipment (DME) portion of the Johnson County VOR...

  8. 78 FR 19985 - Modification of VOR Federal Airways V-68, V-76, V-194, and V-548 in the Vicinity of Houston, TX

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-03

    ... Federal Aviation Administration 14 CFR Part 71 RIN 2120-AA66 Modification of VOR Federal Airways V-68, V-76, V-194, and V-548 in the Vicinity of Houston, TX AGENCY: Federal Aviation Administration (FAA... (VOR) Federal airways V-68, V-76, V-194, and V-548 in the vicinity of Houston, TX. The FAA is...

  9. 75 FR 47709 - Amendment of VOR Federal Airways V-8, V-14, V-38, V-47, V-279, and V-422 in the Vicinity of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-09

    ... Federal Aviation Administration 14 CFR Part 71 RIN 2120-AA66 Amendment of VOR Federal Airways V-8, V-14, V-38, V-47, V-279, and V-422 in the Vicinity of Findlay, OH AGENCY: Federal Aviation Administration... Omnidirectional Range (VOR) Federal Airways V-8, V-14, V-38, V-47, V- 279, and V-422 in the vicinity of......

  10. 75 FR 43818 - Amendment of VOR Federal Airways V-50, V-251, and V-313 in the Vicinity of Decatur, IL

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-27

    ... TRANSPORTATION Federal Aviation Administration 14 CFR Part 71 RIN: 2120-AA66 Amendment of VOR Federal Airways V-50, V-251, and V-313 in the Vicinity of Decatur, IL AGENCY: Federal Aviation Administration (FAA... range (VOR) Federal Airways V-50, V-251, and V-313 in the vicinity of Decatur, IL. The FAA is...

  11. 76 FR 13082 - Amendment of VOR Federal Airways V-1, V-7, V-11 and V-20; Kona, HI

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-10

    ...-11 and V-20; Kona, HI AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule. SUMMARY: This action amends four VHF Omnidirectional Range (VOR) Federal airways in the vicinity of Kona, HI; V... International Keahole Airport property Kailua-Kona, HI. This will enhance the management of aircraft operations...

  12. 75 FR 12674 - Amendment of Jet Routes and VOR Federal Airways in the Vicinity of Gage, OK

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-17

    ... Federal Aviation Administration 14 CFR Part 71 RIN 2120-AA66 Amendment of Jet Routes and VOR Federal Airways in the Vicinity of Gage, OK AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule. SUMMARY: This action amends the legal description of two Jet Routes and seven VHF Omnidirectional Range...

  13. Graphical Analysis of Electromagnetic Coupling on B-737 and B-757 Aircraft for VOR and LOC IPL Data

    NASA Technical Reports Server (NTRS)

    Jafri, Madiha; Ely, Jay; Vahala, Linda

    2005-01-01

    Electromagnetic coupling measurements were performed from numerous passenger cabin locations to aircraft instrument landing system localizer (LOC) and VHF Omni-Ranging (VOR) systems. This paper presents and compares the data for B-757 and B-737 airplanes, and provides a basis for fuzzy modeling of coupling patterns in different types of airplanes and airplanes with different antenna locations.

  14. 76 FR 79140 - Proposed Modification of VOR Federal Airways V-135 and V-137; Southwest United States

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-21

    ... across the United States-Mexican border. DATES: Comments must be received on or before February 6, 2012... Imperial, CA VORTAC. These amendments would benefit cross-border navigation. Additionally, fixes would be established at the border crossing points to simplify air traffic control coordination of flights. VOR...

  15. Vestibular perception and action employ qualitatively different mechanisms. II. VOR and perceptual responses during combined Tilt&Translation.

    PubMed

    Merfeld, Daniel M; Park, Sukyung; Gianna-Poulin, Claire; Black, F Owen; Wood, Scott

    2005-07-01

    To compare and contrast the neural mechanisms that contribute to vestibular perception and action, we measured vestibuloocular reflexes (VOR) and perceptions of tilt and translation. We took advantage of the well-known ambiguity that the otolith organs respond to both linear acceleration and tilt with respect to gravity and investigated the mechanisms by which this ambiguity is resolved. A new motion paradigm that combined roll tilt with inter-aural translation ("Tilt&Translation") was used; subjects were sinusoidally (0.8 Hz) roll tilted but with their ears above or below the rotation axis. This paradigm provided sinusoidal roll canal cues that were the same across trials while providing otolith cues that varied linearly with ear position relative to the earth-horizontal rotation axis. We found that perceived tilt and translation depended on canal cues, with substantial roll tilt and inter-aural translation perceptions reported even when the otolith organs measured no inter-aural force. These findings match internal model predictions that rotational cues from the canals influence the neural processing of otolith cues. We also found horizontal translational VORs that varied linearly with radius; a minimal response was measured when the otolith organs transduced little or no inter-aural force. Hence, the horizontal translational VOR was dependent on otolith cues but independent of canal cues. These findings match predictions that translational VORs are elicited by simple filtering of otolith signals. We conclude that internal models govern human perception of tilt and translation at 0.8 Hz and that high-pass filtering governs the human translational VOR at this same frequency.

  16. Full-Body Gaze Control Mechanisms Elicited During Locomotion: Effects Of VOR Adaptation

    NASA Technical Reports Server (NTRS)

    Mulavara, A. P.; Houser, J.; Peters, B.; Miller, C.; Richards, J.; Marshburn, A.; Brady, R.; Cohen, H.; Bloomberg, J. J.

    2004-01-01

    Control of locomotion requires precise interaction between several sensorimotor subsystems. During locomotion the performer must satisfy two performance criteria: maintain stable forward translation and to stabilize gaze (McDonald, et al., 1997). Precise coordination demands integration of multiple sensorimotor subsystems for fulfilling both criteria. In order to test the general hypothesis that the whole body can serve as an integrated gaze stabilization system, we have previously investigated how the multiple, interdependent full-body sensorimotor subsystems respond to changes in gaze stabilization task constraints during locomotion (Mulavara and Bloomberg, 2003). The results suggest that the full body contributes to gaze stabilization during locomotion, and that its different functional elements respond to changes in visual task constraints. The goal of this study was to determine how the multiple, interdependent, full-body sensorimotor subsystems aiding gaze stabilization during locomotion are functionally coordinated after the vestibulo-ocular reflex (VOR) gain has been altered. We investigated the potential of adaptive remodeling of the full-body gaze control system following exposure to visual-vestibular conflict known to adaptively reduce the VOR. Subjects (n=14) walked (6.4 km/h) on the treadmill before and after they were exposed to 0.5X manifying lenses worn for 30 minutes during self-generated sinusoidal vertical head rotations performed while seated. In this study we measured: temporal parameters of gait, full body sagittal plane segmental kinematics of the head, trunk, thigh, shank and foot, accelerations along the vertical axis at the head and the shank, and the vertical forces acting on the support surface. Results indicate that, following exposure to the 0.5X minifying lenses, there was a significant increase in the duration of stance and stride times, alteration in the amplitude of head movement with respect to space and a significant increase in

  17. Full-Body Gaze Control Mechanisms Elicited During Locomotion: Effects Of VOR Adaptation

    NASA Technical Reports Server (NTRS)

    Mulavara, A. P.; Houser, J.; Peters, B.; Miller, C.; Richards, J.; Marshburn, A.; Brady, R.; Cohen, H.; Bloomberg, J. J.

    2004-01-01

    Control of locomotion requires precise interaction between several sensorimotor subsystems. During locomotion the performer must satisfy two performance criteria: maintain stable forward translation and to stabilize gaze (McDonald, et al., 1997). Precise coordination demands integration of multiple sensorimotor subsystems for fulfilling both criteria. In order to test the general hypothesis that the whole body can serve as an integrated gaze stabilization system, we have previously investigated how the multiple, interdependent full-body sensorimotor subsystems respond to changes in gaze stabilization task constraints during locomotion (Mulavara and Bloomberg, 2003). The results suggest that the full body contributes to gaze stabilization during locomotion, and that its different functional elements respond to changes in visual task constraints. The goal of this study was to determine how the multiple, interdependent, full-body sensorimotor subsystems aiding gaze stabilization during locomotion are functionally coordinated after the vestibulo-ocular reflex (VOR) gain has been altered. We investigated the potential of adaptive remodeling of the full-body gaze control system following exposure to visual-vestibular conflict known to adaptively reduce the VOR. Subjects (n=14) walked (6.4 km/h) on the treadmill before and after they were exposed to 0.5X manifying lenses worn for 30 minutes during self-generated sinusoidal vertical head rotations performed while seated. In this study we measured: temporal parameters of gait, full body sagittal plane segmental kinematics of the head, trunk, thigh, shank and foot, accelerations along the vertical axis at the head and the shank, and the vertical forces acting on the support surface. Results indicate that, following exposure to the 0.5X minifying lenses, there was a significant increase in the duration of stance and stride times, alteration in the amplitude of head movement with respect to space and a significant increase in

  18. A least-squares parameter estimation algorithm for switched hammerstein systems with applications to the VOR

    NASA Technical Reports Server (NTRS)

    Kukreja, Sunil L.; Kearney, Robert E.; Galiana, Henrietta L.

    2005-01-01

    A "Multimode" or "switched" system is one that switches between various modes of operation. When a switch occurs from one mode to another, a discontinuity may result followed by a smooth evolution under the new regime. Characterizing the switching behavior of these systems is not well understood and, therefore, identification of multimode systems typically requires a preprocessing step to classify the observed data according to a mode of operation. A further consequence of the switched nature of these systems is that data available for parameter estimation of any subsystem may be inadequate. As such, identification and parameter estimation of multimode systems remains an unresolved problem. In this paper, we 1) show that the NARMAX model structure can be used to describe the impulsive-smooth behavior of switched systems, 2) propose a modified extended least squares (MELS) algorithm to estimate the coefficients of such models, and 3) demonstrate its applicability to simulated and real data from the Vestibulo-Ocular Reflex (VOR). The approach will also allow the identification of other nonlinear bio-systems, suspected of containing "hard" nonlinearities.

  19. Can low-cost VOR and Omega receivers suffice for RNAV - A new computer-based navigation technique

    NASA Technical Reports Server (NTRS)

    Hollaar, L. A.

    1978-01-01

    It is shown that although RNAV is particularly valuable for the personal transportation segment of general aviation, it has not gained complete acceptance. This is due, in part, to its high cost and the necessary special-handling air traffic control. VOR/DME RNAV calculations are ideally suited for analog computers, and the use of microprocessor technology has been suggested for reducing RNAV costs. Three navigation systems, VOR, Omega, and DR, are compared for common navigational difficulties, such as station geometry, siting errors, ground disturbances, and terminal area coverage. The Kalman filtering technique is described with reference to the disadvantages when using a system including standard microprocessors. An integrated navigation system, using input data from various low-cost sensor systems, is presented and current simulation studies are noted.

  20. Can low-cost VOR and Omega receivers suffice for RNAV - A new computer-based navigation technique

    NASA Technical Reports Server (NTRS)

    Hollaar, L. A.

    1978-01-01

    It is shown that although RNAV is particularly valuable for the personal transportation segment of general aviation, it has not gained complete acceptance. This is due, in part, to its high cost and the necessary special-handling air traffic control. VOR/DME RNAV calculations are ideally suited for analog computers, and the use of microprocessor technology has been suggested for reducing RNAV costs. Three navigation systems, VOR, Omega, and DR, are compared for common navigational difficulties, such as station geometry, siting errors, ground disturbances, and terminal area coverage. The Kalman filtering technique is described with reference to the disadvantages when using a system including standard microprocessors. An integrated navigation system, using input data from various low-cost sensor systems, is presented and current simulation studies are noted.

  1. Vestibular perception and action employ qualitatively different mechanisms. I. Frequency response of VOR and perceptual responses during Translation and Tilt.

    PubMed

    Merfeld, Daniel M; Park, Sukyung; Gianna-Poulin, Claire; Black, F Owen; Wood, Scott

    2005-07-01

    To investigate the neural mechanisms that humans use to process the ambiguous force measured by the otolith organs, we measured vestibuloocular reflexes (VORs) and perceptions of tilt and translation. One primary goal was to determine if the same, or different, mechanisms contribute to vestibular perception and action. We used motion paradigms that provided identical sinusoidal inter-aural otolith cues across a broad frequency range. We accomplished this by sinusoidally tilting (20 degrees, 0.005-0.7 Hz) subjects in roll about an earth-horizontal, head-centered, rotation axis ("Tilt") or sinusoidally accelerating (3.3 m/s2, 0.005-0.7 Hz) subjects along their inter-aural axis ("Translation"). While identical inter-aural otolith cues were provided by these motion paradigms, the canal cues were substantially different because roll rotations were present during Tilt but not during Translation. We found that perception was dependent on canal cues because the reported perceptions of both roll tilt and inter-aural translation were substantially different during Translation and Tilt. These findings match internal model predictions that rotational cues from the canals influence the neural processing of otolith cues. We also found horizontal translational VORs at frequencies >0.2 Hz during both Translation and Tilt. These responses were dependent on otolith cues and match simple filtering predictions that translational VORs include contributions via simple high-pass filtering of otolith cues. More generally, these findings demonstrate that internal models govern human vestibular "perception" across a broad range of frequencies and that simple high-pass filters contribute to human horizontal translational VORs ("action") at frequencies above approximately 0.2 Hz.

  2. Adaptation of primate vestibuloocular reflex to altered peripheral vestibular inputs. I. Frequency-specific recovery of horizontal VOR after inactivation of the lateral semicircular canals

    NASA Technical Reports Server (NTRS)

    Angelaki, D. E.; Hess, B. J.; Arai, Y.; Suzuki, J.

    1996-01-01

    1. The adaptive plasticity of the vestibuloocular reflex (VOR) following a selective lesion of the peripheral vestibular organs was investigated in rhesus monkeys whose lateral semicircular canals were inactivated by plugging of the canal lumen in both ears. Gain and phase of horizontal, vertical, and torsional slow-phase eye velocity were determined from three-dimensional eye movement recordings obtained acutely after the plugging operation, as well as in regular intervals up to 10 mo later. 2. Acutely after plugging, horizontal VOR was minimal during yaw rotation with gains of < 0.1 at all frequencies. Horizontal VOR gain gradually increased over time, reaching gains of 0.4-0.5 for yaw oscillations at 1.1 Hz approximately 5 mo after lateral canal inactivation. This response recovery was strongly frequency dependent: horizontal VOR gains were largest at the highest frequency tested and progressively decreased for lower frequencies. Below approximately 0.1 Hz, no consistent horizontal VOR could be elicited even 10 mo after plugging. 3. The frequency-dependent changes in gain paralleled changes in horizontal VOR phase. Below approximately 0.1-0.05 Hz large phase leads were present, similarly as in semicircular canal primary afferents. Smaller phase leads were also present at higher frequencies, particularly at 1.1 Hz (the highest frequency tested). 4. Consistent with the afferent-like dynamics of the adapted horizontal VOR, per- and postrotatory horizontal responses to constant-velocity yaw rotations were short lasting. Time constants of the slow-phase eye velocity envelope of the horizontal postrotatory nystagmus were approximately 2 s. Nonetheless, a consistent horizontal optokinetic afternystagmus was evoked in plugged animals. 5. A torsional component that was absent in intact animals was consistently present during yaw rotation acutely after lateral canal inactivation and remained approximately constant thereafter. The frequency response characteristics of this

  3. Adaptation of primate vestibuloocular reflex to altered peripheral vestibular inputs. I. Frequency-specific recovery of horizontal VOR after inactivation of the lateral semicircular canals

    NASA Technical Reports Server (NTRS)

    Angelaki, D. E.; Hess, B. J.; Arai, Y.; Suzuki, J.

    1996-01-01

    1. The adaptive plasticity of the vestibuloocular reflex (VOR) following a selective lesion of the peripheral vestibular organs was investigated in rhesus monkeys whose lateral semicircular canals were inactivated by plugging of the canal lumen in both ears. Gain and phase of horizontal, vertical, and torsional slow-phase eye velocity were determined from three-dimensional eye movement recordings obtained acutely after the plugging operation, as well as in regular intervals up to 10 mo later. 2. Acutely after plugging, horizontal VOR was minimal during yaw rotation with gains of < 0.1 at all frequencies. Horizontal VOR gain gradually increased over time, reaching gains of 0.4-0.5 for yaw oscillations at 1.1 Hz approximately 5 mo after lateral canal inactivation. This response recovery was strongly frequency dependent: horizontal VOR gains were largest at the highest frequency tested and progressively decreased for lower frequencies. Below approximately 0.1 Hz, no consistent horizontal VOR could be elicited even 10 mo after plugging. 3. The frequency-dependent changes in gain paralleled changes in horizontal VOR phase. Below approximately 0.1-0.05 Hz large phase leads were present, similarly as in semicircular canal primary afferents. Smaller phase leads were also present at higher frequencies, particularly at 1.1 Hz (the highest frequency tested). 4. Consistent with the afferent-like dynamics of the adapted horizontal VOR, per- and postrotatory horizontal responses to constant-velocity yaw rotations were short lasting. Time constants of the slow-phase eye velocity envelope of the horizontal postrotatory nystagmus were approximately 2 s. Nonetheless, a consistent horizontal optokinetic afternystagmus was evoked in plugged animals. 5. A torsional component that was absent in intact animals was consistently present during yaw rotation acutely after lateral canal inactivation and remained approximately constant thereafter. The frequency response characteristics of this

  4. [Visual tracking with/without passive whole-body rotation in Parkinson's disease (PD): Dissociation of smooth-pursuit and cancellation of vestibulo-ocular reflex (VOR)].

    PubMed

    Ito, Norie; Takei, Hidetoshi; Chiba, Susumu; Inoue, Kiyoharu; Fukushima, Kikuro

    2016-01-01

    Although impaired smooth-pursuit in Parkinson's disease (PD) is well known, reports are conflicting on the ability to cancel vestibulo-ocular reflex (VOR) when the target moves with head, requiring gaze-pursuit. To compare visual tracking performance with or without passive whole-body rotation, we examined eye movements of 10 PD patients and 6 age-matched controls during sinusoidal horizontal smooth-pursuit and passive whole-body rotation (0.3 Hz, ± 10°). Three tasks were tested: smooth-pursuit, VOR cancellation, and VORx1 while subjects fixated an earth-stationary spot during whole-body rotation. Mean ± SD eye velocity gains (eye velocities/stimulus velocities) of PD patients during the 3 tasks were 0.32 ± 0.24 0.25 ± 0.22, 0.85 ± 0.20, whereas those of controls were 0.91 ± 0.06, 0.14 ± 0.07, 0.94 ± 0.05, respectively. Difference was significant between the two subject groups only during smooth-pursuit. Plotting eye-velocity gains of individual subjects during VOR cancellation against those during smooth-pursuit revealed significant negative linear correlation between the two parameters in the controls, but no correlation was found in PD patients. Based on the regression equation of the controls, we estimated expected eye velocity gains of individual subjects during VOR cancellation from their smooth-pursuit gains. Estimated gains of PD patients during VOR cancellation were significantly different from their actual gains, suggesting that different neural mechanisms operate during VOR cancellation in the controls and PD.

  5. 77 FR 9876 - Proposed Modification of VOR Federal Airways V-10, V-12, and V-508 in the Vicinity of Olathe, KS

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-21

    ... proposing this action to adjust the airway route structure due to the planned decommissioning of the Johnson County VOR/ DME navigation aid located on Johnson County Executive Airport, Olathe, KS. DATES: Comments... The Kansas City Air Route Traffic Control Center requested the decommissioning of the Johnson County...

  6. Experiment K-7-30: Effects of Spaceflight in the Cosmos Biosatellite 2044 on the Vestibular-Ocular Reflex (VOR) of Rhesus Monkeys

    NASA Technical Reports Server (NTRS)

    Cohen, B.; Cohen, N.; Helwig, D.; Solomon, D.; Kozlovskaya, I.; Sirota, M.; Yakushin, S.; Raphan, T.

    1994-01-01

    This technical paper discusses the following: (1) The VOR of two rhesus monkeys was studied before and after 14 days of spaceflight to determine effects of microgravity on the VOR. Horizontal, vertical and roll eye movements were recorded in these and six other monkeys implanted with scleral search coils. Animals were rotated about a vertical axis to determine the gain of the horizontal, vertical and roll VOR. They were rotated about axes tilted from the vertical (off-vertical axis rotation, OVAR) to determine steady state gains and effects of gravity on modulations in eye position and eye velocity. They were also tested for tilt dumping of post-rotatory nystagmus. (2) The gain of the horizontal VOR was close to unity when animals were tested 15 and 18 hours after flight. VOR gain values were similar to those registered before flight. If the gain of the horizontal VOR changes in microgravity, it must revert to normal soon after landing. (3) Steady state velocities of nystagmus induced by off-vertical axis rotation (OVAR) were unchanged by adaptation to microgravity, and the phase of the modulations was similar before and after flight. However, modulations in horizontal eye velocity had more variation after landing and were on mean about 50% larger for angles of tilt of the axis of rotation between 50 and 90?/s after flight. This difference was similar in both animals and was significant. (4) A striking finding was that tilt dumping was lost in the one animal tested for this function. This loss persisted for several days after return. This is reminiscent of the loss of response to pitch while rotating in the M-131 experiments of Skylab, and must be studied in detail in future spaceflights. (5) Thus, two major findings emerged from these studies: after spaceflight the modulation of horizontal eye velocity was larger during OVAR, and one animal lost its ability to tilt-dump its nystagmus. Both findings are consistent with the postulate that adaptation to microgravity

  7. Experiment K-7-30: Effects of Spaceflight in the Cosmos Biosatellite 2044 on the Vestibular-Ocular Reflex (VOR) of Rhesus Monkeys

    NASA Technical Reports Server (NTRS)

    Cohen, B.; Cohen, N.; Helwig, D.; Solomon, D.; Kozlovskaya, I.; Sirota, M.; Yakushin, S.; Raphan, T.

    1994-01-01

    This technical paper discusses the following: (1) The VOR of two rhesus monkeys was studied before and after 14 days of spaceflight to determine effects of microgravity on the VOR. Horizontal, vertical and roll eye movements were recorded in these and six other monkeys implanted with scleral search coils. Animals were rotated about a vertical axis to determine the gain of the horizontal, vertical and roll VOR. They were rotated about axes tilted from the vertical (off-vertical axis rotation, OVAR) to determine steady state gains and effects of gravity on modulations in eye position and eye velocity. They were also tested for tilt dumping of post-rotatory nystagmus. (2) The gain of the horizontal VOR was close to unity when animals were tested 15 and 18 hours after flight. VOR gain values were similar to those registered before flight. If the gain of the horizontal VOR changes in microgravity, it must revert to normal soon after landing. (3) Steady state velocities of nystagmus induced by off-vertical axis rotation (OVAR) were unchanged by adaptation to microgravity, and the phase of the modulations was similar before and after flight. However, modulations in horizontal eye velocity had more variation after landing and were on mean about 50% larger for angles of tilt of the axis of rotation between 50 and 90?/s after flight. This difference was similar in both animals and was significant. (4) A striking finding was that tilt dumping was lost in the one animal tested for this function. This loss persisted for several days after return. This is reminiscent of the loss of response to pitch while rotating in the M-131 experiments of Skylab, and must be studied in detail in future spaceflights. (5) Thus, two major findings emerged from these studies: after spaceflight the modulation of horizontal eye velocity was larger during OVAR, and one animal lost its ability to tilt-dump its nystagmus. Both findings are consistent with the postulate that adaptation to microgravity

  8. Model simulation studies to clarify the effect on saccadic eye movements of initial condition velocities set by the Vestibular Ocular Reflex (VOR)

    NASA Technical Reports Server (NTRS)

    Nam, M. H.; Winters, J. M.; Stark, L.

    1981-01-01

    Voluntary active head rotations produced vestibulo-ocular reflex eye movements (VOR) with the subject viewing a fixation target. When this target jumped, the size of the refixation saccades were a function of the ongoing initial velocity of the eye. Saccades made against the VOR were larger in magnitude. Simulation of a reciprocally innervated model eye movement provided results comparable to the experimental data. Most of the experimental effect appeared to be due to linear summation for saccades of 5 and 10 degree magnitude. For small saccades of 2.5 degrees, peripheral nonlinear interaction of state variables in the neuromuscular plant also played a role as proven by comparable behavior in the simulated model with known controller signals.

  9. The complete genome sequence and analysis of vB_VorS-PVo5, a Vibrio phage infectious to the pathogenic bacterium Vibrio ordalii ATCC-33509.

    PubMed

    Echeverría-Vega, Alex; Morales-Vicencio, Pablo; Saez-Saavedra, Camila; Ceh, Janja; Araya, Rubén

    2016-01-01

    The bacterium Vibrio ordalii is best known as the causative agent of vibriosis outbreaks in fish and thus recognized for generating serious production losses in aquaculture systems. Here we report for the first time on the isolation and the genome sequencing of phage vB_VorS-PVo5, infectious to Vibrio ordalii ATCC 33509. The features as well as the complete genome sequence and annotation of the Vibrio phage are described; vB_VorS-PVo5 consists of a lineal double stranded DNA totaling ~ 80.6 Kb in length. Considering its ability to lyse Vibrio ordalii ATCC 33509, the phage is likely to gain importance in future aquaculture applications by controlling the pathogen and as such replacing antibiotics as the treatment of choice.

  10. Direct causality between single-Purkinje cell activities and motor learning revealed by a cerebellum-machine interface utilizing VOR adaptation paradigm.

    PubMed

    Hirata, Yutaka; Katagiri, Kazuma; Tanaka, Yoshiyuki

    2012-06-01

    A cerebellum-machine interface (CMI) was developed to test direct causality between single-unit cerebellar Purkinje cell activities and motor learning. The CMI converts Purkinje cell simple spike firing rates into a pulse width modulation signal that drives a single-joint robot arm. The CMI has no adaptive capability, thus any changes observed in the robot arm motion can be attributed directly to changes in the Purkinje cell's firing activities. We employed a vestibuloocular reflex (VOR) adaptation paradigm in goldfish as an example of motor learning where desired motion and control error signal of the robot arm were given to the fish as its head rotation and retinal slip, respectively. It is demonstrated that the control error of the robot arm decreased gradually, but not monotonically and in many cases only in one direction. This is the first direct evidence that a single Purkinje cell is capable of adaptive motor control. The results also suggest that a single Purkinje cell can be responsible for directional selective VOR motor learning previously reported in goldfish by Yoshikawa et al. (Conf Proc IEEE Eng Med Biol Soc 1:478-481, 2004) and monkeys by Hirata et al. (J Neurophysiol 85(5):2267-2288, 2002).

  11. Unilateral vestibular deafferentation (UVD) causes permanent asymmetry in the gain of the yaw VOR to high acceleration head impulses in guinea pigs.

    PubMed

    Curthoys, I S; Topple, A N; Halmagyi, G M

    1995-01-01

    Using an acute scleral search coil technique for measuring eye position in alert animals we have shown that after UVD the yaw VOR in the guinea pig shows a permanent gain asymmetry. There is a reduced gain during the first 100 ms of brief, high acceleration horizontal head rotations ("yaw head impulses") towards the operated side, but only a small loss in gain for similar rotations towards the intact side. This result confirms that the horizontal E response during the first 100 ms of an abrupt high acceleration head rotation is a clear indicator of the function of the horizontal canal. These results are similar to those in human patients after unilateral acoustic neuroma operations. The asymmetry in response is large shortly after UVD and decreases over time but is permanent.

  12. Kafka's "Vor dem Gesetz": The Case for an Integrated Approach

    ERIC Educational Resources Information Center

    Pickar, Gertrud Bauer

    1975-01-01

    Uses a parable from a Kafka novel to illustrate and support the premise that language and literature study should be integrated, even in the early stages. Reading short literary works can explain involved language problems better than long explanations, and can also stimulate further literary study. (CHK)

  13. Kafka's "Vor dem Gesetz": The Case for an Integrated Approach

    ERIC Educational Resources Information Center

    Pickar, Gertrud Bauer

    1975-01-01

    Uses a parable from a Kafka novel to illustrate and support the premise that language and literature study should be integrated, even in the early stages. Reading short literary works can explain involved language problems better than long explanations, and can also stimulate further literary study. (CHK)

  14. Messsysteme für die Bildgebung mit Röntgenstrahlung

    NASA Astrophysics Data System (ADS)

    Krieger, Hanno

    Nach einem kurzen Überblick über die heute verwendeten Detektorsysteme zur Erzeugung von Röntgenbildern in der Projektionsradiografie folgt die ausführliche Darstellung der klassischen Kombination von Röntgenfilm und Verstärkungsfolien. Der nächste Abschnitt befasst sich mit den Ausführungen zu Bildverstärkern, den Speicherfolien und den anderen digitalen Festkörperdetektoren. Der Dosisbedarf eines bildgebenden Systems kann bei Film-Folien- Kombinationen durch die Angabe von Empfindlichkeitsklassen definiert werden, bei den digitalen Detektoren geschieht dies mit Hilfe der Dosisindikatoren (Exposure Indicator EI, Abweichungsindikator DI). Im zweiten großen Abschnitt dieses Kapitels werden die Grundlagen der Computertomografie erläutert. Dazu werden zunächst die CT-Gerätegenerationen und die CT-Detektoren besprochen. Nach einer Erläuterung der Rechenverfahren zur Bilderzeugung folgt die Definition der Hounsfield-Einheiten. Den Abschluss bildet eine ausführliche Darstellung der Bildartefakte bei der Computertomografie.

  15. The bedside examination of the vestibulo-ocular reflex (VOR): An update

    PubMed Central

    Kheradmand, A.; Zee, D.S.

    2014-01-01

    Diagnosing dizzy patients remains a daunting challenge to the clinician in spite of modern imaging and increasingly sophisticated electrophysiological testing. Here we review the major bedside tests of the vestibulo-ocular reflex and how, when combined with a proper examination of the other eye movement systems, one can arrive at an accurate vestibular diagnosis. PMID:22981296

  16. Die Anfaenge der Melker Bibliothek - Neue Erkenntnisse zu Handschriften und Fragmenten aus der Zeit vor 1200

    NASA Astrophysics Data System (ADS)

    Glaßner, Christine; Haidinger, Alois

    1996-04-01

    Shortly after Benedictine monks started monastic life in Melk in 1089 the scriptorium was flourishing under abbot Erchenfried (1121-1164). Noteworthy is Cod. 391, a manuscript written in its main part in 1123, but used by the monks as a yearbook with handwritten entries up to the 16th century. This manuscript was also an important source for the publication which dealt with the history of the scriptorium in 12th century. By examining the entries in this book the period of the activity of at least three unknwon writers in this era could be identified. It was the first time that not only the intact volumes but also the manuscripts preserved as fragments in the binding were examined. At the beginning of th 13th century the number of books held in the collection according to the result of this examination was 68. Another remarkable point of the exhibition and of the publication refering to the exhibition was Cod. 412, the oldest manuscript of the monastery, written in early 9th century and containing texts on natural sciences and astronomy by Venerable Bede. Three copies of this manuscript were done during 12th century, one of them probably in Melk, all of them with nearly identical consistency except the catalogue of signs of the zodiac which was ascribed erroneously to Venerable Bede in the Middle Ages: Vatican, Cod. Vat. lat. 643, Zwettl, Cod. 296 (copy of the Vatican manuscript), Klosterneuburg, Cod. 685 (copy of the Zwettl manuscript done in Klosterneuburg). Kurz nach Einführung der Benediktiner in Melk im Jahr 1089 erlebte das Melker Skriptorium unter Abt Erchenfried (1121-1163) seine erste Blüte. Hervorzuheben ist eine im Jahr 1123 angelegte Chronik, die bis in das 16. Jahrhundert durch Annaleneintragungen und andere wichtige Texte zur Geschichte des Klosters ergänzt wurde (Cod. 391). Diese Handschrift ist zugleich eine der wichtigsten Quellen zur Geschichte des Melker Skriptoriums im 12. Jahrhundert, dem sich die Publikation widmet. Mit Hilfe einer genaueren Untersuchung der zeitnahen Eintragungen in diese Handschrift gelang es, die Tätigkeit von zumindest drei wichtigen, im 12. Jahrhundert in Melk identifizierbaren, namentlich nicht bekannten Schreibern chronologisch zuzuordnen. Erstmals wurden die nur fragmentarisch als Makulatur in den Bucheinbänden erhaltenen Handschriften in die Untersuchung einbezogen, so dass für die Wende vom 12. zum 13. Jahrhundert ein Bücherbestand von 68 Handschriften erschlossen werden konnte. Besonders hervorzuheben ist, dass in der Sonderausstellung von 1996 und im Begleitband erstmals eingehend die Bedeutung der ältesten Melker Handschrift, Cod. 412 aus dem frühen 9. Jahrhundert mit naturwissenschaftlichen Texten des Beda Venerabilis, als Vorlage für drei weitere Handschriften diente: Vatikan, Cod. Vat. lat. 643, abgeschrieben wahrscheinlich in Melk, davon abhängig Zwettl, Cod. 296, und Klosterneuburg, Cod. 685. Die Abschriften der Melker Beda-Handschrift sind inhaltlich fast identisch, allerdings um den im Mittelalter fälschlicherweise Beda Venerabilis zugeschriebenen Sternbilderkatalog erweitert.

  17. Gain, phase and frequency stability of DSS-42 and DSS-43 vor Voyage Uranus encounter

    NASA Technical Reports Server (NTRS)

    Cha, A. G.; Levy, R.

    1986-01-01

    Theoretically rigorous definitions are derived of such parameters as RF signal path length, phase delay, and phase/frequency stability in a Cassegrainian antenna applicable to a narrow bandwidth channel, as well as algorithms for evaluating these parameters. This work was performed in support of the Voyager spacecraft encounter with Uranus in January 1986. The information was needed to provide Voyager/Uranus radio science researchers with a rotational basis for deciding the best strategy to operate the three antennas involved during the crucial 5-hour occultation period of the encounter. Such recommendations are made at the end of the article.

  18. Die Keplersche Supernova - Entdeckung vor 400 Jahren [Kepler's supernova: its discovery 400 years ago

    NASA Astrophysics Data System (ADS)

    Posch, Thomas; Maitzen, Hans Michael

    2004-10-01

    We summarize the early observations of SN 1604 made by Johannes Brunowsky and Johannes Kepler in Prague in October 1604. Quoting from Kepler's two books on this subject ("Gründlicher Bericht" and "De stella nova"), we point out that he compared the supernova with respect to its twinkling with an "exquisite multifaceted diamond" and that he thought this object to be rather something like a newly born (proto-)star than a star in its final phase of evolution, as we would call it today. The twinkling of the star was interpreted by Kepler as intrinsic to it rather than an effect of the Earth's atmosphere.

  19. Das baden-württembergische Innovationssystem im Wandel:. Akteure vor neuen Herausforderungen

    NASA Astrophysics Data System (ADS)

    Stahlecker, Thomas; Zenker, Andrea

    2017-09-01

    Recently, new forms of innovation, new actors and actor constellations can be observed, especially in "mature" innovation systems like Baden-Wuerttemberg, that are flanked by new instruments of innovation support. Against the backdrop of an evolved innovation system heuristics, this paper outlines these new developments in Baden-Wuerttemberg. It uses examples to describe characteristic innovation actors, actors from the research landscape, education and the intermediary function of mediators, social actors as well as the aspect of innovation financing and to reveal current tendencies and trends. It becomes clear that the innovation system in Baden-Wuerttemberg has continuously evolved and become more differentiated. Its industries' research efforts and modernization activities as well as innovation-friendly policies contribute to the adaptability of the system and are major influencing factors for the ongoing success of the innovation system. This is supplemented by diverse innovations at the level of actors, institutions and measures. The question concerns the governance and capacity of this complex system given dynamic changing global circumstances.

  20. Horizontal angular VOR changes in orbital and parabolic flight: human neurovestibular studies on SLS-2.

    PubMed

    Oman, C M; Pouliot, C F; Natapoff, A

    1996-07-01

    Further evidence was found for adaptive changes in the vestibular "velocity storage" (VS) component of the vestibuloocular reflex in four shuttle astronauts tested in parabolic flight and before, during, and after a 14-day mission. Nystagmus was recorded during and after 1 min of 120 degrees/s rotation. Gains and time constants were determined by computer analysis. Responses correlated with experience. Two subjects were making their first spaceflight. In parabolic flight, their time constants shortened to an average of 60% of 1 G values, presumably because unfamiliar otolith cues reduced VS. However, after 4-10 days in orbit, their time constants were similar or greater than those preflight, indicating VS recovery. The other two subjects had previously flown in space. Their time constants shortened in orbit to an average of 69% of 1 G values, indicating a persisting reduction of VS. This correlation with spaceflight experience has been seen in 9 of 11 subjects on 3 missions. Head pitch did not significantly "dump" nystagmus as it does on Earth.

  1. [Reasons for rejection of articles vor publication in the Nederlands Tijdschrift voor Geneeskunde in 1990].

    PubMed

    Kan, C C; Lockefeer, J H; Overbeke, A J

    1991-05-11

    To deduce recommendations for authors which decrease the rejection probability we investigated retrospectively which reasons were mentioned in 1990 by the editorial board of the 'Nederlands Tijdschrift voor Geneeskunde' when it rejected original articles, reviews, clinical lessons and case reports, and whether length of the article, professional status of the first author, most relevant specialism and origin of the article influenced the rejection probability. Out of 547 articles 38% (208) were rejected; case reports were rejected most often (49%), reviews least often (33%). Peer review of original articles was the most thorough, of case studies the least. The most frequent reason for rejection in all categories was 'substantial shortcomings', particularly in the original articles (80%). Rejection of clinical lessons and case studies was relatively often due to criteria concerning the clinical message. Both rejected and accepted articles on average exceeded the length limit. Professional status and specialism were associated with a difference in rejection probability (chi 2, p less than 0.05). Specialists had the lowest rejection probability (31%). Nonspecialists benefited from specialist supervision. Articles originating from non-academic institutions were more often rejected than articles from academic centres. We advise authors to judge their articles by means of the criteria mentioned. Consultation of (methodological) experts, literature data bases, and (or) the editorial board can improve their chances. Non-specialists can benefit from the experience and expertise of specialists. In general, scientific attitude and willingness to alter the article according to editorial advice appear to have beneficial results.

  2. Der Physik-Nobelpreis vor 100 Jahren Die Entdeckung des trägen Gases

    NASA Astrophysics Data System (ADS)

    Jacobi, Manfred

    2004-11-01

    Im Jahr 1904 erhielt der britische Physiker Lord Rayleigh (John William Strutt, 1842 bis 1919) den Nobelpreis für seine Untersuchungen über die Dichte von Gasen und die Entdeckung des Edelgases Argon.

  3. The bedside examination of the vestibulo-ocular reflex (VOR): an update.

    PubMed

    Kheradmand, A; Zee, D S

    2012-10-01

    Diagnosing dizzy patients remains a daunting challenge to the clinician in spite of modern imaging and increasingly sophisticated electrophysiological testing. Here we review the major bedside tests of the vestibulo-ocular reflex and how, when combined with a proper examination of the other eye movement systems, one can arrive at an accurate vestibular diagnosis.

  4. 76 FR 61257 - Amendment to Description of VOR Federal Airway V-299; CA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-04

    ... in Title 49 of the United States Code. Subtitle I, section 106 describes the authority of the FAA... Environmental Policy Act in accordance with FAA Order 1050.1E, Environmental Impacts: Polices and Procedures... below 5,000 feet MSL is excluded. The portion outside the United States has no upper limit. Issued in...

  5. 78 FR 9009 - Proposed Amendment of VOR Federal Airway V-595; OR

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-07

    ... terrain and navigation aid coverage issues. DATES: Comments must be received on or before March 25, 2013... regulatory action. List of Subjects in 14 CFR Part 71 Airspace, Incorporation by reference, Navigation (air... comments were received. The NPRM would have terminated V-595 at the HARZL navigation fix, which is...

  6. Sound-evoked vestibulo-ocular reflexes (VOR) in trained monkeys.

    PubMed

    Zhou, Wu; Mustain, W; Simpson, I

    2004-05-01

    Acoustic stimulation of the vestibular system has been well documented in humans and has been accepted as a useful tool to diagnose vestibular disorders. The goal of this study was to establish an awake and behaving primate model that might be useful for investigating the neural mechanisms underlying acoustic activation of the vestibular system. We recorded sound-evoked eye movements in monkeys while they performed ocular motor tasks. In the first part of the study, an acoustic click (1 ms, 99 to approximately 125 db peak SPL) was delivered to one of the monkeys' ears while they fixated on visual targets of varying eccentricities and viewing distances. Acoustic clicks were found to evoke well-defined biphasic eye velocity responses. For the movement in the horizontal direction, the first eye velocity peaks were always away from the stimulated ear. For the movement in the vertical direction, however, the directions of the first eye velocity peaks varied from monkey to monkey. This variability was difficult to interpret in the absence of torsional measurement. Thus, our analysis in this report was focused on horizontal eye movements. We found that click-evoked eye movements were disjunctive, with larger first horizontal eye velocity peaks from the eye ipsilateral to the stimulated ear (the amplitude ratio was 1.8 +/- 0.3, n=4). The amplitudes of the first horizontal peaks were also linearly correlated with gaze eccentricity and viewing distance. In the second part of the study, we found that a brief tone-pulse (100 ms, 125 db peak SPL) evoked eye movements that exhibited a well-defined frequency tuning with the most effective stimulating frequencies ranging from 1 K to 1.5 KHz. These data demonstrate that the sound-evoked eye movements in behaving monkeys are well defined and reproducible. This paradigm may be useful for studying the neural mechanisms underlying acoustic activation of the vestibular system.

  7. Fremdsprachliche Moglichkeiten vor der "eigenen Haustur" (Foreign Language Possibilities at One's Own Doorstep)

    ERIC Educational Resources Information Center

    Zydatiss, Wolfgang

    1973-01-01

    Describes an instructional project, How to Tell a Foreigner to Berlin the Way,'' designed to give 8th graders practical experience in using English; format based on the text London--People ans Pictures,'' Cornelsen-Velhagen & Klasing, Berlin. (RS)

  8. 77 FR 23113 - Modification of VOR Federal Airways V-135 and V-137; Southwest United States

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-18

    ... traffic control coordination for aircraft proceeding across the United States--Mexican border. DATES... benefit cross-border navigation. Additionally, fixes are established at the border crossing points...

  9. Sterblichkeit: der paradoxe Kunstgriff des Lebens - Eine Betrachtung vor dem Hintergrund der modernen Biologie

    NASA Astrophysics Data System (ADS)

    Verbeek, Bernhard

    Leben gibt es auf der Erde seit fast 4 Mio. Jahren, trotz allen Katastrophen. Die Idee des Lebens scheint unsterblich. Der Tod aber offenbar auch. Jedes Lebewesen ist davon bedroht, ja für Menschen und andere "höhere“ Lebewesen ist er im Lebensprogramm eingebaut - todsicher. Diese Tatsache ist alles andere als selbstverständlich. Ist sie überhaupt kompatibel mit dem Prinzip der Evolution, nach dem der am besten Angepasste überlebt?

  10. Tests with Coaxial TACAN Antenna at Doppler Very High Frequency Omnirange (VOR).

    DTIC Science & Technology

    The report describes the performance of Doppler very high frequency omnirange ( DVOR ) systems with and without a coaxially located tactical air...navigation (TACAN) antenna. Flight tests were conducted to determine double-sideband DVOR (DSDVOR) and single-sideband DVOR (SSDVOR) system performance for

  11. 76 FR 13083 - Amendment to VOR Federal Airway V-358; TX

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-10

    ... coincides with the FAA's aeronautical database. DATES: Effective date 0901 UTC, May 5, 2011. The Director of... with the FAA's aeronautical database. Since this is an administrative change, and does not affect...

  12. 78 FR 1751 - Modification of VOR Federal Airway V-170 in the Vicinity of Devils Lake, ND

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-09

    ..., Devils Lake, ND, to support non- radar separation requirements when the restricted area is active. DATES...-radar separation and airway clearance from the newly established R-5402, Devils Lake, ND (77 FR 54860... T- route, in addition to V-170, that would maintain appropriate separation from R-5402. The...

  13. 77 FR 54860 - Proposed Modification of VOR Federal Airway V-170 in the Vicinity of Devils Lake, ND

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-06

    ..., MN; Rochester, MN; Nodine, MN; Dells, WI; INT Dells 097 and Badger, WI, 304 radials; Badger; INT Badger 121 and Pullman, MI, 282 radials; Pullman; Salem, MI. From Erie, PA; Bradford, PA; Slate Run,...

  14. A realistic neural-network simulation of both slow and quick phase components of the guinea pig VOR.

    PubMed

    Cartwright, Andrew D; Gilchrist, Darrin P D; Burgess, Ann M; Curthoys, Ian S

    2003-04-01

    A realistic neural-network model was constructed to simulate production of both the slow-phase and quick-phase components of vestibular nystagmus by incorporating a quick-phase pathway into a previous model of the slow phase. The neurons in the network were modelled by multicompartmental Hodgkin-Huxley-style spiking neurons based on known responses and projections of physiologically identified vestibular neurons. The modelling used the GENESIS software package. The slow-phase network consisted of ganglion and medial vestibular nucleus (MVN) neurons; the latter were constructed using biophysical models of MVN type A and B neurons. The quick-phase network contained several types of bursting cells which have been shown to have major roles in the generation of the quick phase: burster-driver neurons, long-lead burst neurons, pause neurons, excitatory burst neurons and inhibitory burst neurons. Comparison of the output neural responses from the model with guinea pig behavioural responses from the companion paper showed consistency between model and animal data for neuron firing patterns, maximal firing rates, and timing, duration and number of quick phases. Comparisons were made for stable head input and for sinusoidal angular stimuli at a range of frequencies from 0.1 to 2 Hz. Except for data at 0.1 Hz, where the simulation produced one more quick phase per half cycle than the animal data, the number of quick phases was consistent between the model and the animal data. The model was also used to simulate the effects both of unilateral vestibular deafferentation (UVD) and of vestibular compensation after UVD, and the responses in the modelled MVN neurons were affected in a way similar to those measured in guinea pig MVN neurons: the number of quick phases and their timing changed in a similar fashion to that observed in behavioural data.

  15. 75 FR 43813 - Modification of VOR Federal Airways V-82, V-175, V-191, and V-430 in the Vicinity of Bemidji, MN

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-27

    ... terrain and new construction signal interference problems and is planned for decommissioning. An airway... the Order. The FAA has determined that this regulation only involves an established body of technical.... Therefore, this regulation: (1) Is not a ``significant regulatory action'' under Executive Order 12866;...

  16. 75 FR 24504 - Proposed Modification of VOR Federal Airways V-82, V-175, V-191, and V-430 in the Vicinity of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-05

    ... Transportation, Docket Operations, M-30, 1200 New Jersey Avenue SE., West Building Ground Floor, Room W12-140... Group, Office of System Operations Airspace and AIM, Federal Aviation Administration, 800 Independence..., Operations Support Group, Federal Aviation Administration, 2601 Meacham Blvd., Fort Worth, TX 76137....

  17. Die Biomasse mariner Makrobenthos-Gesellschaften im Einflußbereich der Klärschlammverklappung vor der Elbemündung

    NASA Astrophysics Data System (ADS)

    Mühlenhardt-Siegel, U.

    1981-12-01

    The macrofauna of a dumping area in the eastern part of the German Bight (North Sea) was investigated in July, August and November, 1978 at five stations situated on a transect including central and peripheral areas of the dumping region. Abundance and biomass (ash free dry weight) of the macrofauna and its variation from July to November were analysed as well as the biomass of different taxa. Molluscs dominated over polychaetes, crustaceans and echinoderms. A positive correlation seemed to exist between mud content and biomass at the peripherally situated stations. In the central sewage sludge area, however, the biomass values were reduced. In late autumn the biomass decreased in the entire area due to the death of Diastylis rathkei, Abra alba and Pectinaria koreni. These species were replaced by the mollusc Nucula turgida and polychaete Nephtys hombergii. In autumn the biomass values also showed a distinct minimum at the central stations.

  18. Implementation of the Numerical Electromagnetic Code (NEC-2) for Modeling the VOR (Very-High-Frequency Omni-Directional Range) Navigation System in the Presence of Parasitic Scatterers

    DTIC Science & Technology

    1986-06-13

    TIME FROM 0 TO 1/30 SECONDS IN 256 STEPS C DO 20 INC = 1,256 T = DFLOAT(INC-1)/(256.DO*30.D0) CREF = DCMPLX(O.DO,2.DO) C C CALCULATE RECEIVED FIELD... STEPS C DO 20 INC =1,256 T = FLOAT(INC-1)/(2156.D0*30.D0) CBIAS =CMPLX(0.DO,2.DO) C C CALCULATE RECEIVED FIELD FOR GIVEN TIME AND POSITION C CREC(INC...FAZR) AIMVLT(I,N)=VLTSPM(I,N)*DSIN(FAZR) 55 CONTINUE C C OUTSIDE LOOP INCREMENTS AZIMUTH ANGLE IN 5 DEGREE STEPS C 1 00 30 IAZ = 1,7.3 AZ = DFLOAT(IAZ

  19. 78 FR 18928 - Proposed Amendment of Class E Airspace; Tuskegee, AL

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-28

    ... action proposes to amend Class E Airspace at Tuskegee, AL, as the Tuskegee VOR/DME has been... necessary due to the decommissioning of the Tuskegee VOR/DME and cancellation of the VOR approach, and...

  20. 77 FR 3091 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-23

    ... in Part Grand Junction, CO VOR/DME....... *Paces, CO FIX 11500 *13000--MRA *Paces, CO FIX Slolm, CO... Junction, CO VOR/DME....... *Paces, CO FIX 11500 *13000--MRA *Paces, CO FIX Slolm, CO FIX.. 13000 *13000... VOR Federal Airway V591 Is Amended To Read in Part Grand Junction, CO VOR/DME....... *Paces, CO FIX...

  1. 76 FR 37263 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-27

    .... 97.23 VOR, VOR/DME, VOR or TACAN, and VOR/DME or TACAN; Sec. 97.25 LOC, LOC/DME, LDA, LDA/DME, SDF, SDF/DME; Sec. 97.27 NDB, NDB/DME; Sec. 97.29 ILS, ILS/DME, MLS, MLS/DME, MLS/RNAV; Sec. 97.31...

  2. 76 FR 52237 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-22

    .... 97.23 VOR, VOR/DME, VOR or TACAN, and VOR/DME or TACAN; Sec. 97.25 LOC, LOC/DME, LDA, LDA/DME, SDF, SDF/DME; Sec. 97.27 NDB, NDB/DME; Sec. 97.29 ILS, ILS/DME, MLS, MLS/DME, MLS/RNAV; Sec. 97.31...

  3. 78 FR 5132 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-24

    .... 97.23 VOR, VOR/DME, VOR or TACAN, and VOR/DME or TACAN; Sec. 97.25 LOC, LOC/DME, LDA, LDA/DME, SDF, SDF/DME; Sec. 97.27 NDB, NDB/DME; Sec. 97.29 ILS, ILS/DME, MLS, MLS/DME, MLS/RNAV; Sec. 97.31...

  4. 76 FR 55235 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-07

    .... 97.23 VOR, VOR/DME, VOR or TACAN, and VOR/DME or TACAN; Sec. 97.25 LOC, LOC/DME, LDA, LDA/DME, SDF, SDF/DME; Sec. 97.27 NDB, NDB/DME; Sec. 97.29 ILS, ILS/DME, MLS, MLS/DME, MLS/RNAV; Sec. 97.31...

  5. 78 FR 5130 - Standard Instrument Approach Procedures and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-24

    .... 97.23 VOR, VOR/DME, VOR or TACAN, and VOR/DME or TACAN; Sec. 97.25 LOC, LOC/DME, LDA, LDA/DME, SDF, SDF/DME; Sec. 97.27 NDB, NDB/DME; Sec. 97.29 ILS, ILS/DME, MLS, MLS/DME, MLS/RNAV; Sec. 97.31...

  6. 77 FR 18679 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-28

    .... 97.23 VOR, VOR/DME, VOR or TACAN, and VOR/DME or TACAN; Sec. 97.25 LOC, LOC/DME, LDA, LDA/DME, SDF, SDF/DME; Sec. 97.27 NDB, NDB/DME; Sec. 97.29 ILS, ILS/DME, MLS, MLS/DME, MLS/RNAV; Sec. 97.31...

  7. 75 FR 21981 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-27

    .... 97.23 VOR, VOR/DME, VOR or TACAN, and VOR/DME or TACAN; Sec. 97.25 LOC, LOC/DME, LDA, LDA/DME, SDF, SDF/DME; Sec. 97.27 NDB, NDB/DME; Sec. 97.29 ILS, ILS/DME, MLS, MLS/DME, MLS/RNAV; Sec. 97.31...

  8. 78 FR 28133 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-14

    .... 97.23 VOR, VOR/DME, VOR or TACAN, and VOR/DME or TACAN; Sec. 97.25 LOC, LOC/DME, LDA, LDA/DME, SDF, SDF/DME; Sec. 97.27 NDB, NDB/DME; Sec. 97.29 ILS, ILS/DME, MLS, MLS/DME, MLS/RNAV; Sec. 97.31...

  9. 76 FR 16686 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-25

    .... 97.23 Vor, Vor/DME, Vor or TACAN, and Vor/DME or TACAN; Sec. 97.25 LOC, LOC/DME, LDA, LDA/DME, SDF, SDF/DME; Sec. 97.27 NDB, NDB/DME; Sec. 97.29 ILS, ILS/DME, MLS, MLS/DME, MLS/RNAV; Sec. 97.31...

  10. 76 FR 43578 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-21

    .... 97.23 VOR, VOR/DME, VOR or TACAN, and VOR/DME or TACAN; Sec. 97.25 LOC, LOC/DME, LDA, LDA/DME, SDF, SDF/DME; Sec. 97.27 NDB, NDB/DME; Sec. 97.29 ILS, ILS/DME, MLS, MLS/DME, MLS/RNAV; Sec. 97.31...

  11. 77 FR 33085 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-05

    .... 97.23 VOR, VOR/DME, VOR or TACAN, and VOR/DME or TACAN; Sec. 97.25 LOC, LOC/DME, LDA, LDA/DME, SDF, SDF/DME; Sec. 97.27 NDB, NDB/DME; Sec. 97.29 ILS, ILS/DME, MLS, MLS/DME, MLS/RNAV; Sec. 97.31...

  12. "Onkle Karl" aus Milwaukee: Deutsch-amerikanische Einwandererkultur im Spiegel der Jugendliteratur vor hundert Jahren (Uncle Carl from Milwaukee: German-American Newcomer Culture Reflected in Children's Literature a Hundred Years Ago).

    ERIC Educational Resources Information Center

    Weiss, Gerhard

    1998-01-01

    Examines a late nineteenth-century Milwaukee (Wisconsin) publication for children and young people as a reflection of German-American middle-class culture of the time, showing how the spirit of the 1848 revolution and the experience of the American Civil War shaped German-American intellectuals and how the ideals of freedom and equality dominated…

  13. "Onkle Karl" aus Milwaukee: Deutsch-amerikanische Einwandererkultur im Spiegel der Jugendliteratur vor hundert Jahren (Uncle Carl from Milwaukee: German-American Newcomer Culture Reflected in Children's Literature a Hundred Years Ago).

    ERIC Educational Resources Information Center

    Weiss, Gerhard

    1998-01-01

    Examines a late nineteenth-century Milwaukee (Wisconsin) publication for children and young people as a reflection of German-American middle-class culture of the time, showing how the spirit of the 1848 revolution and the experience of the American Civil War shaped German-American intellectuals and how the ideals of freedom and equality dominated…

  14. Curved spaces before Einstein: Karl Schwarzschild's cosmological speculations and the beginnings of relativistic cosmology (German Title: Gekrümmte Universen vor Einstein: Karl Schwarzschilds kosmologische Spekulationen und die Anfänge der relativistischen Kosmologie)

    NASA Astrophysics Data System (ADS)

    Schemmel, Matthias

    In contrast to most of his collegues in astronomy and physics, the German astronomer Karl Schwarzschild immediately recognized the significance of general relativity for physics and astronomy, and played a pioneering role in its early development. In this contribution, it is argued that the clue for understanding Schwarzschild's exceptional reaction to general relativity lies in the study of his prerelativistic work. Long before the rise of general relativity, Schwarzschild occupied himself with foundational problems on the borderline of physics, astronomy, and mathematics that, from today's perspective, belong to the field of problems of that theory. In this contribution, the example of Schwarzschild's early speculations about the non-Euclidean nature of physical space on cosmological scales is presented and their reflection in his reception of general relativity is discussed.

  15. Aviation System Capacity Plan (1991-1992)

    DTIC Science & Technology

    1992-01-01

    DSB) DVOR , 50 ing compatible DME systems will replace existing DME DVORs have been retrofitted with RNMM and DSB, 35 systems at 40 VOR/DME sites. The...at ILSs, and convert estate considerations, and site suitability. Conventional VORs 94 VORs to DSB DVOR are being converted to Doppler VORs to solve...DSUA ................ Dynamic Special-Use Airspace MLS ................... Microwave Landing System DVOR ................ Doppler VOR MOA

  16. 75 FR 8241 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-24

    ... Airpark, RNAV (GPS) RWY 9, Amdt 1 Atlanta, GA, Newman Coweta County, VOR/DME-A, Amdt 8 Le Mars, IA, Le Mars Muni, VOR/DME RWY 36, Amdt 3 Greenville, IL, Greenville, Takeoff Minimums and Obstacle DP, Orig...

  17. 77 FR 50909 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-23

    ... To Read in Part Keating, PA VORTAC Watso, PA FIX 4700 Watso, PA FIX Milton, PA VORTAC...... *4000 *2900--MOCA Milton, PA VORTAC Solberg, NJ VOR/DME.... 4000 Solberg, NJ VOR/DME Tykes, NJ FIX 2300...

  18. 75 FR 916 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-07

    ... Tompkins Rgnl, VOR RWY 14, Amdt 14 Ithaca, NY, Ithaca Tompkins Rgnl, VOR RWY 32, Amdt 2 Isla De Vieques, PR..., Sugar Land Rgnl, NDB RWY 17, Orig, CANCELLED Salt Lake City, UT, Salt Lake City Intl, Takeoff Minimums...

  19. 77 FR 24157 - Proposed Establishment of Area Navigation (RNAV) Routes; Southwestern United States

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-23

    ... portions of VOR Federal airways V-16 and V-202. DATES: Comments must be received on or before June 7, 2012... portions of VOR Federal airways V-16 and V-202 that will be affected by the scheduled decommissioning...

  20. 76 FR 25232 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-04

    ..., VOR/DME RWY 35, Orig-A, CANCELLED Lincoln Park, NJ, Lincoln Park, NDB RWY 1, Amdt 3, CANCELLED Clovis, NM, Clovis Muni, Takeoff Minimums and Obstacle DP, Orig Lima, OH, Lima Allen County, VOR RWY 28,...

  1. 77 FR 23172 - Proposed Amendment of Class E Airspace; Woodland, CA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-18

    ... decommissioning of the Travis VHF Omni-Directional Radio Range (VOR) has made this action necessary for the safety... reconfiguration is necessary due to the proposed decommissioning of the Travis VOR and would enhance the safety...

  2. 77 FR 37799 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-25

    .... Part 97 is amended to read as follows: By amending: Sec. 97.23 VOR, VOR/DME, VOR or TACAN, and VOR/DME or TACAN; Sec. 97.25 LOC, LOC/DME, LDA, LDA/DME, SDF, SDF/DME; Sec. 97.27 NDB, NDB/DME; Sec. 97.29 ILS, ILS/DME, MLS, MLS/DME, MLS/RNAV; Sec. 97.31 RADAR SIAPs; Sec. 97.33 RNAV SIAPs; and Sec....

  3. 14 CFR 91.161 - Special awareness training required for pilots flying under visual flight rules within a 60...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... pilots flying under visual flight rules within a 60-nautical mile radius of the Washington, DC VOR/DME... flight rules within a 60-nautical mile radius of the Washington, DC VOR/DME. (a) Operations within a 60-nautical mile radius of the Washington, DC VOR/DME under visual flight rules (VFR). Except as...

  4. 14 CFR 91.161 - Special awareness training required for pilots flying under visual flight rules within a 60...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... pilots flying under visual flight rules within a 60-nautical mile radius of the Washington, DC VOR/DME... flight rules within a 60-nautical mile radius of the Washington, DC VOR/DME. (a) Operations within a 60-nautical mile radius of the Washington, DC VOR/DME under visual flight rules (VFR). Except as...

  5. 14 CFR 91.161 - Special awareness training required for pilots flying under visual flight rules within a 60...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... pilots flying under visual flight rules within a 60-nautical mile radius of the Washington, DC VOR/DME... flight rules within a 60-nautical mile radius of the Washington, DC VOR/DME. (a) Operations within a 60-nautical mile radius of the Washington, DC VOR/DME under visual flight rules (VFR). Except as...

  6. 14 CFR 91.161 - Special awareness training required for pilots flying under visual flight rules within a 60...

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... pilots flying under visual flight rules within a 60-nautical mile radius of the Washington, DC VOR/DME... flight rules within a 60-nautical mile radius of the Washington, DC VOR/DME. (a) Operations within a 60-nautical mile radius of the Washington, DC VOR/DME under visual flight rules (VFR). Except as...

  7. 77 FR 35836 - Amendment of Air Traffic Service Routes; Southwestern United States

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-15

    ...: This action modifies Jet Route J-2, and VOR Federal airways V- 16, V-66 and V-202 in southern Arizona... Register of May 23, 2012 (77 FR 30437) corrected the description of VOR Federal airway V-16. Interested... VOR Federal airways V-16, V-66 and V-202 in southern Arizona and New Mexico. The FAA is taking...

  8. 78 FR 40078 - Proposed Establishment of Class E Airspace; Cody, WY

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-03

    .../Distance Measuring Equipment (VOR/DME) navigation aid, Cody, WY, to facilitate vectoring of Instrument... route domestic airspace extending upward from 1,200 feet above the surface at the Cody VOR/DME... airspace the Cody VOR/DME, Cody, WY. This proposal will be subject to an environmental analysis...

  9. 78 FR 45475 - Proposed Establishment of Class E Airspace; Rome, OR

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-29

    ... Measuring Equipment (VOR/DME) navigation aid, Rome, OR, to facilitate vectoring of Instrument Flight Rules... route domestic airspace extending upward from 1,200 feet above the surface at the Rome VOR/DME... would establish controlled airspace at the Rome VOR/DME, Rome, OR. This proposal will be subject to...

  10. 14 CFR 93.350 - Definitions.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... of Manhattan Island, thence north along the west bank of the East River to the LGA VOR/DME 6-mile arc... the LGA VOR/DME 6-mile arc to the north tip of Roosevelt Island. (d) New York Class B airspace Hudson... intersect the Colts Neck VOR/DME 012° radial, thence southwest along the Colts Neck 012° radial to...

  11. 76 FR 78576 - Proposed Amendment of Class E Airspace; Hugo, CO

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-19

    .../Distance Measuring Equipment (VOR/DME). This action also would make a minor adjustment to the geographic coordinates of the VOR/DME and make a correction to the regulatory text. DATES: Comments must be received on... vicinity of the Hugo VOR/ DME, CO. The airspace update is necessary due to the decommissioning of the...

  12. 78 FR 41337 - Proposed Establishment of Class E Airspace; Glasgow, MT

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-10

    .../Distance Measuring Equipment (VOR/DME) navigation aid, Glasgow, MT, to facilitate vectoring of Instrument... route domestic airspace extending upward from 1,200 feet above the surface at the Glasgow VOR/DME... controlled airspace the Glasgow VOR/ DME, Glasgow, MT. This proposal will be subject to an...

  13. 14 CFR 93.350 - Definitions.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... of Manhattan Island, thence north along the west bank of the East River to the LGA VOR/DME 6-mile arc... the LGA VOR/DME 6-mile arc to the north tip of Roosevelt Island. (d) New York Class B airspace Hudson... intersect the Colts Neck VOR/DME 012° radial, thence southwest along the Colts Neck 012° radial to...

  14. 78 FR 18266 - Proposed Establishment of Class E Airspace; Gillette, WY

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-26

    ... Radio Range/Distance Measuring Equipment (VOR/DME), Gillette, WY to facilitate vectoring of Instrument... route domestic airspace extending upward from 1,200 feet above the surface at the Gillette VOR/DME... airspace at Gillette VOR/DME, Gillette, WY. This proposal will be subject to an environmental analysis...

  15. 14 CFR 93.350 - Definitions.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... of Manhattan Island, thence north along the west bank of the East River to the LGA VOR/DME 6-mile arc... the LGA VOR/DME 6-mile arc to the north tip of Roosevelt Island. (d) New York Class B airspace Hudson... intersect the Colts Neck VOR/DME 012° radial, thence southwest along the Colts Neck 012° radial to...

  16. 78 FR 25404 - Proposed Establishment of Class E Airspace; Grand Canyon, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-01

    ... Range/Distance Measuring Equipment (VOR/DME) navigation aid, Grand Canyon, AZ, to facilitate vectoring... route domestic airspace extending upward from 1,200 feet above the surface at the Grand Canyon VOR/DME... airspace at the Grand Canyon VOR/DME, Grand Canyon, AZ. This proposal will be subject to an...

  17. 14 CFR 93.350 - Definitions.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... southwest tip of Manhattan Island, thence north along the west bank of the East River to the LGA VOR/DME 6... River, from the LGA VOR/DME 6-mile arc to the north tip of Roosevelt Island. (d) New York Class B... River to intersect the Colts Neck VOR/DME 012° radial, thence southwest along the Colts Neck 012°...

  18. 14 CFR 93.350 - Definitions.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... of Manhattan Island, thence north along the west bank of the East River to the LGA VOR/DME 6-mile arc... the LGA VOR/DME 6-mile arc to the north tip of Roosevelt Island. (d) New York Class B airspace Hudson... intersect the Colts Neck VOR/DME 012° radial, thence southwest along the Colts Neck 012° radial to...

  19. 78 FR 65554 - Establishment of Class E Airspace; Rome, OR

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-01

    ... at the Rome VHF Omni- Directional Radio Range/Distance Measuring Equipment (VOR/DME) ] navigation aid... the surface, at the Rome VOR/DME navigation aid, Rome, OR, to accommodate IFR aircraft under control... within the scope of that authority as it establishes controlled airspace at the Rome VOR/DME, Rome,...

  20. 78 FR 14032 - Proposed Establishment of Class E Airspace; Cherokee, WY

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-04

    .../Distance Measuring Equipment (VOR/DME) navigation aid, Cherokee, WY to facilitate vectoring of Instrument... route domestic airspace extending upward from 1,200 feet above the surface at the Cherokee VOR/DME... airspace at the Cherokee VOR/DME, Cherokee, WY. This proposal will be subject to an environmental...

  1. 75 FR 41773 - Proposed Amendment of Class E Airspace; Arco, ID

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-19

    ....) Burley VOR/DME (Lat. 42 34'49'' N., long. 113 51'57'' W.) That airspace extending from 700 feet above the...-365 to the Burley VOR/DME, thence northwest along V-231 to 29 miles northwest of the Burley VOR/DME on...

  2. 78 FR 9583 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-11

    ... Airway V101 is Amended to Read in Part BURLEY, ID VOR/DME REAPS, ID FIX........ S BND 7000 N BND 9500... BURLEY, ID VOR/DME... *8000 *7000--MOCA Sec. 95.6447 VOR Federal Airway V447 is Amended to Read in Part...

  3. Subchronic vortioxetine treatment -but not escitalopram- enhances pyramidal neuron activity in the rat prefrontal cortex.

    PubMed

    Riga, Maurizio S; Teruel-Martí, Vicent; Sánchez, Connie; Celada, Pau; Artigas, Francesc

    2017-02-01

    Vortioxetine (VOR) is a multimodal antidepressant drug. VOR is a 5-HT3-R, 5-HT7-R and 5-HT1D-R antagonist, 5-HT1B-R partial agonist, 5-HT1A-R agonist, and serotonin transporter (SERT) inhibitor. VOR shows pro-cognitive activity in animal models and beneficial effects on cognitive dysfunction in major depressive patients. Here we compared the effects of 14-day treatments with VOR and escitalopram (ESC, selective serotonin reuptake inhibitor) on neuronal activity in the medial prefrontal cortex (mPFC). Ten groups of rats (5 standard, 5 depleted of 5-HT with p-chlorophenylalanine -pCPA-, used as model of cognitive impairment) were fed with control food or with two doses of VOR-containing food. Four groups were implanted with minipumps delivering vehicle or ESC 10 mg/kg·day s.c. The two VOR doses enable occupation by VOR of SERT+5-HT3-R and all targets, respectively, and correspond to SERT occupancies in patients treated with 5 and 20 VOR mg/day, respectively. Putative pyramidal neurons (n = 985) were recorded extracellularly in the mPFC of anesthetized rats. Sub-chronic VOR administration (but not ESC) significantly increased neuronal discharge in standard and 5-HT-depleted conditions, with a greater effect of the low VOR dose in standard rats. VOR increased neuronal discharge in infralimbic (IL) and prelimbic (PrL) cortices. Hence, oral VOR doses evoking SERT occupancies similar to those in treated patients increase mPFC neuronal discharge. The effect in 5-HT-depleted rats cannot be explained by an antagonist action of VOR at 5-HT3-R and suggests a non-canonical interaction of VOR with 5-HT3-R. These effects may underlie the superior pro-cognitive efficacy of VOR compared with SSRIs in animal models.

  4. Visual influences on the development and recovery of the vestibuloocular reflex in the chicken.

    PubMed

    Goode, C T; Maney, D L; Rubel, E W; Fuchs, A F

    2001-03-01

    Whenever the head turns, the vestibuloocular reflex (VOR) produces compensatory eye movements to help stabilize the image of the visual world on the retina. Uncompensated slip of the visual world across the retina results in a gradual change in VOR gain to minimize the image motion. VOR gain changes naturally during normal development and during recovery from neuronal damage. We ask here whether visual slip is necessary for the development of the chicken VOR (as in other species) and whether it is required for the recovery of the VOR after hair cell loss and regeneration. In the first experiment, chickens were reared under stroboscopic illumination, which eliminated visual slip. The horizontal and vertical VORs (h- and vVORs) were measured at different ages and compared with those of chickens reared in normal light. Strobe-rearing prevented the normal development of both h- and vVORs. After 8 wk of strobe-rearing, 3 days of exposure to normal light caused the VORs to recover partially but not to normal values. In the second experiment, 1-wk-old chicks were treated with streptomycin, which destroys most vestibular hair cells and reduces hVOR gain to zero. In birds, vestibular hair cells regenerate so that after 8 wk in normal illumination they appear normal and hVOR gain returns to values that are normal for birds of that age. The treated birds in this study recovered in either normal or stroboscopic illumination. Their hVOR and vVOR and vestibulocollic reflexes (VCR) were measured and compared with those of untreated, age-matched controls at 8 wk posthatch, when hair cell regeneration is known to be complete. As in previous studies, the gain of the VOR decreased immediately to zero after streptomycin treatment. After 8 wk of recovery under normal light, the hVOR was normal, but vVOR gain was less than normal. After 8 wk of recovery under stroboscopic illumination, hVOR gain was less than normal at all frequencies. VCR recovery was not affected by the strobe

  5. Chemical and functional properties of fibre concentrates obtained from by-products of coconut kernel.

    PubMed

    Yalegama, L L W C; Nedra Karunaratne, D; Sivakanesan, Ramiah; Jayasekara, Chitrangani

    2013-11-01

    The coconut kernel residues obtained after extraction of coconut milk (MR) and virgin coconut oil (VOR) were analysed for their potential as dietary fibres. VOR was defatted and treated chemically using three solvent systems to isolate coconut cell wall polysaccharides (CCWP). Nutritional composition of VOR, MR and CCWPs indicated that crude fibre, neutral detergent fibre, acid detergent fibre and hemicelluloses contents were higher in CCWPs than in VOR and MR. MR contained a notably higher content of fat than VOR and CCWPs. The oil holding capacity, water holding capacity and swelling capacity were also higher in CCWPs than in VOR and MR. All the isolates and MR and VOR had high metal binding capacities. The CCWPs when compared with commercially available fibre isolates, indicated improved dietary fibre properties. These results show that chemical treatment of coconut kernel by-products can enhance the performance of dietary fibre to yield a better product.

  6. Willkommen, Mr. Chance: Methodologische Betrachtungen zur Gute empirischer Forschung in der Padagogik, diskutiert vor allem an der neueren Untersuchung uber Gewalt von Heitmeyer u.a. (1995) = Welcome, Mr. Chance: Methodological Considerations Concerning the Quality of Empirical Research in Educational Science Based on a Recent Study on Violence Published by Heitmeyer et al. (1995).

    ERIC Educational Resources Information Center

    Wellenreuther, Martin

    1997-01-01

    Argues that the usefulness of strictly quantitative research is still questioned in educational studies, primarily due to deficiencies in methodological training. Uses a critique of a recent study by Heitmeyer et al. (1995) to illustrate the requirements of "good" empirical research. Considers the problems of hypothesis testing in field research.…

  7. Studies of the horizontal vestibulo-ocular reflex on STS 7 and 8

    NASA Technical Reports Server (NTRS)

    Thornton, William E.; Uri, John J.; Moore, Thomas P.; Pool, Sam L.

    1988-01-01

    Unpaced voluntary horizontal head oscillation was used to study the Vestibulo-Ocular Reflex (VOR) on Shuttle flights STS 7 and 8. Ten subjects performed head oscillations at 0.33 Hz + or - 30 deg amplitude under the followng conditions: VVOR (visual VOR), eyes open and fixed on a stationary target; VOR-EC, with eyes closed and fixed on the same target in imagination; and VOR-S (VOR suppression), with eyes open and fixed on a head-synchronized target. Effects of weightlessness, flight phase, and Space Motion Sickness (SMS) on head oscillation characteristics were examined. A significant increase in head oscillation frequency was noted inflight in subjects free from SMS. In subjects susceptible to SMS, frequency was reduced during their Symptomatic period. The data also suggest that the amplitude and peak velocity of head oscillation were reduced early inflight. No significant changes were noted in reflex gain or phase in any of the test conditions; however, there was a suggestion of an increase in VVOR and VOR-ES gain early inflight in asymptomatic subjects. A significant difference in VOR-S was found between SMS susceptible and non-susceptible subjects. There is no evidence that any changes in VOR characteristics contributed to SMS.

  8. Habituation and adaptation of the vestibuloocular reflex: a model of differential control by the vestibulocerebellum

    NASA Technical Reports Server (NTRS)

    Cohen, H.; Cohen, B.; Raphan, T.; Waespe, W.

    1992-01-01

    We habituated the dominant time constant of the horizontal vestibuloocular reflex (VOR) of rhesus and cynomolgus monkeys by repeated testing with steps of velocity about a vertical axis and adapted the gain of the VOR by altering visual input with magnifying and reducing lenses. After baseline values were established, the nodulus and ventral uvula of the vestibulocerebellum were ablated in two monkeys, and the effects of nodulouvulectomy and flocculectomy on VOR gain adaptation and habituation were compared. The VOR time constant decreased with repeated testing, rapidly at first and more slowly thereafter. The gain of the VOR was unaffected. Massed trials were more effective than distributed trials in producing habituation. Regardless of the schedule of testing, the VOR time constant never fell below the time constant of the semicircular canals (approximately 5 s). This finding indicates that only the slow component of the vestibular response, the component produced by velocity storage, was habituated. In agreement with this, the time constant of optokinetic after-nystagmus (OKAN) was habituated concurrently with the VOR. Average values for VOR habituation were obtained on a per session basis for six animals. The VOR gain was adapted by natural head movements in partially habituated monkeys while they wore x 2.2 magnifying or x 0.5 reducing lenses. Adaptation occurred rapidly and reached about +/- 30%, similar to values obtained using forced rotation. VOR gain adaptation did not cause additional habituation of the time constant. When the VOR gain was reduced in animals with a long VOR time constant, there were overshoots in eye velocity that peaked at about 6-8 s after the onset or end of constant-velocity rotation. These overshoots occurred at times when the velocity storage integrator would have been maximally activated by semicircular canal input. Since the activity generated in the canals is not altered by visual adaptation, this finding indicates that the gain

  9. Cost-effectiveness analysis of combination antifungal therapy with voriconazole and anidulafungin versus voriconazole monotherapy for primary treatment of invasive aspergillosis in Spain

    PubMed Central

    Grau, Santiago; Azanza, Jose Ramon; Ruiz, Isabel; Vallejo, Carlos; Mensa, Josep; Maertens, Johan; Heinz, Werner J; Barrueta, Jon Andoni; Peral, Carmen; Mesa, Francisco Jesús; Barrado, Miguel; Charbonneau, Claudie; Rubio-Rodríguez, Darío; Rubio-Terrés, Carlos

    2017-01-01

    Objective According to a recent randomized, double-blind clinical trial comparing the combination of voriconazole and anidulafungin (VOR+ANI) with VOR monotherapy for invasive aspergillosis (IA) in patients with hematologic disease or with hematopoietic stem cell transplant, mortality was lower after 6 weeks with VOR+ANI than with VOR monotherapy in a post hoc analysis of patients with galactomannan-based IA. The objective of this study was to compare the cost-effectiveness of VOR+ANI with VOR, from the perspective of hospitals in the Spanish National Health System. Methods An economic model with deterministic and probabilistic analyses was used to determine costs per life-year gained (LYG) for VOR+ANI versus VOR in patients with galactomannan-based IA. Mortality, adverse event rates, and life expectancy were obtained from clinical trial data. The costs (in 2015 euros [€]) of the drugs and the adverse event-related costs were obtained from Spanish sources. A Tornado plot and a Monte Carlo simulation (1,000 iterations) were used to assess uncertainty of all model variables. Results According to the deterministic analysis, for each patient treated with VOR+ANI compared with VOR monotherapy, there would be a total of 0.348 LYG (2.529 vs 2.181 years, respectively) at an incremental cost of €5,493 (€17,902 vs €12,409, respectively). Consequently, the additional cost per LYG with VOR+ANI compared with VOR would be €15,785. Deterministic sensitivity analyses confirmed the robustness of these findings. In the probabilistic analysis, the cost per LYG with VOR+ANI was €15,774 (95% confidence interval: €15,763–16,692). The probability of VOR+ANI being cost-effective compared with VOR was estimated at 82.5% and 91.9%, based on local cost-effectiveness thresholds of €30,000 and €45,000, respectively. Conclusion According to the present economic study, combination therapy with VOR+ANI is cost-effective as primary therapy of IA in galactomannan

  10. Habituation and adaptation of the vestibuloocular reflex: a model of differential control by the vestibulocerebellum

    NASA Technical Reports Server (NTRS)

    Cohen, H.; Cohen, B.; Raphan, T.; Waespe, W.

    1992-01-01

    We habituated the dominant time constant of the horizontal vestibuloocular reflex (VOR) of rhesus and cynomolgus monkeys by repeated testing with steps of velocity about a vertical axis and adapted the gain of the VOR by altering visual input with magnifying and reducing lenses. After baseline values were established, the nodulus and ventral uvula of the vestibulocerebellum were ablated in two monkeys, and the effects of nodulouvulectomy and flocculectomy on VOR gain adaptation and habituation were compared. The VOR time constant decreased with repeated testing, rapidly at first and more slowly thereafter. The gain of the VOR was unaffected. Massed trials were more effective than distributed trials in producing habituation. Regardless of the schedule of testing, the VOR time constant never fell below the time constant of the semicircular canals (approximately 5 s). This finding indicates that only the slow component of the vestibular response, the component produced by velocity storage, was habituated. In agreement with this, the time constant of optokinetic after-nystagmus (OKAN) was habituated concurrently with the VOR. Average values for VOR habituation were obtained on a per session basis for six animals. The VOR gain was adapted by natural head movements in partially habituated monkeys while they wore x 2.2 magnifying or x 0.5 reducing lenses. Adaptation occurred rapidly and reached about +/- 30%, similar to values obtained using forced rotation. VOR gain adaptation did not cause additional habituation of the time constant. When the VOR gain was reduced in animals with a long VOR time constant, there were overshoots in eye velocity that peaked at about 6-8 s after the onset or end of constant-velocity rotation. These overshoots occurred at times when the velocity storage integrator would have been maximally activated by semicircular canal input. Since the activity generated in the canals is not altered by visual adaptation, this finding indicates that the gain

  11. Studies of the horizontal vestibulo-ocular reflex in spaceflight

    NASA Technical Reports Server (NTRS)

    Thornton, William E.; Uri, John J.; Moore, Tom; Pool, Sam

    1989-01-01

    Changes in the vestibulo-ocular reflex (VOR) during space flight have been suspected of contributing to space motion sickness. The horizontal VOR was studied in nine subjects on two space shuttle missions. Active unpaced head oscillation at 0.3 Hz was used as the stimulus to examine the gain and phase of the VOR with and without visual input, as well as the visual suppression of the reflex. No statistically significant changes were noted inflight in the gains or phase shifts of the VOR during any test condition, or between space motion sickness susceptible and nonsusceptible populations. Although VOR suppression was unaffected by spaceflight, the space motion sickness-susceptible group tended to exhibit greater error in the suppression than the nonsusceptible group. It is concluded that at this stimulus frequency, VOR gain is unaffected by space-flight, and any minor individual changes do not seem to contribute to space motion sickness.

  12. Studies of the horizontal vestibulo-ocular reflex in spaceflight

    NASA Technical Reports Server (NTRS)

    Thornton, William E.; Uri, John J.; Moore, Tom; Pool, Sam

    1989-01-01

    Changes in the vestibulo-ocular reflex (VOR) during space flight have been suspected of contributing to space motion sickness. The horizontal VOR was studied in nine subjects on two space shuttle missions. Active unpaced head oscillation at 0.3 Hz was used as the stimulus to examine the gain and phase of the VOR with and without visual input, as well as the visual suppression of the reflex. No statistically significant changes were noted inflight in the gains or phase shifts of the VOR during any test condition, or between space motion sickness susceptible and nonsusceptible populations. Although VOR suppression was unaffected by spaceflight, the space motion sickness-susceptible group tended to exhibit greater error in the suppression than the nonsusceptible group. It is concluded that at this stimulus frequency, VOR gain is unaffected by space-flight, and any minor individual changes do not seem to contribute to space motion sickness.

  13. Abnormal Vestibulo-Ocular Reflexes in Autism: A Potential Endophenotype

    DTIC Science & Technology

    2014-08-01

    rotary nystagmus without optokinetic feedback using a velocity step test. We hypothesize that in ASD vertical eye movement intrusions during horizontal...2: To apply a linear systems analysis based method for testing horizontal VOR without optokinetic feedback using sinusoidal oscillation tests. We...vertical VOR and torsional VOR, both without optokinetic feedback , using velocity step tests. 15. SUBJECT TERMS Vestibulo-ocular reflex, autism 16

  14. Behavior of human horizontal vestibulo-ocular reflex in response to high-acceleration stimuli

    NASA Technical Reports Server (NTRS)

    Maas, E. F.; Huebner, W. P.; Seidman, S. H.; Leigh, R. J.

    1989-01-01

    The horizontal vestibulo-ocular reflex (VOR) during transient, high-acceleration (1900-7100 deg/sec-squared) head rotations was studied in four human subjects. Such stimuli perturbed the angle of gaze and caused illusory movement of a viewed target (oscillopsia). The disturbance of gaze could be attributed to the latency of the VOR (which ranged from 6-15 ms) and inadequate compensatory eye rotations (median VOR gain ranged from 0.61-0.83).

  15. 75 FR 61610 - Modification of Class E Airspace; Arco, ID

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-06

    ...'08'' W.) DuBois VORTAC (Lat. 44 05'20'' N., long. 112 12'34'' W.) Burley VOR/DME (Lat. 42 34'49'' N...Bois VORTAC on V- 257, thence south along V-257 to V-365, thence southeast along V-365 to the Burley VOR/DME, thence northwest along V-231 to 29 miles northwest of the Burley VOR/DME on V-231, to the...

  16. 75 FR 82228 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-30

    ... From To MEA MAA Sec. 95.3000 Low Altitude RNAV Routes Sec. 95.3227 RNAV Route T227 Is Amended To Read... Route Q8 Is Amended To Read in Part Galena, AK VOR/DME Anchorage, AK VOR/DME 18000 45000 From To MEA Sec..., OH VOR/DME Morow, OH FIX 3100 Morow, OH FIX Hires, OH FIX *5000 *2700--MOCA *3000--GNSS MEA Hires,...

  17. Behavior of human horizontal vestibulo-ocular reflex in response to high-acceleration stimuli

    NASA Technical Reports Server (NTRS)

    Maas, E. F.; Huebner, W. P.; Seidman, S. H.; Leigh, R. J.

    1989-01-01

    The horizontal vestibulo-ocular reflex (VOR) during transient, high-acceleration (1900-7100 deg/sec-squared) head rotations was studied in four human subjects. Such stimuli perturbed the angle of gaze and caused illusory movement of a viewed target (oscillopsia). The disturbance of gaze could be attributed to the latency of the VOR (which ranged from 6-15 ms) and inadequate compensatory eye rotations (median VOR gain ranged from 0.61-0.83).

  18. System Engineering and Integration Contract for Implementation of the National Airspace System Plan. Volume 2. Section 5.0 NAS Plan Project Findings.

    DTIC Science & Technology

    1984-08-01

    kits for DVOR , 112 VOT, and 75 Doppler VOR conversion kits. Status UThe VORTAC, VOR, and VOR/DME replacement program is approaching satisfactory...monitoring of additional airport .q. facilities and equipment such as DVOR , ARSR-3, navigation, and communications facilities associated with FSS (by 1988...DHSA Designated Major System Acquisition DOC Department of Defense 1. DOD Department of Defense DUAT Direct User Access Terminal DVOR Doppler Very

  19. General Aviation Activity and Avionics. Calendar Year 1990

    DTIC Science & Technology

    1990-01-01

    200 220 BASIC NA VIGA TION EQUIPMENT 100 Channel VOR (Portable) 4.8( .8%) 100 Channel VOR (Fixed) T73.5 (27.6%) 200 Channel VOR (Portable) 16.9(6.3...0(1.1%) Other LRNA V 1.9 (0. 7%) OTHER NA VIGA TION EQUIPMENT Radar Altimeter 18.4 (6.9%) Weather Radar 22.3 (8.4%) Thunderstorm Detection Equipment

  20. General Aviation Activity and Avionics Survey

    DTIC Science & Technology

    1988-01-01

    Slope 1154 i44.5%) Microwave System No Par 2.3(.9%) VOR NA VIGA TION EQUIPMENT 100 -7nelVR _1:;:68 1(26.2%) 200 Channel VOR 200 Channel VOR .119 0(45 9...OTHER NA VIGA TION EQUIPMENT Radar Altimeter 19. 1(7.3%) Weather Radar 22.4 (8.6%) Thunderstorm Detection Equipment = 14.3(5.5%) No Navigation

  1. 75 FR 54769 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-09

    ....25, 97.27, 97.29, 97.31, 97.33, 97.35 By amending: Sec. 97.23 VOR, VOR/DME, VOR or TACAN, and VOR/DME or TACAN; Sec. 97.25 LOC, LOC/DME, LDA, LDA/DME, SDF, SDF/DME; Sec. 97.27 NDB, NDB/DME; Sec. 97.29 ILS, ILS/DME, MLS, MLS/DME, MLS/RNAV; Sec. 97.31 RADAR SIAPs; Sec. 97.33 RNAV SIAPs; and Sec....

  2. 75 FR 42310 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-21

    ....25, 97.27, 97.29, 97.31, 97.33, 97.35 By amending: Sec. 97.23 VOR, VOR/DME, VOR or TACAN, and VOR/DME or TACAN; Sec. 97.25 LOC, LOC/DME, LDA, LDA/DME, SDF, SDF/DME; Sec. 97.27 NDB, NDB/DME; Sec. 97.29 ILS, ILS/DME, MLS, MLS/DME, MLS/RNAV; Sec. 97.31 RADAR SIAPs; Sec. 97.33 RNAV SIAPs; and Sec....

  3. Vestibulo-ocular reflex abnormality in Parkinson's disease detected by video head impulse test.

    PubMed

    Lv, Wen; Guan, Qiongfeng; Hu, Xingyue; Chen, Jiaqi; Jiang, Hong; Zhang, Lisan; Fan, Weinv

    2017-09-14

    Parkinson's disease (PD) is a common neurodegenerative disease characterized by dopaminergic neuronal loss. The underlying cause of PD is unknown. To assess the clinical relevance of vestibular-ocular reflex (VOR) gain in patients with PD, especially those in the early stages. Sixty-three PD patients and 56 control healthy individuals were enrolled in this study between Mar 2015 and Aug 2015. VOR gains were determined by video head impulse test (vHIT) device. Statistical analysis was performed to assess the difference in VOR gains between PD patients and normal people. The relationship of VOR gain with age, duration and severity of disease was also assessed. In the control group, average VOR gain was 0.98±0.09 on the left side and 0.99±0.16 on the right side. No statistically significant difference was observed between the two sides in the control group (P>0.05). In the PD group, average VOR gain was 1.20±0.22 on the left side and 1.23±0.23 on the right side. No statistically significant difference was observed between the two sides in the PD group (P>0.05). There was a significant difference in VOR gain between the PD (both in early and mid-late stages) and the control group (P<0.05). A weak correlation was observed between VOR gain and the motor Unified Parkinson Disease Rating Scale score. No correlation of VOR gain with age, duration of disease or the Hoehn and Yahr Scale score was observed. VOR gains in PD patients were found to be higher than normal, especially in the early stages of the disease. vHIT is a potential tool to determine the VOR gain in PD patients and may help detect PD at an early stage. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. 78 FR 18264 - Proposed Establishment of Class E Airspace; Tobe, CO

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-26

    ... Federal Aviation Administration 14 CFR Part 71 Proposed Establishment of Class E Airspace; Tobe, CO AGENCY... Measuring Equipment (VOR/ DME), Tobe, CO to facilitate vectoring of Instrument Flight Rules (IFR) aircraft... extending upward from 1,200 feet above the surface at the Tobe VOR/DME, Tobe, CO. This action would...

  5. 76 FR 75445 - Amendment of Class E Airspace; Olathe, KS

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-02

    ... Johnson County VHF Omnidirectional Range/ Distance Measuring Equipment (VOR/DME) at Johnson County... airspace at Johnson County Executive Airport (76 FR 53361) Docket No. FAA-2011-0748. Interested parties... procedures at Johnson County Executive Airport, Olathe, KS. Decommissioning of the Johnson County VOR/DME and...

  6. 76 FR 21622 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-18

    ... Routes Sec. 95.4120 RNAV Route Q120 Is Added To Read SACRAMENTO, CA VORTAC ZORUN, NV FIX *1 45000 8000... FIX *4000 *3400--MOCA Sec. 95.6520 VOR Federal Airway V520 Is Amended To Read in Part SALMON, ID VOR...

  7. Vestibulo-Ocular Response and Balance Control in Children and Young Adults with Mild-to-Moderate Intellectual and Developmental Disability: A Pilot Study

    ERIC Educational Resources Information Center

    Zur, Oz; Ronen, Ayelet; Melzer, Itshak; Carmeli, Eli

    2013-01-01

    The vestibulo-ocular response (VOR) may not be fully developed in children with an intellectual and developmental disability (IDD). This study aimed to identify the presence of VOR deficit in children and young adults with unspecified mild-to-moderate intellectual and developmental disability and its effect on balance control. Twenty-one children…

  8. 76 FR 11675 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-03

    ... Is Amended To Read in Part EAU CLAIRE, WI VORTAC EDGRR, WI FIX *4500 *2900--MOCA EDGRR, WI FIX WAUSAU, WI VORTAC *6000 *3600--MOCA *3600--GNSS MEA WAUSAU R-271 UNUSABLE BYD 10 NM, USE EAU CLAIRE R-087... Point KALAMAZOO, MI VOR/DME JACKSON, MI VOR/DME 36 KALAMAZOO V26 Is Amended To Add Changeover Point EAU...

  9. 78 FR 4354 - Proposed Establishment of Area Navigation (RNAV) Routes; OR

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-22

    ... Omnidirectional Range (VOR) Federal airway that will be removed due to the planned decommissioning of the Portland, OR, VOR/DME in 2013. This action would advance the implementation of RNAV and provide continued en... and Airspace Docket No. 11-ANM-28) and be submitted in triplicate to the Docket Management Facility...

  10. 75 FR 8243 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-24

    ... graphic depiction on charts printed by publishers of aeronautical materials. Thus, the advantages of.../22/10 VOR/DME RWY 16, AMDT 3D. 11-Mar-10 KS HAYS HAYS RGNL 0/2450 1/22/10 VOR/DME RWY 34, AMDT 2D....

  11. 78 FR 78302 - Proposed Modification and Establishment of Air Traffic Service (ATS) Routes in the Vicinity of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-26

    ... Huntingburg, IN (HNB), VHF Omnidirectional Range (VOR)/Distance Measuring Equipment (DME) facility that... and Airspace Docket No. 13-AGL-8) and be submitted in triplicate to the Docket Management Facility... The Huntingburg, IN, (HNB) VOR/DME facility is currently out of service. As a result, aircraft that...

  12. Functional organization of primate translational vestibulo-ocular reflexes and effects of unilateral labyrinthectomy

    NASA Technical Reports Server (NTRS)

    Angelaki, D. E.; McHenry, M. Q.; Newlands, S. D.; Dickman, J. D.

    1999-01-01

    Translational vestibulo-ocular reflexes (trVORs) are characterized by distinct spatio-temporal properties and sensitivities that are proportional to the inverse of viewing distance. Anodal (inhibitory) labyrinthine stimulation (100 microA, < 2 s) during motion decreased the high-pass filtered dynamics, as well as horizontal trVOR sensitivity and its dependence on viewing distance. Cathodal (excitatory) currents had opposite effects. Translational VORs were also affected after unilateral labyrinthectomy. Animals lost their ability to modulate trVOR sensitivity as a function of viewing distance acutely after the lesion. These deficits partially recovered over time, albeit a significant reduction in trVOR sensitivity as a function of viewing distance remained in compensated animals. During fore-aft motion, the effects of unilateral labyrinthectomy were more dramatic. Both acute and compensated animals permanently lost their ability to modulate fore-aft trVOR responses as a function of target eccentricity. These results suggest that (1) the dynamics and viewing distance-dependent properties of the trVORs are very sensitive to changes in the resting firing rate of vestibular afferents and, consequently, vestibular nuclei neurons; (2) the most irregularly firing primary otolith afferents that are most sensitive to labyrinthine electrical stimulation might contribute to reflex dynamics and sensitivity; (3) inputs from both labyrinths are necessary for the generation of the translational VORs.

  13. 78 FR 40381 - Establishment of Class E Airspace; Grand Canyon, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-05

    ... Canyon VHF Omni-Directional Radio Range/Distance Measuring Equipment (VOR/DME) navigation aid, Grand..., at the Grand Canyon VOR/DME navigation aid, Grand Canyon, AZ, to accommodate IFR aircraft under... within the scope of that authority as it establishes controlled airspace at the Grand Canyon...

  14. 78 FR 34555 - Establishment of Class E Airspace; Gillette, WY

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-10

    ... airspace at the Gillette VHF Omni-Directional Radio Range/Distance Measuring Equipment (VOR/DME), Gillette... the surface, at the Gillette VOR/DME navigation aid, Gillette, WY, to accommodate IFR aircraft under... within the scope of that authority as it establishes controlled airspace at the Gillette...

  15. 75 FR 62461 - Revocation and Establishment of Class E Airspace; St. George, UT

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-12

    ... Range/Distance Measuring Equipment (VOR/DME), Localizer Type Directional Aid/Distance Measuring Equipment (LDA/DME) Standard Instrument Approach Procedures (SIAPs) at the new airport. This will improve... more than was needed for the SIAP, and modified portions for the VOR/DME SIAP by reducing the amount...

  16. 76 FR 40600 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-11

    ..., Boise Air Terminal/Gowen Fld, NDB RWY 10R, Amdt 28A Burley, ID, Burley Muni, RNAV (GPS) RWY 20, Orig-A Burley, ID, Burley Muni, VOR-A, Amdt 4B Burley, ID, Burley Muni, VOR/DME-B, Amdt 4B Chicago/Aurora, IL...

  17. 77 FR 27357 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-10

    ...--GNSS MEA *DME/DME/IRU MEA Veluy, ID FIX Burley, ID VOR/DME *24000 45000 *18000--GNSS MEA *DME/DME/IRU MEA Burley, ID VOR/DME Pimie, UT FIX *24000 45000 *18000--GNSS MEA *DME/DME/IRU MEA Pimie, UT FIX...

  18. 77 FR 71495 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-03

    ...-County, Takeoff Minimums and Obstacle DP, Orig Mount Olive, NC, Mount Olive Muni, VOR-A, Amdt 2 Tioga, ND... Olive, NC, effective 15 November, 2012, is hereby rescinded in its entirety: Mount Olive, NC, Mount Olive Muni, VOR-A, Amdt 2 BILLING CODE 4910-13-P...

  19. Vestibulo-Ocular Response and Balance Control in Children and Young Adults with Mild-to-Moderate Intellectual and Developmental Disability: A Pilot Study

    ERIC Educational Resources Information Center

    Zur, Oz; Ronen, Ayelet; Melzer, Itshak; Carmeli, Eli

    2013-01-01

    The vestibulo-ocular response (VOR) may not be fully developed in children with an intellectual and developmental disability (IDD). This study aimed to identify the presence of VOR deficit in children and young adults with unspecified mild-to-moderate intellectual and developmental disability and its effect on balance control. Twenty-one children…

  20. 75 FR 24790 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-06

    ... Ascot, TX FIX Solon, TX FIX *4000 *1500-MOCA Cleep, TX FIX *Legge, TX FIX 3100 *3000-MRA Napoleon, MO... Amended to Read in Part Holly Springs, MS VORTAC......... Gilmore, AR VOR/DME..... 2500 Napoleon, MO... Napoleon, MO VORTAC Lamoni, IA VORTAC....... 2900 Sec. 95.6163 VOR Federal Airway V163 is Amended to Read...

  1. 75 FR 20321 - Proposed Amendment of Class E Airspace; Bozeman, MT

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-19

    ... aircraft using a new VHF Omni-Directional Radio Range (VOR) Standard Instrument Approach Procedure (SIAP) at Gallatin Field Airport. This action would enhance the safety and management of aircraft operations... necessary to accommodate aircraft using the new VOR SIAP's at Gallatin Field Airport, Bozeman, MT....

  2. Aging reduces the high-frequency and short-term adaptation of the vestibulo-ocular reflex in mice.

    PubMed

    Khan, Serajul I; Hübner, Patrick P; Brichta, Alan M; Smith, Doug W; Migliaccio, Americo A

    2017-03-01

    Prevailing evidence indicates a relatively late life decline in human vestibulo-ocular reflex (VOR) function. Although mice are commonly used in mechanistic studies of vestibular function, it remains unclear whether aging produces a corresponding decline in VOR function in mice. We sought to determine how the baseline VOR and its short-term adaptation were affected by aging. We tested 8 young (3-month old) and 8 aged (30-month old-equivalent to a ∼80-year old human) C57BL/6 mice. We measured their VOR response to whole-body static tilts and during 0.1-10 Hz whole-body sinusoidal and transient rotations before and after VOR adaptation training. Our data revealed minimal differences in static counter-tilt response between young and aged mice, but a significant deficit in baseline VOR gain in aged mice during transient rotations. Moreover, aged mice had a significant decrease in short-term VOR adaptation, particularly for training that sought to decrease the VOR response.

  3. The Neural Basis for Learning of Simple Motor Skills.

    ERIC Educational Resources Information Center

    Lisberger, Stephen G.

    1988-01-01

    Discusses the vestibulo-ocular reflex (VOR) which is used to investigate the neural basis for motor learning in monkeys. Suggests organizing principles that may apply in forms of motor learning as a result of similarities among VOR and other motor systems. (Author/RT)

  4. Functional organization of primate translational vestibulo-ocular reflexes and effects of unilateral labyrinthectomy

    NASA Technical Reports Server (NTRS)

    Angelaki, D. E.; McHenry, M. Q.; Newlands, S. D.; Dickman, J. D.

    1999-01-01

    Translational vestibulo-ocular reflexes (trVORs) are characterized by distinct spatio-temporal properties and sensitivities that are proportional to the inverse of viewing distance. Anodal (inhibitory) labyrinthine stimulation (100 microA, < 2 s) during motion decreased the high-pass filtered dynamics, as well as horizontal trVOR sensitivity and its dependence on viewing distance. Cathodal (excitatory) currents had opposite effects. Translational VORs were also affected after unilateral labyrinthectomy. Animals lost their ability to modulate trVOR sensitivity as a function of viewing distance acutely after the lesion. These deficits partially recovered over time, albeit a significant reduction in trVOR sensitivity as a function of viewing distance remained in compensated animals. During fore-aft motion, the effects of unilateral labyrinthectomy were more dramatic. Both acute and compensated animals permanently lost their ability to modulate fore-aft trVOR responses as a function of target eccentricity. These results suggest that (1) the dynamics and viewing distance-dependent properties of the trVORs are very sensitive to changes in the resting firing rate of vestibular afferents and, consequently, vestibular nuclei neurons; (2) the most irregularly firing primary otolith afferents that are most sensitive to labyrinthine electrical stimulation might contribute to reflex dynamics and sensitivity; (3) inputs from both labyrinths are necessary for the generation of the translational VORs.

  5. 14 CFR 95.3 - Symbols.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... changeover point. (b) L means compass locator; (c) LF/MF means low frequency, medium frequency; (d) LFR means low frequency radio range; (e) VOR-E means VOR and distance measuring equipment; and (f) Z means a very high frequency location marker....

  6. 14 CFR 95.3 - Symbols.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... changeover point. (b) L means compass locator; (c) LF/MF means low frequency, medium frequency; (d) LFR means low frequency radio range; (e) VOR-E means VOR and distance measuring equipment; and (f) Z means a very high frequency location marker....

  7. 14 CFR 95.3 - Symbols.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... changeover point. (b) L means compass locator; (c) LF/MF means low frequency, medium frequency; (d) LFR means low frequency radio range; (e) VOR-E means VOR and distance measuring equipment; and (f) Z means a very high frequency location marker....

  8. 76 FR 23687 - Amendment of Federal Airways; Alaska

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-28

    ...'' W.) * * * * * * * T-269 ANN to BET ANN VOR/DME (Lat. 55 03'37'' N., long. 131 34'42'' W.) BKA VORTAC...'' W.) SQA VOR/DME (Lat. 61 05'55'' N., long. 155 38'04'' W.) BET VORTAC (Lat. 60 47'05'' N., long. 161...

  9. 75 FR 25760 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-10

    ... County, RNAV (GPS) RWY 36, Orig Springfield, IL, Abraham Lincoln Capital, ILS OR LOC RWY 22, Amdt 9 Springfield, IL, Abraham Lincoln Capital, RNAV (GPS) RWY 13, Amdt 1 Springfield, IL, Abraham Lincoln Capital, VOR/DME RWY 4, Orig Springfield, IL, Abraham Lincoln Capital, VOR/DME RWY 13, Orig Springfield, IL...

  10. Comparing Azole Plasma Trough Levels in Lung Transplant Recipients: Percentage of Therapeutic Levels and Intrapatient Variability

    PubMed Central

    Weber, Alexandra; Ihle, Franziska; Matthes, Sandhya; Ceelen, Felix; Zimmermann, Gregor; Kneidinger, Nikolaus; Schramm, Rene; Winter, Hauke; Zoller, Michael; Vogeser, Michael; Behr, Juergen; Neurohr, Claus

    2017-01-01

    Background: This study compared therapeutic azole plasma trough levels (APL) of the azole antimycotics itraconazole (ITR), voriconazole (VOR), and posaconazole (POS) in lung transplant recipients and analyzed the influencing factors. In addition, intrapatient variability for each azole was determined. Methods: From July 2012 to July 2015, 806 APL of ITR, VOR, posaconazole liquid (POS-Liq), and posaconazole tablets (POS-Tab) were measured in 173 patients of the Munich Lung Transplantation Program. Therapeutic APL were defined as follows: ITR, ≥700 ng/mL; VOR, 1000–5500 ng/mL; and POS, ≥700 ng/mL (prophylaxis) and ≥1000 ng/mL (therapy). Results: VOR and POS-Tab reached the highest number of therapeutic APL, whereas POS-Liq showed the lowest percentage (therapy: ITR 50%, VOR 70%, POS-Liq 38%, and POS-Tab 82%; prophylaxis: ITR 62%, VOR 85%, POS-Liq 49%, and POS-Tab 76%). Risk factors for subtherapeutic APL of all azoles were the azole dose (ITR, P < 0.001; VOR, P = 0.002; POS-Liq, P = 0.006) and age over 60 years (ITR, P = 0.003; VOR, P = 0.002; POS-Liq, P = 0.039; POS-Tab, P < 0.001). Cystic fibrosis was a significant risk factor for subtherapeutic APL for VOR and POS-Tab (VOR, P = 0.002; POS-Tab, P = 0.005). Double lung transplantation (LTx) was significantly associated with less therapeutic APL for VOR and POS-Liq (VOR, P = 0.030; POS-Liq, P < 0.001). Concomitant therapy with 80 mg pantoprazole led to significantly fewer therapeutic POS APL as compared to 40 mg (POS-Liq, P = 0.015; POS-Tab, P < 0.001). VOR displayed the greatest intrapatient variability (46%), whereas POS-Tab showed the lowest (32%). Conclusions: Our study showed that VOR and POS-Tab achieve the highest percentage of therapeutic APL in patients with LTx; POS-Tab showed the lowest intrapatient variability. APL are significantly influenced by azole dose, age, cystic fibrosis, type of LTx, and comedication with proton-pump inhibitors. Considering the high number of subtherapeutic APL

  11. Vestibulo-Oculomotor Reflex Recording Using the Scleral Search Coil Technique. Review of Peripheral Vestibular Disorders

    PubMed Central

    Boleas-Aguirre, Marisol; Migliaccio, Amerio A.; Carey, John P.

    2010-01-01

    Our goal is to review vestibulo-oculomotor reflex (VOR) studies on several peripheral vestibular disorders (Ménière’s disease, vestibular neuritis, benign paroxysmal positional vertigo, superior canal dehiscence syndrome, and vestibular neuroma), using the scleral search coil (SSC) technique. Head movements are detected by vestibular receptors and the elicited VOR is responsible for compensatory 3 dimensional eye movements. Therefore, to study the VOR it is necessary to assess the direction and velocity of 3 dimensional head, and eye movements. This can be achieved using the SSC technique. Interaction between a scleral search coil and an alternating magnetic field generates an electrical signal that is proportional to eye position. Ideally, eye rotation axis is aligned with head rotation axis and VOR gain (eye velocity/head velocity) for horizontal and vertical head rotations is almost 1. The VOR gain, however, for torsional head rotations is smaller and about 0.7. PMID:17683700

  12. Light conditions affect the roll-induced vestibuloocular reflex in Xenopus laevis tadpoles

    NASA Astrophysics Data System (ADS)

    El-Yamany, Nabil A.

    2008-12-01

    In Xenopus laevis tadpoles, effects of asymmetrical light conditions on the roll-induced vestibuloocular reflex (rVOR) were tested for the developmental period between stage 47 and 49. For comparison, the rVOR was tested in dim- and high-symmetrical light environments. Test parameters were the rVOR gain and rVOR amplitude. Under all light conditions, the rVOR increased from tadpole stage 47 to 49. For all stages, the asymmetrical light field induced the strongest response, the dim light field the weakest one. The response for the left and right eye was identical, even if the tadpoles were tested under asymmetrical light conditions. The experiments can be considered as hints (1) for an age-dependent light sensitivity of vestibular neurons, and (2) for the existence of control systems for coordinated eye movements that has its origin in the proprioceptors of the extraocular eye muscles.

  13. Effects of adaptation of vestibulo-ocular reflex function on manual target localization

    NASA Technical Reports Server (NTRS)

    Bloomberg, J. J.; Merkle, L. A.; Barry, S. R.; Huebner, W. P.; Cohen, H. S.; Mueller, S. A.; Fordice, J.

    2000-01-01

    The goal of the present study was to determine if adaptive modulation of vestibulo-ocular reflex (VOR) function is associated with commensurate alterations in manual target localization. To measure the effects of adapted VOR on manual responses we developed the Vestibular-Contingent Pointing Test (VCP). In the VCP test, subjects pointed to a remembered target following passive whole body rotation in the dark. In the first experiment, subjects performed VCP before and after wearing 0.5X minifying lenses that adaptively attenuate horizontal VOR gain. Results showed that adaptive reduction in horizontal VOR gain was accompanied by a commensurate change in VCP performance. In the second experiment, bilaterally labyrinthine deficient (LD) subjects were tested to confirm that vestibular cues were central to the spatial coding of both eye and hand movements during VCP. LD subjects performed significantly worse than normal subjects. These results demonstrate that adaptive change in VOR can lead to alterations in manual target localization.

  14. Effects of adaptation of vestibulo-ocular reflex function on manual target localization

    NASA Technical Reports Server (NTRS)

    Bloomberg, J. J.; Merkle, L. A.; Barry, S. R.; Huebner, W. P.; Cohen, H. S.; Mueller, S. A.; Fordice, J.

    2000-01-01

    The goal of the present study was to determine if adaptive modulation of vestibulo-ocular reflex (VOR) function is associated with commensurate alterations in manual target localization. To measure the effects of adapted VOR on manual responses we developed the Vestibular-Contingent Pointing Test (VCP). In the VCP test, subjects pointed to a remembered target following passive whole body rotation in the dark. In the first experiment, subjects performed VCP before and after wearing 0.5X minifying lenses that adaptively attenuate horizontal VOR gain. Results showed that adaptive reduction in horizontal VOR gain was accompanied by a commensurate change in VCP performance. In the second experiment, bilaterally labyrinthine deficient (LD) subjects were tested to confirm that vestibular cues were central to the spatial coding of both eye and hand movements during VCP. LD subjects performed significantly worse than normal subjects. These results demonstrate that adaptive change in VOR can lead to alterations in manual target localization.

  15. Plasticity within non-cerebellar pathways rapidly shapes motor performance in vivo

    PubMed Central

    Mitchell, Diana E.; Della Santina, Charles C.; Cullen, Kathleen E.

    2016-01-01

    Although cerebellar mechanisms are vital to maintain accuracy during complex movements and to calibrate simple reflexes, recent in vitro studies have called into question the widely held view that synaptic changes within cerebellar pathways exclusively guide alterations in motor performance. Here we investigate the vestibulo-ocular reflex (VOR) circuitry by applying temporally precise activation of vestibular afferents in awake-behaving monkeys to link plasticity at different neural sites with changes in motor performance. Behaviourally relevant activation patterns produce rapid attenuation of direct pathway VOR neurons, but not their nerve input. Changes in the strength of this pathway are sufficient to induce a lasting decrease in the evoked VOR. In addition, indirect brainstem pathways display complementary nearly instantaneous changes, contributing to compensating for the reduced sensitivity of primary VOR neurons. Taken together, our data provide evidence that multiple sites of plasticity within VOR pathways can rapidly shape motor performance in vivo. PMID:27157829

  16. Age-related changes in human vestibulo-ocular and optokinetic reflexes: Pseudorandom rotation tests

    NASA Technical Reports Server (NTRS)

    Peterka, R. J.; Black, F. O.; Schoenhoff, M. B.

    1989-01-01

    The dynamic response properties of horizontal vestibulo-ocular reflex (VOR) and optokinetic reflex (OKR) were characterized in 216 human subjects ranging in age from 7 to 81 years. The object of this cross-sectional study was to determine the effects of aging on VOR and OKR reflex dynamics, and to identify the distributions of parameters which describe VOR and OKR responses to pseudorandom stimuli in a putatively normal population. In general, VOR and OKR response parameters changed in a manner consistent with declining function with increasing age. For the VOR this was reflected in declining response amplitudes, although the magnitude of the decline was small relative to the variability of the data. For the OKR the lag time of the response, probably associated with the time required for visual information processing, increased linearly with age at a rate of about 1 ms per year.

  17. Radioaktive Biomaterialien

    NASA Astrophysics Data System (ADS)

    Assmann, Walter

    In der Strahlentherapie von Tumorgewebe (Radioonkologie) nutzt man die zellschädigende Wirkung verschiedener Strahlenarten zur gezielten Abtötung der Tumorzellen. Um bei der perkutanen Bestrahlung die Strahlenschäden im gesunden Gewebe in Grenzen zu halten, wird der Tumor aus verschiedenen Richtungen mit gut fokussiertem Strahl behandelt. Moderne Bestrahlungsanlagen sind durch Steuerung über leistungsfähige Rechner in der Lage, ein millimetergenaues Bestrahlungsprogramm abzufahren, das individuell auf den jeweiligen Tumor abgestimmt ist. Ein ganz anderer Weg, das umgebende gesunde Gewebe zu schonen, wird in der sog. Brachytherapie beschritten. Hier wird ein kurzreichweitiger, radioaktiver Strahler entweder direkt in das Tumorgewebe (interstitiell) oder in grosser Nähe (intrakavitär) permanent oder nur für eine bestimmte Zeitdauer eingebracht. Ein Beispiel ist die Behandlung des Prostatakarzinoms durch die Implantation von dünnwandigen metallischen Hülsen (seeds) von nur wenigen Millimetern Länge und knapp einem Millimeter Durchmesser, die minimalinvasiv mittels feiner Kanülen in die Prostata eingebracht werden. Sie enthalten ein künstliches Radionuklid mit typisch einigen Wochen Halbwertszeit, dessen therapeutisch wirksame Strahlungsdosis sich auf wenige Millimeter des umgebenden Gewebes beschränkt. Wesentlich für den Erfolg einer Strahlentherapie mit derartig kurzreichweitigen Strahlern ist eine Lagekontrolle mit entsprechend hoher räumlicher Auflösung.

  18. Comparison between habituation of the cat vestibulo-ocular reflex by velocity steps and sinusoidal vestibular stimulation in the dark.

    PubMed

    Clément, Gilles; Flandrin, Jean-Marc; Courjon, Jean-Hubert

    2002-01-01

    Changes in the horizontal vestibulo-ocular reflex (VOR) in darkness were investigated in naive cats during: (1) repeated sessions of angular velocity steps, (2) one continuous 1-h session of sinusoidal oscillations at 0.01, 0.02, 0.04, or 0.12 Hz, and (3) repeated sessions of 1-h sinusoidal oscillations at 0.02 and 0.04 Hz. Before and after each vestibular training, the VOR response parameters elicited by both velocity steps and sinusoidal oscillations were measured in order to evaluate the transfer of habituation from one stimulus to the other. After training with velocity steps, the amplitude and duration of the VOR to velocity steps decreased by about 67% and 52%, respectively. This vestibular habituation transferred to the VOR response generated by sinusoidal oscillations, since a decrease in VOR gain was observed at 0.02 and 0.04 Hz, and an increase in phase lead was observed at 0.02, 0.04, and 0.08 Hz. After 1 h exposure to sinusoidal oscillations, the VOR gain was only reduced by 21-28%, whereas VOR phase lead decreased. The same changes were observed during subsequent sessions, with no retention of the response decrements from one session to the next. At the end of sinusoidal training, the amplitude of the VOR generated by velocity steps was slightly altered. After sinusoidal training, the weak changes in the VOR gain accompanied by a decrease in the VOR phase lead, and the absence of retention of these effects from one session to the next, suggest these changes are not characteristics of a vestibular habituation. Previous reports of vestibular habituation induced by repeated sinusoidal oscillations may be confounded by the fact that the angular velocity steps used for quantifying the effects may have been responsible for this habituation.

  19. Role of Cerebellum in Motion Perception and Vestibulo-ocular Reflex—Similarities and Disparities

    PubMed Central

    Shaikh, Aasef G.; Palla, Antonella; Marti, Sarah; Olasagasti, Itsaso; Optican, Lance M.; Zee, David S.; Straumann, Dominik

    2012-01-01

    Vestibular velocity storage enhances the efficacy of the angular vestibulo-ocular reflex (VOR) during relatively low-frequency head rotations. This function is modulated by GABA-mediated inhibitory cerebellar projections. Velocity storage also exists in perceptual pathway and has similar functional principles as VOR. However, it is not known whether the neural substrate for perception and VOR overlap. We propose two possibilities. First, there is the same velocity storage for both VOR and perception; second, there are nonoverlapping neural networks: one might be involved in perception and the other for the VOR. We investigated these possibilities by measuring VOR and perceptual responses in healthy human subjects during whole-body, constant-velocity rotation steps about all three dimensions (yaw, pitch, and roll) before and after 10 mg of 4-aminopyridine (4-AP). 4-AP, a selective blocker of inward rectifier potassium conductance, can lead to increased synchronization and precision of Purkinje neuron discharge and possibly enhance the GABAergic action. Hence 4-AP could reduce the decay time constant of the perceived angular velocity and VOR. We found that 4-AP reduced the decay time constant, but the amount of reduction in the two processes, perception and VOR, was not the same, suggesting the possibility of nonoverlapping or partially overlapping neural substrates for VOR and perception. We also noted that, unlike the VOR, the perceived angular velocity gradually built up and plateau prior to decay. Hence, the perception pathway may have additional mechanism that changes the dynamics of perceived angular velocity beyond the velocity storage. 4-AP had no effects on the duration of build-up of perceived angular velocity, suggesting that the higher order processing of perception, beyond the velocity storage, might not occur under the influence of mechanism that could be influenced by 4-AP. PMID:22777507

  20. The sensitivity of an immature vestibular system to altered gravity.

    PubMed

    Gabriel, Martin; Frippiat, Jean-Pol; Frey, Herbert; Horn, Eberhard R

    2012-07-01

    Stimulus deprivation or stimulus augmentation can induce long-lasting modifications to sensory and motor systems. If deprivation is effective only during a limited period of life this phase is called "critical period." A critical period was described for the development of the roll-induced vestibuloocular reflex (rVOR) of Xenopus laevis using spaceflights. Spaceflight durations and basic conditions of Xenopus' development did not make it possible to answer the question whether exposure of the immature vestibular organ to weightlessness affects rVOR development. The embryonic development of Pleurodeles waltl is slow enough to solve this problem because the rVOR cannot be induced before 15 dpf. Stage 20-21 embryos (4 dpf) were exposed to microgravity during a 10-day spaceflight, or to 3g hypergravity following the same time schedule. After termination of altered gravity, the rVOR was recorded twice in most animals. The main observations were as follows: (1) after the first rVOR appearance at stage 37 (16 dpf), both rVOR gain and amplitude increased steadily up to saturation levels of 0.22 and 20°, respectively. (2) Three days after termination of microgravity, flight and ground larvae showed no rVOR; 1 day later, the rVOR could be induced only in ground larvae. Differences disappeared after 3 weeks. (3) For 10 days after 3g exposure, rVOR development was similar to that of 1g-controls but 3 weeks later, 3g-larvae showed a larger rVOR than 1g-controls. These observations indicate that the immature vestibular system is transiently sensitive to microgravity exposure and that exposure of the immature vestibular system to hypergravity leads to a slowly growing vestibular sensitization.

  1. Combination therapy of advanced invasive pulmonary aspergillosis in transiently neutropenic rats using human pharmacokinetic equivalent doses of voriconazole and anidulafungin.

    PubMed

    van de Sande, Wendy W J; Mathot, Ron A A; ten Kate, Marian T; van Vianen, Wim; Tavakol, Mehri; Rijnders, Bart J A; Bakker-Woudenberg, Irma A J M

    2009-05-01

    At present, voriconazole (VOR) is the drug of first choice for treating invasive pulmonary aspergillosis (IPA). However, particularly in advanced stages of disease and in the severely immunocompromised host, the mortality remains substantial. The combination of VOR with an echinocandin may improve the therapeutic outcome. We investigate here whether combining VOR and anidulafungin (ANI) in advanced IPA in transiently neutropenic rats results in a higher therapeutic efficacy. Since VOR is metabolized more rapidly in rodents than in humans, dosage adjustment for VOR is necessary to obtain an area under the plasma concentration-time curve (AUC) in rodents that is equivalent to that of humans. In this study, the pharmacokinetics of VOR and ANI in rats were elucidated, and dosage schedules were applied that produced AUCs similar to those of humans. The developed dose schedules were well tolerated by the rats, without effects on renal and hepatic functions. VOR showed excellent efficacy in early IPA (100% rat survival). In advanced IPA, VOR was less efficacious (50% rat survival), whereas a significant decrease in galactomannan concentrations in lungs and sera was found in surviving rats. ANI administered in advanced IPA resulted in 22% rat survival, and the serum concentrations of fungal galactomannan were slightly but not significantly decreased. The addition of ANI to VOR did not result in significantly increased therapeutic efficacy in advanced IPA, resulting in 67% rat survival and a significant decrease in galactomannan concentration in serum. In conclusion, VOR monotherapy is therapeutically effective in the treatment of advanced-stage IPA and superior to the use of ANI. Combining both agents does not significantly improve the therapeutic outcome.

  2. Adaptation of the vestibulo-ocular reflex for forward-eyed foveate vision

    PubMed Central

    Migliaccio, Americo A; Minor, Lloyd B; Santina, Charles C Della

    2010-01-01

    To maintain visual fixation on a distant target during head rotation, the angular vestibulo-ocular reflex (aVOR) should rotate the eyes at the same speed as the head and in exactly the opposite direction. However, in primates for which the 3-dimensional (3D) aVOR has been extensively characterised (humans and squirrel monkeys (Saimiri sciureus)), the aVOR response to roll head rotation about the naso-occipital axis is lower than that elicited by yaw and pitch, causing errors in aVOR magnitude and direction that vary with the axis of head rotation. In other words, primates keep the central part of the retinal image on the fovea (where photoreceptor density and visual acuity are greatest) but fail to keep that image from twisting about the eyes' resting optic axes. We tested the hypothesis that aVOR direction dependence is an adaptation related to primates' frontal-eyed, foveate status through comparison with the aVOR of a lateral-eyed, afoveate mammal (Chinchilla lanigera). As chinchillas' eyes are afoveate and never align with each other, we predicted that the chinchilla aVOR would be relatively low in gain and isotropic (equal in gain for every head rotation axis). In 11 normal chinchillas, we recorded binocular 3D eye movements in darkness during static tilts, 20–100 deg s−1 whole-body sinusoidal rotations (0.5–15 Hz), and 3000 deg s−2 acceleration steps. Although the chinchilla 3D aVOR gain changed with both frequency and peak velocity over the range we examined, we consistently found that it was more nearly isotropic than the primate aVOR. Our results suggest that primates' anisotropic aVOR represents an adaptation to their forward-eyed, foveate status. In primates, yaw and pitch aVOR must be compensatory to stabilise images on both foveae, whereas roll aVOR can be under-compensatory because the brain tolerates torsion of binocular images that remain on the foveae. In contrast, the lateral-eyed chinchilla faces different adaptive demands and thus

  3. Application of alkyl polyglycoside surfactant in ultrasonic-assisted extraction followed by macroporous resin enrichment for the separation of vitexin-2″-O-rhamnoside and vitexin from Crataegus pinnatifida leaves.

    PubMed

    Han, Feng; Guo, Yupin; Gu, Huiyan; Li, Fenglan; Hu, Baozhong; Yang, Lei

    2016-02-15

    An alkyl polyglycoside (APG) surfactant was used in ultrasonic-assisted extraction to effectively extract vitexin-2″-O-rhamnoside (VOR) and vitexin (VIT) from Crataegus pinnatifida leaves. APG0810 was selected as the surfactant. The extraction process was optimized for ultrasonic power, the APG concentration, ultrasonic time, soaking time, and liquid-solid ratio. The proposed approach showed good recovery (99.80-102.50% for VOR and 98.83-103.19% for VIT) and reproducibility (relative standard deviation, n=5; 3.7% for VOR and 4.2% for VIT) for both components. The proposed sample preparation method is both simple and effective. The use of APG for extraction of key herbal ingredients shows great potential. Ten widely used commercial macroporous resins were evaluated in a screening study to identify a suitable resin for the separation and purification of VOR and VIT. After comparing static and dynamic adsorption and desorption processes, HPD100B was selected as the most suitable resin. After column adsorption and desorption on this resin, the target compounds VOR and VIT can be effectively separated from the APG0810 extraction solution. Recoveries of VOR and VIT were 89.27%±0.42% and 85.29%±0.36%, respectively. The purity of VOR increased from 35.0% to 58.3% and the purity of VIT increased from 12.5% to 19.9%. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Adaptation of the vertical vestibulo-ocular reflex in cats during low-frequency vertical rotation.

    PubMed

    Fushiki, Hiroaki; Maruyama, Motoyoshi; Shojaku, Hideo

    2017-04-27

    We examined plastic changes in the vestibulo-ocular reflex (VOR) during low-frequency vertical head rotation, a condition under which otolith inputs from the vestibular system are essential for VOR generation. For adaptive conditioning of the vertical VOR, 0.02Hz sinusoidal pitch rotation for one hour about the earth's horizontal axis was synchronized with out-of-phase vertical visual stimulation from a random dot pattern. A vertical VOR was well evoked when the upright animal rotated around the earth-horizontal axis (EHA) at low frequency due to the changing gravity stimulus and dynamic stimulation of the otoliths. After adaptive conditioning, the amplitude of the vertical VOR increased by an average of 32.1%. Our observations showing plasticity in the otolithic contribution to the VOR may provide a new strategy for visual-vestibular mismatch training in patients with otolithic disorders. This low-frequency vertical head rotation protocol also provides a model for investigating the mechanisms underlying the adaptation of VORs mediated by otolith activation. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Long-Lasting Visuo-Vestibular Mismatch in Freely-Behaving Mice Reduces the Vestibulo-Ocular Reflex and Leads to Neural Changes in the Direct Vestibular Pathway.

    PubMed

    Carcaud, Julie; França de Barros, Filipa; Idoux, Erwin; Eugène, Daniel; Reveret, Lionel; Moore, Lee E; Vidal, Pierre-Paul; Beraneck, Mathieu

    2017-01-01

    Calibration of the vestibulo-ocular reflex (VOR) depends on the presence of visual feedback. However, the cellular mechanisms associated with VOR modifications at the level of the brainstem remain largely unknown. A new protocol was designed to expose freely behaving mice to a visuo-vestibular mismatch during a 2-week period. This protocol induced a 50% reduction of the VOR. In vivo pharmacological experiments demonstrated that the VOR reduction depends on changes located outside the flocculus/paraflocculus complex. The cellular mechanisms associated with the VOR reduction were then studied in vitro on brainstem slices through a combination of vestibular afferent stimulation and patch-clamp recordings of central vestibular neurons. The evoked synaptic activity demonstrated that the efficacy of the synapses between vestibular afferents and central vestibular neurons was decreased. In addition, a long-term depression protocol failed to further decrease the synapse efficacy, suggesting that the VOR reduction might have occurred through depression-like mechanisms. Analysis of the intrinsic membrane properties of central vestibular neurons revealed that the synaptic changes were supplemented by a decrease in the spontaneous discharge and excitability of a subpopulation of neurons. Our results provide evidence that a long-lasting visuo-vestibular mismatch leads to changes in synaptic transmission and intrinsic properties of central vestibular neurons in the direct VOR pathway. Overall, these results open new avenues for future studies on visual and vestibular interactions conducted in vivo and in vitro.

  6. Long-Lasting Visuo-Vestibular Mismatch in Freely-Behaving Mice Reduces the Vestibulo-Ocular Reflex and Leads to Neural Changes in the Direct Vestibular Pathway

    PubMed Central

    Carcaud, Julie; França de Barros, Filipa; Eugène, Daniel; Reveret, Lionel; Moore, Lee E.; Vidal, Pierre-Paul

    2017-01-01

    Abstract Calibration of the vestibulo-ocular reflex (VOR) depends on the presence of visual feedback. However, the cellular mechanisms associated with VOR modifications at the level of the brainstem remain largely unknown. A new protocol was designed to expose freely behaving mice to a visuo-vestibular mismatch during a 2-week period. This protocol induced a 50% reduction of the VOR. In vivo pharmacological experiments demonstrated that the VOR reduction depends on changes located outside the flocculus/paraflocculus complex. The cellular mechanisms associated with the VOR reduction were then studied in vitro on brainstem slices through a combination of vestibular afferent stimulation and patch-clamp recordings of central vestibular neurons. The evoked synaptic activity demonstrated that the efficacy of the synapses between vestibular afferents and central vestibular neurons was decreased. In addition, a long-term depression protocol failed to further decrease the synapse efficacy, suggesting that the VOR reduction might have occurred through depression-like mechanisms. Analysis of the intrinsic membrane properties of central vestibular neurons revealed that the synaptic changes were supplemented by a decrease in the spontaneous discharge and excitability of a subpopulation of neurons. Our results provide evidence that a long-lasting visuo-vestibular mismatch leads to changes in synaptic transmission and intrinsic properties of central vestibular neurons in the direct VOR pathway. Overall, these results open new avenues for future studies on visual and vestibular interactions conducted in vivo and in vitro. PMID:28303261

  7. HIV-1 Expression Within Resting CD4+ T Cells After Multiple Doses of Vorinostat

    PubMed Central

    Archin, Nancy M.; Bateson, Rosalie; Tripathy, Manoj K.; Crooks, Amanda M.; Yang, Kuo-Hsiung; Dahl, Noelle P.; Kearney, Mary F.; Anderson, Elizabeth M.; Coffin, John M.; Strain, Matthew C.; Richman, Douglas D.; Robertson, Kevin R.; Kashuba, Angela D.; Bosch, Ronald J.; Hazuda, Daria J.; Kuruc, Joann D.; Eron, Joseph J.; Margolis, David M.

    2014-01-01

    Background. A single dose of the histone deacetylase inhibitor vorinostat (VOR) up-regulates HIV RNA expression within resting CD4+ T cells of treated, aviremic human immunodeficiency virus (HIV)–positive participants. The ability of multiple exposures to VOR to repeatedly disrupt latency has not been directly measured, to our knowledge. Methods. Five participants in whom resting CD4+ T-cell–associated HIV RNA (rc-RNA) increased after a single dose of VOR agreed to receive daily VOR Monday through Wednesday for 8 weekly cycles. VOR serum levels, peripheral blood mononuclear cell histone acetylation, plasma HIV RNA single-copy assays, rc-RNA, total cellular HIV DNA, and quantitative viral outgrowth assays from resting CD4+ T cells were assayed. Results. VOR was well tolerated, with exposures within expected parameters. However, rc-RNA measured after dose 11 (second dose of cycle 4) or dose 22 (second dose of cycle 8) increased significantly in only 3 of the 5 participants, and the magnitude of the rc-RNA increase was much reduced compared with that after a single dose. Changes in histone acetylation were blunted. Results of quantitative viral outgrowth and other assays were unchanged. Conclusions. Although HIV latency is disrupted by an initial VOR dose, the effect of subsequent doses in this protocol was much reduced. We hypothesize that the global effect of VOR results in a refractory period of ≥24 hours. The optimal schedule for VOR administration is still to be defined. PMID:24620025

  8. Contribution of irregular semicircular canal afferents to the horizontal vestibuloocular response during constant velocity rotation

    NASA Technical Reports Server (NTRS)

    Angelaki, D. E.; Perachio, A. A.

    1993-01-01

    1. The effects of constant anodal currents (100 microA) delivered bilaterally to both labyrinths on the horizontal vestibuloocular response (VOR) were studied in squirrel monkeys during steps of angular velocity in the dark. We report that bilateral anodal currents decreased eye velocity approximately 30-50% during the period of galvanic stimulation without a change in the time constant of VOR. The decrease in eye velocity, present during steps of angular velocity, was not observed during sinusoidal head rotation at 0.2, 0.5, and 1 Hz. The results suggest that responses from irregular vestibular afferents influence VOR amplitude during constant velocity rotation.

  9. North Atlantic OMEGA Navigation System Validation

    DTIC Science & Technology

    1980-07-21

    Coordinates 7-18 7-7 Aeroflot Flight Zone OMEGA Accuracies vs DME or DME /VOR Coordinates 7-18 7-8 Alabama Getty Measurements 7-20 7-9 British Respect...navigation equipment on board the aircraft during the tests consisted of TAC.N VOR/ DME , sextant and a driftmeter. The majority of flight hours were...measurement of two (2) distances from DME , or azimuth and distance for VOR/ DME with distances from the radio beacons of not more than 40 KM. During the

  10. The vestibulo-ocular reflex and its possible roles in space motion sickness

    NASA Technical Reports Server (NTRS)

    Watt, Douglas G. D.

    1987-01-01

    Prolonged exposure to an inappropriate vestibulo-ocular reflex (VOR) will usually lead to motion sickness, and it has been predicted on theoretical grounds that VOR gain may be decreased in weightlessness. While experiments during parabolic flight in aircraft tend to confirm this prediction, experiments during orbital spaceflight have led to apparently contradictory results. It is suggested that VOR gain is reduced initially, but that rapid compensatory mechanisms restore it to normal within minutes of reaching weightlessness. However, even though this process may lead to the rapid return of functionally normal gaze stability, it may not protect against the development of motion sickness.

  11. Earth horizontal axis rotational responses in patients with unilateral peripheral vestibular deficits

    NASA Technical Reports Server (NTRS)

    Furman, Joseph M. R.; Kamerer, Donald B.; Wall, Conrad, III

    1989-01-01

    The vestibulo-ocular reflex (VOR) of five patients with surgically confirmed unilateral peripheral vestibular lesions is evaluated. Testing used both earth vertical axis (EVA) and earth horizontal axis (EHA) yaw rotation. Results indicated that the patients had short VOR time constants, asymmetric responses to both EVA and EHA rotation, and normal EHA modulation components. These findings suggest that unilateral peripheral vestibular loss causes a shortened VOR time constant even with the addition of dynamic otolithic stimulation and causes an asymmetry in semicircular canal-ocular reflexes and one aspect of otolith-ocular reflexes.

  12. Earth horizontal axis rotational responses in patients with unilateral peripheral vestibular deficits

    NASA Technical Reports Server (NTRS)

    Furman, Joseph M. R.; Kamerer, Donald B.; Wall, Conrad, III

    1989-01-01

    The vestibulo-ocular reflex (VOR) of five patients with surgically confirmed unilateral peripheral vestibular lesions is evaluated. Testing used both earth vertical axis (EVA) and earth horizontal axis (EHA) yaw rotation. Results indicated that the patients had short VOR time constants, asymmetric responses to both EVA and EHA rotation, and normal EHA modulation components. These findings suggest that unilateral peripheral vestibular loss causes a shortened VOR time constant even with the addition of dynamic otolithic stimulation and causes an asymmetry in semicircular canal-ocular reflexes and one aspect of otolith-ocular reflexes.

  13. A Sparse Matrix Approach for Simultaneous Quantification of Nystagmus and Saccade

    NASA Technical Reports Server (NTRS)

    Kukreja, Sunil L.; Stone, Lee; Boyle, Richard D.

    2012-01-01

    The vestibulo-ocular reflex (VOR) consists of two intermingled non-linear subsystems; namely, nystagmus and saccade. Typically, nystagmus is analysed using a single sufficiently long signal or a concatenation of them. Saccade information is not analysed and discarded due to insufficient data length to provide consistent and minimum variance estimates. This paper presents a novel sparse matrix approach to system identification of the VOR. It allows for the simultaneous estimation of both nystagmus and saccade signals. We show via simulation of the VOR that our technique provides consistent and unbiased estimates in the presence of output additive noise.

  14. Computer Programs for EMC Based on the Methods of Moments.

    DTIC Science & Technology

    1980-04-01

    WIRES has been used to predict bearing errors experienced by aircraft and caused by wire obstacles in the field of an airport VOR/ DVOR station (87]. In...by the presence of metallic bodies of revolution near VOR/ DVOR airport stations [87]. 60 The original body-of-revolution code is on deposit with the...34Effects of Scattering by Obstacles in the Field of VOR/ DVOR ," Report No. FAA-RD-74-153, Syracuse University- FAA; Sept. 1974. 88. H. Gruenberg

  15. 76 FR 4061 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-24

    ..., AL, Huntsville Intl--Carl T Jones Field, RADAR-1, Amdt 10 Mobile, AL, Mobile Downtown, VOR RWY 14... 18 Akron, OH, Akron-Canton Rgnl, RNAV (GPS) RWY 23, Orig Oklahoma City, OK, Will Rogers World, ILS...

  16. 76 FR 56969 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-15

    ..., Orig Greenville, TX, Majors, TACAN RWY 35, Orig Wheeler, TX, Wheeler Muni, RNAV (GPS) RWY 17, Orig Wheeler, TX, Wheeler Muni, RNAV (GPS) RWY 35, Orig Wheeler, TX, Wheeler Muni, VOR/DME-A, Amdt 2 Milwaukee...

  17. Evaluation of Microwave Landing System (MLS) effect on the delivery performance of a fixed-path metering and spacing system

    NASA Technical Reports Server (NTRS)

    Credeur, L.; Davis, C. M.; Capron, W. R.

    1981-01-01

    Metering and spacing (M & S) system's algorithms described assume an aircraft two dimensional are navigation capability. The three navigation systems compared were: very high frequency omnidirectional range/distance measuring equipment (VOR/DME) and ILS, VOR/DME and + or - 40 MLS, and VOR/DME and + or - 60 MLS. Other factors studied were M & S tentative schedule point location, route geometry effects, and approach gate location effects. Summarized results are: the MLS offers some improvement over VOR/DME and ILS if all approach routes contain computer assisted turns; pilot reaction to moving the gate closer to the runway threshold may adversely affect M & S performance; and coupling en route metering to terminal scheduling transfers most of the terminal holding to more full efficient, higher altitude en route delay.

  18. Spatial Transformation of the Vestibulo-Ocular Reflex during Spaceflight

    NASA Technical Reports Server (NTRS)

    Clement, Gilles; Wood, Scott J.; Reschke, Millard F.

    1996-01-01

    It was hypothesized that the absence of the gravitational reference cues may be responsible for adaptive changes in the vestibulo-ocular reflex (VOR). These changes result in the alteration of the direction of the compensatory slow phase (SP) eye movements in microgravity. In order to test this hypothesis, the direction of the VOR SP relative to head motion was investigated in three astronauts during and after an eight-day orbital flight by passive sinusoidal pitch or yaw angular motion at two frequencies. The results of the inflight and postflight testing are considered. The observed deviation between VOR SP and head motion suggests that spatial transformation in the VOR occurred during adaptation to microgravity. It is considered that, although this spatial transformation might be due to a sensory bias, it may reflect central changes in the reference system used for spatial orientation in microgravity.

  19. National Airspace System: Air Traffic Control and Airspace Management Operational Concept NAS-SR-132

    DTIC Science & Technology

    1992-12-01

    provides continuous prerecorded weather advisories over selected VORs and includes Severe Weather Forecast Alerts (AWW), Significant Meteorological...Automated Terminal Information Service AWOS Automated Weather Observation Station AWP Aviation Weather Processor AWW Severe Weather Forecast Alerts

  20. 78 FR 57472 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-19

    ... Sec. 95.6002 VOR Federal Airway V2 Is Amended To Read in Part BADGER, WI VORTAC SUDDS, WI FIX 2900... BADGER, WI VORTAC MUSKEGON, MI VORTAC 56 BADGER. V216 Is Amended To Delete Changeover Point...

  1. Spatial Transformation of the Vestibulo-Ocular Reflex during Spaceflight

    NASA Technical Reports Server (NTRS)

    Clement, Gilles; Wood, Scott J.; Reschke, Millard F.

    1996-01-01

    It was hypothesized that the absence of the gravitational reference cues may be responsible for adaptive changes in the vestibulo-ocular reflex (VOR). These changes result in the alteration of the direction of the compensatory slow phase (SP) eye movements in microgravity. In order to test this hypothesis, the direction of the VOR SP relative to head motion was investigated in three astronauts during and after an eight-day orbital flight by passive sinusoidal pitch or yaw angular motion at two frequencies. The results of the inflight and postflight testing are considered. The observed deviation between VOR SP and head motion suggests that spatial transformation in the VOR occurred during adaptation to microgravity. It is considered that, although this spatial transformation might be due to a sensory bias, it may reflect central changes in the reference system used for spatial orientation in microgravity.

  2. 75 FR 22215 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-28

    ..., SC, Pickens County, RNAV (GPS) RWY 23, Orig Pickens, SC, Pickens County, VOR/DME-A, Amdt 1 Athens, TX, Athens Muni, RNAV (GPS) RWY 17, Orig Athens, TX, Athens Muni, RNAV (GPS) RWY 35, Orig Athens, TX, Athens...

  3. Neural substrates underlying vestibular compensation: contribution of peripheral versus central processing.

    PubMed

    Cullen, Kathleen E; Minor, Lloyd B; Beraneck, Mathieu; Sadeghi, Soroush G

    2009-01-01

    The vestibulo-ocular reflex (VOR), which functions to stabilize gaze and ensure clear vision during everyday activities, shows impressive adaptation in response to environmental requirements. In particular, the VOR exhibits remarkable recovery following the loss of unilateral labyrinthine input as a result of injury or disease. The relative simplicity of the pathways that mediate the VOR, make it an excellent model system for understanding the changes (learning) that occur in the brain following peripheral vestibular loss to yield adaptive changes. This mini review considers the findings of behavioral, single unit recording and lesion studies of VOR compensation. Recent experiments have provided evidence that the brain makes use of multiple plasticity mechanisms (i.e., changes in peripheral as well as central processing) during the course of vestibular compensation to accomplish the sensory-motor transformations required to accurately guide behavior.

  4. 77 FR 23171 - Proposed Amendment of Class E Airspace; Fairfield, CA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-18

    ... proposed decommissioning of the Travis VHF Omni-Directional Radio Range (VOR) has made this action... Travis AFB, Fairfield, CA. Airspace reconfiguration is necessary due to the proposed decommissioning of...

  5. Unfälle mit Pkw

    NASA Astrophysics Data System (ADS)

    Burg, Heinz

    Der Verkehrsunfall ereignete sich innerorts auf einer Kreuzung mit rechts vor links Regelung. Es galt dort die allgemeine Geschwindigkeitsbegrenzung auf 50 km/h. Zur Unfallzeit war es hell und trocken. Die Fahrbahn hatte eine Schwarzdecke.

  6. Voriconazole therapeutic drug monitoring: results of a prematurely discontinued randomized multicenter trial

    PubMed Central

    Neofytos, D.; Ostrander, D.; Shoham, S.; Laverdiere, M.; Hiemenz, J.; Nguyen, H.; Clark, W.; Brass, L.; Lu, N.; Marr, K.A.

    2015-01-01

    Background Voriconazole (VOR) levels are highly variable, with potential implications to both efficacy and safety. We hypothesized that VOR therapeutic drug monitoring (TDM) will decrease the incidence of treatment failures and adverse events (AEs). Methods We initiated a prospective, randomized, non-blinded multicenter study to compare clinical outcomes in adult patients randomized to standard dosing (clinician-driven) vs. TDM (doses adjusted based on levels). VOR trough levels were obtained on day 5, 14, 28, and 42 (or at completion of drug; ± 3 days). Real-time dose adjustments were made to maintain a range between 1–5 μg/mL on the TDM-arm, while levels were assessed retrospectively in the standard arm. Patient questionnaires were administered to assess subjective AEs. Results The study was discontinued prematurely, after 29 patients were enrolled. Seventeen (58.6%) patients experienced 38 AEs: visual changes (22/38, 57.9%), neurological symptoms (13/38, 34.2%), and liver abnormalities (3/38, 7.9%). VOR was discontinued in 7 (25%) patients because of an AE (4 standard-arm, 3 TDM-arm). VOR levels were frequently out of range in the standard-arm (8 tests >5 μg/mL; 9 tests < 1 μg/mL). Three dose changes occurred in the TDM-arm for VOR levels <1 μg/mL. Levels decreased over time in the standard-arm, with mean VOR levels lower at end of therapy compared to TDM (1.3 vs. 4.6 μg/mL, P = 0.008). Conclusions VOR TDM has become widespread clinical practice, based on known variability in drug levels, which impaired accrual in this study. Although comparative conclusions are limited, observations of variability and waning levels over time support TDM. PMID:26346408

  7. Altered gravitational experience during early periods of life affects the static vestibulo-ocular reflex of tadpoles of the southern clawed toad, Xenopus laevis Daudin.

    PubMed

    Sebastian, C; Esseling, K; Horn, E

    1996-11-01

    The effects of altered gravitational forces (AGF) on the development of the static vestibulo-ocular reflex (VOR) were investigated in Xenopus laevis tadpoles exposed to hypergravity (1.4g; 3g) or microgravity conditions (German spacelab mission D-2) for 9-10 days. The effects of light conditions during development were also tested by exposing tadpoles to either complete darkness (DD) or 12:12 h light-dark conditions (LD). The static VOR was induced by lateral roll. The efficacy of the VOR circuit after termination of AGF conditions was described by the peak-to-peak amplitude of the sinusoidal VOR characteristics (i.e. amplitude). The static VOR was first observed at stage 41 for both LD and DD tadpoles. Its further development was retarded in the DD tadpoles compared with the LD tadpoles up to stage 48. Microgravity as well as hypergravity exposure caused a significant (P < 0.05, at least) decrease in the static VOR amplitude during the first week after termination of the AGF period. The decreases were 39.4% in the microgravity group, 16.2% in the 1.4g group and 24.9-42.9% in the 3g group compared with the 1g ground-reared siblings at the same developmental stages. The response deficits usually disappeared but persisted for at least 2 weeks in animals whose development was retarded by hypergravity exposure. It is postulated (i) that gravity exerts an important influence on the normal development of the roll-induced static VOR; (ii) that hypergravity exposure decreases the sensitivity of the gravity-sensitive system so that recordings under 1g conditions cause a weaker static VOR; and (iii) that the vestibulo-spinal pathway possesses a higher degree of plasticity than the vestibulo-ocular pathway.

  8. 75 FR 80680 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-23

    ..., Amdt 1A. 13 Jan-11 TX Corsicana C David Campbell 0/8376 11/23/10 VOR/DME B, Amdt 1. Field-Corsicana Muni. 13 Jan-11 TX Corsicana C David Campbell 0/8806 11/23/10 NDB RWY 32, Amdt 3. Field-Corsicana Muni. 13 Jan-11 TX Corsicana C David Campbell 0/8807 11/23/10 VOR/DME A, Amdt 1. Field-Corsicana Muni. 13...

  9. The three-dimensional vestibulo-ocular reflex evoked by high-acceleration rotations in the squirrel monkey.

    PubMed

    Migliaccio, Americo A; Schubert, Michael C; Jiradejvong, Patpong; Lasker, David M; Clendaniel, Richard A; Minor, Lloyd B

    2004-12-01

    The aim of this study was to determine if the angular vestibulo-ocular reflex (VOR) in response to pitch, roll, left anterior-right posterior (LARP), and right anterior-left posterior (RALP) head rotations exhibited the same linear and nonlinear characteristics as those found in the horizontal VOR. Three-dimensional eye movements were recorded with the scleral search coil technique. The VOR in response to rotations in five planes (horizontal, vertical, torsional, LARP, and RALP) was studied in three squirrel monkeys. The latency of the VOR evoked by steps of acceleration in darkness (3,000 degrees /s(2) reaching a velocity of 150 degrees /s) was 5.8+/-1.7 ms and was the same in response to head rotations in all five planes of rotation. The gain of the reflex during the acceleration was 36.7+/-15.4% greater than that measured at the plateau of head velocity. Polynomial fits to the trajectory of the response show that eye velocity is proportional to the cube of head velocity in all five planes of rotation. For sinusoidal rotations of 0.5-15 Hz with a peak velocity of 20 degrees /s, the VOR gain did not change with frequency (0.74+/-0.06, 0.74+/-0.07, 0.37+/-0.05, 0.69+/-0.06, and 0.64+/-0.06, for yaw, pitch, roll, LARP, and RALP respectively). The VOR gain increased with head velocity for sinusoidal rotations at frequencies > or =4 Hz. For rotational frequencies > or =4 Hz, we show that the vertical, torsional, LARP, and RALP VORs have the same linear and nonlinear characteristics as the horizontal VOR. In addition, we show that the gain, phase and axis of eye rotation during LARP and RALP head rotations can be predicted once the pitch and roll responses are characterized.

  10. National Positioning, Navigation and Timing (PNT) Architecture Workshop at Volpe, 26 April 2007

    DTIC Science & Technology

    2007-04-17

    Urban Enclosed Under Surface Space Nav Terrestrial Nav ISR / Targeting Traffic Management Logistics Manufacturing Agriculture Cooperative Location...As-Is” PNT Architecture (2007) EMI EMI C2 Infrastructure & Enablers GALILEO (GIOVE-A) GPS GLONASS GPS Compass WAAS EGNOS TASS LORAN-C VOR/ DME ...Infrastructure & Enablers SCA GALILEO GPS GLONASS GPS Compass IRNSS QZSS WAAS EGNOS GAGAN TASS eLORAN VOR/ DME , TACAN ILS, NDB Tracking N S EW Compass Clock INS

  11. An Investigation of Horizontal Combined Eye-Head Tracking in Patients with Abnormal Vestibular and Smooth Pursuit Eye Movements

    NASA Technical Reports Server (NTRS)

    Huebner, William P.; Leigh, R. John; Seidman, Scott H.; Billian, Carl

    1993-01-01

    We investigated the interaction of smooth ocular pursuit (SP) and the vestibulo-ocular reflex (VOR) during horizontal, combined eye-head tracking (CEHT) in patients with abnormalities of either the VOR or SP movements. Our strategy was to apply transient stimuli that capitalized on the different latencies to onset of SP and the VOR. During CEHT of a target moving at 15 deg/sec, normal subjects and patients with VOR deficits all tracked the target with a gain close to 1.O. When the heads of normal subjects were suddenly and unexpectedly braked to a halt during CEHT, the eye promptly began to move in the orbit to track the target, but eye-in-orbit velocity transiently fell to about 60-70% of target velocity. In patients with deficient labyrinthine function, following the onset of the head brake, eye movements to track the target were absent, and SP movements were not generated until about 100 msec later. In patients with deficient SP, CEHT was superior to SP tracking with the head stationary; after the onset of the head brake, tracking eye movements were initiated promptly, but eye velocity was less than 50% of target velocity and increased only slightly thereafter. These results indicate that at least two mechanisms operate to overcome the VOR and allow gaze to track the target during CEHT: (1) the SP system provides a signal to cancel a normally-operating VOR (this cancellation signal is not needed by labyrinthine-deficient patients who have no VOR to cancel), and (2) a reduction of the gain of the VOR is achieved, an ability that is preserved even in patients with cerebral lesions that impair SP.

  12. Vestibulo-ocular reflex of the squirrel monkey during eccentric rotation with centripetal acceleration along the naso-occipital axis

    NASA Technical Reports Server (NTRS)

    Merfeld, D. M.; Paloski, W. H. (Principal Investigator)

    1996-01-01

    The vestibulo-ocular reflexes (VOR) are determined not only by angular acceleration, but also by the presence of gravity and linear acceleration. This phenomenon was studied by measuring three-dimensional nystagmic eye movements, with implanted search coils, in four male squirrel monkeys. Monkeys were rotated in the dark at 200 degrees/s, centrally or 79 cm off-axis, with the axis of rotation always aligned with gravity and the spinal axis of the upright monkeys. The monkey's position relative to the centripetal acceleration (facing center or back to center) had a dramatic influence on the VOR. These studies show that a torsional response was always elicited that acted to shift the axis of eye rotation toward alignment with gravito-inertial force. On the other hand, a slow phase downward vertical response usually existed, which shifted the axis of eye rotation away from the gravito-inertial force. These findings were consistent across all monkeys. In another set of tests, the same monkeys were rapidly tilted about their interaural (pitch) axis. Tilt orientations of 45 degrees and 90 degrees were maintained for 1 min. Other than a compensatory angular VOR during the rotation, no consistent eye velocity response was ever observed during or following the tilt. The absence of any response following tilt proves that the observed torsional and vertical responses were not a positional nystagmus. Model simulations qualitatively predict all components of these eccentric rotation and tilt responses. These simulations support the conclusion that the VOR during eccentric rotation may consist of two components: a linear VOR and a rotational VOR. The model predicts a slow phase downward, vertical, linear VOR during eccentric rotation even though there was never a change in the force aligned with monkey's spinal (Z) axis. The model also predicts the torsional components of the response that shift the rotation axis of the angular VOR toward alignment with gravito-inertial force.

  13. Behavioral analysis of signals that guide learned changes in the amplitude and dynamics of the vestibulo-ocular reflex

    NASA Technical Reports Server (NTRS)

    Raymond, J. L.; Lisberger, S. G.

    1996-01-01

    We characterized the dependence of motor learning in the monkey vestibulo-ocular reflex (VOR) on the duration, frequency, and relative timing of the visual and vestibular stimuli used to induce learning. The amplitude of the VOR was decreased or increased through training with paired head and visual stimulus motion in the same or opposite directions, respectively. For training stimuli that consisted of simultaneous pulses of head and target velocity 80-1000 msec in duration, brief stimuli caused small changes in the amplitude of the VOR, whereas long stimuli caused larger changes in amplitude as well as changes in the dynamics of the reflex. When the relative timing of the visual and vestibular stimuli was varied, brief image motion paired with the beginning of a longer vestibular stimulus caused changes in the amplitude of the reflex alone, but the same image motion paired with a later time in the vestibular stimulus caused changes in the dynamics as well as the amplitude of the VOR. For training stimuli that consisted of sinusoidal head and visual stimulus motion, low-frequency training stimuli induced frequency-selective changes in the VOR, as reported previously, whereas high-frequency training stimuli induced changes in the amplitude of the VOR that were more similar across test frequency. The results suggest that there are at least two distinguishable components of motor learning in the VOR. One component is induced by short-duration or high-frequency stimuli and involves changes in only the amplitude of the reflex. A second component is induced by long-duration or low-frequency stimuli and involves changes in the amplitude and dynamics of the VOR.

  14. Aging Increases Compensatory Saccade Amplitude in the Video Head Impulse Test.

    PubMed

    Anson, Eric R; Bigelow, Robin T; Carey, John P; Xue, Quan-Li; Studenski, Stephanie; Schubert, Michael C; Weber, Konrad P; Agrawal, Yuri

    2016-01-01

    Rotational vestibular function declines with age resulting in saccades as a compensatory mechanism to improve impaired gaze stability. Small reductions in rotational vestibulo-ocular reflex (VOR) gain that would be considered clinically normal have been associated with compensatory saccades. We evaluated whether compensatory saccade characteristics varied as a function of age, independent of semicircular canal function as quantified by VOR gain. Horizontal VOR gain was measured in 243 participants age 27-93 from the Baltimore Longitudinal Study of Aging using video head impulse testing. Latency and amplitude of the first saccade (either covert - occurring during head impulse, or overt - occurring following head impulse) were measured for head impulses with compensatory saccades (n = 2230 head impulses). The relationship between age and saccade latency, as well as the relationship between age and saccade amplitude, were evaluated using regression analyses adjusting for VOR gain, gender, and race. Older adults (mean age 75.9) made significantly larger compensatory saccades relative to younger adults (mean age 45.0). In analyses adjusted for VOR gain, there was a significant association between age and amplitude of the first compensatory covert saccade (β = 0.015, p = 0.008). In analyses adjusted for VOR gain, there was a significant association between age and amplitude of the first compensatory overt saccade (β = 0.02, p < 0.001). Compensatory saccade latencies did not vary significantly by age. We observed that aging increases the compensatory catch-up saccade amplitude in healthy adults after controlling for VOR gain. Size of compensatory saccades may be useful in addition to VOR gain for characterizing vestibular function in aging adults.

  15. Epidemiology of Vestibulo-Ocular Reflex Function: Data from the Baltimore Longitudinal Study of Aging

    PubMed Central

    Li, Carol; Layman, Andrew J.; Geary, Robert; Anson, Eric; Carey, John P.; Ferrucci, Luigi; Agrawal, Yuri

    2014-01-01

    Objective To determine age-related changes in vestibulo-ocular reflex (VOR) function in community-dwelling adults, and evaluate these for associations with demographic characteristics and cardiovascular risk factors. Study Design Cross-sectional analysis within the Baltimore Longitudinal Study of Aging (BLSA), a longitudinal prospective cohort study. Setting Vestibular testing laboratory within an acute care teaching hospital. Patients Community-dwelling adults enrolled in the BLSA. Intervention(s) Horizontal VOR gain measurement using video head-impulse testing and visual acuity testing. Main Outcome Measure(s) VOR gain was calculated as the ratio of eye velocity to head velocity. Demographic and cardiovascular risk factor data were collected through study questionnaires. Results One hundred nine subjects were analyzed with mean age (SD) 69.9 years (14.2), with a range from 26 to 92 years. VOR gain remained stable from age 26 to 79 after which it significantly declined at a rate of 0.012/year (p = 0.033) in adjusted analyses. Individuals aged 80 years or older had a nearly 8-fold increased odds of VOR gain less than 0.80 relative to those aged less than 80 years in multivariate models (prevalence of 13.2% vs. 2.8%; OR 7.79, 95% CI: 1.04–58.38). Otherwise, VOR gain did not differ significantly across demographic or cardiovascular risk groups. Conclusion We report age-related decline in VOR function in individuals aged 80 years and older. Further analyses are in progress to establish the significance of these VOR abnormalities to functional and mobility outcomes in older individuals. PMID:25275869

  16. Canal and otolith vestibulo-ocular reflexes to vertical and off vertical axis rotations in children learning to walk.

    PubMed

    Wiener-Vacher, S R; Toupet, F; Narcy, P

    1996-09-01

    In order to determine the characteristics of the vestibulo-ocular reflexes (VORs) as a function of age and posturo-motor development, a group of 26 normal children (6 to 25 months old) were tested at three different stages of posturo-motor control: prior to as well as during the first attempts to walk without support, and during the first year of independent walking. The test consisted of electro-oculographic (EOG) recordings of the VOR responses to horizontal semi-circular canal and otolith stimulations. The canal VOR was elicited in seated subjects by rotatory impulsions about a vertical axis (acceleration and deceleration both at 40 degrees/s2, separated by a rotation at 60 degrees/s velocity). The otolith VOR was elicited by inclining the rotating chair by 9 degrees respect to gravity. For the canal VOR, the time constant and the highest initial slow phase velocity were measured. The otolith VOR was characterized by the amplitude of the modulation and the bias (offset of baseline from zero) of the slow phase velocity averaged over 10 to 20 rotation cycles, for both the horizontal and vertical components of the response. The pooled values of these data show that canal VOR parameters did not vary significantly either with age of the children or with their stage of posturo-motor control. However, the otolith VOR parameters changed during the period of learning to walk: the modulation of the horizontal component increased and the modulation of the vertical component decreased significantly. Thus the ability to walk without support is marked by a significant change in the otolith but not canal responses; since the vestibular sensory organs develop anatomically at the same rate these results indicate that central nervous system processors of canal and otolith information develop independently.

  17. National Airspace System: Air-Ground Communications Operational Concept NAS-SR-1361

    DTIC Science & Technology

    1990-01-01

    Communications Switching System (ICSS). In addition to the ICSS, AFSS personnel have direct voice interface with VOR equipment to provide emergency voice...FSDPS supports the AFSS work station which is combined in various configurations to support the different AFSS operational positions. Direct voice ... interface in the form of emergency messages are transmitted over the VOR in the same manner as the facility voice identification. NASSRS Requirement

  18. Kernkraftwerke

    NASA Astrophysics Data System (ADS)

    Allelein, H. J.

    Die Nutzung der Kernenergie ist untrennbar mit dem Element Uran verknüpft. Da die Umwandlung eines Elements in ein anderes auf chemischem Weg nicht möglich ist, muss das heute vorhandene Uran durch kosmische Prozesse vor Entstehung der Erde entstanden sein. Reines Uran ist ein silberweiß glänzendes, relativ weiches Schwermetall. In der Elementhäufigkeit steht Uran vor Gold, Silber oder Quecksilber.

  19. Vestibulo-ocular reflex of the squirrel monkey during eccentric rotation with centripetal acceleration along the naso-occipital axis

    NASA Technical Reports Server (NTRS)

    Merfeld, D. M.; Paloski, W. H. (Principal Investigator)

    1996-01-01

    The vestibulo-ocular reflexes (VOR) are determined not only by angular acceleration, but also by the presence of gravity and linear acceleration. This phenomenon was studied by measuring three-dimensional nystagmic eye movements, with implanted search coils, in four male squirrel monkeys. Monkeys were rotated in the dark at 200 degrees/s, centrally or 79 cm off-axis, with the axis of rotation always aligned with gravity and the spinal axis of the upright monkeys. The monkey's position relative to the centripetal acceleration (facing center or back to center) had a dramatic influence on the VOR. These studies show that a torsional response was always elicited that acted to shift the axis of eye rotation toward alignment with gravito-inertial force. On the other hand, a slow phase downward vertical response usually existed, which shifted the axis of eye rotation away from the gravito-inertial force. These findings were consistent across all monkeys. In another set of tests, the same monkeys were rapidly tilted about their interaural (pitch) axis. Tilt orientations of 45 degrees and 90 degrees were maintained for 1 min. Other than a compensatory angular VOR during the rotation, no consistent eye velocity response was ever observed during or following the tilt. The absence of any response following tilt proves that the observed torsional and vertical responses were not a positional nystagmus. Model simulations qualitatively predict all components of these eccentric rotation and tilt responses. These simulations support the conclusion that the VOR during eccentric rotation may consist of two components: a linear VOR and a rotational VOR. The model predicts a slow phase downward, vertical, linear VOR during eccentric rotation even though there was never a change in the force aligned with monkey's spinal (Z) axis. The model also predicts the torsional components of the response that shift the rotation axis of the angular VOR toward alignment with gravito-inertial force.

  20. 77 FR 66536 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-06

    ... F Kennedy 2/1321 09/25/12 VOR OR GPS RWY 13L/13R, Amdt 18B Intl. 15-Nov-12 CA Fullerton Fullerton... 2/2119 09/25/12 VOR-A, Orig-B R. Washburn Field. 15-Nov-12 OK Muskogee Davis Field....... 2/2507 09..., Orig 15-Nov-12 VT Burlington......... Burlington Intl... 2/4045 10/03/12 RNAV (GPS) Z RWY 15, Orig-C...

  1. 78 FR 20783 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-08

    .... Changeover Points From To MEA Sec. 95.6001 Victor Routes-U.S. Sec. 95.6001 VOR Federal Airway V1 Is Amended... VORTAC, E BND **3100--MOCA **5300--GNSS MEA VAMPS, WA FIX BANDR, WA FIX E BND *8400 W BND *7700 *7700--GNSS MEA BANDR, WA FIX *BEEZR, WA FIX 8400 *9000--MRA Sec. 95.6003 VOR Federal Airway V3 Is Amended...

  2. 75 FR 10995 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-10

    ... From To MEA Sec. 95.0040 Colored Federal Airways Sec. 95.50 Green Federal Airway G10 Is Amended To Read... Island, AK BILBE, AK FIX 3000 NDB/DME Bilbe, AK FIX Elfee, AK NDB *6000 *3800--MOCA ] From To MEA MAA Sec... Deadhorse, AK VOR/DME 2200 17500 From To MEA Sec. 95.6001 Victor Routes--U.S. Sec. 95.6016 VOR...

  3. Physik gestern und heute Von der Metallstange zum Hochenergielaser

    NASA Astrophysics Data System (ADS)

    Heering, Peter

    2002-05-01

    Im Mai 1752 wurde in Marly bei Paris auf Anregung des amerikanischen Forschers und Politikers Benjamin Franklin erstmals die elektrische Natur des Blitzes nachgewiesen. Damals beschrieb Franklin auch eine technische Vorrichtung, die als Schutz von Gebäuden vor Blitzschlägen dienen sollte: den Blitzableiter. Diese aus heutiger Sicht scheinbar triviale Vorrichtung wurde aber keineswegs unmittelbar akzeptiert. Und bis heute ist die Forschung zum Schutz von Einrichtungen vor Blitzschlägen nicht abgeschlossen.

  4. Broadcast control of air traffic

    NASA Technical Reports Server (NTRS)

    Litchford, G. B.

    1971-01-01

    The proceedings of a conference on the Omega navigation system are presented. Three significant low frequency/very low frequency possibilities are considered as follows: (1) use of Worldwide (WW) Omega, (2) use of an Omega-like system optimized for aviation in the continental United States, (3) a mix use of WW Omega and Vor, U.S. Omega and VOR, and U.S./WW Omega. It is concluded that all possibilites can be tested with current plans for WW Omega.

  5. Interaction between cervico-ocular and vestibulo-ocular reflexes in normal adults.

    PubMed

    Jürgens, R; Mergner, T

    1989-01-01

    The interaction of the cervico-ocular reflex (COR) and the vestibulo-ocular reflex (VOR) was studied in 20 human Subjects (Ss) during application of synergistic and antagonistic combinations of neck and vestibular stimuli, and during two different psychophysical tasks related to the Ss' self-motion sensation. Slow and quick eye movement responses were analyzed separately. Neck stimulation produced by horizontal rotation of the trunk about the stationary head elicited slow COR eye movements of very low gain; COR direction was anticompensatory, unlike the compensatory one of the VOR. During either a synergistic combination of neck and labyrinthine stimuli (head rotation on stationary trunk) or an antagonistic combination (head-to-trunk rotation counter to head-in-space rotation), the resulting slow eye movements were slightly larger than those during labyrinthine stimulation alone (whole body rotation). This weak neck contribution could be described by a directionally non-specific enhancement of VOR gain and a linear summation of VOR and COR slow phases. These effects were essentially independent of whether the Ss estimated the magnitude of their head turning or trunk turning in space. If Ss were estimating their trunk turning, neck stimulation also evoked quick eye movements, but these were small and hardly affected the VOR quick phases during the combined stimulations. In contrast, if Ss estimated their head turning, neck stimulation evoked large quick phases, which interfered with the quick phases of the VOR; during the synergistic combination of head and neck stimuli. COR quick phases added to those of the VOR, thereby shifting the gaze in the direction of head rotation (reorientation of gaze). With the antagonistic combination they subtracted, so that the VOR slow phase could compensate the head rotation in space (stabilization of gaze). These findings suggest that (1) the slow phase of the COR has no functional significance in intact humans and (2) the quick

  6. Investment Strategy for DoD Automatic Test Systems. Volume 1. Summary and Analyses

    DTIC Science & Technology

    1994-01-01

    programmability. AM (ILS,VOR), TACAN, and ATLAS integration. Linear Pulse, FSK, MSK. BPSK, QPSK, OQPSK (GPS), generic spread spec- trumn hardware (FrE...libraries. This will lower recurring TPS BPSK. QPSK. OQPSK designated ATS). engineering cost. (GPS), generic spread spec- tum hardware. RF Power -70 to...Sec, Synchro Generators Communication High Accuracy AM (ILS & VOR), TACAN, Linear Pulse. FSK, Waveforms MSK. BPSK, QPSK, OQPSK (GPS), Spread Spectrum 10

  7. An Investigation of Horizontal Combined Eye-Head Tracking in Patients with Abnormal Vestibular and Smooth Pursuit Eye Movements

    NASA Technical Reports Server (NTRS)

    Huebner, William P.; Leigh, R. John; Seidman, Scott H.; Billian, Carl

    1993-01-01

    We investigated the interaction of smooth ocular pursuit (SP) and the vestibulo-ocular reflex (VOR) during horizontal, combined eye-head tracking (CEHT) in patients with abnormalities of either the VOR or SP movements. Our strategy was to apply transient stimuli that capitalized on the different latencies to onset of SP and the VOR. During CEHT of a target moving at 15 deg/sec, normal subjects and patients with VOR deficits all tracked the target with a gain close to 1.O. When the heads of normal subjects were suddenly and unexpectedly braked to a halt during CEHT, the eye promptly began to move in the orbit to track the target, but eye-in-orbit velocity transiently fell to about 60-70% of target velocity. In patients with deficient labyrinthine function, following the onset of the head brake, eye movements to track the target were absent, and SP movements were not generated until about 100 msec later. In patients with deficient SP, CEHT was superior to SP tracking with the head stationary; after the onset of the head brake, tracking eye movements were initiated promptly, but eye velocity was less than 50% of target velocity and increased only slightly thereafter. These results indicate that at least two mechanisms operate to overcome the VOR and allow gaze to track the target during CEHT: (1) the SP system provides a signal to cancel a normally-operating VOR (this cancellation signal is not needed by labyrinthine-deficient patients who have no VOR to cancel), and (2) a reduction of the gain of the VOR is achieved, an ability that is preserved even in patients with cerebral lesions that impair SP.

  8. Behavioral analysis of signals that guide learned changes in the amplitude and dynamics of the vestibulo-ocular reflex

    NASA Technical Reports Server (NTRS)

    Raymond, J. L.; Lisberger, S. G.

    1996-01-01

    We characterized the dependence of motor learning in the monkey vestibulo-ocular reflex (VOR) on the duration, frequency, and relative timing of the visual and vestibular stimuli used to induce learning. The amplitude of the VOR was decreased or increased through training with paired head and visual stimulus motion in the same or opposite directions, respectively. For training stimuli that consisted of simultaneous pulses of head and target velocity 80-1000 msec in duration, brief stimuli caused small changes in the amplitude of the VOR, whereas long stimuli caused larger changes in amplitude as well as changes in the dynamics of the reflex. When the relative timing of the visual and vestibular stimuli was varied, brief image motion paired with the beginning of a longer vestibular stimulus caused changes in the amplitude of the reflex alone, but the same image motion paired with a later time in the vestibular stimulus caused changes in the dynamics as well as the amplitude of the VOR. For training stimuli that consisted of sinusoidal head and visual stimulus motion, low-frequency training stimuli induced frequency-selective changes in the VOR, as reported previously, whereas high-frequency training stimuli induced changes in the amplitude of the VOR that were more similar across test frequency. The results suggest that there are at least two distinguishable components of motor learning in the VOR. One component is induced by short-duration or high-frequency stimuli and involves changes in only the amplitude of the reflex. A second component is induced by long-duration or low-frequency stimuli and involves changes in the amplitude and dynamics of the VOR.

  9. Epidemiology of vestibulo-ocular reflex function: data from the Baltimore Longitudinal Study of Aging.

    PubMed

    Li, Carol; Layman, Andrew J; Geary, Robert; Anson, Eric; Carey, John P; Ferrucci, Luigi; Agrawal, Yuri

    2015-02-01

    To determine age-related changes in vestibulo-ocular reflex (VOR) function in community-dwelling adults, and evaluate these for associations with demographic characteristics and cardiovascular risk factors. Cross-sectional analysis within the Baltimore Longitudinal Study of Aging (BLSA), a longitudinal prospective cohort study. Vestibular testing laboratory within an acute care teaching hospital. Community-dwelling adults enrolled in the BLSA. Horizontal VOR gain measurement using video head-impulse testing and visual acuity testing. VOR gain was calculated as the ratio of eye velocity to head velocity. Demographic and cardiovascular risk factor data were collected through study questionnaires. One hundred nine subjects were analyzed with mean age (SD) 69.9 years (14.2), with a range from 26 to 92 years. VOR gain remained stable from age 26 to 79 after which it significantly declined at a rate of 0.012/year (p = 0.033) in adjusted analyses. Individuals aged 80 years or older had a nearly 8-fold increased odds of VOR gain less than 0.80 relative to those aged less than 80 years in multivariate models (prevalence of 13.2% vs. 2.8%; OR 7.79, 95% CI: 1.04-58.38). Otherwise, VOR gain did not differ significantly across demographic or cardiovascular risk groups. We report age-related decline in VOR function in individuals aged 80 years and older. Further analyses are in progress to establish the significance of these VOR abnormalities to functional and mobility outcomes in older individuals.

  10. Baclofen, motion sickness susceptibility and the neural basis for velocity storage.

    PubMed

    Cohen, Bernard; Dai, Mingjia; Yakushin, Sergei B; Raphan, Theodore

    2008-01-01

    Reduction of the dominant time constant (T(VOR)) of the angular vestibulo-ocular reflex (aVOR) by habituation is associated with a decrease in motion sickness susceptibility. Baclofen, a GABA(b) agonist, reduces the time constant of the velocity storage integrator in the aVOR in a dose-dependent manner. The high frequency aVOR gain is unaltered by baclofen. Here we demonstrate that the reduction in T(VOR) produced by oral administration of 20 mg of baclofen causes a significant reduction in motion sickness susceptibility, tested with roll while rotating (RWR). These data show that motion sickness susceptibility can be pharmacologically manipulated with a GABA(b) agonist and support our conclusion that motion sickness is generated through velocity storage. We also show how baclofen acts on velocity storage at the neural level. A vestibular-plus-saccade (VPS) neuron was recorded in the rostral medial vestibular nucleus (rMVN) of a cynomolgus monkey, an area where we postulate that velocity storage is generated. The cell had a time constant during steps of velocity that was close to that of the T(VOR). After parenteral administration of baclofen, there was a similar decrease in the time constants of the VPS neuron and the T(VOR). This is the first demonstration of the concurrence of unit and aVOR time constants before and after baclofen. The data support the hypothesis that the velocity storage integrator is generated through activity of vestibular-only (VO) and VPS neurons in rMVN and suggest that GABA(b) synapses on VO and VPS neurons are likely to be involved in the baclofen-induced reduction in motion sickness susceptibility.

  11. A Reevaluation of the Vestibulo-Ocular Reflex: New Ideas of its Purpose, Properties, Neural Substrate, and Disorders

    NASA Technical Reports Server (NTRS)

    Leigh, R. John; Brandt, Thomas

    1992-01-01

    Conventional views of the Vestibulo-Ocular Reflex (VOR) have emphasized testing with caloric stimuli and by passively rotating patients at low frequencies in a chair. The properties of the VOR tested under these conditions differ from the performance of this reflex during the natural function for which it evolved-locomotion. Only the VOR (and not visually mediated eye movements) can cope with the high-frequency angular and linear perturbations of the head that occur during locomotion; this is achieved by generating eye movements at short latency (less than 16 msec). Interpretation of vestibular testing is enhanced by the realization that, although the di- and trisynaptic components of the VOR are essential for this short-latency response, the overall accuracy and plasticity of the VOR depend upon a distributed, parallel network of neurons involving the vestibular nuclei. Neurons in this network variously encode inputs from the labyrinthine semicircular canals and otoliths, as well as from the visual and somatosensory systems. The central vestibular pathways branch to contact vestibular cortex (for perception) and the spinal cord (for control of posture). Thus, the vestibular nuclei basically coordinate the stabilization of gaze and posture, and contribute to the perception of verticality and self-motion. Consequently, brainstem disorders that disrupt the VOR cause not just only nystagmus, but also instability of posture (eg, increased fore-aft sway in patients with downbeat nystagmus) and disturbance of spatial orientation (eg, tilt of the subjective visual vertical in Wallenberg's syndrome).

  12. Intra-Attack Vestibuloocular Reflex Changes in Ménière's Disease

    PubMed Central

    Finlay, John B.

    2016-01-01

    Ménière's attack has been shown to temporarily alter the vestibuloocular reflex (VOR). A patient with unilateral Ménière's disease was serially evaluated with the video Head Impulse Test during single, untreated episodes of acute vertigo. Spontaneous nystagmus activity was concurrently recorded in order to establish the three typical phases of Ménière's attack (irritative, paralytic, and recovery) and correlate them with VOR performance. The onset of attack was associated with a quick change in VOR gain on the side of the affected ear. While a rapidly progressive reduction of the VOR was evident at the paralytic nystagmus phase, in the recovery phase the VOR gain returned to normal and the direction of the previous nystagmus reversed. The membrane rupture potassium intoxication theory provides a good foundation with which to explain these dynamic VOR changes and the observed triphasic direction behavior of the spontaneous nystagmus. We additionally postulated that endolymphatic fluid displacement could have a synergic effect during the earliest phase of attack. PMID:28018691

  13. Spatial orientation of the angular vestibulo-ocular reflex.

    PubMed

    Cohen, B; Wearne, S; Dai, M; Raphan, T

    1999-01-01

    During vestibular nystagmus, optokinetic nystagmus (OKN), and optokinetic afternystagmus (OKAN), the axis of eye rotation tends to align with the vector sum of linear accelerations acting on the head. This includes gravitational acceleration and the linear accelerations generated by translation and centrifugation. We define the summed vector of gravitational and linear accelerations as gravito-inertial acceleration (GIA) and designate the phenomenon of alignment as spatial orientation of the angular vestibuloocular reflex (aVOR). On the basis of studies in the monkey, we postulated that the spatial orientation of the aVOR is dependent on the slow (velocity storage) component of the aVOR, not on the short latency, compensatory aVOR component, which is in head-fixed coordinates. Experiments in which velocity storage was abolished by midline medullary section support this postulate. The velocity storage component of the aVOR is likely to be generated in the vestibular nuclei, and its spatial orientation was shown to be controlled through the nodulus and uvula of the vestibulocerebellum. Separate regions of the nodulus/uvula appear to affect the horizontal and vertical/torsional components of the response differently. Velocity storage is weaker in humans than in monkeys, but responds in a similar fashion in both species. We postulate that spatial orientation of the aVOR plays an important role in aligning gaze with the GIA and in maintaining balance during angular locomotion.

  14. Readaptation of the vestibuloocular reflex to 1g-Condition in immature lower vertebrates ( Xenopus laevis) after micro- or hypergravity exposure

    NASA Astrophysics Data System (ADS)

    Sebastian, C.; Horn, E.; Eβeling, K.; Neubert, J.

    The effects of altered gravitational conditions (AGC) on the development of the static vestibulo-ocular reflex (VOR) and readaptation to 1g were investigated in the amphibian Xenopus laevis. Tadpoles were exposed to microgravity (μg) during the German Space Mission D-2 for 10 days, using the STATEX closed survival system, or to 3g for 9 days during earth-bound experiments. At the beginning of AGC, the tadpoles had not yet developed the static VOR. The main results were: (i) Tadpoles with ug- or 3g-experience had a lower gain of the static VOR than the 1g-controls during the 2nd and 5th post-AGC days, (ii) Readaptation to response levels of 1g-reared controls usually occurred during the following weeks, except in slowly developing tadpoles with 3g-experience. Readaptation was less pronounced if, during the acute VOR test, tadpoles were rolled from the inclined to the normal posture than in the opposite test situation. It is postulated that (i) gravity is necessarily involved in the development of the static VOR, but only during a period including the time before onset of the first behavioural response; and (ii) readaptation which is superimposed by the processes of VOR development depends on many factors including the velocity of development, the actual excitation level of the vestibular systems and the neuroplastic properties of its specific pathways.

  15. Readaptation of the vestibuloocular reflex to 1g-condition in immature lower vertebrates (Xenopus laevis) after micro- or hypergravity exposure.

    PubMed

    Sebastian, C; Horn, E; Esseling, K; Neubert, J

    1995-01-01

    The effects of altered gravitational conditions (AGC) on the development of the static vestibulo-ocular reflex (VOR) and readaptation to 1g were investigated in the amphibian Xenopus laevis. Tadpoles were exposed to microgravity during the German Space Mission D-2 for 10 days, using the STATEX closed survival system, or to 3g for 9 days during earth-bound experiments. At the beginning of AGC, the tadpoles had not yet developed the static VOR. The main results were: (i) Tadpoles with microgravity- or 3g-experience had a lower gain of the static VOR than the 1g-controls during the 2nd and 5th post-AGC days. (ii) Readaptation to response levels of 1g-reared controls usually occurred during the following weeks, except in slowly developing tadpoles with 3g-experience. Readaptation was less pronounced if, during the acute VOR test, tadpoles were rolled from the inclined to the normal posture than in the opposite test situation. It is postulated that (i) gravity is necessarily involved in the development of the static VOR, but only during a period including the time before onset of the first behavioural response; and (ii) readaptation which is superimposed by the processes of VOR development depends on many factors including the velocity of development, the actual excitation level of the vestibular systems and the neuroplastic properties of its specific pathways.

  16. A new vestibulo-ocular reflex recording system designed for routine vestibular clinical use.

    PubMed

    Funabiki, K; Naito, Y; Matsuda, K; Honjo, I

    1999-01-01

    A new vestibulo-ocular reflex (VOR) recording system was developed, which consists of an infrared eye camera, a small velocity sensor and a frequency modulator. Using this system, the head velocity signal was frequency modulated and simultaneously recorded as a sound signal on the audio track of a Hi8 video recorder with eye images. This device enabled recording of the VOR response in routine vestibular clinical practice. The reliability and effectiveness of this system were estimated by recording and analysing the VOR response against manually controlled rotation in normal subjects (n = 22) and in patients with unilateral severe vestibular hypofunction (n = 11). VOR gain on clockwise rotation viewed from the top was defined as R gain, and counterclockwise rotation as L gain. Directional preponderance (DP%) was also calculated. VOR gain towards the diseased side was significantly lower than that towards the intact side, and also significantly lower than that of normal subjects. DP% of unilateral vestibular hypofunction cases was significantly larger than that of normal subjects. These findings indicate that this VOR recording system reliably detects severe unilateral vestibular hypofunction.

  17. Three-dimensional organization of otolith-ocular reflexes in rhesus monkeys. II. Inertial detection of angular velocity

    NASA Technical Reports Server (NTRS)

    Angelaki, D. E.; Hess, B. J.

    1996-01-01

    1. The dynamic contribution of otolith signals to three-dimensional angular vestibuloocular reflex (VOR) was studied during off-vertical axis rotations in rhesus monkeys. In an attempt to separate response components to head velocity from those to head position relative to gravity during low-frequency sinusoidal oscillations, large oscillation amplitudes were chosen such that peak-to-peak head displacements exceeded 360 degrees. Because the waveforms of head position and velocity differed in shape and frequency content, the particular head position and angular velocity sensitivity of otolith-ocular responses could be independently assessed. 2. During both constant velocity rotation and low-frequency sinusoidal oscillations, the otolith system generated two different types of oculomotor responses: 1) modulation of three-dimensional eye position and/or eye velocity as a function of head position relative to gravity, as presented in the preceding paper, and 2) slow-phase eye velocity as a function of head angular velocity. These two types of otolith-ocular responses have been analyzed separately. In this paper we focus on the angular velocity responses of the otolith system. 3. During constant velocity off-vertical axis rotations, a steady-state nystagmus was elicited that was maintained throughout rotation. During low-frequency sinusoidal off-vertical axis oscillations, dynamic otolith stimulation resulted primarily in a reduction of phase leads that characterize low-frequency VOR during earth-vertical axis rotations. Both of these effects are the result of an internally generated head angular velocity signal of otolithic origin that is coupled through a low-pass filter to the VOR. No change in either VOR gain or phase was observed at stimulus frequencies larger than 0.1 Hz. 4. The dynamic otolith contribution to low-frequency angular VOR exhibited three-dimensional response characteristics with some quantitative differences in the different response components. For

  18. Three-dimensional organization of otolith-ocular reflexes in rhesus monkeys. II. Inertial detection of angular velocity

    NASA Technical Reports Server (NTRS)

    Angelaki, D. E.; Hess, B. J.

    1996-01-01

    1. The dynamic contribution of otolith signals to three-dimensional angular vestibuloocular reflex (VOR) was studied during off-vertical axis rotations in rhesus monkeys. In an attempt to separate response components to head velocity from those to head position relative to gravity during low-frequency sinusoidal oscillations, large oscillation amplitudes were chosen such that peak-to-peak head displacements exceeded 360 degrees. Because the waveforms of head position and velocity differed in shape and frequency content, the particular head position and angular velocity sensitivity of otolith-ocular responses could be independently assessed. 2. During both constant velocity rotation and low-frequency sinusoidal oscillations, the otolith system generated two different types of oculomotor responses: 1) modulation of three-dimensional eye position and/or eye velocity as a function of head position relative to gravity, as presented in the preceding paper, and 2) slow-phase eye velocity as a function of head angular velocity. These two types of otolith-ocular responses have been analyzed separately. In this paper we focus on the angular velocity responses of the otolith system. 3. During constant velocity off-vertical axis rotations, a steady-state nystagmus was elicited that was maintained throughout rotation. During low-frequency sinusoidal off-vertical axis oscillations, dynamic otolith stimulation resulted primarily in a reduction of phase leads that characterize low-frequency VOR during earth-vertical axis rotations. Both of these effects are the result of an internally generated head angular velocity signal of otolithic origin that is coupled through a low-pass filter to the VOR. No change in either VOR gain or phase was observed at stimulus frequencies larger than 0.1 Hz. 4. The dynamic otolith contribution to low-frequency angular VOR exhibited three-dimensional response characteristics with some quantitative differences in the different response components. For

  19. Characterization of the 3D angular vestibulo-ocular reflex in C57BL6 mice

    PubMed Central

    Migliaccio, Americo A.; Meierhofer, Robert; Della Santina, Charles C.

    2011-01-01

    We characterized the three-dimensional angular vestibulo-ocular reflex (3D aVOR) of adult C57BL6 mice during static tilt testing, sinusoidal and high-acceleration rotations and compared it with that of another lateral-eyed mammal with afoveate retinae (chinchilla) and two primate species with forward eye orientation and retinal foveae (human and squirrel monkey). Noting that visual acuity in mice is poor compared to chinchillas and even worse compared to primates, we hypothesized that the mouse 3D aVOR would be relatively low in gain (eye-velocity/head-velocity) compared to other species and would fall off for combinations of head rotation velocity and frequency for which peak-to-peak position changes fall below the minimum visual angle resolvable by mice. We also predicted that as in chinchilla, the mouse 3D aVOR would be more isotropic (eye/head velocity gain independent of head rotation axis) and better aligned with the axis of head rotation than the 3D aVOR of primates. In 12 adult C57BL6 mice, binocular 3D eye movements were measured in darkness during whole-body static tilts, 20-100°/s whole-body sinusoidal rotations (0.02-10 Hz) and acceleration steps of 3000°/s2 to a 150°/s plateau (dominant spectral content 8-12 Hz). Our results show that the mouse has a robust static tilt counter-roll response gain of ~0.35 (eye-position Δ / head-position Δ) and mid-frequency aVOR gain (~0.6-0.8), but relatively low aVOR gain for high frequency sinusoidal head rotations and for steps of head rotation acceleration (~0.5). Due to comparatively poor static visual acuity in the mouse, a perfectly compensatory 3D aVOR would confer relatively little benefit during high-frequency, low amplitude movements. Therefore our data suggest that the adaptive drive for maintaining a compensatory 3D aVOR depends on the static visual acuity in different species. Like chinchillas, mice have a much more nearly isotropic 3D aVOR than do the primates for which comparable data are available

  20. Experimental tests of a superposition hypothesis to explain the relationship between the vestibuloocular reflex and smooth pursuit during horizontal combined eye-head tracking in humans

    NASA Technical Reports Server (NTRS)

    Huebner, W. P.; Leigh, R. J.; Seidman, S. H.; Thomas, C. W.; Billian, C.; DiScenna, A. O.; Dell'Osso, L. F.

    1992-01-01

    1. We used a modeling approach to test the hypothesis that, in humans, the smooth pursuit (SP) system provides the primary signal for cancelling the vestibuloocular reflex (VOR) during combined eye-head tracking (CEHT) of a target moving smoothly in the horizontal plane. Separate models for SP and the VOR were developed. The optimal values of parameters of the two models were calculated using measured responses of four subjects to trials of SP and the visually enhanced VOR. After optimal parameter values were specified, each model generated waveforms that accurately reflected the subjects' responses to SP and vestibular stimuli. The models were then combined into a CEHT model wherein the final eye movement command signal was generated as the linear summation of the signals from the SP and VOR pathways. 2. The SP-VOR superposition hypothesis was tested using two types of CEHT stimuli, both of which involved passive rotation of subjects in a vestibular chair. The first stimulus consisted of a "chair brake" or sudden stop of the subject's head during CEHT; the visual target continued to move. The second stimulus consisted of a sudden change from the visually enhanced VOR to CEHT ("delayed target onset" paradigm); as the vestibular chair rotated past the angular position of the stationary visual stimulus, the latter started to move in synchrony with the chair. Data collected during experiments that employed these stimuli were compared quantitatively with predictions made by the CEHT model. 3. During CEHT, when the chair was suddenly and unexpectedly stopped, the eye promptly began to move in the orbit to track the moving target. Initially, gaze velocity did not completely match target velocity, however; this finally occurred approximately 100 ms after the brake onset. The model did predict the prompt onset of eye-in-orbit motion after the brake, but it did not predict that gaze velocity would initially be only approximately 70% of target velocity. One possible

  1. Experimental tests of a superposition hypothesis to explain the relationship between the vestibuloocular reflex and smooth pursuit during horizontal combined eye-head tracking in humans

    NASA Technical Reports Server (NTRS)

    Huebner, W. P.; Leigh, R. J.; Seidman, S. H.; Thomas, C. W.; Billian, C.; DiScenna, A. O.; Dell'Osso, L. F.

    1992-01-01

    1. We used a modeling approach to test the hypothesis that, in humans, the smooth pursuit (SP) system provides the primary signal for cancelling the vestibuloocular reflex (VOR) during combined eye-head tracking (CEHT) of a target moving smoothly in the horizontal plane. Separate models for SP and the VOR were developed. The optimal values of parameters of the two models were calculated using measured responses of four subjects to trials of SP and the visually enhanced VOR. After optimal parameter values were specified, each model generated waveforms that accurately reflected the subjects' responses to SP and vestibular stimuli. The models were then combined into a CEHT model wherein the final eye movement command signal was generated as the linear summation of the signals from the SP and VOR pathways. 2. The SP-VOR superposition hypothesis was tested using two types of CEHT stimuli, both of which involved passive rotation of subjects in a vestibular chair. The first stimulus consisted of a "chair brake" or sudden stop of the subject's head during CEHT; the visual target continued to move. The second stimulus consisted of a sudden change from the visually enhanced VOR to CEHT ("delayed target onset" paradigm); as the vestibular chair rotated past the angular position of the stationary visual stimulus, the latter started to move in synchrony with the chair. Data collected during experiments that employed these stimuli were compared quantitatively with predictions made by the CEHT model. 3. During CEHT, when the chair was suddenly and unexpectedly stopped, the eye promptly began to move in the orbit to track the moving target. Initially, gaze velocity did not completely match target velocity, however; this finally occurred approximately 100 ms after the brake onset. The model did predict the prompt onset of eye-in-orbit motion after the brake, but it did not predict that gaze velocity would initially be only approximately 70% of target velocity. One possible

  2. Unilateral adaptation of the human angular vestibulo-ocular reflex.

    PubMed

    Migliaccio, Americo A; Schubert, Michael C

    2013-02-01

    A recent study showed that the angular vestibulo-ocular reflex (VOR) can be better adaptively increased using an incremental retinal image velocity error signal compared with a conventional constant large velocity-gain demand (×2). This finding has important implications for vestibular rehabilitation that seeks to improve the VOR response after injury. However, a large portion of vestibular patients have unilateral vestibular hypofunction, and training that raises their VOR response during rotations to both the ipsilesional and contralesional side is not usually ideal. We sought to determine if the vestibular response to one side could selectively be increased without affecting the contralateral response. We tested nine subjects with normal vestibular function. Using the scleral search coil and head impulse techniques, we measured the active and passive VOR gain (eye velocity / head velocity) before and after unilateral incremental VOR adaptation training, consisting of self-generated (active) head impulses, which lasted ≈ 15 min. The head impulses consisted of rapid, horizontal head rotations with peak-amplitude 15°, peak-velocity 150°/s and peak-acceleration 3,000°/s(2). The VOR gain towards the adapting side increased after training from 0.92 ± 0.18 to 1.11 ± 0.22 (+22.7 ± 20.2 %) during active head impulses and from 0.91 ± 0.15 to 1.01 ± 0.17 (+11.3 ± 7.5 %) during passive head impulses. During active impulses, the VOR gain towards the non-adapting side also increased by ≈ 8 %, though this increase was ≈ 70 % less than to the adapting side. A similar increase did not occur during passive impulses. This study shows that unilateral vestibular adaptation is possible in humans with a normal VOR; unilateral incremental VOR adaptation may have a role in vestibular rehabilitation. The increase in passive VOR gain after active head impulse adaptation suggests that the training effect is robust.

  3. Velocity storage in the human vertical rotational vestibulo-ocular reflex.

    PubMed

    Bertolini, G; Ramat, S

    2011-03-01

    Human horizontal rotational vestibulo-ocular reflex (rVOR) has been extensively investigated: the horizontal semicircular canals sense yaw rotations with high-pass filter dynamics and a time constant (TC) around 5 s, yet the rVOR response shows a longer TC due to a central processing stage, known as velocity storage mechanism (VSM). It is generally assumed that the vertical rVOR behaves similarly to the horizontal one; however, VSM processing of the human vertical rVOR is still to be proven. We investigated the vertical rVOR in eight healthy human subjects using three experimental paradigms: (1) per- and post-rotatory around an earth-vertical axis (ear down rotations, EDR), (2) post-rotatory around an earth-horizontal axis with different stopping positions (static otolith stimulation), (3) per-rotatory around an earth-horizontal axis (dynamic otolith stimulation). We found that the TC of vertical rVOR responses ranged 3-10 s, depending both on gravity and on the direction of rotation. The shortest TC were found in response to post-rotatory earth-horizontal stimulation averaging 3.6 s, while they were prolonged in EDR stimulation, i.e. when the head angular velocity vector is aligned with gravity, with a mean value of about 6.0 s. Overall, the longest TC were observed in per-rotatory earth-horizontal stimulation, averaging 7.8 s. The finding of longer TC in EDR than in post-rotatory earth-horizontal stimulation indicates a role for the VSM in the vertical rVOR, although its contribution appears to be weaker than on the horizontal rVOR and may be directionally asymmetric. The results from per-rotatory earth-horizontal stimulation, instead, imply a role for the otoliths in controlling the duration of the vertical rVOR response. We found no reorientation of the response toward earth horizontal, indicating a difference between human and monkey rVOR.

  4. Transactivation of bad by vorinostat-induced acetylated p53 enhances doxorubicin-induced cytotoxicity in cervical cancer cells.

    PubMed

    Lee, Sook-Jeong; Hwang, Sung-Ook; Noh, Eun Joo; Kim, Dong-Uk; Nam, Miyoung; Kim, Jong Hyeok; Nam, Joo Hyun; Hoe, Kwang-Lae

    2014-02-14

    Vorinostat (VOR) has been reported to enhance the cytotoxic effects of doxorubicin (DOX) with fewer side effects because of the lower DOX dosage in breast cancer cells. In this study, we investigated the novel mechanism underlying the synergistic cytotoxic effects of VOR and DOX co-treatment in cervical cancer cells HeLa, CaSki and SiHa cells. Co-treatment with VOR and DOX at marginal doses led to the induction of apoptosis through caspase-3 activation, poly (ADP-ribose) polymerase cleavage and DNA micronuclei. Notably, the synergistic growth inhibition induced by the co-treatment was attributed to the upregulation of the pro-apoptotic protein Bad, as the silencing of Bad expression using small interfering RNA (siRNA) abolished the phenomenon. As siRNA against p53 did not result in an increase in acetylated p53 and the consequent upregulation of Bad, the observed Bad upregulation was mediated by acetylated p53. Moreover, a chromatin immunoprecipitation analysis showed that the co-treatment of HeLa cells with VOR and DOX increased the recruitment of acetylated p53 to the bad promoter, with consequent bad transactivation. Conversely, C33A cervical cancer cells containing mutant p53 co-treated with VOR and DOX did not exhibit Bad upregulation, acetylated p53 induction or consequent synergistic growth inhibition. Together, the synergistic growth inhibition of cervical cancer cell lines induced by co-treatment with VOR and DOX can be attributed to the upregulation of Bad, which is induced by acetylated p53. These results show for the first time that the acetylation of p53, rather than histones, is a mechanism for the synergistic growth inhibition induced by VOR and DOX co-treatments.

  5. Relation between head impulse tests, rotating chair tests, and stance and gait posturography after an acute unilateral peripheral vestibular deficit.

    PubMed

    Allum, John H J; Honegger, Flurin

    2013-08-01

    Vestibulo-ocular reflex (VOR) deficits and balance instability during stance and gait are typical for an acute unilateral peripheral vestibular deficit (AUPVD). The relation between different VOR measures with recovery is unknown, as is the relation of VOR measures to balance control. To answer these questions, we examined changes over time in caloric canal paresis (CP), head impulse tests (HIT), whole body rotation (ROT) tests of the horizontal VOR, and changes in trunk sway during stance and gait tests, for cases of presumed vestibular neuritis. HIT was performed with short ca. 200 degrees per second head turns, ROT with triangular 24-second velocity profiles (peak 120 degrees per second, acceleration 20 degrees per second squared). To measure balance control, body-worn gyroscopes measured pitch (anterior-posterior) and roll (lateral) sway angles and angular velocities at lumbar 1 to 3. Changes during recover in ROT and HIT responses to the deficit side were equally well related (R = 0.8, p < 0.001) to changes in caloric CP values. ROT but not HIT responses to the normal side were also related to CP responses (R = 0.53, p = 0.02). Spontaneous nystagmus levels were related to changes instance balance control (R = 0.52, p = 0.001). Balance during gait improved over time but was not well correlated with changes in VOR measures (R = 0.26 max., p > 0.05). Both HIT and ROT track VOR recovery on the deficit side due to central compensation and peripheral recovery. However, only ROT track changes in the central compensation of normal side responses. The weak correlations between VOR and stance and gait tests suggest that the latter should also be tested to judge the effect of an AUPVD on balance control.

  6. Normative data for rotational chair stratified by age.

    PubMed

    Chan, Fung M; Galatioto, Jessica; Amato, Michael; Kim, Ana H

    2016-02-01

    The purpose of this study is to examine the range of vestibulo-ocular reflex (VOR) gain on rotary chair (RC) testing in subjects without ear and vestibular problems stratified by age and gender. Prospective cross-sectional study. One hundred subjects ranging in age from 6 to 78 years underwent RC testing. VOR gains at frequencies ranging from 0.01 to 0.64 Hz were recorded. The PROC MIXED procedure in SAS was used to analyze differences in VOR gain between gender and the following age groups: group 1 (6-12 years), group 2 (13-17 years), group 3 (18-30 years), group 4 (31-50 years), and group 5 (>50 years). Twenty subjects were recruited for each of the five groups. Group 1 showed the highest average VOR gain compared to all other age groups (P < .05). There was an inverse correlation between VOR gain and age (P < .05). The lowest frequency (0.01 Hz) had the highest correlation between VOR gain and age (r = -0.425; P < .0001). Our study demonstrates VOR gain differences with age, especially in the preadolescent and geriatric groups. The current manufacturer-provided normative data do not serve as an accurate reference, especially for these two age groups. A larger population of all age groups should be compared to the current RC manufacturer normative values to ensure that they accurately reflect the true normative data. 2. © 2015 The American Laryngological, Rhinological and Otological Society, Inc.

  7. Transformation of Vestibular Signals Into Motor Commands in the Vestibuloocular Reflex Pathways of Monkeys

    PubMed Central

    Ramachandran, Ramnarayan; Lisberger, Stephen G.

    2008-01-01

    Parallel pathways mediate the rotatory vestibuloocular reflex (VOR). If the VOR undergoes adaptive modification with spectacles that change the magnification of the visual scene, signals in one neural pathway are modified, whereas those in another are not. By recording the responses of vestibular afferents and abducens neurons for vestibular oscillations at frequencies from 0.5 to 50 Hz, we have elucidated how vestibular signals are processed in the modified versus unmodified VOR pathways. For the small stimuli we used (±15°/s), the afferents with the most regular spontaneous discharge fired throughout the cycle of oscillation even at 50 Hz, whereas afferents with more irregular discharge showed phase locking. For all afferents, the firing rate was in phase with stimulus head velocity at low frequencies and showed progressive phase lead as frequency increased. Sensitivity to head velocity increased steadily as a function of frequency. Abducens neurons showed highly regular spontaneous discharge and very little evidence of phase locking. Their sensitivity to head velocity during the VOR was relatively flat across frequencies; firing rate lagged head velocity at low frequencies and shifted to large phase leads as stimulus frequency increased. When afferent responses were provided as inputs to a two-pathway model of the VOR, the output of the model reproduced the responses of abducens neurons if the unmodified and modified VOR pathways had frequency-dependent internal gains and included fixed time delays of 1.5 and 9 ms. The phase shifts predicted by the model provide fingerprints for identifying brain stem neurons that participate in the modified versus unmodified VOR pathways. PMID:16760348

  8. Three-dimensional analysis of otolith-ocular reflex during eccentric rotation in humans.

    PubMed

    Takimoto, Yasumitsu; Imai, Takao; Okumura, Tomoko; Takeda, Noriaki; Inohara, Hidenori

    2016-10-01

    When a participant is rotated while displaced from the axis of rotation (eccentric rotation, ER), both rotational stimulation and linear acceleration are applied to the participant. As linear acceleration stimulates the otolith, the vestibulo-ocular reflex (VOR) caused by the otolith (linear VOR; lVOR) would be induced during ER. Ten participants were rotated sinusoidally at a maximum angular velocity of 50°/s and at frequencies of 0.1, 0.3, 0.5, and 0.7Hz. The radius of rotation during ER was 90cm. The participants sat on a chair at three different positions: on the axis (center rotation, CR), at 90cm backward from the axis (nose-in ER, NI-ER) and at 90cm forward from the axis (nose-out ER, NO-ER). Their eye movements during rotation were recorded and analyzed three-dimensionally. The VOR gain during NI-ER was lower at 0.5 and 0.7Hz, and that during NO-ER was higher at 0.3, 0.5, and 0.7Hz than during CR. These results indicate that lVOR actually worked at 0.5 and 0.7Hz during ER and that the enhancement and decline of the VOR gain relative to the VOR gain during CR was seen in humans. Thus, we suggest that otolith function can be assessed via rotational testing of NI-ER and NO-ER. Copyright © 2016 Elsevier Ireland Ltd and Japan Neuroscience Society. All rights reserved.

  9. Prolonged asymmetric vestibular stimulation induces opposite, long-term effects on self-motion perception and ocular responses.

    PubMed

    Pettorossi, V E; Panichi, R; Botti, F M; Kyriakareli, A; Ferraresi, A; Faralli, M; Schieppati, M; Bronstein, A M

    2013-04-01

    Self-motion perception and the vestibulo-ocular reflex (VOR) were investigated in healthy subjects during asymmetric whole body yaw plane oscillations while standing on a platform in the dark. Platform oscillation consisted of two half-sinusoidal cycles of the same amplitude (40°) but different duration, featuring a fast (FHC) and a slow half-cycle (SHC). Rotation consisted of four or 20 consecutive cycles to probe adaptation further with the longer duration protocol. Self-motion perception was estimated by subjects tracking with a pointer the remembered position of an earth-fixed visual target. VOR was measured by electro-oculography. The asymmetric stimulation pattern consistently induced a progressive increase of asymmetry in motion perception, whereby the gain of the tracking response gradually increased during FHCs and decreased during SHCs. The effect was observed already during the first few cycles and further increased during 20 cycles, leading to a totally distorted location of the initial straight-ahead. In contrast, after some initial interindividual variability, the gain of the slow phase VOR became symmetric, decreasing for FHCs and increasing for SHCs. These oppositely directed adaptive effects in motion perception and VOR persisted for nearly an hour. Control conditions using prolonged but symmetrical stimuli produced no adaptive effects on either motion perception or VOR. These findings show that prolonged asymmetric activation of the vestibular system leads to opposite patterns of adaptation of self-motion perception and VOR. The results provide strong evidence that semicircular canal inputs are processed centrally by independent mechanisms for perception of body motion and eye movement control. These divergent adaptation mechanisms enhance awareness of movement toward the faster body rotation, while improving the eye stabilizing properties of the VOR.

  10. Three-dimensional ocular kinematics during eccentric rotations: evidence for functional rather than mechanical constraints

    NASA Technical Reports Server (NTRS)

    Angelaki, Dora E.

    2003-01-01

    Previous studies have reported that the translational vestibuloocular reflex (TVOR) follows a three-dimensional (3D) kinematic behavior that is more similar to visually guided eye movements, like pursuit, rather than the rotational VOR (RVOR). Accordingly, TVOR rotation axes tilted with eye position toward an eye-fixed reference frame rather than staying relatively fixed in the head like in the RVOR. This difference arises because, contrary to the RVOR where peripheral image stability is functionally important, the TVOR like pursuit and saccades cares to stabilize images on the fovea. During most natural head and body movements, both VORs are simultaneously activated. In the present study, we have investigated in rhesus monkeys the 3D kinematics of the combined VOR during yaw rotation about eccentric axes. The experiments were motivated by and quantitatively compared with the predictions of two distinct hypotheses. According to the first (fixed-rule) hypothesis, an eye-position-dependent torsion is computed downstream of a site for RVOR/TVOR convergence, and the combined VOR axis would tilt through an angle that is proportional to gaze angle and independent of the relative RVOR/TVOR contributions to the total eye movement. This hypothesis would be consistent with the recently postulated mechanical constraints imposed by extraocular muscle pulleys. According to the second (image-stabilization) hypothesis, an eye-position-dependent torsion is computed separately for the RVOR and the TVOR components, implying a processing that takes place upstream of a site for RVOR/TVOR convergence. The latter hypothesis is based on the functional requirement that the 3D kinematics of the combined VOR should be governed by the need to keep images stable on the fovea with slip on the peripheral retina being dependent on the different functional goals of the two VORs. In contrast to the fixed-rule hypothesis, the data demonstrated a variable eye-position-dependent torsion for the

  11. Three-dimensional ocular kinematics during eccentric rotations: evidence for functional rather than mechanical constraints

    NASA Technical Reports Server (NTRS)

    Angelaki, Dora E.

    2003-01-01

    Previous studies have reported that the translational vestibuloocular reflex (TVOR) follows a three-dimensional (3D) kinematic behavior that is more similar to visually guided eye movements, like pursuit, rather than the rotational VOR (RVOR). Accordingly, TVOR rotation axes tilted with eye position toward an eye-fixed reference frame rather than staying relatively fixed in the head like in the RVOR. This difference arises because, contrary to the RVOR where peripheral image stability is functionally important, the TVOR like pursuit and saccades cares to stabilize images on the fovea. During most natural head and body movements, both VORs are simultaneously activated. In the present study, we have investigated in rhesus monkeys the 3D kinematics of the combined VOR during yaw rotation about eccentric axes. The experiments were motivated by and quantitatively compared with the predictions of two distinct hypotheses. According to the first (fixed-rule) hypothesis, an eye-position-dependent torsion is computed downstream of a site for RVOR/TVOR convergence, and the combined VOR axis would tilt through an angle that is proportional to gaze angle and independent of the relative RVOR/TVOR contributions to the total eye movement. This hypothesis would be consistent with the recently postulated mechanical constraints imposed by extraocular muscle pulleys. According to the second (image-stabilization) hypothesis, an eye-position-dependent torsion is computed separately for the RVOR and the TVOR components, implying a processing that takes place upstream of a site for RVOR/TVOR convergence. The latter hypothesis is based on the functional requirement that the 3D kinematics of the combined VOR should be governed by the need to keep images stable on the fovea with slip on the peripheral retina being dependent on the different functional goals of the two VORs. In contrast to the fixed-rule hypothesis, the data demonstrated a variable eye-position-dependent torsion for the

  12. Adaptation of the macular vestibuloocular reflex to altered gravitational conditions in a fish (Oreochromis mossambicus).

    PubMed

    Horn, E; Sebastian, C

    2002-01-01

    Young fish (Oreochromis mossambicus) were exposed to microgravity (micro g) for 9 to 10 days, or to hypergravity (hg) for 9 days. For several weeks after termination of micro g and hg, the roll-induced static vestibuloocular reflex (rVOR) was recorded. In stage 11/12-fish, the rVOR amplitude (angle between the maximal up and down movement of an eye during a complete 360 degree lateral roll) of micro g-animals increased significantly by 25% compared to 1 g-controls during the first post-flight week but decreased to the control level during the second post-flight week. Microgravity had no effect in stage 14/16 fish on the rVOR amplitude. After 3 g-exposure, the rVOR amplitude was significantly reduced for both groups compared to their 1 g-controls. Readaptation to 1 g-condition was completed during the second post-3 g week. We postulate a critical period during which the development of the macular vestibuloocular reflex depends on gravitational input, and which is limited by the first appearance of the rVOR. At this period of early development, exposure to microgravity sensitizes the vestibular system while hypergravity desensitizes it.

  13. Signals and Learning Rules Guiding Oculomotor Plasticity

    PubMed Central

    Shin, Soon-Lim; Zhao, Grace Q.

    2014-01-01

    The learning of motor skills is thought to occur largely through trial and error; however, the error signals and rules controlling the induction of motor learning have not been fully elucidated. We evaluated the learning rules that translate the sensory and motor cues available during training into learned changes in the gain and phase of the vestibulo-ocular reflex (VOR) of mice. Contrary to previous theories, neither the phase of retinal image motion relative to head motion nor the phase of retinal image motion relative to eye movement could consistently predict the direction of the learned change in the gain of the VOR across all training conditions tested. Instead, the phase of the gaze movement relative to head motion during training was the best predictor of whether learning would increase or decrease the gain of the VOR. Learned changes in the phase of the VOR were best predicted by a different cue–the phase of the eye movement relative to head motion during training. These results provide new constraints on the neural mechanisms implementing the adaptive calibration of the VOR by cerebellum-dependent motor learning. PMID:25100597

  14. Vergence-dependent adaptation of the vestibulo-ocular reflex

    NASA Technical Reports Server (NTRS)

    Lewis, Richard F.; Clendaniel, Richard A.; Zee, David S.; Shelhamer, M. J. (Principal Investigator)

    2003-01-01

    The gain of the vestibulo-ocular reflex (VOR) normally depends on the distance between the subject and the visual target, but it remains uncertain whether vergence angle can be linked to changes in VOR gain through a process of context-dependent adaptation. In this study, we examined this question with an adaptation paradigm that modified the normal relationship between vergence angle and retinal image motion. Subjects were rotated sinusoidally while they viewed an optokinetic (OKN) stimulus through either diverging or converging prisms. In three subjects the diverging prisms were worn while the OKN stimulus moved out of phase with the head, and the converging prisms were worn when the OKN stimulus moved in-phase with the head. The relationship between the vergence angle and OKN stimulus was reversed in the fourth subject. After 2 h of training, the VOR gain at the two vergence angles changed significantly in all of the subjects, evidenced by the two different VOR gains that could be immediately accessed by switching between the diverged and converged conditions. The results demonstrate that subjects can learn to use vergence angle as the contextual cue that retrieves adaptive changes in the angular VOR.

  15. Role of video-head impulse test in lateralization of vestibulopathy: Comparative study with caloric test.

    PubMed

    Park, Pona; Park, Joo Hyun; Kim, Ji Soo; Koo, Ja-Won

    2017-12-01

    To evaluate the lateralization value of video head-impulse test (vHIT) for the diagnosis of vestibulopathy and to analyze cases showing dissociated results with caloric test. In total, 19 healthy volunteers and 92 dizzy patients who underwent both a caloric test and a vHIT were enrolled. Patients were divided into two groups depending on their fluctuating pattern of vertigo. The vestibulo-ocular reflex (VOR) gain and gain asymmetry (GA) of a vHIT as well as unilateral weakness (UW) and the sum of the slow-phase velocities (SPVs) of warm and cold irrigation of the same side were compared. A cutoff value of VOR gain of a vHIT was also calculated using a receiver-operating characteristic curve. A VOR gain in an affected ear and GA of a vHIT showed a statistically significant correlation with UW in a caloric test. The cutoff value of a vHIT was determined to be 0.875, derived under the assumption that UW of a caloric test ≤25% is normal. However, the parameters of the two tests were dissociated in 18%. A VOR gain of vHIT is a valuable objective parameter with a lateralization value determining vestibular hypofunction. However, considering substantial dissociation between a vHIT and a caloric test, these tests can be complementary tools for the lateralization of vestibular impairment for the comprehensive evaluation of patients' VOR. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. What is the minimal vestibular function required for compensation?

    NASA Technical Reports Server (NTRS)

    Black, F. O.; Wade, S. W.; Nashner, L. M.

    1996-01-01

    Living with an uncompensated, abnormal vestibular system requires oppressive modification of life style and often prevents return to work and activities of daily living. Patients with vestibular abnormalities were studied to determine the minimal residual vestibular function required to achieve compensation. Three groups of patients with (a) complete unilateral loss of vestibular function with normal horizontal canal-vestibulo-ocular (HCVOR) function in the opposite ear, (b) complete unilateral loss with abnormal HCVOR function in the opposite ear, and (c) bilateral reduction of vestibular function from aminoglycoside toxicity underwent vestibuloocular (VOR), optokinetic (OKN), visual-VOR (VVOR), and computerized dynamic posturography (CDP) tests before and after therapeutic procedures. Results suggest that a minimal VOR response amplitude must be present for compensation of VVOR function to occur. The roles of VOR and OKN phase shifts in vestibular compensation are more complicated and require further study. Compensation of vestibulospinal function does not necessarily accompany VOR or VVOR compensation. Ascending and descending vestibular compensatory mechanisms may involve different spatial sensory inputs. Results of these studies have important implications for the diagnosis and treatment of patients with vestibular disorders, including selection and monitoring of patients for therapeutic regimens such as vestibular nerve section and streptomycin therapy.

  17. Recovery of the high-acceleration vestibulo-ocular reflex after vestibular neuritis.

    PubMed

    Palla, A; Straumann, D

    2004-12-01

    Vestibular neuritis (VN) usually leads to a sudden gain asymmetry of the high-acceleration horizontal vestibulo-ocular reflex (VOR). We asked whether this asymmetry decreases over time indicating peripheral recovery and/or central compensation. The horizontal VOR during rapid rotational head impulses to both sides was recorded with search coils in 37 patients at different time periods (1-240 weeks) after the onset of VN. In ten patients, sequential measurements were performed. Gains of the VOR during head impulses toward the ipsilesional side significantly increased after the initial drop (average gains: < 1 week: 0.35; 1-4 weeks: 0.33; 4-40 weeks: 0.55; 40-240 weeks: 0.50). Gains on the contralesional side, however, were only slightly reduced and showed no significant change. We conclude that, in contrast to patients after hemilabyrinthectomy or unilateral vestibular neurectomy, the ocular response to ipsilesional rotations in patients after VN improves over time. This finding suggests that ipsilesional recovery is peripheral or, if central, depends on spared peripheral function. The physiology of linear and nonlinear VOR pathways predicts a considerable gain reduction for contralesional head impulses if central compensation mechanisms are not engaged. Thus, the relatively preserved gain on the contralesional side can be explained only by central "upregulation". Apparently, for high accelerations of the head, effective central compensation after VN does not aim to balance the gains of the VOR but tries to boost the contralesional gain close to normal.

  18. The vestibulo-ocular reflex and velocity storage in spinocerebellar ataxia 8.

    PubMed

    Anderson, J H; Yavuz, M C; Kazar, B M; Christova, P; Gomez, C M

    2002-10-01

    The autosomal dominant spinocerebellar ataxias (SCAs) are a group of neurodegenerative diseases characterized by progressive instability of posture and gait, incoordination, ocular motor dysfunction, and dysarthria due to degeneration of cerebellar and brainstem neurons. Among the more than 20 genetically distinct subtypes, SCA8 is one of several wherein clinical observations indicate that cerebellar dysfunction is primary, and there is little evidence for other CNS involvement. The aim of the present work was to study the decay of the horizontal vestibulo-ocular reflex (VOR) after a short period of constant acceleration to understand the pathophysiology of the VOR due to cerebellar Purkinje cell degeneration in SCA8. The VOR was recorded in patients with genetically defined SCA8 during rotation in the dark. Moderate to severely affected patients had a qualitatively intact VOR, but there were quantitative differences in the gain and dynamics compared to normal controls. During angular velocity ramp rotations, there was a reversal in the direction of the VOR that was more pronounced in SCA8 compared to controls. Modeling studies indicate that there are significant changes in the velocity storage network, including abnormal feedback of an eye position signal into the network that contributes to this reversal. These and other results will help to identify features that are diagnostic for SCA subtypes and provide new information about selective vulnerability of neurons controlling vestibular reflexes.

  19. Eye-head coordination in the guinea pig II. Responses to self-generated (voluntary) head movements

    PubMed Central

    Shanidze, N.; Kim, A. H.; Loewenstein, S.; Raphael, Y.; King, W. M.

    2010-01-01

    Retinal image stability is essential for vision but may be degraded by head movements. The vestibulo-ocular reflex (VOR) compensates for passive perturbations of head position and is usually assumed to be the major neural mechanism for ocular stability. During our recent investigation of vestibular reflexes in guinea pigs free to move their heads (Shanidze et al 2010), we observed compensatory eye movements that could not have been initiated either by vestibular or neck proprioceptive reflexes because they occurred with zero or negative latency with respect to head movement. These movements always occurred in association with self-generated (active) head or body movements and thus anticipated a voluntary movement. We found the anticipatory responses to differ from those produced by the VOR in two significant ways. First, anticipatory responses are characterized by temporal synchrony with voluntary head movements (latency ~1 msec versus ~7 msec for the VOR). Second, the anticipatory responses have higher gains (0.80 versus 0.46 for the VOR) and thus more effectively stabilize the retinal image during voluntary head movements. We suggest that anticipatory responses act synergistically with the VOR to stabilize retinal images. Furthermore, they are independent of actual vestibular sensation since they occur in guinea pigs with complete peripheral vestibular lesions. Conceptually, anticipatory responses could be produced by a feed-forward neural controller that transforms efferent motor commands for head movement into estimates of the sensory consequences of those movements. PMID:20697698

  20. Traumatic brain injury and vestibulo-ocular function: current challenges and future prospects

    PubMed Central

    Wallace, Bridgett; Lifshitz, Jonathan

    2016-01-01

    Normal function of the vestibulo-ocular reflex (VOR) coordinates eye movement with head movement, in order to provide clear vision during motion and maintain balance. VOR is generated within the semicircular canals of the inner ear to elicit compensatory eye movements, which maintain stability of images on the fovea during brief, rapid head motion, otherwise known as gaze stability. Normal VOR function is necessary in carrying out activities of daily living (eg, walking and riding in a car) and is of particular importance in higher demand activities (eg, sports-related activities). Disruption or damage in the VOR can result in symptoms such as movement-related dizziness, blurry vision, difficulty maintaining balance with head movements, and even nausea. Dizziness is one of the most common symptoms following traumatic brain injury (TBI) and is considered a risk factor for a prolonged recovery. Assessment of the vestibular system is of particular importance following TBI, in conjunction with oculomotor control, due to the intrinsic neural circuitry that exists between the ocular and vestibular systems. The purpose of this article is to review the physiology of the VOR and the visual-vestibular symptoms associated with TBI and to discuss assessment and treatment guidelines for TBI. Current challenges and future prospects will also be addressed. PMID:28539811

  1. Age-related changes in human vestibulo-ocular reflexes: Sinusoidal rotation and caloric tests

    NASA Technical Reports Server (NTRS)

    Peterka, R. J.; Black, F. O.; Schoenhoff, M. B.

    1989-01-01

    The dynamic response properties of horizontal vestibulo-ocular reflex (VOR) were characterized in 216 human subjects ranging in age from 7 to 81 years. The object of this cross-sectional study was to determine the effects of aging on VOR dynamics, and to identify the distributions of parameters which describe VOR responses to caloric and to sinusoidal rotational stimuli in a putatively normal population. Caloric test parameters showed no consistent trend with age. Rotation test parameters showed declining response amplitude and slightly less compensatory response phase with increasing age. The magnitudes of these changes were not large relative to the variability within the population. The age-related trends in VOR were not consistent with the anatomic changes in the periphery reported by others which showed an increasing rate of peripheral hair cell and nerve fiber loss in subjects over 55 years. The poor correlation between physiological and anatomical data suggest that adaptive mechanisms in the central nervous system are important in maintaining the VOR.

  2. Generalized Hamiltonian point vortex dynamics on arbitrary domains using the method of fundamental solutions

    NASA Astrophysics Data System (ADS)

    Ashbee, T. L.; Esler, J. G.; McDonald, N. R.

    2013-08-01

    A new algorithm (VOR-MFS) is presented for the solution of a generalized Hamiltonian model of point vortex dynamics in an arbitrary two-dimensional computational domain. The VOR-MFS algorithm utilizes the method of fundamental solutions (MFS) to obtain an approximation to the model Hamiltonian by solution of an appropriate boundary value problem. Unlike standard point vortex methods, VOR-MFS requires knowledge only of the free-space (R2) Green's function for the problem as opposed to the domain-adapted Green's function, permitting solution of a much wider range of problems. VOR-MFS is first validated against a vortex image model for the case of (2D Euler) multiple vortex motion in both circular and 'Neumann-oval' shaped domains. It is then demonstrated that VOR-MFS can solve for quasi-geostrophic shallow water point vortex motion in the same domains. The exponential convergence of the MFS method is shown to lead to good conservation properties for each of the solutions presented.

  3. Adaptation of the macular vestibuloocular reflex to altered gravitational conditions in a fish ( Oreochromis mossambicus)

    NASA Astrophysics Data System (ADS)

    Horn, E.; Sebastian, C.

    Young fish ( Oreochromis mossambicus) were exposed to microgravity (μg) for 9 to 10 days, or to hypergravity (hg) for 9 days. For several weeks after termination of μg and hg, the roll-induced static vestibuloocular reflex (rVOR) was recorded. In stage 11/12-fish, the rVOR amplitude (angle between the maximal up and down movement of an eye during a complete 360° lateral roll) of μg-animals increased significantly by 25% compared to 1g-controls during the first post-flight week but decreased to the control level during the second post-flight week. Microgravity had no effect in stage 14/16 fish on the rVOR amplitude. After 3g-exposure, the rVOR amplitude was significantly reduced for both groups compared to their 1g-controls. Readaptation to 1g-condition was completed during the second post-3g week. We postulate a critical period during which the development of the macular vestibuloocular reflex depends on gravitational input, and which is limited by the first appearence of the rVOR. At this period of early development, exposure to microgravity sensitizes the vestibular system while hypergravity desensitizes it.

  4. Target neurons of floccular middle zone inhibition in medial vestibular nucleus.

    PubMed

    Sato, Y; Kanda, K; Kawasaki, T

    1988-04-19

    Unitary activities of 288 neurons were recorded extracellularly in the medial vestibular nucleus (MV) in anesthetized cats. In 19 neurons, located in the rostral part of the MV adjacent to the stria acustica, floccular middle zone stimulation resulted in cessation of spontaneous discharges. Systematic microstimulation in the brainstem during recording of 16 of 19 target neurons of floccular middle zone inhibition revealed that the target neurons projected to the ipsilateral abducens nucleus (ABN), and not to the contralateral ABN nor the oculomotor nucleus. The conjugate ipsilateral horizontal eye movement elicited by middle zone stimulation may be mediated by this pathway to motoneurons and internuclear neurons in the ipsilateral ABN. In additional experiments, the MV neurons responding antidromically to ipsilateral ABN stimulation and orthodromically to ipsilateral 8 nerve stimulation were recorded extracellularly. In only 7 of 36 recorded neurons, middle zone stimulation depressed the orthodromic and spontaneous activities. Many neurons were free of floccular inhibition. As to the route of floccular inhibitory control over the vestibulo-ocular reflex (VOR) during visual-vestibular stimulation, we propose that the interaction of target and VOR relay neurons takes place at the ipsilateral ABN and modulates the VOR, in addition to well known Ito's proposal that the interaction of the floccular output and the VOR takes place at secondary vestibular neurons and modulates the VOR.

  5. Vergence-dependent adaptation of the vestibulo-ocular reflex

    NASA Technical Reports Server (NTRS)

    Lewis, Richard F.; Clendaniel, Richard A.; Zee, David S.; Shelhamer, M. J. (Principal Investigator)

    2003-01-01

    The gain of the vestibulo-ocular reflex (VOR) normally depends on the distance between the subject and the visual target, but it remains uncertain whether vergence angle can be linked to changes in VOR gain through a process of context-dependent adaptation. In this study, we examined this question with an adaptation paradigm that modified the normal relationship between vergence angle and retinal image motion. Subjects were rotated sinusoidally while they viewed an optokinetic (OKN) stimulus through either diverging or converging prisms. In three subjects the diverging prisms were worn while the OKN stimulus moved out of phase with the head, and the converging prisms were worn when the OKN stimulus moved in-phase with the head. The relationship between the vergence angle and OKN stimulus was reversed in the fourth subject. After 2 h of training, the VOR gain at the two vergence angles changed significantly in all of the subjects, evidenced by the two different VOR gains that could be immediately accessed by switching between the diverged and converged conditions. The results demonstrate that subjects can learn to use vergence angle as the contextual cue that retrieves adaptive changes in the angular VOR.

  6. Video Head Impulse Test for Early Diagnosis of Vestibular Neuritis Among Acute Vertigo.

    PubMed

    Guan, Qiongfeng; Zhang, Lisan; Hong, Wenke; Yang, Yi; Chen, Zhaoying; Lu, Peilin; Zhang, Dan; Hu, Xingyue

    2017-09-01

    This study assesses the value of the video head impulse test (vHIT) for early diagnosis of vestibular neuritis (VN) among acute vertigo. Thirty-three cases of vestibular neuritis (VN), 96 patients with other acute vertigo (AV), and 50 cases of normal controls used vHIT to quantitatively test a pair of horizontal vestibulo-ocular reflection (VOR) gains, two pairs of vertical VOR gains, and the corresponding three pairs of VOR gain asymmetry. The peculiarity of VOR gains in VN and the differences between VN and other AV, normal controls by vHIT, were collected and analyzed. There were statistically significant differences in the three pairs of VOR gains asymmetry between VN and other AV, and normal controls (P<0.01). The sensitivity was 87.9% and specificity was 94.3% in differentiating VN from normal and other acute vertigo by vHIT. This study shows vHIT has advantages in the diagnosis of VN in acute vertigo with good sensitivity and specificity and indicates a widespread clinical application.

  7. The Vestibulo-ocular Reflex During Active Head Motion in Chiari II Malformation

    PubMed Central

    Salman, Michael S.; Sharpe, James A.; Lillakas, Linda; Dennis, Maureen; Steinbach, Martin J.

    2008-01-01

    Background Chiari type II malformation (CII) is a developmental anomaly of the cerebellum and brainstem, which are important structures for processing the vestibulo-ocular reflex (VOR). We investigated the effects of the deformity of CII on the angular VOR during active head motion. Methods Eye and head movements were recorded using an infrared eye tracker and magnetic head tracker in 20 participants with CII [11 males, age range 8-19 years, mean (SD) 14.4 (3.2) years]. Thirty-eight age-matched healthy children and adolescents (21 males) constituted the control group. Participants were instructed to ‘look’ in darkness at the position of their thumb, placed 25 cm away, while they made horizontal and vertical sinusoidal head rotations at frequencies of about 0.5 Hz and 2 Hz. Parametric and non-parametric tests were used to compare the two groups. Results The VOR gains, the ratio of eye to head velocities, were abnormally low in two participants with CII and abnormally high in one participant with CII. Conclusion The majority of participants with CII had normal VOR performance in this investigation. However, the deformity of CII can impair the active angular VOR in some patients with CII. Low gain is attributed to brainstem damage and high gain to cerebellar dysfunction. PMID:18973069

  8. Comparison of smooth pursuit and combined eye-head tracking in human subjects with deficient labyrinthine function

    NASA Technical Reports Server (NTRS)

    Leigh, R. J.; Thurston, S. E.; Sharpe, J. A.; Ranalli, P. J.; Hamid, M. A.

    1987-01-01

    The effects of deficient labyrinthine function on smooth visual tracking with the eyes and head were investigated, using ten patients with bilateral peripheral vestibular disease and ten normal controls. Active, combined eye-head tracking (EHT) was significantly better in patients than smooth pursuit with the eyes alone, whereas normal subjects pursued equally well in both cases. Compensatory eye movements during active head rotation in darkness were always less in patients than in normal subjects. These data were used to examine current hypotheses that postulate central cancellation of the vestibulo-ocular reflex (VOR) during EHT. A model that proposes summation of an integral smooth pursuit command and VOR/compensatory eye movements is consistent with the findings. Observation of passive EHT (visual fixation of a head-fixed target during en bloc rotation) appears to indicate that in this mode parametric gain changes contribute to modulation of the VOR.

  9. Herausforderungen für künftige Lernumgebungen am Beispiel der Fakultät für Medizin

    NASA Astrophysics Data System (ADS)

    Gergintchev, Ivan; Graf, Stephan

    Nach der weit reichenden Etablierung von eLearning in den letzten Jahren stehen nahezu alle deutschen Hochschulen vor der Aufgabe, wettbewerbsfähige hochschulübergreifende Mechanismen sowie entsprechende organisatorische Rahmenbedingungen zu schaffen. Vor allem die Umsetzung von EBologna und die Unterstützung kooperativer Bildungsangebote verstärken diese Notwendigkeit. Motiviert durch die Veränderungen im Bereich der Hochschullehre und die Herausforderungen für künftige Lernumgebungen schlagen wir eine Integrationslösung im Sinne eines Learning Gateway vor, die zur webgestützten Abwicklung von kooperativen Bildungsangeboten in heterogen Lernumgebungen eingesetzt werden kann. Ihre Praxisanwendung verdeutlichen wir anschließend im komplexen Szenario der Medizin an der TUM. Die Evaluierung der Umsetzung belegt den deutlichen Mehrwert des Ansatzes.

  10. Voluntary presetting of the vestibular ocular reflex permits gaze stabilization despite perturbation of fast head movements

    NASA Technical Reports Server (NTRS)

    Zangemeister, Wolfgang H.

    1989-01-01

    Normal subjects are able to change voluntarily and continuously their head-eye latency together with their compensatory eye movement gain. A continuous spectrum of intent-latency modes of the subject's coordinated gaze through verbal feedback could be demonstrated. It was also demonstrated that the intent to counteract any perturbation of head-eye movement, i.e., the mental set, permitted the subjects to manipulate consciously their vestibular ocular reflex (VOR) gain. From the data, it is inferred that the VOR is always on. It may be, however, variably suppressed by higher cortical control. With appropriate training, head-mounted displays should permit an easy VOR presetting that leads to image stabilization, perhaps together with a decrease of possible misjudgements.

  11. Note: high frequency vibration rejection using a linear shaft actuator-based image stabilizing device via vestibulo-ocular reflex adaptation control method.

    PubMed

    Koh, Doo-Yeol; Kim, Young-Kook; Kim, Kyung-Soo; Kim, Soohyun

    2013-08-01

    In mobile robotics, obtaining stable image of a mounted camera is crucial for operating a mobile system to complete given tasks. This note presents the development of a high-speed image stabilizing device using linear shaft actuator, and a new image stabilization method inspired by human gaze stabilization process known as vestibulo-ocular reflex (VOR). In the proposed control, the reference is adaptively adjusted by the VOR adaptation control to reject residual vibration of a camera as the VOR gain converges to optimal state. Through experiments on a pneumatic vibrator, it will be shown that the proposed system is capable of stabilizing 10 Hz platform vibration, which shows potential applicability of the device to a high-speed mobile robot.

  12. Comparison of smooth pursuit and combined eye-head tracking in human subjects with deficient labyrinthine function

    NASA Technical Reports Server (NTRS)

    Leigh, R. J.; Thurston, S. E.; Sharpe, J. A.; Ranalli, P. J.; Hamid, M. A.

    1987-01-01

    The effects of deficient labyrinthine function on smooth visual tracking with the eyes and head were investigated, using ten patients with bilateral peripheral vestibular disease and ten normal controls. Active, combined eye-head tracking (EHT) was significantly better in patients than smooth pursuit with the eyes alone, whereas normal subjects pursued equally well in both cases. Compensatory eye movements during active head rotation in darkness were always less in patients than in normal subjects. These data were used to examine current hypotheses that postulate central cancellation of the vestibulo-ocular reflex (VOR) during EHT. A model that proposes summation of an integral smooth pursuit command and VOR/compensatory eye movements is consistent with the findings. Observation of passive EHT (visual fixation of a head-fixed target during en bloc rotation) appears to indicate that in this mode parametric gain changes contribute to modulation of the VOR.

  13. Eye and head motion during head turns in spaceflight

    NASA Technical Reports Server (NTRS)

    Thornton, William E.; Uri, John J.; Moore, Thomas P.; Pool, Sam L.

    1988-01-01

    Eye-head motion was studied pre-, in- and postflight during single voluntary head turns. A transient increase in vestibulo-ocular reflex (VOR) gain occurred early in the flight, but later trended toward normal. This increased gain was produced by a relative increase in eye counterrotation velocity. Asymmetries in gain with right and left turns also occurred, caused by asymmetries in eye counterrotation velocities. These findings were remarkably similar to those from Soviet primate studies using gaze fixation targets, except the human study trended more rapidly toward normal. These findings differ substantially from those measuring VOR gain by head oscillation, in which no significant changes were found inflight. No visual disturbances were noted in either test condition or in normal activities. These head turn studies are the only ones to date documenting any functional change in VOR in weightlessness.

  14. Prolonged reduction of motion sickness sensitivity by visual-vestibular interaction

    PubMed Central

    Raphan, Ted; Cohen, Bernard

    2011-01-01

    The angular vestibulo-ocular reflex (aVOR) and optokinetic nystagmus (OKN) were elicited simultaneously at low frequencies to study effects of habituation of the velocity storage time constant in the vestibular system on motion sickness. Twenty-nine subjects, eleven of whom were susceptible to motion sickness from common transportation, were habituated by sinusoidal rotation at 0.017 Hz at peak velocities from 5 to 20°/s, while they watched a full-field OKN stimulus. The OKN stripes rotated in the same direction and at the same frequency as the subjects, but at a higher velocity. This produced an OKN opposite in direction to the aVOR response. Motion sickness sensitivity was evaluated with off-vertical axis rotation (OVAR) and by the response to transportation before and after 5 days of visual-vestibular habituation. Habituation did not induce motion sickness or change the aVOR gains, but it shortened the vestibular time constants in all subjects. This greatly reduced motion sickness produced by OVAR and sensitivity to common transport in the motion susceptible subjects, which persisted for up to 18 weeks. Two motion susceptible subjects who only had aVOR/OKN habituation without being tested with OVAR also became asymptomatic. Normal subjects who were not habituated had no reduction in either their aVOR time constants or motion sickness sensitivity. The opposing aVOR/OKN stimulation, which has not been studied before, was well tolerated, and for the first time was an effective technique for rapid and prolonged habituation of motion sickness without exposure to drugs or other nauseating habituation stimuli. PMID:21287155

  15. A reevaluation of the vestibulo-ocular reflex: new ideas of its purpose, properties, neural substrate, and disorders

    NASA Technical Reports Server (NTRS)

    Leigh, R. J.; Brandt, T.

    1993-01-01

    Conventional views of the vestibulo-ocular reflex (VOR) have emphasized testing with caloric stimuli and by passively rotating patients at low frequencies in a chair. The properties of the VOR tested under these conditions differ from the performance of this reflex during the natural function for which it evolved--locomotion. Only the VOR (and not visually mediated eye movements) can cope with the high-frequency angular and linear perturbations of the head that occur during locomotion; this is achieved by generating eye movements at short latency (< 16 msec). Interpretation of vestibular testing is enhanced by the realization that, although the di- and trisynaptic components of the VOR are essential for this short-latency response, the overall accuracy and plasticity of the VOR depend upon a distributed, parallel network of neurons involving the vestibular nuclei. Neurons in this network variously upon a distributed, parallel network of neurons involving the vestibular nuclei. Neurons in this network variously encode inputs from the labyrinthine semicircular canals and otoliths, as well as from the visual and somatosensory systems. The central vestibular pathways branch to contact vestibular cortex (for perception) and the spinal cord (for control of posture). Thus, the vestibular nuclei basically coordinate the stabilization of gaze and posture, and contribute to the perception of verticality and self-motion. Consequently, brainstem disorders that disrupt the VOR cause not just only nystagmus, but also instability of posture (eg, increased fore-aft sway in patients with downbeat nystagmus) and disturbance of spatial orientation (eg, tilt of the subjective visual vertical in Wallenberg's syndrome).

  16. A reevaluation of the vestibulo-ocular reflex: new ideas of its purpose, properties, neural substrate, and disorders

    NASA Technical Reports Server (NTRS)

    Leigh, R. J.; Brandt, T.

    1993-01-01

    Conventional views of the vestibulo-ocular reflex (VOR) have emphasized testing with caloric stimuli and by passively rotating patients at low frequencies in a chair. The properties of the VOR tested under these conditions differ from the performance of this reflex during the natural function for which it evolved--locomotion. Only the VOR (and not visually mediated eye movements) can cope with the high-frequency angular and linear perturbations of the head that occur during locomotion; this is achieved by generating eye movements at short latency (< 16 msec). Interpretation of vestibular testing is enhanced by the realization that, although the di- and trisynaptic components of the VOR are essential for this short-latency response, the overall accuracy and plasticity of the VOR depend upon a distributed, parallel network of neurons involving the vestibular nuclei. Neurons in this network variously upon a distributed, parallel network of neurons involving the vestibular nuclei. Neurons in this network variously encode inputs from the labyrinthine semicircular canals and otoliths, as well as from the visual and somatosensory systems. The central vestibular pathways branch to contact vestibular cortex (for perception) and the spinal cord (for control of posture). Thus, the vestibular nuclei basically coordinate the stabilization of gaze and posture, and contribute to the perception of verticality and self-motion. Consequently, brainstem disorders that disrupt the VOR cause not just only nystagmus, but also instability of posture (eg, increased fore-aft sway in patients with downbeat nystagmus) and disturbance of spatial orientation (eg, tilt of the subjective visual vertical in Wallenberg's syndrome).

  17. Modification of the Passive Vestibulo-Ocular Reflex During and After Short-Duration Spaceflight

    NASA Technical Reports Server (NTRS)

    Wood, S. J.; Reschke, M. F.

    2011-01-01

    The vestibulo-ocular reflex (VOR) is mediated by integration of canal and otolith inputs to generate compensatory eye movements during head movements. We hypothesized that adaptive change in vestibular processing of gravitoinertial cues would be reflected by plane specific modification of the VOR during passive whole-body rotation during and after spaceflight. Using a repeated measures design, the VOR was assessed in four payload crewmembers in yaw, pitch and roll planes during multiple sessions before, during and after an 8 day orbital mission (STS-42). Rotation was about an earth-vertical axis during ground tests, with the head located off-axis by up to 45cm during pitch and roll rotation (peak acceleration less than 0.2g). The motion profiles included sum-of-sinusoids between 0.02 - 1.39 Hz (yaw), single sinusoids between 0.05-1.25 Hz (yaw and pitch) and velocity steps (yaw, pitch and roll). Eye movements were recorded with both video and electro-oculographic techniques. As expected, VOR gain changes were greater in pitch than in yaw. During pitch rotation, there was a progressive shift in the axis of eye movements during the flight, which was also present during the early post-flight period. This increased horizontal component during pitch, most prevalent at 0.2 Hz, was interpreted as an increase in a translational vergence response elicited during eccentric rotation as subjects imagined a wall fixed target. There was also an increased horizontal component during the eccentric roll step runs performed on flight day 7. These results are consistent with a frequency-dependent increase in otolith-mediated translational VOR responses following adaptation to microgravity. We conclude that the adaptive changes in the VOR are likely to be greatest in the frequency range where there is a cross-over of otolith-mediated tilt and translation responses.

  18. Velocity-selective adaptation of the horizontal and cross-axis vestibulo-ocular reflex in the mouse.

    PubMed

    Hübner, Patrick P; Khan, Serajul I; Migliaccio, Americo A

    2014-10-01

    One commonly observed phenomenon of vestibulo-ocular reflex (VOR) adaptation is a frequency-selective change in gain (eye velocity/head velocity) and phase (relative timing between the vestibular stimulus and response) based on the frequency content of the adaptation training stimulus. The neural mechanism behind this type of adaptation is not clear. Our aim was to determine whether there were other parameter-selective effects on VOR adaptation, specifically velocity-selective and acceleration-selective changes in the horizontal VOR gain and phase. We also wanted to determine whether parameter selectivity was also in place for cross-axis adaptation training (a visual-vestibular training stimulus that elicits a vestibular-evoked torsional eye movement during horizontal head rotations). We measured VOR gain and phase in 17 C57BL/6 mice during baseline (no adaptation training) and after gain-increase, gain-decrease and cross-axis adaptation training using a sinusoidal visual-vestibular (mismatch) stimulus with whole-body rotations (vestibular stimulus) with peak velocity 20 and 50°/s both with a fixed frequency of 0.5 Hz. Our results show pronounced velocity selectivity of VOR adaptation. The difference in horizontal VOR gain after gain-increase versus gain-decrease adaptation was maximal when the sinusoidal testing stimulus matched the adaptation training stimulus peak velocity. We also observed similar velocity selectivity after cross-axis adaptation training. Our data suggest that frequency selectivity could be a manifestation of both velocity and acceleration selectivity because when one of these is absent, e.g. acceleration selectivity in the mouse, frequency selectivity is also reduced.

  19. The mammalian efferent vestibular system plays a crucial role in the high-frequency response and short-term adaptation of the vestibuloocular reflex

    PubMed Central

    Hübner, Patrick P.; Khan, Serajul I.

    2015-01-01

    Although anatomically well described, the functional role of the mammalian efferent vestibular system (EVS) remains unclear. Unlike in fish and reptiles, the mammalian EVS does not seem to play a role in modulation of primary afferent activity in anticipation of active head movements. However, it could play a role in modulating long-term mechanisms requiring plasticity such as vestibular adaptation. We measured the efficacy of vestibuloocular reflex (VOR) adaptation in α9-knockout mice. These mice carry a missense mutation of the gene encoding the α9 nicotinic acetylcholine receptor (nAChR) subunit. The α9 nAChR subunit is expressed in the vestibular and auditory periphery, and its loss of function could compromise peripheral input from the predominantly cholinergic EVS. We measured the VOR gain (eye velocity/head velocity) in 26 α9-knockout mice and 27 cba129 control mice. Mice were randomly assigned to one of three groups: gain-increase adaptation (1.5×), gain-decrease adaptation (0.5×), or no adaptation (baseline, 1×). After adaptation training (horizontal rotations at 0.5 Hz with peak velocity 20°/s), we measured the sinusoidal (0.2–10 Hz, 20–100°/s) and transient (1,500–6,000°/s2) VOR in complete darkness. α9-Knockout mice had significantly lower baseline gains compared with control mice. This difference increased with stimulus frequency (∼5% <1 Hz to ∼25% >1 Hz). Moreover, vestibular adaptation (difference in VOR gain of gain-increase and gain-decrease adaptation groups as % of gain increase) was significantly reduced in α9-knockout mice (17%) compared with control mice (53%), a reduction of ∼70%. Our results show that the loss of α9 nAChRs moderately affects the VOR but severely affects VOR adaptation, suggesting that the EVS plays a crucial role in vestibular plasticity. PMID:26424577

  20. The Cerebellar Nodulus/Uvula Integrates Otolith Signals for the Translational Vestibulo-Ocular Reflex

    PubMed Central

    Walker, Mark F.; Tian, Jing; Shan, Xiaoyan; Tamargo, Rafael J.; Ying, Howard; Zee, David S.

    2010-01-01

    Background The otolith-driven translational vestibulo-ocular reflex (tVOR) generates compensatory eye movements to linear head accelerations. Studies in humans indicate that the cerebellum plays a critical role in the neural control of the tVOR, but little is known about mechanisms of this control or the functions of specific cerebellar structures. Here, we chose to investigate the contribution of the nodulus and uvula, which have been shown by prior studies to be involved in the processing of otolith signals in other contexts. Methodology/Principal Findings We recorded eye movements in two rhesus monkeys during steps of linear motion along the interaural axis before and after surgical lesions of the cerebellar uvula and nodulus. The lesions strikingly reduced eye velocity during constant-velocity motion but had only a small effect on the response to initial head acceleration. We fit eye velocity to a linear combination of head acceleration and velocity and to a dynamic mathematical model of the tVOR that incorporated a specific integrator of head acceleration. Based on parameter optimization, the lesion decreased the gain of the pathway containing this new integrator by 62%. The component of eye velocity that depended directly on head acceleration changed little (gain decrease of 13%). In a final set of simulations, we compared our data to the predictions of previous models of the tVOR, none of which could account for our experimental findings. Conclusions/ Significance Our results provide new and important information regarding the neural control of the tVOR. Specifically, they point to a key role for the cerebellar nodulus and uvula in the mathematical integration of afferent linear head acceleration signals. This function is likely to be critical not only for the tVOR but also for the otolith-mediated reflexes that control posture and balance. PMID:21085587

  1. Density and success of bird nests relative to grazing on western Montana grasslands

    USGS Publications Warehouse

    Fondell, Thomas F.; Ball, I.J.

    2004-01-01

    Grassland birds are declining at a faster rate than any other group of North American bird species. Livestock grazing is the primary economic use of grasslands in the western United States, but the effects of this use on distribution and productivity of grassland birds are unclear. We examined nest density and success of ground-nesting birds on grazed and ungrazed grasslands in western Montana. In comparison to grazed plots, ungrazed plots had reduced forb cover, increased litter cover, increased litter depth, and increased visual obstruction readings (VOR) of vegetation. Nest density among 10 of 11 common bird species was most strongly correlated with VOR of plots, and greatest nest density for each species occurred where mean VOR of the plot was similar to mean VOR at nests. Additionally, all bird species were relatively consistent in their choice of VOR at nests despite substantial differences in VOR among plots. We suggest that birds selected plots based in part on availability of suitable nest sites and that variation in nest density relative to grazing reflected the effect of grazing on availability of nest sites. Nest success was similar between grazed plots and ungrazed plots for two species but was lower for nests on grazed plots than on ungrazed plots for two other species because of increased rates of predation, trampling, or parasitism by brown-headed cowbirds (Molothrus ater). Other species nested almost exclusively on ungrazed plots (six species) or grazed plots (one species), precluding evaluation of the effects of grazing on nest success. We demonstrate that each species in a diverse suite of ground-nesting birds preferentially used certain habitats for nesting and that grazing altered availability of preferred nesting habitats through changes in vegetation structure and plant species composition. We also show that grazing directly or indirectly predisposed some bird species to increased nesting mortality. Management alternatives that avoid

  2. Interaction between otolith organ and semicircular canal vestibulo-ocular reflexes during eccentric rotation in humans.

    PubMed

    Gianna-Poulin, Claire C; Peterka, Robert J

    2008-03-01

    Controversy remains about the linearity of the interaction between horizontal semicircular canal and otolith organ vestibulo-ocular reflexes (VORs) in the generation of horizontal eye movements during head movements including both rotational and translational components. We used three eccentric rotation techniques to investigate this interaction in human subjects: (1) the tangential interaural acceleration was varied using three head positions (on-axis, 25 and 40 cm ahead of the rotational axis), while angular head velocity remained unchanged; (2) the magnitude of the angular head velocity was varied with head eccentricity to keep the tangential interaural acceleration unchanged; (3) the subject's head was oriented either upright or 90 degrees forward from upright (nose-down). Experiments were performed in complete darkness with the subjects remembering a close earth-fixed target (20 cm distant) while being rotated at 1.2 and 1.8 Hz. Our data showed that the translational component of the VOR evoked during eccentric yaw rotation increased proportionally with an increase in head eccentricity, i.e. with tangential acceleration. We also found that the translational component of the VOR was equal for motion stimuli producing identical interaural tangential accelerations even when angular velocities differed. In addition, we found that the translational component of the VOR evoked during head upright eccentric rotation was equal to the translational VOR evoked during nose-down rotation for a given stimulus and head eccentricity. We conclude that these three findings are in agreement with what would be expected from a linear interaction (i.e. algebraic summation) between otolith organ and horizontal canal VORs for the generation of horizontal compensatory eye movements during head motion.

  3. Textilverstärkte Kunststoffbauteile in funktionsintegrierender Leichtbauweise

    NASA Astrophysics Data System (ADS)

    Kroll, Lothar

    Der Mensch ist anisotrop aufgebaut. Vor allem die tragenden Hochleistungskomponenten mit hoher Funktionsintegration, wie Knochen und Knorpel, weisen eine ausgeprägte anisotrope Eigenschaftscharakteristik auf, die an den wirkenden Kraftflusslinien ausgerichtet ist und so extrem leichte Bauweisen zulässt. Daher stellt sich die berechtigte Frage: Warum sind technische Hochleistungsstrukturen noch nicht in dieser idealen Bauweise ausgeführt? Der wesentliche Grund dafür ist, dass sich die erforderlichen beanspruchungsgerechten Werkstoffkonstruktionen und vor allem die zugehörigen Technologien erst am Anfang des Entwicklungsstadiums befinden. Die Natur hatte hier viel mehr Zeit, derartige ressourceneffiziente Werkstoffkonstruktionen zu optimieren und umzusetzen.

  4. An age-dependent sensitivity of the roll-induced vestibuloocular reflex to hypergravity exposure of several days in an amphibian (Xenopus laevis).

    PubMed

    Sebastian, C E; Pfau, K; Horn, E R

    1998-01-01

    In tadpoles of the Southern Clawed Toad (Xenopus laevis), the effects of an exposure to hypergravity of several days duration on the development of the roll-induced static vestibuloocular reflex (rVOR) were investigated. Special attention was given to the onset of the 9 or 12 days lasting 3G-period during early life. First recordings of the rVOR characteristics for complete 360 degrees rolls of the tadpoles were performed 24 hrs after the end of the 3G-period. The rVOR peak-to-peak amplitudes as well as the VOR-gain for a roll angle of 15 degrees from 3G-and 1G-samples recorded at the 2nd and 3rd day after 3G-termination agreed for the youngest group, but were reduced by approx. 30% in the older tadpoles. Long-term observations lasting up to 8 weeks after termination of the 3G-period, demonstrated (i) an early retardation of the development, and (ii) a developmental acceleration in all groups so that after 2 weeks in the stage 6/9- and 33/36-samples and after 8 weeks in the stage 45-tadpoles, the rVOR-amplitude as well as the rVOR-gain for a 15 degrees roll were at the same level in both the 3G- and the 1G-samples. The results support the existence of a sensitive period for the rVOR development, and additionally demonstrate the importance of the period of the first appearance of the rVOR for the development of adaptive properties of the underlying neuronal network. They also demonstrate the dominant efficiency of genetic programs in the functional development of the vestibular system. Methodological approaches are discussed which will be useful in the further description of the critical period. They include studies on the neuronogenesis and synaptic maturation within the vestibular pathways as well as on the fundamentals of buoyancy control during swimming. A modular but closed mini-system for experimental use is described which allows survival periods lasting many weeks and multiple types of treatments of developing aquatic animals in orbit, controlled

  5. Therapie des metastasierten kastrationsresistenten Prostatakarzinoms mit Abirateronacetat im klinischen Alltag.

    PubMed

    Wolff, Johannes Maria

    2017-01-01

    Abirateronacetat, das in Kombination mit Prednison/Prednisolon verabreicht wird, spielt eine wichtige Rolle in der Therapie des metastasierten kastrationsresistenten Prostatakarzinoms. Im Folgenden wurden besondere Aspekte der Therapie im klinischen Alltag zusammengestellt. Sie betreffen unter anderem die Dosierung - auch vor dem Hintergrund der Markteinführung einer neuen Formulierung von Abirateronacetat. Hinzu kommt die Verträglichkeit, vor allem in Bezug auf kardiovaskuläre und Kortikoid-bedingte Nebenwirkungen. Des Weiteren werden Kriterien genannt, nach denen die Therapie nicht zu früh umgestellt werden sollte. © 2017 S. Karger GmbH, Freiburg.

  6. Short-term adaptive changes in the human vestibulo-ocular reflex arc.

    PubMed

    Gonshor, A; Jones, G M

    1976-04-01

    1. Two sets of experiments have examined the vestibulo-ocular response (VOR) to repeated sinusoidal rotation (A) in the dark and (B) after attempting visual tracking of a mirror-reversed image of the visual surround.2. In both A and B a horizontal sinusoidal rotational stimulus of 1/6 Hz and 60 degrees /sec angular velocity amplitude was employed, specifically chosen to lie within the presumed range of natural stimulation of the semicircular canals.3. In A each of seven subjects underwent ten 2-min runs of the standard stimulus in the dark on each of three consecutive days, with 3-min rest periods between runs. Using d.c. electro-oculography (EOG) the VOR gain was measured throughout as eye velocity/head velocity. Mental arousal was maintained by competitive mental arithmetic. Constancy of EOG gain was assured by 50 min dark adaptation before experimentation.4. The results of A showed no consistent change of VOR gain over the three times scales of a run, a day and the 3-day experiment.5. In B the same subjects underwent a similar pattern of vestibular stimulation, but during eight of the 2-min daily runs they attempted the reversed visual tracking task. VOR gain was measured during the 1st, 6th and last runs which were conducted in the dark for this purpose. Constancy of EOG gain was maintained by using red light throughout.6. The results of B showed a substantial (approx. 25%) and highly significant (P < 0.001) reduction of VOR gain attributable solely to the 16 min of reversed visual tracking attempted during the 50 min daily experiment. In addition the pre-test control gain was lower on day 3 than on day 1 (approx. 10% attenuation, P < 0.01) indicating a small cumulative effect from beginning to end of the 3-day experiment.7. It is concluded (A) that the repeated vestibular stimulus did not itself cause significant attenuation of VOR gain, but (B) that superposition of a reversed visual tracking task did induce retained VOR attenuation which was solely due to

  7. Kernschmelze Der nachhaltige Einfluss von Nuklearwaffen auf Politik und Wirtschaft

    NASA Astrophysics Data System (ADS)

    Greiner, Bernd

    "Was sollen wir von einer Kultur halten, der die Ethik stets als wesentliches Element des menschlichen Lebens galt, die aber - außer in fachlicher oder spieltheoretischer Terminologie - nicht in der Lage war, über die Möglichkeit zu sprechen, nahezu alle Menschen zu töten?" Der Fragesteller gehört zu den berühmtesten Physikern des 20. Jahrhunderts und zu den nach wie vor Umstrittensten. über ihn wurde in den 1960er Jahren ein international viel beachtetes Theaterstück geschrieben, vor wenigen Jahren gar eine Oper.

  8. Tantal

    NASA Astrophysics Data System (ADS)

    Dettner, H. W.; Franssen, H.; Giesen, K.; Hayes, E. T.; Holetzko, H.; Keysselitz, B.; Loebich, O.; Pelzel, E.; Reinsch, W.; Rostoker, W.; Saur, G.; Volk, K. E.; Wallbaum, H. J.; Borchers, Heinz; Schmidt, Ernst

    Tantal gehört zu den seltenen Metallen. In der Erdrinde kommt es in geringeren Mengen vor als Platin oder Uran. Die Welterzeugung an Tantal betrug 1957 etwa 400 t [K 2]. Tantal kommt in der Natur — wie das Schwestermetall Niob, mit dem es immer vergesellschaftet ist und von dem es nur sehr schwierig getrennt werden kann — fast ausschließlich in Form von Oxyden vor. Die wertvollsten Erze sind Tantalit (Eisen-Mangan-Tantalat mit 42...84% Ta2O5), Niob-Tantalit und Tantal-Niobit (25...40% Ta2O5).

  9. Herausforderungen durch die deutsche Wiedervereinigung

    NASA Astrophysics Data System (ADS)

    Stäglin, Reiner

    Die Wiedervereinigung stellte auch die Statistik vor große Aufgaben. Die als Organ der staatlichen Planung staatsnah orientierte Statistik der DDR musste auf das zur Neutralität und wissenschaftlichen Unabhängigkeit verpflichtete System der Bundesrepublik umgestellt werden. Ebenso verlangten die Universitäten eine Neuorientierung. Die Deutsche Statistische Gesellschaft hat sich vor allem dreier Aufgaben mit großem Engagement, aber auch mit Bedachtsamkeit angenommen: Aufnahme und Integration der Statistiker aus den neuen Bundesländern in die Gesellschaft, Begleitung der Neuausrichtung des Faches Statistik an deren Hochschulen und Sicherung sowie Nutzung von Datenbeständen der ehemaligen DDR.

  10. An age-dependent sensitivity of the roll-induced vestibuloocular reflex to hypergravity exposure of several days in an amphibian ( Xenopus laevis)

    NASA Astrophysics Data System (ADS)

    Sebastian, C. E.; Pfau, K.; Horn, E. R.

    In tadpoles of the Southern Clawed Toad ( Xenopus laevis), the effects of an exposure to hypergravity of several days duration on the development of the roll-induced static vestibuloocular reflex (rVOR) were investigated. Special attention was given to the onset of the 9 or 12 days lasting 3G-period during early life. First recordings of the rVOR characteristics for complete 360 ° rolls of the tadpoles were performed 24 hrs after the end of the 3G-period. The rVOR peak-to-peak amplitudes as well as the VOR-gain for a roll angle of 15 ° from 3G-and 1G-samples recorded at the 2nd and 3rd day after 3G-termination agreed for the youngest group, but were reduced by approx. 30% in the older tadpoles. Long-term observations lasting up to 8 weeks after termination of the 3G-period, demonstrated (i) an early retardation of the development, and (ii) a developmental acceleration in all groups so that after 2 weeks in the stage 6/9- and 33/36-samples and after 8 weeks in the stage 45-tadpoles, the rVOR-amplitude as well as the rVOR-gain for a 15 ° roll were at the same level in both the 3G- and the 1G-samples. The results support the existence of a sensitive period for the rVOR development, and additionally demonstrate the importance of the period of the first appearance of the rVOR for the development of adaptive properties of the underlying neuronal network. They also demonstrate the dominant efficiency of genetic programs in the functional development of the vestibular system. Methodological approaches are discussed which will be useful in the further description of the critical period. They include studies on the neuronogenesis and synaptic maturation within the vestibular pathways as well as on the fundamentals of buoyancy control during swimming. A modular but closed mini-system for experimental use is described which allows survival periods lasting many weeks and multiple types of treatments of developing aquatic animals in orbit, controlled automatically.

  11. Visual-vestibular interaction during standing, walking, and running.

    PubMed

    Demer, J L; Viirre, E S

    1996-01-01

    In artificial laboratory situations where subjects undergo repetitive self-generated or externally imposed head rotations, visual-vestibular interaction during the wearing of telescopic spectacles can markedly augment gain of the vestibulo-ocular reflex (VOR). The present study was conducted to determine whether the wearing of these aids for the visually impaired is associated with similar visual-vestibular interaction during more natural activities. Angular eye and head movements of unrestrained normal volunteers were measured using magnetic search coils. In some subjects, head translations and rotations were also monitored by a flux gate magnetometer array. Measurements were performed of the VOR in darkness, and of the visually enhanced VOR (VVOR) in lit conditions, during three natural activities: 1) standing quietly; 2) walking in place; 3) running in place. These data were compared with similar measurements during repetitive voluntary head oscillations at 0.8 Hz in pitch or yaw. During VVOR, subjects viewed a target placed 6 to 10 m away and remembered this target during VOR trials in darkness. To assess the effects of altering visual-vestibular interactions, VVOR testing during normal vision was augmented by wearing of binocular telescopic spectacles of 2X, 4X, and 6X powers. Dorsoventral and mediolateral head translations were consistently phase-locked with pitch and yaw head rotations, respectively, such that head translation at least partially compensated for rotational disturbances of gaze. Angular velocity of the head was greater during walking than during standing, and was greater still during running, with a greater increase in each case for pitch as compared with yaw. Eye movements were phase compensatory for head movements. VOR gain (eye velocity divided by head velocity) was near 1.0 in both pitch and yaw during standing and during actively generated head rotation. During walking and running there was a significant decrease in angular VOR gain in

  12. A brief review of the clinical anatomy of the vestibular-ocular connections—how much do we know?

    PubMed Central

    Bronstein, A M; Patel, M; Arshad, Q

    2015-01-01

    The basic connectivity from the vestibular labyrinth to the eye muscles (vestibular ocular reflex, VOR) has been elucidated in the past decade, and we summarise this in graphic format. We also review the concept of ‘velocity storage', a brainstem integrator that prolongs vestibular responses. Finally, we present new discoveries of how complex visual stimuli, such as binocular rivalry, influence VOR processing. In contrast to the basic brainstem circuits, cortical vestibular circuits are far from being understood, but parietal-vestibular nuclei projections are likely to be involved. PMID:25412719

  13. 78 FR 40385 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-05

    ....... Lake Village 3/0454 6/13/13 VOR/DME B, Amdt Muni. 6. 7/25/13 WA Deer Park....... Deer Park...... 3/0893........... Grayling AAF... 3/1341 6/13/13 RNAV (GPS) RWY 14, Orig. 7/25/13 GA Americus........ Jimmy Carter 3/1379 6...

  14. 75 FR 51663 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-23

    ... August 6, 2010. John M. Allen, Director, Flight Standards Service. Adoption of the Amendment 0...) RWY 27, Orig Tifton, GA, Henry Tift Myers, NDB RWY 33, Amdt 1 Tifton, GA, Henry Tift Myers, RNAV (GPS) RWY 28, Orig Tifton, GA, Henry Tift Myers, RNAV (GPS) RWY 33, Orig Tifton, GA, Henry Tift Myers, VOR...

  15. The Effects of Blast Trauma (Impulse Noise) on Hearing: A Parametric Study. Part 2

    DTIC Science & Technology

    1988-07-21

    Callier Centw Vor Comamunicat.on Disorders The Universit.v o" i’as 4t Dallas Tfiai•, T,’xas 75235 App,’,Je, foc pitblic ieleas; distrib;rtion is unliniitd...applicable) Communication Disorders I 6c. ADDRESS (Giy, State, and ZIPCode) 7b. ADDRESS (City. State. and ZIP Code) The University of Texas at Dallas Dallas

  16. 78 FR 18268 - Proposed Establishment of Class E Airspace; Blue Mesa, CO

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-26

    ... Federal Aviation Administration 14 CFR Part 71 Proposed Establishment of Class E Airspace; Blue Mesa, CO.../Distance Measuring Equipment (VOR/DME), Blue Mesa, CO to facilitate vectoring of Instrument Flight Rules..., Blue Mesa, CO. This action would contain aircraft while in IFR conditions under control of Denver...

  17. 78 FR 34556 - Establishment of Class E Airspace; Tobe, CO

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-10

    ... Federal Aviation Administration 14 CFR Part 71 Establishment of Class E Airspace; Tobe, CO AGENCY: Federal... at the Tobe VHF Omni- Directional Radio Range/Distance Measuring Equipment (VOR/DME), Tobe, CO, to... proposed rulemaking (NPRM) to establish controlled airspace at Tobe, CO (78 FR 18264). Interested...

  18. 77 FR 4708 - Proposed Amendment of Class E Airspace; Tobe, CO

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-31

    ... Federal Aviation Administration 14 CFR Part 71 Proposed Amendment of Class E Airspace; Tobe, CO AGENCY... action proposes to amend Class E airspace at Tobe, CO. Decommissioning of the Tobe Tactical Air... and management of aircraft operations in the vicinity of the Tobe VOR/ DME, CO. Class E...

  19. 75 FR 19541 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-15

    ... to provide safe and efficient use of the navigable airspace and to promote safe flight operations... Obstacle DP, Orig Red Oak, IA, Red Oak Muni, NDB RWY 17, Amdt 9 Flora, IL, Flora Muni, RNAV (GPS) RWY 21..., Mount Carmel Muni, NDB OR GPS RWY 4, Amdt 5, CANCELLED Mount Carmel, IL, Mount Carmel Muni, VOR RWY 22...

  20. 76 FR 43580 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-21

    ..., 2011. John M. Allen, Director, Flight Standards Service. Adoption of the Amendment Accordingly... Harbor, MI, Southwest Michigan Rgnl, VOR RWY 28, Amdt 19 Holland, MI, Tulip City, RNAV (GPS) RWY 8, Amdt.../Pike County/John E Lewis Field, RNAV (GPS) RWY 15, Amdt 1 Raymond, MS, John Bell Williams, ILS OR LOC...

  1. Supply Chain Management

    NASA Astrophysics Data System (ADS)

    Bauer, Jürgen

    Die Produktionslogistik hat im Rahmen der Materialbeschaffung und der Belieferung von externen Kunden vielfältige Beziehungen zu Lieferanten und Kunden. Im Ansatz des Supply Chain Managements (Lieferkettenmanagement), kurz auch als SCM bezeichnet, versucht man, sowohl Lieferanten als auch Kunden in die gesamte Logistikplanung zu integrieren. SCM umfasst dabei vor allem folgende Aufgaben: Bedarfs- und Bestandsplanung der Materialien entlang der Lieferkette

  2. 76 FR 54148 - Proposed Amendment of Class E Airspace; Emmonak, AK

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-31

    ... AK E5 Emmonak, AK Emmonak Airport, AK (Lat. 62 47'10'' N., long. 164 29'27'' W.) Emmonak VOR/DME (Lat... Federal Aviation Administration 14 CFR Part 71 Proposed Amendment of Class E Airspace; Emmonak, AK AGENCY... action proposes to revise Class E airspace at Emmonak, AK. The amendment of two standard instrument...

  3. 76 FR 75447 - Amendment of Class E Airspace; Emmonak, AK

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-02

    ... Emmonak, AK Emmonak Airport, AK (Lat. 62 47'10'' N., long. 164 29'27'' W.) Emmonak VOR/DME (Lat. 62 47'05... Federal Aviation Administration 14 CFR Part 71 Amendment of Class E Airspace; Emmonak, AK AGENCY: Federal... Emmonak, AK. The revision of two standard instrument approach procedures at the Emmonak Airport has made...

  4. 78 FR 4353 - Proposed Amendment of Area Navigation (RNAV) Route T-266; AK

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-22

    ... Annette Island, AK (ANN) RADKY, AK Fix (Lat. 58 08'00'' N., long. 134 29'56'' W.) XADZY, AK WP (Lat. 57 01...'56'' W.) DOOZI, AK Fix (Lat. 55 37'57'' N., long. 132 10'29'' W.) Annette Island, AK (ANN) VOR/DME...) Route T-266; AK AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of proposed...

  5. Development of visual-display aid to air navigation

    NASA Technical Reports Server (NTRS)

    Matcovich, T. J.

    1973-01-01

    The developments are discussed in the design of a liquid-crystal, visual display, air navigation aid, which uses two VOR signals to locate the aircraft. The system concepts, liquid crystal materials, stability tests, and the electronic system are described. It is concluded that a navigational aid of this type is technically feasible, but not at the projected low cost.

  6. 78 FR 45478 - Proposed Establishment of Class E Airspace; Salmon, ID

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-29

    ... Federal Aviation Administration 14 CFR Part 71 Proposed Establishment of Class E Airspace; Salmon, ID...: This action proposes to establish Class E airspace at the Salmon VHF Omni-Directional Radio Range/Distance Measuring Equipment (VOR/DME) navigation aid, Salmon, ID, to facilitate vectoring of...

  7. 76 FR 53361 - Proposed Revocation and Amendment of Class E Airspace; Olathe, KS

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-26

    ..., and amend Class E airspace at Olathe, KS. Decommissioning of the Johnson County VHF Omni-directional Range/ Distance Measuring Equipment (VOR/DME) at Johnson County Executive Airport, Olathe, KS, has made... Johnson County Executive Airport. DATES: 0901 UTC. Comments must be received on or before October 11, 2011...

  8. 77 FR 9841 - Modification of Area Navigation Route T-288; WY

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-21

    ...-288 by adding a new segment between the Rapid City, SD, VORTAC (RAP) and the Gillette, WY, VOR/DME... 32'37'' W.) KARAS, WY INT (Lat. 44 16'23'' N., long. 104 18'50'' W.) Rapid City, SD (RAP) VORTAC (Lat...

  9. Historisches Rätsel: Punkt, Punkt, Komma, Strich

    NASA Astrophysics Data System (ADS)

    Loos, Andreas

    2006-01-01

    Es kommt nicht oft vor, dass jemand unter 30 ist, wenn er den Physik-Nobelpreis erhält - auch, wenn Alfred Nobel eigentlich die Idee hatte, junge Entdeckertypen zu fördern. Beim Gesuchten hat es aber mal geklappt, und zwar gemeinsam mit seinem Vater. Mit 25 Jahren ist er bis heute der Benjamin unter den Noblen Herren.

  10. Gating of neural error signals during motor learning

    PubMed Central

    Kimpo, Rhea R; Rinaldi, Jacob M; Kim, Christina K; Payne, Hannah L; Raymond, Jennifer L

    2014-01-01

    Cerebellar climbing fiber activity encodes performance errors during many motor learning tasks, but the role of these error signals in learning has been controversial. We compared two motor learning paradigms that elicited equally robust putative error signals in the same climbing fibers: learned increases and decreases in the gain of the vestibulo-ocular reflex (VOR). During VOR-increase training, climbing fiber activity on one trial predicted changes in cerebellar output on the next trial, and optogenetic activation of climbing fibers to mimic their encoding of performance errors was sufficient to implant a motor memory. In contrast, during VOR-decrease training, there was no trial-by-trial correlation between climbing fiber activity and changes in cerebellar output, and climbing fiber activation did not induce VOR-decrease learning. Our data suggest that the ability of climbing fibers to induce plasticity can be dynamically gated in vivo, even under conditions where climbing fibers are robustly activated by performance errors. DOI: http://dx.doi.org/10.7554/eLife.02076.001 PMID:24755290

  11. Vestibulo-Ocular Responses to Vertical Translation using a Hand-Operated Chair as a Field Measure of Otolith Function

    NASA Technical Reports Server (NTRS)

    Wood, S. J.; Campbell, D. J.; Reschke, M. F.; Prather, L.; Clement, G.

    2016-01-01

    The translational Vestibulo-Ocular Reflex (tVOR) is an important otolith-mediated response to stabilize gaze during natural locomotion. One goal of this study was to develop a measure of the tVOR using a simple hand-operated chair that provided passive vertical motion. Binocular eye movements were recorded with a tight-fitting video mask in ten healthy subjects. Vertical motion was provided by a modified spring-powered chair (swopper.com) at approximately 2 Hz (+/- 2 cm displacement) to approximate the head motion during walking. Linear acceleration was measured with wireless inertial sensors (Xsens) mounted on the head and torso. Eye movements were recorded while subjects viewed near (0.5m) and far (approximately 4m) targets, and then imagined these targets in darkness. Subjects also provided perceptual estimates of target distances. Consistent with the kinematic properties shown in previous studies, the tVOR gain was greater with near targets, and greater with vision than in darkness. We conclude that this portable chair system can provide a field measure of otolith-ocular function at frequencies sufficient to elicit a robust tVOR.

  12. 78 FR 44874 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-25

    ... Amended To Read in Part JUNCTION, TX VORTAC SAN ANTONIO, TX VORTAC.. 4100 Sec. 95.6245 VOR Federal Airway...--MOCA MEA IS ESTABLISHED WITH A GAP IN NAVIGATION SIGNAL COVERAGE. From To MEA MAA Sec. 95.7001 Jet... Changeover Point V198 Is Amended To Delete Changeover Point JUNCTION, TX VORTAC SAN ANTONIO, TX VORTAC...

  13. [Activities of Psychology Dept., California Univ.

    NASA Technical Reports Server (NTRS)

    Bridgeman, Bruce

    1998-01-01

    We have completed two studies during the grant period, with manuscripts published or ready for submission for publication: (1) Dual adaptation and adaptive generalization in the human vestibuloocular reflex and (2) Frequency vs. acceleration specificity in human VOR adaptation. In the 1st study two studies examined the possibility that rotational VOR plasticity is subject to dual adaptation and adaptive generalization. Subjects in the experimental condition were exposed to an altered visual-vestibular environment for about four minutes every day for five consecutive days. The working hours between these testing sessions constituted re-exposure to the normal visual environment. Thus, subjects were repeatedly adapting and re-adapting to both environments which is a condition designed to produce dual adaptation. In each training session a measure of baseline VOR gain was obtained (in the dark). A small laser spot (the only visual stimulus) was systematically moved in the same direction as the subject's head, but by half the angle of rotation (target/head gain = 0.5). This resulted in adaptation values relativized to the non-adapted gain of each subject. These values were then analyzed using an analysis of variance with day and session (within a day) as factors. In the 2nd study human VOR adaption has been assumed to be frequency specific, despite the fact that the semicircular canals are simulated by rotational acceleration and not frequency per se.

  14. Vegetative characteristics of swift fox denning and foraging sites in southwestern South Dakota

    Treesearch

    Daniel W. Uresk; Kieth E. Severson; Jody Javersak

    2003-01-01

    Vegetative characteristics of swift fox (Vulpes velox) denning and foraging habitats were studied in southwestern South Dakota. We followed 14 radio-collared foxes over a two-year period and identified 17 den sites and 82 foraging sites. Height-density of vegetation (visual obstruction reading, VOR) was determined on each den and foraging site and on...

  15. 75 FR 66344 - Amendment of Jet Route J-93; CA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-28

    ... Federal Aviation Administration 14 CFR Part 71 RIN 2120-AA66 Amendment of Jet Route J-93; CA AGENCY... action proposes to amend Jet Route J-93 in California between the Julian VHF Omnidirectional Radio Range... is necessary to realign Jet Route J-93 with the revised location of the Penasco VOR. The Proposal...

  16. 77 FR 24156 - Proposed Amendment of Air Traffic Service Routes; Southwestern United States

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-23

    ... Route J-2, and VOR Federal airways V-16, V-66, and V-202 in southern Arizona and New Mexico. The FAA is... V-16, V-66, and V-202. This action is necessary due to the decommissioning of the Cochise, AZ... remainder of the route would be unchanged). The portion of V-16 that currently extends from Tucson, AZ;...

  17. Adaptive Digital Signature Design and Short-Data-Record Adaptive Filtering

    DTIC Science & Technology

    2008-04-01

    of signal parameters via rotational invariance techniques FDMA frequency − division multiple − access GLR generalized likelihood ratio ISI inter...of sensor networks do not fa- vor time-division multiple-access (TDMA) developments. Similarly, frequency- division multiple-access ( FDMA ), would

  18. 77 FR 45922 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-02

    ..., Plymouth Muni, ILS OR LOC/DME RWY 6, Amdt 1B Worcester, MA, Worcester Rgnl, VOR/DME RWY 33, Amdt 1 Mackinac..., Amdt 11 Iliamna, AK, Iliamna, RNAV (GPS) RWY 35, Amdt 2 King Salmon, AK, King Salmon, ILS OR LOC/DME... 2 San Francisco, CA, San Francisco Intl, ILS OR LOC RWY 28L, Amdt 23 San Francisco, CA,...

  19. 77 FR 18681 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-28

    ... Austin, MN, Austin Muni, ILS OR LOC RWY 35, Amdt 1 Austin, MN, Austin Muni, RNAV (GPS) RWY 35, Amdt 1..., Orig Kansas City, MO, Charles B. Wheeler Downtown, ILS OR LOC RWY 3, Amdt 3 Kansas City, MO, Charles B..., ILS OR LOC RWY 22R, Amdt 5B Poughkeepsie, NY, Dutchess County, VOR/DME RWY 6, Amdt 7 Batavia,...

  20. 77 FR 24369 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-24

    ..., ILS OR LOC RWY 36L, Orig Napa, CA, Napa County, LOC RWY 36L, Amdt 2D, CANCELLED Oroville, CA, Oroville..., Oroville Muni, VOR-A, Amdt 7 Washington, DC, Ronald Reagan Washington National, COPTER ILS OR LOC/DME RWY 1, Amdt 1 Washington, DC, Ronald Reagan Washington National, ILS OR LOC/DME RWY 1, ILS RWY 1 (SA CAT...

  1. Reversal of Motor Learning in the Vestibulo-Ocular Reflex in the Absence of Visual Input

    ERIC Educational Resources Information Center

    Cohen, Marlene R.; Meissner, Geoffrey W.; Schafer, Robert J.; Raymond, Jennifer L.

    2004-01-01

    Motor learning in the vestibulo-ocular reflex (VOR) and eyeblink conditioning use similar neural circuitry, and they may use similar cellular plasticity mechanisms. Classically conditioned eyeblink responses undergo extinction after prolonged exposure to the conditioned stimulus in the absence of the unconditioned stimulus. We investigated the…

  2. Learning in a Simple Motor System

    ERIC Educational Resources Information Center

    Broussard, Dianne M.; Kassardjian, Charles D.

    2004-01-01

    Motor learning is a very basic, essential form of learning that appears to share common mechanisms across different motor systems. We evaluate and compare a few conceptual models for learning in a relatively simple neural system, the vestibulo-ocular reflex (VOR) of vertebrates. We also compare the different animal models that have been used to…

  3. 76 FR 77113 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-12

    ... to: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html . Availability_All SIAPs are available online free of charge. Visit nfdc.faa.gov to register. Additionally... Amdt 5. Northern Field. 12-Jan-12 KY Greenville Muhlenberg 1/2171 11/9/11 VOR/DME A, Amdt County. 5. 12...

  4. Vier Jahrhunderte Spannung

    NASA Astrophysics Data System (ADS)

    Loos, Andreas

    2000-06-01

    Im Jahre 1600 begründete William Gilbert die Elektrizitätslehre. Seitdem versuchten die Naturforscher dieses merkwürdige Phänomen zu ergründen und vor allem in Maschinen zu bändigen. Ein an Irrwegen und Gefahren reiches Zeitalter begann.

  5. 77 FR 1015 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-09

    ... Rgnl, RNAV (GPS) RWY 35, Amdt 2 Houston, TX, Sugar Land Rgnl, VOR/DME-A, Amdt 2 Marshall, TX, Harrison County, GPS RWY 33, Orig-F, CANCELLED Marshall, TX, Harrison County, RNAV (GPS) RWY 15, Orig Marshall, TX, Harrison County, RNAV (GPS) RWY 33, Orig Marshall, TX, Harrison County, Takeoff Minimums and Obstacle DP...

  6. 78 FR 29613 - Modification and Revocation of Air Traffic Service Routes; Jackson, MS

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-21

    ... published in the NPRM. Jet routes are published in paragraph 2004, and VOR Federal airways are published in... August 8, 2012 and effective September 15, 2012, is amended as follows: Paragraph 2004 Jet Routes... Liberal 137 and Will Rogers, OK, 284 radials; Will Rogers; Belcher, LA; Magnolia, MS; Meridian, MS...

  7. Results of a Loran-C flight test using an absolute data reference. [vhf monirange navigation system and discrete address beacon system

    NASA Technical Reports Server (NTRS)

    Fischer, J. P.

    1981-01-01

    A closed circuit flight test was conducted using VORs and NDBs as reference points. The Loran-C data collected during the flight was then compared against a reference provided by a discrete address beacon system facility. Information on the equipment configuration in the aircraft, the flight procedure, and the results obtained are presented.

  8. 75 FR 54057 - Proposed Modification of Class E Airspace; Portland, OR

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-03

    ... the Localizer/Distance Measuring Equipment (LOC/DME) for Standard Instrument Approach Procedures.... Controlled airspace is necessary to accommodate aircraft using the LOC/DME SIAPs at Portland International...'41'' W.) Corvallis VOR/DME (Lat. 45[deg]29'58'' N., long. 123[deg]17'37'' W.) McMinnville...

  9. USSR Report: Political and Sociological Affairs.

    DTIC Science & Technology

    1983-07-27

    8217PODRYAD’? The concept is rather hard to translate into other languages. The English "contract", the French "sous- traitanceVor the Spanish " contrato ...the attention of the Central Committee of the Ukrainian Commu- nist Party. These tasks were put forward by the 26th Party Con- gress and the

  10. 77 FR 12452 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-01

    ... and Obstacle DP, Amdt 4 Durango, CO, Durango-La Plata County, VOR/DME RWY 3, Amdt 5 Pueblo, CO, Pueblo... Obstacle DP, Amdt 2 Miami, FL, Miami Intl, ILS OR LOC RWY 8R, Amdt 30B Hilo, HI, Hilo Intl, ILS OR LOC...

  11. 78 FR 5254 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-25

    ... Office, 6500 South MacArthur Blvd., Oklahoma City, OK 73169 or, 4. The National Archives and Records..., Mike Monroney Aeronautical Center, 6500 South MacArthur Blvd., Oklahoma City, OK 73169 (Mail Address: P..., Jonesboro Muni, VOR RWY 23, Amdt 11 Melbourne, AR, Melbourne Muni--John E Miller Field, RNAV (GPS) RWY...

  12. Representing the effects of stratosphere–troposphere exchange on 3-D O3 distributions in chemistry transport models using a potential vorticity-based parameterization

    EPA Science Inventory

    Downward transport of ozone (O3) from the stratosphere can be a significant contributor to tropospheric O3 background levels. However, this process often is not well represented in current regional models. In this study, we develop a seasonally and spatially varying potential vor...

  13. 76 FR 64005 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-17

    ... Iverson, Takeoff Minimums and Obstacle DP, Orig Park Rapids, MN, Park Rapids Muni-Konshok Field, Takeoff... Renton, WA, Renton Muni, Takeoff Minimums and Obstacle DP, Amdt 8 Janesville, WI, Southern Wisconsin Rgnl, ILS OR LOC RWY 32, Amdt 1A Janesville, WI, Southern Wisconsin Rgnl, VOR RWY 4, Amdt 27, CANCELLED...

  14. Gravity-dependent nystagmus and inner-ear dysfunction suggest anterior and posterior inferior cerebellar artery infarct.

    PubMed

    Shaikh, Aasef G; Miller, Benjamin R; Sundararajan, Sophia; Katirji, Bashar

    2014-04-01

    Cerebellar lesions may present with gravity-dependent nystagmus, where the direction and velocity of the drifts change with alterations in head position. Two patients had acute onset of hearing loss, vertigo, oscillopsia, nausea, and vomiting. Examination revealed gravity-dependent nystagmus, unilateral hypoactive vestibulo-ocular reflex (VOR), and hearing loss ipsilateral to the VOR hypofunction. Traditionally, the hypoactive VOR and hearing loss suggest inner-ear dysfunction. Vertigo, nausea, vomiting, and nystagmus may suggest peripheral or central vestibulopathy. The gravity-dependent modulation of nystagmus, however, localizes to the posterior cerebellar vermis. Magnetic resonance imaging in our patients revealed acute cerebellar infarct affecting posterior cerebellar vermis, in the vascular distribution of the posterior inferior cerebellar artery (PICA). This lesion explains the gravity-dependent nystagmus, nausea, and vomiting. Acute onset of unilateral hearing loss and VOR hypofunction could be the manifestation of inner-ear ischemic injury secondary to the anterior inferior cerebellar artery (AICA) compromise. In cases of combined AICA and PICA infarction, the symptoms of peripheral vestibulopathy might masquerade the central vestibular syndrome and harbor a cerebellar stroke. However, the gravity-dependent nystagmus allows prompt identification of acute cerebellar infarct. Copyright © 2014 National Stroke Association. Published by Elsevier Inc. All rights reserved.

  15. 76 FR 11978 - Proposed Amendment of Federal Airways; Alaska

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-04

    ... Federal airways in Alaska. Due to construction of wind turbines on Fire Island, AK, the Anchorage VOR is... (Lat. 55 46'00'' N., long. 161 59'56'' W.) PDN NDB/DME (Lat. 56 57'15'' N., long. 158 38'51'' W.) BATTY...

  16. 76 FR 61673 - 36(b)(1) Arms Sales Notification

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-05

    ... Dipping SONAR, AAQ-22 Forward Looking Infrared Radar (FLIR), AN/APS-143C (V) 3 RADAR, ARC-210 UHF Radio... following: HELRAS Helicopter Dipping SONAR, AAQ-22 Forward Looking Infrared Radar (FLIR), AN/APS-143C (V) 3 RADAR, ARC-210 UHF Radio, APX-72 Transponder, AN/ARN- 147 VOR/ILS, AN/ARN-149 Receiver (ADF), HF-9000 HF...

  17. 76 FR 33136 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-08

    ... Points From To MEA Sec. 95.6001 Victor Routes--U.S. Sec. 95.6003 VOR Federal Airway V3 IS AMENDED TO READ IN PART....... Vance, SC VORTAC........ Florence, SC VORTAC..... *2000 *2000--GNSS MEA Vance R-047 to... Hodni, ID FIX *12000 *10800--MOCA *10800--GNSS MEA Hodni, ID FIX Grips, WY FIX *16000...

  18. 76 FR 72094 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-22

    ... From To MEA &95.6001 Victor Routes-U.S. &95.6014 VOR Federal Airway V14 is Amended to Read in Part Will... Read in Part Sandhills, NC VORTAC *RAEFO, NC FIX **6000 *6000-MRA **2000-MOCA **3000-GNSS MEA *Raefo... Amended to Read in Part Malae, NY FIX Plattsburgh, NY VORTAC.. *7000 *6100-MOCA *6100-GNSS MEA...

  19. Recovery of otolith function in patients with benign paroxysmal positional vertigo evaluated by sinusoidal off-vertical axis rotation.

    PubMed

    Sugita-Kitajima, Akemi; Koizuka, Izumi

    2008-05-09

    The vestibulo-ocular reflex (VOR) was studied via sinusoidal off-vertical axis rotation (OVAR) to evaluate otolith function in patients with benign paroxysmal positional vertigo (BPPV). Subjects were sinusoidally rotated with eyes open in complete darkness at frequencies of 0.4 and 0.8 Hz with a maximum angular velocity of 60 degrees /s in earth vertical axis rotation (EVAR) and OVAR. Ten patients with BPPV patients were investigated. We performed OVAR tests for all patients for the following different points and compared otolith function: (1) The point at which patients had typical nystagmus; we call this state 'Before', that is, before recovery. (2) The point when their nystagmus disappeared; we call this state 'After' that is, after nystagmus disappear. Results showed that VOR gain during OVAR at 0.8 Hz in a 30 degrees nose-up position in BPPV patients was significantly less than the gain during EVAR at the point Before. On the other hand, gain was not significantly different between EVAR and OVAR at the point After. VOR gain itself at 0.8 Hz nose-up OVAR showed a significant increase at the point After compared to Before. This increase of VOR gain might be caused by the recovery of the otolith function in patients with BPPV.

  20. 75 FR 63712 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-18

    ... Continent, VOR RWY 14, Amdt 1D Boston, MA, General Edward Lawrence Logan Intl, Takeoff Minimums and Obstacle DP, Amdt 13 Salisbury, MD, Salisbury-Ocean City Wicomico Rgnl, ILS OR LOC RWY 32, Amdt 8 Salisbury, MD, Salisbury-Ocean City Wicomico Rgnl, RNAV (GPS) RWY 5, Amdt 1 Salisbury, MD, Salisbury-Ocean...

  1. 14 CFR 93.95 - General operating procedures.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... omni-directional radio range (VOR) 132° radial. (e) Aircraft navigating in a southeasterly direction... authorized by the Administrator, no person may operate an aircraft in the airspace described in § 93.93.... (b) The aircraft must be equipped as specified in § 91.215(b) of this chapter replying on code...

  2. 14 CFR 93.95 - General operating procedures.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... omni-directional radio range (VOR) 132° radial. (e) Aircraft navigating in a southeasterly direction... authorized by the Administrator, no person may operate an aircraft in the airspace described in § 93.93.... (b) The aircraft must be equipped as specified in § 91.215(b) of this chapter replying on code...

  3. 75 FR 39152 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-08

    ..., Takeoff Minimums and Obstacle DP, Orig Homerville, GA, Homerville, VOR/DME-A, Amdt 4 McRae, GA, Telfair-Wheeler, RNAV (GPS) RWY 21, Amdt 1 McRae, GA, Telfair-Wheeler, Takeoff Minimums and Obstacle DP, Amdt...

  4. 14 CFR 93.95 - General operating procedures.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... omni-directional radio range (VOR) 132° radial. (e) Aircraft navigating in a southeasterly direction... authorized by the Administrator, no person may operate an aircraft in the airspace described in § 93.93.... (b) The aircraft must be equipped as specified in § 91.215(b) of this chapter replying on code...

  5. 78 FR 11980 - Amendment of Class E Airspace; Casper, WY

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-21

    ... VOR Omnidirectional Range Tactical Air Navigation (VORTAC) has made reconfiguration necessary for the safety and management of aircraft operations at the airport. DATES: Effective date, 0901 UTC, May 2, 2013... language in the regulatory text. This action enhances the safety and management of aircraft...

  6. 14 CFR 93.95 - General operating procedures.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... omni-directional radio range (VOR) 132° radial. (e) Aircraft navigating in a southeasterly direction... authorized by the Administrator, no person may operate an aircraft in the airspace described in § 93.93.... (b) The aircraft must be equipped as specified in § 91.215(b) of this chapter replying on code...

  7. 78 FR 75455 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-12

    ...: Effective 9 January 2014 Little Rock, AR, Bill and Hillary Clinton National/Adams Field, RNAV (GPS) RWY 18..., Gatlinburg-Pigeon Forge, VOR/DME RWY 10, Amdt 6A Nacogdoches, TX, A L Mangham JR. Rgnl, ILS OR LOC RWY 36...

  8. 14 CFR 171.13 - Reports.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Reports. 171.13 Section 171.13 Aeronautics... FACILITIES NON-FEDERAL NAVIGATION FACILITIES VOR Facilities § 171.13 Reports. The owner of each facility to which this subpart applies shall make the following reports on forms furnished by the FAA, at the times...

  9. Reversal of Motor Learning in the Vestibulo-Ocular Reflex in the Absence of Visual Input

    ERIC Educational Resources Information Center

    Cohen, Marlene R.; Meissner, Geoffrey W.; Schafer, Robert J.; Raymond, Jennifer L.

    2004-01-01

    Motor learning in the vestibulo-ocular reflex (VOR) and eyeblink conditioning use similar neural circuitry, and they may use similar cellular plasticity mechanisms. Classically conditioned eyeblink responses undergo extinction after prolonged exposure to the conditioned stimulus in the absence of the unconditioned stimulus. We investigated the…

  10. Chromatic contrast sensitivity during optokinetic nystagmus, visually enhanced vestibulo-ocular reflex, and smooth pursuit eye movements.

    PubMed

    Schütz, Alexander C; Braun, Doris I; Gegenfurtner, Karl R

    2009-05-01

    Recently we showed that sensitivity for chromatic- and high-spatial frequency luminance stimuli is enhanced during smooth-pursuit eye movements (SPEMs). Here we investigated whether this enhancement is a general property of slow eye movements. Besides SPEM there are two other classes of eye movements that operate in a similar range of eye velocities: the optokinetic nystagmus (OKN) is a reflexive pattern of alternating fast and slow eye movements elicited by wide-field visual motion and the vestibulo-ocular reflex (VOR) stabilizes the gaze during head movements. In a natural environment all three classes of eye movements act synergistically to allow clear central vision during self- and object motion. To test whether the same improvement of chromatic sensitivity occurs during all of these eye movements, we measured human detection performance of chromatic and luminance line stimuli during OKN and contrast sensitivity during VOR and SPEM at comparable velocities. For comparison, performance in the same tasks was tested during fixation. During the slow phase of OKN we found a similar enhancement of chromatic detection rate like that during SPEM, whereas no enhancement was observable during VOR. This result indicates similarities between slow-phase OKN and SPEM, which are distinct from VOR.

  11. Learning in a Simple Motor System

    ERIC Educational Resources Information Center

    Broussard, Dianne M.; Kassardjian, Charles D.

    2004-01-01

    Motor learning is a very basic, essential form of learning that appears to share common mechanisms across different motor systems. We evaluate and compare a few conceptual models for learning in a relatively simple neural system, the vestibulo-ocular reflex (VOR) of vertebrates. We also compare the different animal models that have been used to…

  12. Representing the effects of stratosphere–troposphere exchange on 3-D O3 distributions in chemistry transport models using a potential vorticity-based parameterization

    EPA Science Inventory

    Downward transport of ozone (O3) from the stratosphere can be a significant contributor to tropospheric O3 background levels. However, this process often is not well represented in current regional models. In this study, we develop a seasonally and spatially varying potential vor...

  13. 14 CFR 171.7 - Performance requirements.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...) The VOR must perform in accordance with the “International Standards and Recommended Practices, Aeronautical Telecommunications,” Part I, paragraph 3.3 (Annex 10 to the Convention on International Civil...-service test evaluation period, for calibration and stability The tests are made with a...

  14. 14 CFR 171.7 - Performance requirements.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...) The VOR must perform in accordance with the “International Standards and Recommended Practices, Aeronautical Telecommunications,” Part I, paragraph 3.3 (Annex 10 to the Convention on International Civil...-service test evaluation period, for calibration and stability The tests are made with a...

  15. 14 CFR 171.7 - Performance requirements.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...) The VOR must perform in accordance with the “International Standards and Recommended Practices, Aeronautical Telecommunications,” Part I, paragraph 3.3 (Annex 10 to the Convention on International Civil...-service test evaluation period, for calibration and stability The tests are made with a...

  16. Low-frequency otolith and semicircular canal interactions after canal inactivation

    NASA Technical Reports Server (NTRS)

    Angelaki, D. E.; Merfeld, D. M.; Hess, B. J.

    2000-01-01

    During sustained constant velocity and low-frequency off-vertical axis rotations (OVAR), otolith signals contribute significantly to slow-phase eye velocity. The adaptive plasticity of these responses was investigated here after semicircular canal plugging. Inactivation of semicircular canals results in a highly compromised and deficient vestibulo-ocular reflex (VOR). Based on the VOR enhancement hypothesis, one could expect an adaptive increase of otolith-borne angular velocity signals due to combined otolith/canal inputs after inactivation of the semicircular canals. Contrary to expectations, however, the steady-state slow-phase velocity during constant velocity OVAR decreased in amplitude over time. A similar progressive decrease in VOR gain was also observed during low-frequency off-vertical axis oscillations. This response deterioration was present in animals with either lateral or vertical semicircular canals inactivated and was limited to the plane(s) of the plugged canals. The results are consistent with the idea that the low-frequency otolith signals do not simply enhance VOR responses. Rather, the nervous system appears to correlate vestibular sensory information from the otoliths and the semicircular canals to generate an integral response to head motion.

  17. Tipps und Tricks

    NASA Astrophysics Data System (ADS)

    Häger, Wolfgang; Bauermeister, Dirk

    Hier wollen wir einige uns nützlich erscheinende Hinweise zur Arbeit mit dem Inventor geben. Dabei geht es vor allem darum, das Arbeiten mit dem Inventor zu vereinfachen. Die Beispiele stellen eine unvollständige Aufzählung dar und sollen dazu anregen, nach alternativen Vorgehensweisen zu suchen (hier sei noch einmal ausdrücklich auf das Internet verwiesen).

  18. Responses evoked by a vestibular implant providing chronic stimulation.

    PubMed

    Thompson, Lara A; Haburcakova, Csilla; Gong, Wangsong; Lee, Daniel J; Wall, Conrad; Merfeld, Daniel M; Lewis, Richard F

    2012-01-01

    Patients with bilateral vestibular loss experience dehabilitating visual, perceptual, and postural difficulties, and an implantable vestibular prosthesis that could improve these symptoms would be of great benefit to these patients. In previous work, we have shown that a one-dimensional, unilateral canal prosthesis can improve the vestibulooccular reflex (VOR) in canal-plugged squirrel monkeys. In addition to the VOR, the potential effects of a vestibular prosthesis on more complex, highly integrative behaviors, such as the perception of head orientation and posture have remained unclear. We tested a one-dimensional, unilateral prosthesis in a rhesus monkey with bilateral vestibular loss and found that chronic electrical stimulation partially restored the compensatory VOR and also that percepts of head orientation relative to gravity were improved. However, the one-dimensional prosthetic stimulation had no clear effect on postural stability during quiet stance, but sway evoked by head-turns was modestly reduced. These results suggest that not only can the implementation of a vestibular prosthesis provide partial restitution of VOR but may also improve perception and posture in the presence of bilateral vestibular hypofunction (BVH). In this review, we provide an overview of our previous and current work directed towards the eventual clinical implementation of an implantable vestibular prosthesis.

  19. Automatic Classification of the Vestibulo-Ocular Reflex Nystagmus: Integration of Data Clustering and System Identification.

    PubMed

    Ranjbaran, Mina; Smith, Heather L H; Galiana, Henrietta L

    2016-04-01

    The vestibulo-ocular reflex (VOR) plays an important role in our daily activities by enabling us to fixate on objects during head movements. Modeling and identification of the VOR improves our insight into the system behavior and improves diagnosis of various disorders. However, the switching nature of eye movements (nystagmus), including the VOR, makes dynamic analysis challenging. The first step in such analysis is to segment data into its subsystem responses (here slow and fast segment intervals). Misclassification of segments results in biased analysis of the system of interest. Here, we develop a novel three-step algorithm to classify the VOR data into slow and fast intervals automatically. The proposed algorithm is initialized using a K-means clustering method. The initial classification is then refined using system identification approaches and prediction error statistics. The performance of the algorithm is evaluated on simulated and experimental data. It is shown that the new algorithm performance is much improved over the previous methods, in terms of higher specificity.

  20. 14 CFR 171.7 - Performance requirements.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Performance requirements. 171.7 Section 171.7 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) NAVIGATIONAL FACILITIES NON-FEDERAL NAVIGATION FACILITIES VOR Facilities § 171.7 Performance requirements....

  1. 14 CFR 171.7 - Performance requirements.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Performance requirements. 171.7 Section 171.7 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) NAVIGATIONAL FACILITIES NON-FEDERAL NAVIGATION FACILITIES VOR Facilities § 171.7 Performance requirements....

  2. 76 FR 38581 - Proposed Amendment of Class D and E Airspace and Revocation of Class E Airspace; Manassas, VA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-01

    ... areas and remove Class E airspace at Manassas Municipal/Harry P. Davis Airport, Manassas, VA. A Standard... surface airspace at Manassas Municipal/Harry P. Davis Airport, Manassas, VA. Cancellation of the VOR... safety and management of IFR operations at Manassas Municipal/Harry P. Davis Airport. Class D and E...

  3. 76 FR 6053 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-03

    ... Francisco, CA, San Francisco Intl, VOR-B, Amdt 6 Washington, DC, Ronald Reagan Washington National, Takeoff... Caledonia, MN, Houston County, GPS RWY 31, Orig, CANCELLED Branson, MO, M. Graham Clark-Taney County, RNAV (GPS) RWY 12, Orig Branson, MO, M. Graham Clark-Taney County, RNAV (GPS) RWY 30, Orig Branson, MO,...

  4. Multisensor Signal Processing Techniques (Hybrid GPS/LORAN-C with RAIM)

    DTIC Science & Technology

    1991-09-01

    Global Positioning System ( GPS ) and the Long Range Navigation System LORAN-C. The...in these developments are new satellite technologies such as the NAVSTAR Global Positioning System ( GPS ) and improvements of existing systems such as...Omnidirectional Range (VOR) stations, the Global Positioning System ( GPS ) satellites, and stars (celestial fixes). A vehicle can obtain range (p) or bearing

  5. Visual Vestibular Interaction in the Dynamic Visual Acuity Test during Voluntary Head Rotation

    NASA Technical Reports Server (NTRS)

    Lee, Moo Hoon; Durnford, Simon; Crowley, John; Rupert, Angus

    1996-01-01

    Although intact vestibular function is essential in maintaining spatial orientation, no good screening tests of vestibular function are available to the aviation community. High frequency voluntary head rotation was selected as a vestibular stimulus to isolate the vestibulo-ocular reflex (VOR) from visual influence. A dynamic visual acuity test that incorporates voluntary head rotation was evaluated as a potential vestibular function screening tool. Twenty-seven normal subjects performed voluntary sinusoidal head rotation at frequencies from 0.7-4.0 Hz under three different visual conditions: visually-enhanced VOR, normal VOR, and visually suppressed VOR. Standardized Baily-Lovie chart letters were presented on a computer monitor in front of the subject, who then was asked to read the letters while rotating his head horizontally. The electro-oculogram and dynamic visual acuity score were recorded and analyzed. There were no significant differences in gain or phase shift among three visual conditions in the frequency range of 2.8 to 4.0 Hz. The dynamic visual acuity score shifted less than 0.3 logMAR at frequencies under 2.0 Hz. The dynamic visual acuity test at frequencies a round 2.0 Hz can be recommended for evaluating vestibular function.

  6. 76 FR 28171 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-16

    ... 2011 Sioux City, IA, Sioux Gateway/Col. Bud Day Field, ILS OR LOC RWY 31, Amdt 25 Cheboygan, MI..., Amdt 2 Newport, VT, Newport State, Takeoff Minimums and Obstacle DP, Amdt 3 Effective 30 JUN 2011... 25, Amdt 1A Kodiak, AK, Kodiak, VOR Y RWY 25, Amdt 1A Point Lay, AK, Point Lay LRRS, NDB RWY 5,...

  7. Studies of the vestibulo-ocular reflex on STS 4, 5 and 6

    NASA Technical Reports Server (NTRS)

    Thornton, William E.; Pool, Sam L.; Moore, Thomas P.; Uri, John J.

    1988-01-01

    The vestibulo-ocular reflex (VOR) may be altered by weightlessness. Since this reflex plays a large role in visual stabilization, it was important to document any changes caused by space flight. This is a report on findings on STS-4 through 6 and is part of a larger study of neurosensory adaptation done on STS-4 through 8. Voluntary horizontal head oscillations at 1/3 Hz with amplitude of 30 deg right and left of center were recorded by a potentiometer and compared to eye position recorded by electroculography under the following conditions: eyes open, head fixed, tracking horizontal targets switched 0, 15, and 30 degrees right and left (optokinetic reflex - OKR - and calibration); eyes open and fixed on static external target with oscillation, (vestibulo ocular reflex, eyes closed - VOR EC); eyes open and wearing opaque goggles with target fixed in imagination (vestibulo-ocular reflex, eyes shaded - VOR ES); and eyes open and fixed on a head synchronized target with head oscillation (VOR suppression). No significant changes were found in voluntary head oscillation frequency or amplitude in those with (n=5), and without (n=3), space motion sickness (SMS), with phase of flight or test condition. Variations in head oscillation were too small to have produced detectable changes in test results.

  8. The role of drug efflux pumps in Malassezia pachydermatis and Malassezia furfur defence against azoles.

    PubMed

    Iatta, Roberta; Puttilli, Maria Rita; Immediato, Davide; Otranto, Domenico; Cafarchia, Claudia

    2017-03-01

    This study aims to evaluate the effect of efflux pump modulators (EPMs) on the minimal inhibitory concentration (MIC) of fluconazole (FLZ) and voriconazole (VOR) in Malassezia furfur and Malassezia pachydermatis. The in vitro efficacy of azoles, in combination with EPMs (ie haloperidol-HAL, promethazine-PTZ and cyclosporine A-CYS), against 21 M. furfur from bloodstream infection patients and 14 M. pachydermatis from the skin of dogs with dermatitis, was assessed using a broth microdilution chequerboard analysis. Data were analysed using the model-fractional inhibitory concentration index (FICI) method. The MIC of FLZ and VOR of Malassezia spp. decreased in the presence of sub-inhibitory concentrations of HAL and/or PTZ. The synergic effect was observed only in strains with FLZ MIC≥128 μg/mL for M. furfur, FLZ MIC≥64 μg/mL for M. pachydermatis and VOR MIC≥4 μg/mL in both Malassezia spp. These results suggest that the drug efflux pumps are involved as defence mechanisms to azole drugs in Malassezia yeast. The synergism might be related to an increased expression of efflux pump genes, eventually resulting in azole resistance phenomena. Finally, the above FLZ and VOR MIC values might be considered the cut-off to discriminate susceptible and resistant strains.

  9. Mol-Gastronomie Mayonnaise, Aioli & Co

    NASA Astrophysics Data System (ADS)

    Vilgis, Thomas

    2004-09-01

    Hätten Sie einmal Lust auf selbst gemachte Mayonnaise? Oder ein cremiges, nach Knoblauch duftendes Aioli? Mögen Sie Fisch und eine kräftige Remoulade? Kein Problem, vor allem für Physiker, denn sie wissen, was zu tun ist, schließlich gehorchen all diese Kulinarien bestimmten molekularen Prinzipien.

  10. Reduction of ocular counter-rolling by adaptation to space

    NASA Technical Reports Server (NTRS)

    Dai, Mingjia; Mcgarvie, Leigh; Kozlovskaya, Inessa; Sirota, Mischa; Raphan, Theodore; Cohen, Bernard

    1993-01-01

    We studied the three-dimensional vestibulo-ocular reflex (VOR) of rhesus monkeys before and after the COSMOS Biosatellite 2229 Mission of 1992-1993. This included tests of ocular counter-rolling (OCR), the gain of the vestibulo-ocular reflex (VOR), and spatial orientation of velocity storage. A four-axis vestibular and oculomotor stimulator was transported to the Institute of Biomedical Problems in Moscow for the pre- and postflight ground-based testing. Twelve normal juvenile male rhesus monkey were implanted surgically with eye coils and tested 60-90 days before spaceflight. Two monkey (7906 and 6151), selected from the twelve as flight animals, flew from 12/29/92 to 1/10/93. Upon recovery, they were tested for 11 days postflight along with three control animals. Compensatory ocular torsion was produced in two ways: (1) Lateral head tilts evoked OCR through otolith-ocular reflexes. OCR was also measured dynamically during off-vertical axis rotation (OVAR). (2) Rotation about a naso-occipital axis that was either vertical of horizontal elicited torsional nystagmus through semicircular canal-ocular reflexes (roll VOR). OCR from the otoliths was substantially reduced (70 percent) for 11 days after reentry on both modes of testing. The gain of the roll VOR was also decreased, but less than OCR. These data demonstrate that there was a long-lasting depression of torsional or roll eye movements after adaptation to microgravity in these monkeys, especially those movements produced by the otolith organs.

  11. 78 FR 14010 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-04

    ...). Issued in Washington, DC, on February 15, 2013. John M. Allen, Director, Flight Standards Service...-Chippewa County, VOR RWY 14, Amdt 5 Cleveland, OH, Cleveland-Hopkins Intl, ILS PRM RWY 6L, Orig-D, CANCELED Cleveland, OH, Cleveland-Hopkins Intl, ILS PRM RWY 24R, Amdt 1, CANCELED Cleveland, OH, Cleveland-Hopkins...

  12. Neural processing of gravito-inertial cues in humans. I. Influence of the semicircular canals following post-rotatory tilt

    NASA Technical Reports Server (NTRS)

    Zupan, L. H.; Peterka, R. J.; Merfeld, D. M.; Peterson, B. W. (Principal Investigator)

    2000-01-01

    Sensory systems often provide ambiguous information. Integration of various sensory cues is required for the CNS to resolve sensory ambiguity and elicit appropriate responses. The vestibular system includes two types of sensors: the semicircular canals, which measure head rotation, and the otolith organs, which measure gravito-inertial force (GIF), the sum of gravitational force and inertial force due to linear acceleration. According to Einstein's equivalence principle, gravitational force is indistinguishable from inertial force due to linear acceleration. As a consequence, otolith measurements must be supplemented with other sensory information for the CNS to distinguish tilt from translation. The GIF resolution hypothesis states that the CNS estimates gravity and linear acceleration, so that the difference between estimates of gravity and linear acceleration matches the measured GIF. Both otolith and semicircular canal cues influence this estimation of gravity and linear acceleration. The GIF resolution hypothesis predicts that inaccurate estimates of both gravity and linear acceleration can occur due to central interactions of sensory cues. The existence of specific patterns of vestibuloocular reflexes (VOR) related to these inaccurate estimates can be used to test the GIF resolution hypothesis. To investigate this hypothesis, we measured eye movements during two different protocols. In one experiment, eight subjects were rotated at a constant velocity about an earth-vertical axis and then tilted 90 degrees in darkness to one of eight different evenly spaced final orientations, a so-called "dumping" protocol. Three speeds (200, 100, and 50 degrees /s) and two directions, clockwise (CW) and counterclockwise (CCW), of rotation were tested. In another experiment, four subjects were rotated at a constant velocity (200 degrees /s, CW and CCW) about an earth-horizontal axis and stopped in two different final orientations (nose-up and nose-down), a so

  13. Altered gravity affects ventral root activity during fictive swimming and the static vestibuloocular reflex in young tadpoles (Xenopus laevis).

    PubMed

    Böser, S; Dournon, C; Gualandris-Parisot, L; Horn, E

    2008-03-01

    During early periods of life, modifications of the gravitational environment affect the development of sensory, neuronal and motor systems. The vestibular system exerts significant effects on motor networks that control eye and body posture as well as swimming. The objective of the present study was to study whether altered gravity (AG) affects vestibuloocular and spinal motor systems in a correlated manner. During the French Soyuz taxi flight Andromède to the International Space Station ISS (launch: October 21, 2001; landing: October 31, 2001) Xenopus laevis embryos were exposed for 10 days to microgravity (microg). In addition, a similar experiment with 3g-hypergravity (3g) was performed in the laboratory. At onset of AG, embryos had reached developmental stages 24 to 27. After exposure to AG, each tadpole was tested for its roll-induced vestibuloocular reflex (rVOR) and 3 hours later it was tested for the neuronal activity recorded from the ventral roots (VR) during fictive swimming. During the post-AG recording periods tadpoles had reached developmental stages 45 to 47. It was observed that microgravity affected VR activity during fictive swimming and rVOR. In particular, VR activity changes included a significant decrease of the rostrocaudal delay and a significant increase of episode duration. The rVOR-amplitude was transiently depressed. Hypergravity was less effective on the locomotor pattern; occurring effects on fictive swimming were the opposite of microg effects. As after microgravity, the rVOR was depressed after 3g-exposure. All modifications of the rVOR and VR-activity recovered to normal levels within 4 to 7 days after termination of AG. Significant correlations between the rVOR amplitude and VR activity of respective tadpoles during the recording period have been observed in both tadpoles with or without AG experience. The data are consistent with the assumptions that during this period of life which is characterized by a progressive development

  14. The effect of binocular eye position and head rotation plane on the human torsional vestibuloocular reflex.

    PubMed

    Migliaccio, Americo A; Della Santina, Charles C; Carey, John P; Minor, Lloyd B; Zee, David S

    2006-08-01

    We examined how the gain of the torsional vestibulo-ocular reflex (VOR) (defined as the instantaneous eye velocity divided by inverted head velocity) in normal humans is affected by eye position, target distance, and the plane of head rotation. In six normal subjects we measured three-dimensional (3D) eye and head rotation axes using scleral search coils, and 6D head position using a magnetic angular and linear position measurement device, during low-amplitude (approximately 20 degrees ), high-velocity (approximately 200 degrees/s), high-acceleration (approximately 4000 degrees /s2) rapid head rotations or 'impulses.' Head impulses were imposed manually and delivered in five planes: yaw (horizontal canal plane), pitch, roll, left anterior-right posterior canal plane (LARP), and right anterior-left posterior canal plane (RALP). Subjects were instructed to fix on one of six targets at eye level. Targets were either straight-ahead, 20 degrees left or 20 degrees right from midline, at distance 15 or 124 cm from the subject. Two subjects also looked at more eccentric targets, 30 degrees left or 30 degrees right from midline. We found that the vertical and horizontal VOR gains increased with the proximity of the target to the subject. Previous studies suggest that the torsional VOR gain should decrease with target proximity. We found, however, that the torsional VOR gain did not change for all planes of head rotation and for both target distances. We also found a dynamic misalignment of the vertical positions of the eyes during the torsional VOR, which was greatest during near viewing with symmetric convergence. This dynamic vertical skew during the torsional VOR arises, in part, because when the eyes are converged, the optical axes are not parallel to the naso-occipital axes around which the eyes are rotating. In five of six subjects, the average skew ranged 0.9 degrees -2.9 degrees and was reduced to <0.4 degrees by a 'torsional' quick-phase (around the naso

  15. The vestibulo-ocular reflex of the squirrel monkey during eccentric rotation and roll tilt

    NASA Technical Reports Server (NTRS)

    Merfeld, D. M.; Young, L. R.

    1995-01-01

    The vestibulo-ocular reflexes (VOR) are determined not only by angular acceleration, but also by the presence of gravity and linear acceleration. This phenomenon was studied by measuring three-dimensional nystagmic eye movements, with implanted search coils, in six male squirrel monkeys during eccentric rotation. Monkeys were rotated in the dark at a constant velocity of 200 degrees/s (centrally or 79 cm off axis) with the axis of rotation always aligned with gravity and the spinal axis of the upright monkeys. The monkey's orientation (facing-motion or back-to-motion) had a dramatic influence on the VOR. These experiments show that: (a) the axis of eye rotation always shifted toward alignment with gravito-inertial force; (b) the peak value of horizontal slow phase eye velocity was greater with the monkey facing-motion than with back-to-motion; and (c) the time constant of horizontal eye movement decay was smaller with the monkey facing-motion than with back-to-motion. All of these findings were statistically significant and consistent across monkeys. In another set of tests, the same monkeys were rapidly tilted about their naso-occipital (roll) axis. Tilted orientations of 45 degrees and 90 degrees were maintained for 1 min. Other than a compensatory angular VOR during the angular rotation, no consistent eye velocity response was observed during or following the tilt for any of the six monkeys. The absence of any eye movement response following tilt weighs against the possibility that translational linear VOR responses are due to simple high-pass filtering of the otolith signals. The VOR response during eccentric rotation was divided into the more familiar angular VOR and linear VOR components. The angular component is known to depend upon semicircular canal dynamics and central influences. The linear component of the response decays rapidly with a mean duration of only 6.6 s, while the axis of eye rotation rapidly aligns (< 10 s) with gravito-inertial force. These

  16. The vestibulo-ocular reflex of the squirrel monkey during eccentric rotation and roll tilt

    NASA Technical Reports Server (NTRS)

    Merfeld, D. M.; Young, L. R.

    1995-01-01

    The vestibulo-ocular reflexes (VOR) are determined not only by angular acceleration, but also by the presence of gravity and linear acceleration. This phenomenon was studied by measuring three-dimensional nystagmic eye movements, with implanted search coils, in six male squirrel monkeys during eccentric rotation. Monkeys were rotated in the dark at a constant velocity of 200 degrees/s (centrally or 79 cm off axis) with the axis of rotation always aligned with gravity and the spinal axis of the upright monkeys. The monkey's orientation (facing-motion or back-to-motion) had a dramatic influence on the VOR. These experiments show that: (a) the axis of eye rotation always shifted toward alignment with gravito-inertial force; (b) the peak value of horizontal slow phase eye velocity was greater with the monkey facing-motion than with back-to-motion; and (c) the time constant of horizontal eye movement decay was smaller with the monkey facing-motion than with back-to-motion. All of these findings were statistically significant and consistent across monkeys. In another set of tests, the same monkeys were rapidly tilted about their naso-occipital (roll) axis. Tilted orientations of 45 degrees and 90 degrees were maintained for 1 min. Other than a compensatory angular VOR during the angular rotation, no consistent eye velocity response was observed during or following the tilt for any of the six monkeys. The absence of any eye movement response following tilt weighs against the possibility that translational linear VOR responses are due to simple high-pass filtering of the otolith signals. The VOR response during eccentric rotation was divided into the more familiar angular VOR and linear VOR components. The angular component is known to depend upon semicircular canal dynamics and central influences. The linear component of the response decays rapidly with a mean duration of only 6.6 s, while the axis of eye rotation rapidly aligns (< 10 s) with gravito-inertial force. These

  17. Neural processing of gravito-inertial cues in humans. I. Influence of the semicircular canals following post-rotatory tilt

    NASA Technical Reports Server (NTRS)

    Zupan, L. H.; Peterka, R. J.; Merfeld, D. M.; Peterson, B. W. (Principal Investigator)

    2000-01-01

    Sensory systems often provide ambiguous information. Integration of various sensory cues is required for the CNS to resolve sensory ambiguity and elicit appropriate responses. The vestibular system includes two types of sensors: the semicircular canals, which measure head rotation, and the otolith organs, which measure gravito-inertial force (GIF), the sum of gravitational force and inertial force due to linear acceleration. According to Einstein's equivalence principle, gravitational force is indistinguishable from inertial force due to linear acceleration. As a consequence, otolith measurements must be supplemented with other sensory information for the CNS to distinguish tilt from translation. The GIF resolution hypothesis states that the CNS estimates gravity and linear acceleration, so that the difference between estimates of gravity and linear acceleration matches the measured GIF. Both otolith and semicircular canal cues influence this estimation of gravity and linear acceleration. The GIF resolution hypothesis predicts that inaccurate estimates of both gravity and linear acceleration can occur due to central interactions of sensory cues. The existence of specific patterns of vestibuloocular reflexes (VOR) related to these inaccurate estimates can be used to test the GIF resolution hypothesis. To investigate this hypothesis, we measured eye movements during two different protocols. In one experiment, eight subjects were rotated at a constant velocity about an earth-vertical axis and then tilted 90 degrees in darkness to one of eight different evenly spaced final orientations, a so-called "dumping" protocol. Three speeds (200, 100, and 50 degrees /s) and two directions, clockwise (CW) and counterclockwise (CCW), of rotation were tested. In another experiment, four subjects were rotated at a constant velocity (200 degrees /s, CW and CCW) about an earth-horizontal axis and stopped in two different final orientations (nose-up and nose-down), a so

  18. Effect of aging and direction of impulse in video head impulse test.

    PubMed

    Kim, Tae Hwan; Kim, Min-Beom

    2017-09-12

    The aim of this study was to identify the difference of gain value in the video head impulse test (vHIT) according to the age of the patient and the direction of the impulse. All participants were subjected to vHIT with horizontal semicircular canal (HSCC). vHIT with vertical canal (posterior and anterior semicircular canal [PSCC and ASCC]) additionally was performed in 434 participants. The mean vestibulo-ocular reflex (VOR) gain was maintained in patients in the HSCC at below 70 years (1.025 ± 0.08) and in the vertical canal at below 80 years (PSCC: 0.965 ± 0.12, ASCC: 0.975 ± 0.14). However, the decrease of VOR gain was significant in patients over 70 years in the HSCC (0.978 ± 0.35, P < .001) and in patients over 80 years in the vertical canal (PSCC: 0.828 ± 0.16, ASCC: 0.851 ± 0.13, P < .001). In addition, a VOR gain of rightward impulse was higher than the leftward impulse, but there was no difference based on the direction of impulse in the vertical impulse test. VOR gain declines with increasing age, over 70 years on the horizontal canal, and over 80 years on the vertical canal. Additionally, horizontal VOR gain of rightward impulse was higher than the leftward impulse in right-eye recordings only, but the vertical canal showed no difference of gain according to the direction of impulse. 2b. Laryngoscope, 2017. © 2017 The American Laryngological, Rhinological and Otological Society, Inc.

  19. Compensatory saccades in head impulse testing influence the dynamic visual acuity of patients with unilateral peripheral vestibulopathy1.

    PubMed

    Wettstein, V G; Weber, K P; Bockisch, C J; Hegemann, S C

    2016-11-03

    Both the dynamic visual acuity (DVA) test and the video head-impulse test (vHIT) are fast and simple ways to assess peripheral vestibulopathy. After losing peripheral vestibular function, some patients show better DVA performance than others, suggesting good compensatory mechanisms. It seems possible that compensatory covert saccades could be responsible for improved DVA. To investigate VOR gain and compensatory saccades with vHIT and compare them to the DVA of patients with unilateral peripheral vestibulopathy. VOR gain deficit and compensatory saccades were measured with vHIT. VOR gain was calculated for each trial as mean eye velocity divided by mean head velocity during 4 samples between 24 ms - 40 ms after peak head acceleration. DVA was then assessed. VHIT was analyzed for percentage of covert saccades and for cumulative overt saccade amplitude. Twenty-four patients with unilateral vestibular deficit were included. A control group of 113 healthy subjects provided normal data. On the affected side, pathologic values for DVA (mean 0.83 logMAR±0.25 SD) and VOR gain (mean 0.16±0.13) were obtained, whereas the healthy side showed normal values (0.53 logMAR±0.15 for DVA and 0.89±0.18 for VOR gain). Yet, DVA performance on the affected side was significantly better in patients with higher covert saccade percentage (p = 0.012) and lower cumulative overt saccade amplitude (p < 0.001). Compensatory covert saccades seen in vHIT correlate with improved performance of DVA-testing in patients with unilateral peripheral vestibular loss. Hence, in addition to testing peripheral vestibulopathy, our results indicate a way for assessing rehabilitatory compensation in such patients by DVA in addition to vHIT.

  20. Dynamic properties of the human vestibulo-ocular reflex during head rotations in roll

    NASA Technical Reports Server (NTRS)

    Seidman, S. H.; Leigh, R. J.; Tomsak, R. L.; Grant, M. P.; Dell'Osso, L. F.

    1995-01-01

    We investigated the dynamic properties of the human vestibulo-ocular reflex (VOR) during roll head rotations in three human subjects using the magnetic search coil technique. In the first of two experiments, we quantify the behavior of the ocular motor plant in the torsional plane. The subject's eye was mechanically displaced into intorsion, extorsion or abduction, and the dynamic course of return of the eye to its resting position was measured. The mean predominant time constants of return were 210 msec from intorsion, 83 msec from extorsion, and 217 msec from abduction, although there was considerable variability of results from different trials and subjects. In the second experiment, we quantify the efficacy of velocity-to-position integration of the vestibular signal. Position-step stimuli were used to test the torsional or horizontal VOR, being applied with subjects heads erect or supine. After a torsional position-step, the eye drifted back to its resting position, but after a horizontal position-step the eye held its new horizontal position. To interpret these responses we used a simple model of the VOR with parameters of the ocular motor plant set to values determined during Exp 1. The time constant of the velocity-to-position neural integrator was smaller (typically 2 sec) in the torsional plane than in the horizontal plane (> 20 sec). No disconjugacy of torsional eye movements was observed. Thus, the dynamic properties of the VOR in roll differ significantly from those of the VOR in yaw, reflecting different visual demands placed on this reflex in these two planes.

  1. Translational Vestibulo-Ocular Reflexes During Off-Vertical Axis Rotation

    NASA Technical Reports Server (NTRS)

    Wood, Scott J.; Clement, Gilles

    2009-01-01

    The translational vestibulo-ocular reflex (tVOR) is an otolith-mediated response that stabilizes near vision during linear acceleration at higher frequencies where visually mediated reflexes are not adequate. The modulation of horizontal and vergence eye movements during Off-Vertical Axis Rotation (OVAR) are presumed to reflect the tVOR in response to the continuously varying linear acceleration in the interaural and nasooccipital axes, respectively. The purpose of this study was to examine the effect of frequency and fixation distance on the modulation of slow phase eye velocity (SPV) as further evidence that the tVOR is elicited during OVAR. Eighteen subjects were rotated about their longitudinal axis tilted by 30 deg off-vertical. Rotational velocities varied between 18 and 288 deg/sec corresponding to a frequency range of 0.05 to 0.8 Hz. Fixation distance was altered by asking subjects to imagine stationary targets that were briefly presented at 0.5, 1 and 2 m during some rotation cycles. The target flash was 40 msec in the nose-up position at eye level. Oculomotor responses were recorded in the dark using infrared binocular videography. Sinusoidal curve fits were used to derive amplitude, phase and bias velocity of the eye movements across multiple rotation cycles. Consistent with previous studies, the modulation of both horizontal and vergence SPV increased with stimulus frequency. The effect of fixation distance was negligible at lower frequencies. The modulation of horizontal and vergence SPV was; however, proportional to fixation distance during OVAR at 0.8 Hz. This increasing sensitivity and dependence on fixation distance of horizontal and vergence SPV during OVAR is consistent with tVOR characteristics measured during other types of linear motion. We conclude that the modulation of horizontal and vergence SPV will be diagnostically more useful at higher stimulus frequencies where the tVOR is more robust.

  2. The video head impulse test during post-rotatory nystagmus: physiology and clinical implications.

    PubMed

    Mantokoudis, Georgios; Tehrani, Ali S Saber; Xie, Li; Eibenberger, Karin; Eibenberger, Bernhard; Roberts, Dale; Newman-Toker, David E; Zee, David S

    2016-01-01

    The aim of this study was to test the effects of a sustained nystagmus on the head impulse response of the vestibulo-ocular reflex (VOR) in healthy subjects. VOR gain (slow-phase eye velocity/head velocity) was measured using video head impulse test goggles. Acting as a surrogate for a spontaneous nystagmus (SN), a post-rotatory nystagmus (PRN) was elicited after a sustained, constant-velocity rotation, and then head impulses were applied. 'Raw' VOR gain, uncorrected for PRN, in healthy subjects in response to head impulses with peak velocities in the range of 150°/s-250°/s was significantly increased (as reflected in an increase in the slope of the gain versus head velocity relationship) after inducing PRN with slow phases of nystagmus of high intensity (>30°/s) in the same but not in the opposite direction as the slow-phase response induced by the head impulses. The values of VOR gain themselves, however, remained in the normal range with slow-phase velocities of PRN < 30°/s. Finally, quick phases of PRN were suppressed during the first 20-160 ms of a head impulse; the time frame of suppression depended on the direction of PRN but not on the duration of the head impulse. Our results in normal subjects suggest that VOR gains measured using head impulses may have to be corrected for any superimposed SN when the slow-phase velocity of nystagmus is relatively high and the peak velocity of the head movements is relatively low. The suppression of quick phases during head impulses may help to improve steady fixation during rapid head movements.

  3. Translational Vestibulo-Ocular Reflexes During Off-Vertical Axis Rotation

    NASA Technical Reports Server (NTRS)

    Wood, Scott J.; Clement, Gilles

    2009-01-01

    The translational vestibulo-ocular reflex (tVOR) is an otolith-mediated response that stabilizes near vision during linear acceleration at higher frequencies where visually mediated reflexes are not adequate. The modulation of horizontal and vergence eye movements during Off-Vertical Axis Rotation (OVAR) are presumed to reflect the tVOR in response to the continuously varying linear acceleration in the interaural and nasooccipital axes, respectively. The purpose of this study was to examine the effect of frequency and fixation distance on the modulation of slow phase eye velocity (SPV) as further evidence that the tVOR is elicited during OVAR. Eighteen subjects were rotated about their longitudinal axis tilted by 30 deg off-vertical. Rotational velocities varied between 18 and 288 deg/sec corresponding to a frequency range of 0.05 to 0.8 Hz. Fixation distance was altered by asking subjects to imagine stationary targets that were briefly presented at 0.5, 1 and 2 m during some rotation cycles. The target flash was 40 msec in the nose-up position at eye level. Oculomotor responses were recorded in the dark using infrared binocular videography. Sinusoidal curve fits were used to derive amplitude, phase and bias velocity of the eye movements across multiple rotation cycles. Consistent with previous studies, the modulation of both horizontal and vergence SPV increased with stimulus frequency. The effect of fixation distance was negligible at lower frequencies. The modulation of horizontal and vergence SPV was; however, proportional to fixation distance during OVAR at 0.8 Hz. This increasing sensitivity and dependence on fixation distance of horizontal and vergence SPV during OVAR is consistent with tVOR characteristics measured during other types of linear motion. We conclude that the modulation of horizontal and vergence SPV will be diagnostically more useful at higher stimulus frequencies where the tVOR is more robust.

  4. Ocular motor responses to abrupt interaural head translation in normal humans

    NASA Technical Reports Server (NTRS)

    Ramat, Stefano; Zee, David S.; Shelhamer, M. J. (Principal Investigator)

    2003-01-01

    We characterized the interaural translational vestibulo-ocular reflex (tVOR) in 6 normal humans to brief (approximately 200 ms), high-acceleration (0.4-1.4g) stimuli, while they fixed targets at 15 or 30 cm. The latency was 19 +/- 5 ms at 15-cm and 20 +/- 12 ms at 30-cm viewing. The gain was quantified using the ratio of actual to ideal behavior. The median position gain (at time of peak head velocity) was 0.38 and 0.37, and the median velocity gain, 0.52 and 0.62, at 15- and 30-cm viewing, respectively. These results suggest the tVOR scales proportionally at these viewing distances. Likewise, at both viewing distances, peak eye velocity scaled linearly with peak head velocity and gain was independent of peak head acceleration. A saccade commonly occurred in the compensatory direction, with a greater latency (165 vs. 145 ms) and lesser amplitude (1.8 vs. 3.2 deg) at 30- than 15-cm viewing. Even with saccades, the overall gain at the end of head movement was still considerably undercompensatory (medians 0.68 and 0.77 at 15- and 30-cm viewing). Monocular viewing was also assessed at 15-cm viewing. In 4 of 6 subjects, gains were the same as during binocular viewing and scaled closely with vergence angle. In sum the low tVOR gain and scaling of the response with viewing distance and head velocity extend previous results to higher acceleration stimuli. tVOR latency (approximately 20 ms) was lower than previously reported. Saccades are an integral part of the tVOR, and also scale with viewing distance.

  5. Genetic examination and mass balance analysis of pyruvate/amino acid oxidation pathways in the hyperthermophilic archaeon Thermococcus kodakarensis.

    PubMed

    Nohara, Kenta; Orita, Izumi; Nakamura, Satoshi; Imanaka, Tadayuki; Fukui, Toshiaki

    2014-11-01

    The present study investigated the simultaneous oxidation of pyruvate and amino acids during H2-evolving growth of the hyperthermophilic archaeon Thermococcus kodakarensis. The comparison of mass balance between a cytosolic hydrogenase (HYH)-deficient strain (the ΔhyhBGSL strain) and the parent strain indicated that NADPH generated via H2 uptake by HYH was consumed by reductive amination of 2-oxoglutarate catalyzed by glutamate dehydrogenase. Further examinations were done to elucidate functions of three enzymes potentially involved in pyruvate oxidation: pyruvate formate-lyase (PFL), pyruvate:ferredoxin oxidoreductase (POR), and 2-oxoisovalerate:ferredoxin oxidoreductase (VOR) under the HYH-deficient background in T. kodakarensis. No significant change was observed by deletion of pflDA, suggesting that PFL had no critical role in pyruvate oxidation. The growth properties and mass balances of ΔporDAB and ΔvorDAB strains indicated that POR and VOR specifically functioned in oxidation of pyruvate and branched-chain amino acids, respectively, and the lack of POR or VOR was compensated for by promoting the oxidation of another substrate driven by the remaining oxidoreductase. The H2 yields from the consumed pyruvate and amino acids were increased from 31% by the parent strain to 67% and 82% by the deletion of hyhBGSL and double deletion of hyhBGSL and vorDAB, respectively. Significant discrepancies in the mass balances were observed in excess formation of acetate and NH3, suggesting the presence of unknown metabolisms in T. kodakarensis grown in the rich medium containing pyruvate.

  6. Ocular motor responses to abrupt interaural head translation in normal humans.

    PubMed

    Ramat, Stefano; Zee, David S

    2003-08-01

    We characterized the interaural translational vestibulo-ocular reflex (tVOR) in 6 normal humans to brief (approximately 200 ms), high-acceleration (0.4-1.4g) stimuli, while they fixed targets at 15 or 30 cm. The latency was 19 +/- 5 ms at 15-cm and 20 +/- 12 ms at 30-cm viewing. The gain was quantified using the ratio of actual to ideal behavior. The median position gain (at time of peak head velocity) was 0.38 and 0.37, and the median velocity gain, 0.52 and 0.62, at 15- and 30-cm viewing, respectively. These results suggest the tVOR scales proportionally at these viewing distances. Likewise, at both viewing distances, peak eye velocity scaled linearly with peak head velocity and gain was independent of peak head acceleration. A saccade commonly occurred in the compensatory direction, with a greater latency (165 vs. 145 ms) and lesser amplitude (1.8 vs. 3.2 deg) at 30- than 15-cm viewing. Even with saccades, the overall gain at the end of head movement was still considerably undercompensatory (medians 0.68 and 0.77 at 15- and 30-cm viewing). Monocular viewing was also assessed at 15-cm viewing. In 4 of 6 subjects, gains were the same as during binocular viewing and scaled closely with vergence angle. In sum the low tVOR gain and scaling of the response with viewing distance and head velocity extend previous results to higher acceleration stimuli. tVOR latency (approximately 20 ms) was lower than previously reported. Saccades are an integral part of the tVOR, and also scale with viewing distance.

  7. Combined autophagy and HDAC inhibition: a phase I safety, tolerability, pharmacokinetic, and pharmacodynamic analysis of hydroxychloroquine in combination with the HDAC inhibitor vorinostat in patients with advanced solid tumors.

    PubMed

    Mahalingam, Devalingam; Mita, Monica; Sarantopoulos, John; Wood, Leslie; Amaravadi, Ravi K; Davis, Lisa E; Mita, Alain C; Curiel, Tyler J; Espitia, Claudia M; Nawrocki, Steffan T; Giles, Francis J; Carew, Jennifer S

    2014-08-01

    We previously reported that inhibition of autophagy significantly augmented the anticancer activity of the histone deacetylase (HDAC) inhibitor vorinostat (VOR) through a cathepsin D-mediated mechanism. We thus conducted a first-in-human study to investigate the safety, preliminary efficacy, pharmacokinetics (PK), and pharmacodynamics (PD) of the combination of the autophagy inhibitor hydroxychloroquine (HCQ) and VOR in patients with advanced solid tumors. Of 27 patients treated in the study, 24 were considered fully evaluable for study assessments and toxicity. Patients were treated orally with escalating doses of HCQ daily (QD) (d 2 to 21 of a 21-d cycle) in combination with 400 mg VOR QD (d one to 21). Treatment-related adverse events (AE) included grade 1 to 2 nausea, diarrhea, fatigue, weight loss, anemia, and elevated creatinine. Grade 3 fatigue and/or myelosuppression were observed in a minority of patients. Fatigue and gastrointestinal AE were dose-limiting toxicities. Six-hundred milligrams HCQ and 400 mg VOR was established as the maximum tolerated dose and recommended phase II regimen. One patient with renal cell carcinoma had a confirmed durable partial response and 2 patients with colorectal cancer had prolonged stable disease. The addition of HCQ did not significantly impact the PK profile of VOR. Treatment-related increases in the expression of CDKN1A and CTSD were more pronounced in tumor biopsies than peripheral blood mononuclear cells. Based on the safety and preliminary efficacy of this combination, additional clinical studies are currently being planned to further investigate autophagy inhibition as a new approach to increase the efficacy of HDAC inhibitors.

  8. Dynamic properties of the human vestibulo-ocular reflex during head rotations in roll

    NASA Technical Reports Server (NTRS)

    Seidman, S. H.; Leigh, R. J.; Tomsak, R. L.; Grant, M. P.; Dell'Osso, L. F.

    1995-01-01

    We investigated the dynamic properties of the human vestibulo-ocular reflex (VOR) during roll head rotations in three human subjects using the magnetic search coil technique. In the first of two experiments, we quantify the behavior of the ocular motor plant in the torsional plane. The subject's eye was mechanically displaced into intorsion, extorsion or abduction, and the dynamic course of return of the eye to its resting position was measured. The mean predominant time constants of return were 210 msec from intorsion, 83 msec from extorsion, and 217 msec from abduction, although there was considerable variability of results from different trials and subjects. In the second experiment, we quantify the efficacy of velocity-to-position integration of the vestibular signal. Position-step stimuli were used to test the torsional or horizontal VOR, being applied with subjects heads erect or supine. After a torsional position-step, the eye drifted back to its resting position, but after a horizontal position-step the eye held its new horizontal position. To interpret these responses we used a simple model of the VOR with parameters of the ocular motor plant set to values determined during Exp 1. The time constant of the velocity-to-position neural integrator was smaller (typically 2 sec) in the torsional plane than in the horizontal plane (> 20 sec). No disconjugacy of torsional eye movements was observed. Thus, the dynamic properties of the VOR in roll differ significantly from those of the VOR in yaw, reflecting different visual demands placed on this reflex in these two planes.

  9. Ocular motor responses to abrupt interaural head translation in normal humans

    NASA Technical Reports Server (NTRS)

    Ramat, Stefano; Zee, David S.; Shelhamer, M. J. (Principal Investigator)

    2003-01-01

    We characterized the interaural translational vestibulo-ocular reflex (tVOR) in 6 normal humans to brief (approximately 200 ms), high-acceleration (0.4-1.4g) stimuli, while they fixed targets at 15 or 30 cm. The latency was 19 +/- 5 ms at 15-cm and 20 +/- 12 ms at 30-cm viewing. The gain was quantified using the ratio of actual to ideal behavior. The median position gain (at time of peak head velocity) was 0.38 and 0.37, and the median velocity gain, 0.52 and 0.62, at 15- and 30-cm viewing, respectively. These results suggest the tVOR scales proportionally at these viewing distances. Likewise, at both viewing distances, peak eye velocity scaled linearly with peak head velocity and gain was independent of peak head acceleration. A saccade commonly occurred in the compensatory direction, with a greater latency (165 vs. 145 ms) and lesser amplitude (1.8 vs. 3.2 deg) at 30- than 15-cm viewing. Even with saccades, the overall gain at the end of head movement was still considerably undercompensatory (medians 0.68 and 0.77 at 15- and 30-cm viewing). Monocular viewing was also assessed at 15-cm viewing. In 4 of 6 subjects, gains were the same as during binocular viewing and scaled closely with vergence angle. In sum the low tVOR gain and scaling of the response with viewing distance and head velocity extend previous results to higher acceleration stimuli. tVOR latency (approximately 20 ms) was lower than previously reported. Saccades are an integral part of the tVOR, and also scale with viewing distance.

  10. Kinematics of Vertical Saccades during the Yaw Vestibulo-ocular Reflex in Humans

    PubMed Central

    Crane, Benjamin T.; Tian, Junru; Demer, Joseph L.

    2007-01-01

    Purpose Listing’s law (LL) constrains the rotational axes of saccades and pursuit eye movements to Listing’s plane (LP). In the velocity domain, LL is ordinarily equivalent to a tilt in the ocular velocity axis equal to half the change in eye position, giving a tilt angle ratio (TAR) of 0.5. This study was undertaken to investigate vertical saccade behavior after the yaw vestibulo-ocular reflex (VOR) had driven eye torsion out of LP, an initial condition causing the position and velocity domain formulations of LL to differ. Methods Binocular eye and head motions were recorded with magnetic search coils in eight humans. With the head immobile, LP was determined for each eye, and mean TAR was 0.50 ± 0.07 (mean ± SD) for horizontal and 0.45 ± 0.11 for vertical saccades. The VOR was evoked by transient, whole-body yaw at 2800 deg/s2 peak acceleration, capable of evoking large, uninterrupted VOR slow phases. Before rotation, subjects viewed a target at eye level, 20° up, or 20° down. In two thirds of the trials, the target moved upward or downward at systematically varying times, triggering a vertical saccade during the horizontal VOR slow phase. Results Because the head rotation axis was generally misaligned with LP, the eye averaged 3.6° out of LP at vertical saccade onset. During the saccade, eye position continued to depart LP by an average 0.8°. The horizontal TAR at saccade onset was 0.29 ± 0.07. At peak saccade velocity 35 ± 3 ms later, the vertical TAR was 0.45 ± 0.07, statistically similar to that of head fixed saccades. Saccades did not return to LP. Conclusions Although they did not observe the position domain formulation of LL, vertical saccades, during the VOR, observed the half-angle velocity domain formulation of LL. PMID:16043853

  11. Effect of viewing distance on the generation of vertical eye movements during locomotion

    NASA Technical Reports Server (NTRS)

    Moore, S. T.; Hirasaki, E.; Cohen, B.; Raphan, T.

    1999-01-01

    Vertical head and eye coordination was studied as a function of viewing distance during locomotion. Vertical head translation and pitch movements were measured using a video motion analysis system (Optotrak 3020). Vertical eye movements were recorded using a video-based pupil tracker (Iscan). Subjects (five) walked on a linear treadmill at a speed of 1.67 m/s (6 km/h) while viewing a target screen placed at distances ranging from 0.25 to 2.0 m at 0. 25-m intervals. The predominant frequency of vertical head movement was 2 Hz. In accordance with previous studies, there was a small head pitch rotation, which was compensatory for vertical head translation. The magnitude of the vertical head movements and the phase relationship between head translation and pitch were little affected by viewing distance, and tended to orient the naso-occipital axis of the head at a point approximately 1 m in front of the subject (the head fixation distance or HFD). In contrast, eye velocity was significantly affected by viewing distance. When viewing a far (2-m) target, vertical eye velocity was 180 degrees out of phase with head pitch velocity, with a gain of 0. 8. This indicated that the angular vestibulo-ocular reflex (aVOR) was generating the eye movement response. The major finding was that, at a close viewing distance (0.25 m), eye velocity was in phase with head pitch and compensatory for vertical head translation, suggesting that activation of the linear vestibulo-ocular reflex (lVOR) was contributing to the eye movement response. There was also a threefold increase in the magnitude of eye velocity when viewing near targets, which was consistent with the goal of maintaining gaze on target. The required vertical lVOR sensitivity to cancel an unmodified aVOR response and generate the observed eye velocity magnitude for near targets was almost 3 times that previously measured. Supplementary experiments were performed utilizing body-fixed active head pitch rotations at 1 and 2 Hz

  12. Extreme vestibulo-ocular adaptation induced by prolonged optical reversal of vision.

    PubMed

    Gonshor, A; Jones, G M

    1976-04-01

    1. These experiments investigated plastic changes in the vestibulo-ocular reflex (VOR) of human subjects consequent to long-term optical reversal of vision during free head movement. Horizontal vision-reversal was produced by head-mounted dove prisms. Four normal adults were continuously exposed to these conditions during 2, 6, 7 and 27 days respectively.2. A sinusoidal rotational stimulus, previously shown to be nonhabituating (1/6 Hz; 60 degrees /sec amplitude), was used to test the VOR in the dark at frequent intervals both during the period of vision-reversal and an equal period after return to normal vision. D.c. electro-oculography (EOG) was used to record eye movement, taking care to avoid changes of EOG gain due to light/dark adaptation of the retina.3. All subjects showed substantial reduction of VOR gain (eye velocity/head velocity) during the first 2 days of vision-reversal. The 6-, 7- and 27-day subjects showed further reduction of gain which reached a low plateau at about 25% the normal value by the end of one week. At this time the attenuation of some EOG records was so marked as to defy extraction of a meaningful sinusoidal signal.4. After removal of the prisms VOR gain recovered along a time course which approximated that of the original adaptive attenuation.5. In the 27-day experiment large changes of phase developed in the VOR during the second week of vision-reversal. These changes generally progressed in a lagging sense, to reach 130 degrees phase lag relative to normal by the beginning of the third week. Accompanying this was a considerable restoration of gain from 25 to 50% the normal value. These adapted conditions, which approximate functional reversal of the reflex, were then maintained steady, even overnight, until return to normal vision on the 28th day.6. Thereafter, whereas VOR phase returned to near-normal in 2 hr, restoration of gain occupied a further 2-3 weeks.7. There was a highly systematic relation between instantaneous gain and

  13. Non-linear eye movements during visual-vestibular interaction under body oscillation with step-mode lateral linear acceleration.

    PubMed

    Mori, Shigeo; Katayama, Naomi

    2005-02-01

    We investigated visual-vestibular interactions in normal humans, where a constant speed of optokinetic stimulation was combined with whole body oscillation of lateral linear acceleration (10 m stroke). The acceleration mode was not sinusoidal, but rectangular (step). The pure optokinetic reflex (reference OKR) and the OKR under combined stimulation (combined OKR) were induced by a random-dot pattern projected onto a hemispherical dome-screen affixed to a chair on a linear accelerator. The translational vestibulo-ocular reflex (tVOR) was determined separately in the dark during acceleration-step oscillation. Since the tVOR was masked by the OKR under combined stimulation, the interaction was assessed as changes in combined-OKR velocity at two segments of opposing acceleration; in other words, tVOR directions identical to (agonistic) and opposite to (antagonistic) the OKR direction. When a moderate optokinetic stimulus-speed of 40 deg/s was combined with a moderate acceleration of 0.3 G (3.0 m/s2) as in Experiment 1 (N=10), the combined-OKR velocity always increased during the agonistic condition, and the motion of the visual pattern was perceived as slow and clear in this segment. On the other hand, during the antagonistic condition, the combined-OKR velocity either remained unchanged or increased moderately, and the motion of the visual pattern was sensed as fast and unclear. Notably, in most subjects, the velocity difference in combined-OKR between the agonistic and antagonistic conditions was around the value of the tVOR velocity. In five of the ten subjects who completed an additional test session with the acceleration level increased from 0.3 to 0.5 G (4.9 m/s2), similar findings were maintained individually, suggesting independent behavior of tVOR. Therefore, we hypothesized that the interaction could be direction-selective; in other words, both tVOR and OKR are additive during the agonistic condition, but tVOR is suppressed during the antagonistic condition

  14. Effect of viewing distance on the generation of vertical eye movements during locomotion

    NASA Technical Reports Server (NTRS)

    Moore, S. T.; Hirasaki, E.; Cohen, B.; Raphan, T.

    1999-01-01

    Vertical head and eye coordination was studied as a function of viewing distance during locomotion. Vertical head translation and pitch movements were measured using a video motion analysis system (Optotrak 3020). Vertical eye movements were recorded using a video-based pupil tracker (Iscan). Subjects (five) walked on a linear treadmill at a speed of 1.67 m/s (6 km/h) while viewing a target screen placed at distances ranging from 0.25 to 2.0 m at 0. 25-m intervals. The predominant frequency of vertical head movement was 2 Hz. In accordance with previous studies, there was a small head pitch rotation, which was compensatory for vertical head translation. The magnitude of the vertical head movements and the phase relationship between head translation and pitch were little affected by viewing distance, and tended to orient the naso-occipital axis of the head at a point approximately 1 m in front of the subject (the head fixation distance or HFD). In contrast, eye velocity was significantly affected by viewing distance. When viewing a far (2-m) target, vertical eye velocity was 180 degrees out of phase with head pitch velocity, with a gain of 0. 8. This indicated that the angular vestibulo-ocular reflex (aVOR) was generating the eye movement response. The major finding was that, at a close viewing distance (0.25 m), eye velocity was in phase with head pitch and compensatory for vertical head translation, suggesting that activation of the linear vestibulo-ocular reflex (lVOR) was contributing to the eye movement response. There was also a threefold increase in the magnitude of eye velocity when viewing near targets, which was consistent with the goal of maintaining gaze on target. The required vertical lVOR sensitivity to cancel an unmodified aVOR response and generate the observed eye velocity magnitude for near targets was almost 3 times that previously measured. Supplementary experiments were performed utilizing body-fixed active head pitch rotations at 1 and 2 Hz

  15. Characterizing high-velocity angular vestibulo-ocular reflex function in service members post-blast exposure

    PubMed Central

    Scherer, Matthew R.; Shelhamer, Mark J.; Schubert, Michael C.

    2011-01-01

    Blasts (explosions) are the most common mechanism of injury in modern warfare. Traumatic brain injury (TBI) and dizziness are common sequelae associated with blasts, and many service members (SMs) report symptoms worsen with activity. The purpose of this study was to measure angular vestibulo-ocular reflex gain (aVOR) of blast-exposed SMs with TBI during head impulse testing. We also assessed their symptoms during exertion. Twenty-four SMs recovering from TBI were prospectively assigned to one of two groups based on the presence or absence of dizziness. Wireless monocular scleral search coil and rate sensor were used to characterize active and passive yaw and pitch head and eye rotations. Visual analog scale (VAS) was used to monitor symptoms during fast walking/running. For active yaw head impulses, aVOR gains were significantly lower in the symptomatic group (0.79 ± 0.15) versus asymptomatic (0.87 ± 0.18), but not for passive head rotation. For pitch head rotation, the symptomatic group had both active (0.915 ± 0.24) and passive (0.878 ± 0.22) aVOR gains lower than the asymptomatic group (active 1.03 ± 0.27, passive 0.97 ± 0.23). Some SMs had elevated aVOR gain. VAS scores for all symptoms were highest during exertion. Our data suggest symptomatic SMs with TBI as a result of blast have varied aVOR gain during high-velocity head impulses and provide compelling evidence of pathology affecting the vestibular system. Potential loci of injury in this population include the following: disruption of pathways relaying vestibular efference signals, differential destruction of type I vestibular hair cells, or selective damage to irregular afferent pathways—any of which may explain the common discrepancy between reports of vestibular-like symptoms and laboratory testing results. significantly reduced pitch aVOR in symptomatic SMs and peak symptom severity during exertional testing support earlier findings in the chronic blast-exposed active duty SMs. PMID:21113582

  16. Horizontal vestibuloocular reflex evoked by high-acceleration rotations in the squirrel monkey. III. Responses after labyrinthectomy

    NASA Technical Reports Server (NTRS)

    Lasker, D. M.; Hullar, T. E.; Minor, L. B.; Shelhamer, M. J. (Principal Investigator)

    2000-01-01

    The horizontal angular vestibuloocular reflex (VOR) evoked by high-frequency, high-acceleration rotations was studied in four squirrel monkeys after unilateral labyrinthectomy. Spontaneous nystagmus was measured at the beginning and end of each testing session. During the period that animals were kept in darkness (4 days), the nystagmus at each of these times measured approximately 20 degrees /s. Within 18-24 h after return to the light, the nystagmus (measured in darkness) decreased to 2.8 +/- 1.5 degrees /s (mean +/- SD) when recorded at the beginning but was 20.3 +/- 3.9 degrees /s at the end of the testing session. The latency of the VOR measured from responses to steps of acceleration (3,000 degrees /s(2) reaching a velocity of 150 degrees /s) was 8.4 +/- 0.3 ms for responses to ipsilesional rotations and 7.7 +/- 0.4 ms for contralesional rotations. During the period that animals were kept in darkness after the labyrinthectomy, the gain of the VOR measured during the steps of acceleration was 0.67 +/- 0.12 for contralesional rotations and 0.39 +/- 0.04 for ipsilesional rotations. Within 18-24 h after return to light, the VOR gain for contralesional rotations increased to 0.87 +/- 0.08, whereas there was only a slight increase for ipsilesional rotations to 0.41 +/- 0. 06. A symmetrical increase in the gain measured at the plateau of head velocity was noted after the animals were returned to light. The VOR evoked by sinusoidal rotations of 2-15 Hz, +/-20 degrees /s, showed a better recovery of gain at lower (2-4 Hz) than at higher (6-15 Hz) frequencies. At 0.5 Hz, gain decreased symmetrically when the peak amplitude was increased from 20 to 100 degrees /s. At 10 Hz, gain was decreased for ipsilesional half-cycles and increased for contralesional half-cycles when velocity was raised from 20 to 50 degrees /s. A model incorporating linear and nonlinear pathways was used to simulate the data. Selective increases in the gain for the linear pathway accounted for the

  17. Horizontal vestibuloocular reflex evoked by high-acceleration rotations in the squirrel monkey. I. Normal responses

    NASA Technical Reports Server (NTRS)

    Minor, L. B.; Lasker, D. M.; Backous, D. D.; Hullar, T. E.; Shelhamer, M. J. (Principal Investigator)

    1999-01-01

    The horizontal angular vestibuloocular reflex (VOR) evoked by high-frequency, high-acceleration rotations was studied in five squirrel monkeys with intact vestibular function. The VOR evoked by steps of acceleration in darkness (3,000 degrees /s(2) reaching a velocity of 150 degrees /s) began after a latency of 7.3 +/- 1.5 ms (mean +/- SD). Gain of the reflex during the acceleration was 14.2 +/- 5.2% greater than that measured once the plateau head velocity had been reached. A polynomial regression was used to analyze the trajectory of the responses to steps of acceleration. A better representation of the data was obtained from a polynomial that included a cubic term in contrast to an exclusively linear fit. For sinusoidal rotations of 0.5-15 Hz with a peak velocity of 20 degrees /s, the VOR gain measured 0.83 +/- 0.06 and did not vary across frequencies or animals. The phase of these responses was close to compensatory except at 15 Hz where a lag of 5.0 +/- 0.9 degrees was noted. The VOR gain did not vary with head velocity at 0.5 Hz but increased with velocity for rotations at frequencies of >/=4 Hz (0. 85 +/- 0.04 at 4 Hz, 20 degrees /s; 1.01 +/- 0.05 at 100 degrees /s, P < 0.0001). No responses to these rotations were noted in two animals that had undergone bilateral labyrinthectomy indicating that inertia of the eye had a negligible effect for these stimuli. We developed a mathematical model of VOR dynamics to account for these findings. The inputs to the reflex come from linear and nonlinear pathways. The linear pathway is responsible for the constant gain across frequencies at peak head velocity of 20 degrees /s and also for the phase lag at higher frequencies being less than that expected based on the reflex delay. The frequency- and velocity-dependent nonlinearity in VOR gain is accounted for by the dynamics of the nonlinear pathway. A transfer function that increases the gain of this pathway with frequency and a term related to the third power of head

  18. A critical period for functional vestibular development in zebrafish

    NASA Technical Reports Server (NTRS)

    Moorman, Stephen J.; Cordova, Rodolfo; Davies, Sarah A.

    2002-01-01

    We have determined a critical period for vestibular development in zebrafish by using a bioreactor designed by NASA to simulate microgravity for cells in culture. A critical period is defined as the briefest period of time during development when stimulus deprivation results in long lasting or permanent sensory deficits. Zebrafish eggs were collected within 3 hours of being laid and fertilized. In experiment 1, eggs were placed in the bioreactor at 3, 24, 30, 36, 48, or 72 hours postfertilization (hPF) and maintained in the bioreactor until 96 hPF. In experiment 2, eggs were placed in the bioreactor immediately after they were collected and maintained in the bioreactor until 24, 36, 48, 60, 66, 72, or 96 hPF. Beginning at 96 hPF, all larvae had their vestibulo-ocular reflexes (VOR) evaluated once each day for 5 days. Only larvae that hatched from eggs that were placed in the bioreactor before 30 hPF in experiment 1 or removed from the bioreactor later than 66 hPF in experiment 2 had VOR deficits that persisted for at least 5 days. These data suggest a critical period for vestibular development in the zebrafish that begins before 30 hPF and ends after 66 hPF. To confirm this, zebrafish eggs were placed in the bioreactor at 24 hPF and removed at 72 hPF. VORs were evaluated in these larvae once each day for 5 days beginning at 96 hPF. These larvae had VOR deficits that persisted for at least 5 days. In addition, larvae that had been maintained in the bioreactor from 24 to 66 hPF or from 30 to 72 hPF, had only temporary VOR deficits. In a final experiment, zebrafish eggs were placed in the bioreactor at 3 hPF and removed at 96 hPF but the bioreactor was turned off from 24 hPF to 72 hPF. These larvae had normal VORs when they were removed from the bioreactor at 96 hPF. Taken as a whole, these data support the idea that there is a critical period for functional maturation of the zebrafish vestibular system. The developmental period identified includes the timeframe

  19. A critical period for functional vestibular development in zebrafish

    NASA Technical Reports Server (NTRS)

    Moorman, Stephen J.; Cordova, Rodolfo; Davies, Sarah A.

    2002-01-01

    We have determined a critical period for vestibular development in zebrafish by using a bioreactor designed by NASA to simulate microgravity for cells in culture. A critical period is defined as the briefest period of time during development when stimulus deprivation results in long lasting or permanent sensory deficits. Zebrafish eggs were collected within 3 hours of being laid and fertilized. In experiment 1, eggs were placed in the bioreactor at 3, 24, 30, 36, 48, or 72 hours postfertilization (hPF) and maintained in the bioreactor until 96 hPF. In experiment 2, eggs were placed in the bioreactor immediately after they were collected and maintained in the bioreactor until 24, 36, 48, 60, 66, 72, or 96 hPF. Beginning at 96 hPF, all larvae had their vestibulo-ocular reflexes (VOR) evaluated once each day for 5 days. Only larvae that hatched from eggs that were placed in the bioreactor before 30 hPF in experiment 1 or removed from the bioreactor later than 66 hPF in experiment 2 had VOR deficits that persisted for at least 5 days. These data suggest a critical period for vestibular development in the zebrafish that begins before 30 hPF and ends after 66 hPF. To confirm this, zebrafish eggs were placed in the bioreactor at 24 hPF and removed at 72 hPF. VORs were evaluated in these larvae once each day for 5 days beginning at 96 hPF. These larvae had VOR deficits that persisted for at least 5 days. In addition, larvae that had been maintained in the bioreactor from 24 to 66 hPF or from 30 to 72 hPF, had only temporary VOR deficits. In a final experiment, zebrafish eggs were placed in the bioreactor at 3 hPF and removed at 96 hPF but the bioreactor was turned off from 24 hPF to 72 hPF. These larvae had normal VORs when they were removed from the bioreactor at 96 hPF. Taken as a whole, these data support the idea that there is a critical period for functional maturation of the zebrafish vestibular system. The developmental period identified includes the timeframe

  20. Horizontal vestibuloocular reflex evoked by high-acceleration rotations in the squirrel monkey. I. Normal responses

    NASA Technical Reports Server (NTRS)

    Minor, L. B.; Lasker, D. M.; Backous, D. D.; Hullar, T. E.; Shelhamer, M. J. (Principal Investigator)

    1999-01-01

    The horizontal angular vestibuloocular reflex (VOR) evoked by high-frequency, high-acceleration rotations was studied in five squirrel monkeys with intact vestibular function. The VOR evoked by steps of acceleration in darkness (3,000 degrees /s(2) reaching a velocity of 150 degrees /s) began after a latency of 7.3 +/- 1.5 ms (mean +/- SD). Gain of the reflex during the acceleration was 14.2 +/- 5.2% greater than that measured once the plateau head velocity had been reached. A polynomial regression was used to analyze the trajectory of the responses to steps of acceleration. A better representation of the data was obtained from a polynomial that included a cubic term in contrast to an exclusively linear fit. For sinusoidal rotations of 0.5-15 Hz with a peak velocity of 20 degrees /s, the VOR gain measured 0.83 +/- 0.06 and did not vary across frequencies or animals. The phase of these responses was close to compensatory except at 15 Hz where a lag of 5.0 +/- 0.9 degrees was noted. The VOR gain did not vary with head velocity at 0.5 Hz but increased with velocity for rotations at frequencies of >/=4 Hz (0. 85 +/- 0.04 at 4 Hz, 20 degrees /s; 1.01 +/- 0.05 at 100 degrees /s, P < 0.0001). No responses to these rotations were noted in two animals that had undergone bilateral labyrinthectomy indicating that inertia of the eye had a negligible effect for these stimuli. We developed a mathematical model of VOR dynamics to account for these findings. The inputs to the reflex come from linear and nonlinear pathways. The linear pathway is responsible for the constant gain across frequencies at peak head velocity of 20 degrees /s and also for the phase lag at higher frequencies being less than that expected based on the reflex delay. The frequency- and velocity-dependent nonlinearity in VOR gain is accounted for by the dynamics of the nonlinear pathway. A transfer function that increases the gain of this pathway with frequency and a term related to the third power of head

  1. Horizontal vestibuloocular reflex evoked by high-acceleration rotations in the squirrel monkey. III. Responses after labyrinthectomy

    NASA Technical Reports Server (NTRS)

    Lasker, D. M.; Hullar, T. E.; Minor, L. B.; Shelhamer, M. J. (Principal Investigator)

    2000-01-01

    The horizontal angular vestibuloocular reflex (VOR) evoked by high-frequency, high-acceleration rotations was studied in four squirrel monkeys after unilateral labyrinthectomy. Spontaneous nystagmus was measured at the beginning and end of each testing session. During the period that animals were kept in darkness (4 days), the nystagmus at each of these times measured approximately 20 degrees /s. Within 18-24 h after return to the light, the nystagmus (measured in darkness) decreased to 2.8 +/- 1.5 degrees /s (mean +/- SD) when recorded at the beginning but was 20.3 +/- 3.9 degrees /s at the end of the testing session. The latency of the VOR measured from responses to steps of acceleration (3,000 degrees /s(2) reaching a velocity of 150 degrees /s) was 8.4 +/- 0.3 ms for responses to ipsilesional rotations and 7.7 +/- 0.4 ms for contralesional rotations. During the period that animals were kept in darkness after the labyrinthectomy, the gain of the VOR measured during the steps of acceleration was 0.67 +/- 0.12 for contralesional rotations and 0.39 +/- 0.04 for ipsilesional rotations. Within 18-24 h after return to light, the VOR gain for contralesional rotations increased to 0.87 +/- 0.08, whereas there was only a slight increase for ipsilesional rotations to 0.41 +/- 0. 06. A symmetrical increase in the gain measured at the plateau of head velocity was noted after the animals were returned to light. The VOR evoked by sinusoidal rotations of 2-15 Hz, +/-20 degrees /s, showed a better recovery of gain at lower (2-4 Hz) than at higher (6-15 Hz) frequencies. At 0.5 Hz, gain decreased symmetrically when the peak amplitude was increased from 20 to 100 degrees /s. At 10 Hz, gain was decreased for ipsilesional half-cycles and increased for contralesional half-cycles when velocity was raised from 20 to 50 degrees /s. A model incorporating linear and nonlinear pathways was used to simulate the data. Selective increases in the gain for the linear pathway accounted for the

  2. The effect of vestibulo-ocular reflex deficits and covert saccades on dynamic vision in opioid-induced vestibular dysfunction.

    PubMed

    Ramaioli, Cecilia; Colagiorgio, Paolo; Sağlam, Murat; Heuser, Fabian; Schneider, Erich; Ramat, Stefano; Lehnen, Nadine

    2014-01-01

    Patients with bilateral vestibular dysfunction cannot fully compensate passive head rotations with eye movements, and experience disturbing oscillopsia. To compensate for the deficient vestibulo-ocular reflex (VOR), they have to rely on re-fixation saccades. Some can trigger "covert" saccades while the head still moves; others only initiate saccades afterwards. Due to their shorter latency, it has been hypothesized that covert saccades are particularly beneficial to improve dynamic visual acuity, reducing oscillopsia. Here, we investigate the combined effect of covert saccades and the VOR on clear vision, using the Head Impulse Testing Device-Functional Test (HITD-FT), which quantifies reading ability during passive high-acceleration head movements. To reversibly decrease VOR function, fourteen healthy men (median age 26 years, range 21-31) were continuously administrated the opioid remifentanil intravenously (0.15 µg/kg/min). VOR gain was assessed with the video head-impulse test, functional performance (i.e. reading) with the HITD-FT. Before opioid application, VOR and dynamic reading were intact (head-impulse gain: 0.87±0.08, mean±SD; HITD-FT rate of correct answers: 90±9%). Remifentanil induced impairment in dynamic reading (HITD-FT 26±15%) in 12/14 subjects, with transient bilateral vestibular dysfunction (head-impulse gain 0.63±0.19). HITD-FT score correlated with head-impulse gain (R = 0.63, p = 0.03) and with gain difference (before/with remifentanil, R = -0.64, p = 0.02). One subject had a non-pathological head-impulse gain (0.82±0.03) and a high HITD-FT score (92%). One subject triggered covert saccades in 60% of the head movements and could read during passive head movements (HITD-FT 93%) despite a pathological head-impulse gain (0.59±0.03) whereas none of the 12 subjects without covert saccades reached such high performance. In summary, early catch-up saccades may improve dynamic visual function. HITD-FT is an appropriate method

  3. The Effect of Vestibulo-Ocular Reflex Deficits and Covert Saccades on Dynamic Vision in Opioid-Induced Vestibular Dysfunction

    PubMed Central

    Ramaioli, Cecilia; Colagiorgio, Paolo; Sağlam, Murat; Heuser, Fabian; Schneider, Erich; Ramat, Stefano; Lehnen, Nadine

    2014-01-01

    Patients with bilateral vestibular dysfunction cannot fully compensate passive head rotations with eye movements, and experience disturbing oscillopsia. To compensate for the deficient vestibulo-ocular reflex (VOR), they have to rely on re-fixation saccades. Some can trigger “covert” saccades while the head still moves; others only initiate saccades afterwards. Due to their shorter latency, it has been hypothesized that covert saccades are particularly beneficial to improve dynamic visual acuity, reducing oscillopsia. Here, we investigate the combined effect of covert saccades and the VOR on clear vision, using the Head Impulse Testing Device – Functional Test (HITD-FT), which quantifies reading ability during passive high-acceleration head movements. To reversibly decrease VOR function, fourteen healthy men (median age 26 years, range 21–31) were continuously administrated the opioid remifentanil intravenously (0.15 µg/kg/min). VOR gain was assessed with the video head-impulse test, functional performance (i.e. reading) with the HITD-FT. Before opioid application, VOR and dynamic reading were intact (head-impulse gain: 0.87±0.08, mean±SD; HITD-FT rate of correct answers: 90±9%). Remifentanil induced impairment in dynamic reading (HITD-FT 26±15%) in 12/14 subjects, with transient bilateral vestibular dysfunction (head-impulse gain 0.63±0.19). HITD-FT score correlated with head-impulse gain (R = 0.63, p = 0.03) and with gain difference (before/with remifentanil, R = −0.64, p = 0.02). One subject had a non-pathological head-impulse gain (0.82±0.03) and a high HITD-FT score (92%). One subject triggered covert saccades in 60% of the head movements and could read during passive head movements (HITD-FT 93%) despite a pathological head-impulse gain (0.59±0.03) whereas none of the 12 subjects without covert saccades reached such high performance. In summary, early catch-up saccades may improve dynamic visual function. HITD-FT is an

  4. Is vestibular self-motion perception controlled by the velocity storage? Insights from patients with chronic degeneration of the vestibulo-cerebellum.

    PubMed

    Bertolini, Giovanni; Ramat, Stefano; Bockisch, Christopher J; Marti, Sarah; Straumann, Dominik; Palla, Antonella

    2012-01-01

    The rotational vestibulo-ocular reflex (rVOR) generates compensatory eye movements in response to rotational head accelerations. The velocity-storage mechanism (VSM), which is controlled by the vestibulo-cerebellar nodulus and uvula, determines the rVOR time constant. In healthy subjects, it has been suggested that self-motion perception in response to earth-vertical axis rotations depends on the VSM in a similar way as reflexive eye movements. We aimed at further investigating this hypothesis and speculated that if the rVOR and rotational self-motion perception share a common VSM, alteration in the latter, such as those occurring after a loss of the regulatory control by vestibulo-cerebellar structures, would result in similar reflexive and perceptual response changes. We therefore set out to explore both responses in patients with vestibulo-cerebellar degeneration. Reflexive eye movements and perceived rotational velocity were simultaneously recorded in 14 patients with chronic vestibulo-cerebellar degeneration (28-81 yrs) and 12 age-matched healthy subjects (30-72 yrs) after the sudden deceleration (90°/s2) from constant-velocity (90°/s) rotations about the earth-vertical yaw and pitch axes. rVOR and perceived rotational velocity data were analyzed using a two-exponential model with a direct pathway, representing semicircular canal activity, and an indirect pathway, implementing the VSM. We found that VSM time constants of rVOR and perceived rotational velocity co-varied in cerebellar patients and in healthy controls (Pearson correlation coefficient for yaw 0.95; for pitch 0.93, p<0.01). When constraining model parameters to use the same VSM time constant for rVOR and perceived rotational velocity, moreover, no significant deterioration of the quality of fit was found for both populations (variance-accounted-for >0.8). Our results confirm that self-motion perception in response to rotational velocity-steps may be controlled by the same velocity storage network

  5. Visually induced adaptation in three-dimensional organization of primate vestibuloocular reflex

    NASA Technical Reports Server (NTRS)

    Angelaki, D. E.; Hess, B. J.

    1998-01-01

    The adaptive plasticity of the spatial organization of the vestibuloocular reflex (VOR) has been investigated in intact and canal-plugged primates using 2-h exposure to conflicting visual (optokinetic, OKN) and vestibular rotational stimuli about mutually orthogonal axes (generating torsional VOR + vertical OKN, torsional VOR + horizontal OKN, vertical VOR + horizontal OKN, and horizontal VOR + vertical OKN). Adaptation protocols with 0.5-Hz (+/-18 degrees ) head movements about either an earth-vertical or an earth-horizontal axis induced orthogonal response components as high as 40-70% of those required for ideal adaptation. Orthogonal response gains were highest at the adapting frequency with phase leads present at lower and phase lags present at higher frequencies. Furthermore, the time course of adaptation, as well as orthogonal response dynamics were similar and relatively independent of the particular visual/vestibular stimulus combination. Low-frequency (0. 05 Hz, vestibular stimulus: +/-60 degrees ; optokinetic stimulus: +/-180 degrees ) adaptation protocols with head movements about an earth-vertical axis induced smaller orthogonal response components that did not exceed 20-40% of the head velocity stimulus (i.e., approximately 10% of that required for ideal adaptation). At the same frequency, adaptation with head movements about an earth-horizontal axis generated large orthogonal responses that reached values as high as 100-120% of head velocity after 2 h of adaptation (i.e., approximately 40% of ideal adaptation gains). The particular spatial and temporal response characteristics after low-frequency, earth-horizontal axis adaptation in both intact and canal-plugged animals strongly suggests that the orienting (and perhaps translational) but not inertial (velocity storage) components of the primate otolith-ocular system exhibit spatial adaptability. Due to the particular nested arrangement of the visual and vestibular stimuli, the optic flow pattern

  6. Visually induced adaptation in three-dimensional organization of primate vestibuloocular reflex

    NASA Technical Reports Server (NTRS)

    Angelaki, D. E.; Hess, B. J.

    1998-01-01

    The adaptive plasticity of the spatial organization of the vestibuloocular reflex (VOR) has been investigated in intact and canal-plugged primates using 2-h exposure to conflicting visual (optokinetic, OKN) and vestibular rotational stimuli about mutually orthogonal axes (generating torsional VOR + vertical OKN, torsional VOR + horizontal OKN, vertical VOR + horizontal OKN, and horizontal VOR + vertical OKN). Adaptation protocols with 0.5-Hz (+/-18 degrees ) head movements about either an earth-vertical or an earth-horizontal axis induced orthogonal response components as high as 40-70% of those required for ideal adaptation. Orthogonal response gains were highest at the adapting frequency with phase leads present at lower and phase lags present at higher frequencies. Furthermore, the time course of adaptation, as well as orthogonal response dynamics were similar and relatively independent of the particular visual/vestibular stimulus combination. Low-frequency (0. 05 Hz, vestibular stimulus: +/-60 degrees ; optokinetic stimulus: +/-180 degrees ) adaptation protocols with head movements about an earth-vertical axis induced smaller orthogonal response components that did not exceed 20-40% of the head velocity stimulus (i.e., approximately 10% of that required for ideal adaptation). At the same frequency, adaptation with head movements about an earth-horizontal axis generated large orthogonal responses that reached values as high as 100-120% of head velocity after 2 h of adaptation (i.e., approximately 40% of ideal adaptation gains). The particular spatial and temporal response characteristics after low-frequency, earth-horizontal axis adaptation in both intact and canal-plugged animals strongly suggests that the orienting (and perhaps translational) but not inertial (velocity storage) components of the primate otolith-ocular system exhibit spatial adaptability. Due to the particular nested arrangement of the visual and vestibular stimuli, the optic flow pattern

  7. Compensatory and orienting eye movements induced by off-vertical axis rotation (OVAR) in monkeys.

    PubMed

    Kushiro, Keisuke; Dai, Mingjia; Kunin, Mikhail; Yakushin, Sergei B; Cohen, Bernard; Raphan, Theodore

    2002-11-01

    Nystagmus induced by off-vertical axis rotation (OVAR) about a head yaw axis is composed of a yaw bias velocity and modulations in eye position and velocity as the head changes orientation relative to gravity. The bias velocity is dependent on the tilt of the rotational axis relative to gravity and angular head velocity. For axis tilts <15 degrees, bias velocities increased monotonically with increases in the magnitude of the projected gravity vector onto the horizontal plane of the head. For tilts of 15-90 degrees, bias velocity was independent of tilt angle, increasing linearly as a function of head velocity with gains of 0.7-0.8, up to the saturation level of velocity storage. Asymmetries in OVAR bias velocity and asymmetries in the dominant time constant of the angular vestibuloocular reflex (aVOR) covaried and both were reduced by administration of baclofen, a GABA(B) agonist. Modulations in pitch and roll eye positions were in phase with nose-down and side-down head positions, respectively. Changes in roll eye position were produced mainly by slow movements, whereas vertical eye position changes were characterized by slow eye movements and saccades. Oscillations in vertical and roll eye velocities led their respective position changes by approximately 90 degrees, close to an ideal differentiation, suggesting that these modulations were due to activation of the orienting component of the linear vestibuloocular reflex (lVOR). The beating field of the horizontal nystagmus shifted the eyes 6.3 degrees /g toward gravity in side down position, similar to the deviations observed during static roll tilt (7.0 degrees /g). This demonstrates that the eyes also orient to gravity in yaw. Phases of horizontal eye velocity clustered ~180 degrees relative to the modulation in beating field and were not simply differentiations of changes in eye position. Contributions of orientating and compensatory components of the lVOR to the modulation of eye position and velocity were

  8. Characterizing high-velocity angular vestibulo-ocular reflex function in service members post-blast exposure.

    PubMed

    Scherer, Matthew R; Shelhamer, Mark J; Schubert, Michael C

    2011-02-01

    Blasts (explosions) are the most common mechanism of injury in modern warfare. Traumatic brain injury (TBI) and dizziness are common sequelae associated with blasts, and many service members (SMs) report symptoms worsen with activity. The purpose of this study was to measure angular vestibulo-ocular reflex gain (aVOR) of blast-exposed SMs with TBI during head impulse testing. We also assessed their symptoms during exertion. Twenty-four SMs recovering from TBI were prospectively assigned to one of two groups based on the presence or absence of dizziness. Wireless monocular scleral search coil and rate sensor were used to characterize active and passive yaw and pitch head and eye rotations. Visual analog scale (VAS) was used to monitor symptoms during fast walking/running. For active yaw head impulses, aVOR gains were significantly lower in the symptomatic group (0.79 ± 0.15) versus asymptomatic (0.87 ± 0.18), but not for passive head rotation. For pitch head rotation, the symptomatic group had both active (0.915 ± 0.24) and passive (0.878 ± 0.22) aVOR gains lower than the asymptomatic group (active 1.03 ± 0.27, passive 0.97 ± 0.23). Some SMs had elevated aVOR gain. VAS scores for all symptoms were highest during exertion. Our data suggest symptomatic SMs with TBI as a result of blast have varied aVOR gain during high-velocity head impulses and provide compelling evidence of pathology affecting the vestibular system. Potential loci of injury in this population include the following: disruption of pathways relaying vestibular efference signals, differential destruction of type I vestibular hair cells, or selective damage to irregular afferent pathways-any of which may explain the common discrepancy between reports of vestibular-like symptoms and laboratory testing results. Significantly reduced pitch aVOR in symptomatic SMs and peak symptom severity during exertional testing support earlier findings in the chronic blast-exposed active duty SMs.

  9. A Positive Vestibular/Ocular Motor Screening (VOMS) Is Associated With Increased Recovery Time After Sports-Related Concussion in Youth and Adolescent Athletes.

    PubMed

    Anzalone, Anthony J; Blueitt, Damond; Case, Tami; McGuffin, Tiffany; Pollard, Kalyssa; Garrison, J Craig; Jones, Margaret T; Pavur, Robert; Turner, Stephanie; Oliver, Jonathan M

    2017-02-01

    Vestibular and ocular motor impairments are routinely reported in patients with sports-related concussion (SRC) and may result in delayed return to play (RTP). The Vestibular/Ocular Motor Screening (VOMS) assessment has been shown to be consistent and sensitive in identifying concussion when used as part of a comprehensive examination. To what extent these impairments or symptoms are associated with length of recovery is unknown. To examine whether symptom provocation or clinical abnormality in specific domains of the VOMS results in protracted recovery (time from SRC to commencement of RTP protocol). Cohort study (prognosis); Level of evidence, 2. A retrospective chart review was conducted of 167 patients (69 girls, 98 boys; mean ± SD age, 15 ± 2 years [range, 11-19 years]) presenting with SRC in 2014. During the initial visit, VOMS was performed in which symptom provocation or clinical abnormality (eg, unsmooth eye movements) was documented by use of a dichotomous scale (0 = not present, 1 = present). The VOMS used in this clinic consisted of smooth pursuits (SMO_PUR), horizontal and vertical saccades (HOR_SAC and VER_SAC), horizontal and vertical vestibular ocular reflex (HOR_VOR and VER_VOR), near point of convergence (NPC), and accommodation (ACCOM). Domains were also categorized into ocular motor (SMO_PUR, HOR_SAC, VER_SAC, NPC, ACCOM) and vestibular (HOR_VOR, VER_VOR). Cox proportional hazard models were used to explore the relationship between the domains and recovery. Alpha was set at P ≤ .05. Symptom provocation and/or clinical abnormality in all domains except NPC ( P = .107) and ACCOM ( P = .234) delayed recovery (domain, hazard ratio [95% CI]: SMO_PUR, 0.65 [0.47-0.90], P = .009; HOR_SAC, 0.68 [0.50-0.94], P = .018; VER_SAC, 0.55 [0.40-0.75], P < .001; HOR_VOR, 0.68 [0.49-0.94], P = .018; VER_VOR, 0.60 [0.44-0.83], P = .002). The lowest crude hazard ratio was for ocular motor category (0.45 [0.32-0.63], P < .001). These data suggest that symptom

  10. Latency and initiation of the human vestibuloocular reflex to pulsed galvanic stimulation.

    PubMed

    Aw, Swee T; Todd, Michael J; Halmagyi, G Michael

    2006-08-01

    Cathodal galvanic currents activate primary vestibular afferents, whereas anodal currents inhibit them. Pulsed galvanic vestibular stimulation (GVS) was used to determine the latency and initiation of the human vestibuloocular reflex. Three-dimensional galvanic vestibuloocular reflex (g-VOR) was recorded with binocular dual-search coils in response to a bilateral bipolar 100-ms rectangular pulse of current at 0.9 (near-threshold), 2.5, 5.0, 7.5, and 10.0 mA in 11 normal subjects. The g-VOR consisted of three components: conjugate torsional eye rotation away from cathode toward anode; vertical divergence (skew deviation) with hypertropia of the eye on the cathodal and hypotropia of the eye on the anodal sides; and conjugate horizontal eye rotation away from cathode toward anode. The g-VOR was repeatable across all subjects, its magnitude a linear function of the current intensity, its latency about 9.0 ms with GVS of >or=2.5 mA, and was not suppressed by visual fixation. At 10-mA stimulation, the g-VOR [x, y, z] on the cathodal side was [0.77 +/- 0.10, -0.05 +/- 0.05, -0.18 +/- 0.06 degrees ] (mean +/- 95% confidence intervals) and on the anodal side was [0.79 +/- 0.10, 0.16 +/- 0.05, -0.19 +/- 0.06 degrees ], with a vertical divergence of 0.20 degrees . Although the horizontal g-VOR could have arisen from activation of the horizontal semicircular canal afferents, the vertical-torsional g-VOR resembled the vestibuloocular reflex in response to roll-plane head rotation about an Earth-horizontal axis and might be a result of both vertical semicircular canal and otolith afferent activations. Pulsed GVS is a promising technique to investigate latency and initiation of the human vestibuloocular reflex because it does not require a large mechanical apparatus nor does it pose problems of head inertia or slippage.

  11. Atomic Basic Blocks

    NASA Astrophysics Data System (ADS)

    Scheler, Fabian; Mitzlaff, Martin; Schröder-Preikschat, Wolfgang

    Die Entscheidung, einen zeit- bzw. ereignisgesteuerten Ansatz für ein Echtzeitsystem zu verwenden, ist schwierig und sehr weitreichend. Weitreichend vor allem deshalb, weil diese beiden Ansätze mit äußerst unterschiedlichen Kontrollflussabstraktionen verknüpft sind, die eine spätere Migration zum anderen Paradigma sehr schwer oder gar unmöglich machen. Wir schlagen daher die Verwendung einer Zwischendarstellung vor, die unabhängig von der jeweils verwendeten Kontrollflussabstraktion ist. Für diesen Zweck verwenden wir auf Basisblöcken basierende Atomic Basic Blocks (ABB) und bauen darauf ein Werkzeug, den Real-Time Systems Compiler (RTSC) auf, der die Migration zwischen zeit- und ereignisgesteuerten Systemen unterstützt.

  12. Impairment of LTD and cerebellar learning by Purkinje cell–specific ablation of cGMP-dependent protein kinase I

    PubMed Central

    Feil, Robert; Hartmann, Jana; Luo, Chongde; Wolfsgruber, Wiebke; Schilling, Karl; Feil, Susanne; Barski, Jaroslaw J.; Meyer, Michael; Konnerth, Arthur; De Zeeuw, Chris I.; Hofmann, Franz

    2003-01-01

    The molecular basis for cerebellar plasticity and motor learning remains controversial. Cerebellar Purkinje cells (PCs) contain a high concentration of cGMP-dependent protein kinase type I (cGKI). To investigate the function of cGKI in long-term depression (LTD) and cerebellar learning, we have generated conditional knockout mice lacking cGKI selectively in PCs. These cGKI mutants had a normal cerebellar morphology and intact synaptic calcium signaling, but strongly reduced LTD. Interestingly, no defects in general behavior and motor performance could be detected in the LTD-deficient mice, but the mutants exhibited an impaired adaptation of the vestibulo-ocular reflex (VOR). These results indicate that cGKI in PCs is dispensable for general motor coordination, but that it is required for cerebellar LTD and specific forms of motor learning, namely the adaptation of the VOR. PMID:14568994

  13. The Chinchilla's vestibulo-ocular reflex

    NASA Technical Reports Server (NTRS)

    Merwin, W. H., Jr.; Wall, Conrad, III; Tomko, D. L.

    1989-01-01

    The horizontal vestibulo-ocular reflex (VOR) was measured and characterized in seven adult chinchillas using 0.01 to 1.0 Hz angular velocity sinusoids. Gains were less than compensatory, and were variable from day to day, but phases were highly repeatable both within and between animals. The best fitting transfer function to the average data of all animals had a dominant time constant of 7.5 sec, and an adaptation operator with a time constant of 24.0 sec. There were certain nonlinearities in the horizontal VOR of this animal, and it was difficult to elicit a robust optokinetic response. Results are discussed in relation to similar measurements in other species.

  14. Navigation Signal Disturbances by Multipath Propagation - Scaled Measurements with a Universal Channel Sounder Architecture

    NASA Astrophysics Data System (ADS)

    Geise, Robert; Neubauer, Bjoern; Zimmer, Georg

    2015-11-01

    The performance of navigation systems is always reduced by unwanted multipath propagation. This is especially of practical importance for airborne navigation systems like the instrument landing system (ILS) or the VHF omni directional radio range (VOR). Nevertheless, the quantitative analysis of corresponding, potentially harmful multipath propagation disturbances is very difficult due to the large parameter space. Experimentally difficulties arise due to very expensive, real scale measurement campaigns and numerical simulation techniques still have shortcomings which are briefly discussed. In this contribution a new universal approach is introduced on how to measure very flexibly multipath propagation effects for arbitrary navigation systems using a channel sounder architecture in a scaled measurement environment. Two relevant scenarios of multipath propagation and the impact on navigation signals are presented. The first describes disturbances of the ILS due to large taxiing aircraft. The other example shows the influence of rotating wind turbines on the VOR.

  15. Einführung in die Renaturierungsökologie

    NASA Astrophysics Data System (ADS)

    Zerbe, Stefan; Wiegleb, Gerhard; Rosenthal, Gert

    Durch die übernutzung der Naturressourcen sind heute weltweit viele natürliche wie auch durch Kultur entstandene ökosysteme und Landschaften in ihren Funktionen und Leistungen stark beeinträchtigt oder sogar völlig zerstört. Bereits vor mehr als einem Jahrzehnt konstatierte (1995), dass ca. 45 % der terrestrischen Landoberfläche nur eine reduzierte Kapazität für die zukünftige Landnutzung haben. Als Grund hob er eine in der Vergangenheit nicht nachhaltige Landbewirtschaftung hervor. Mit einer gezielten Renaturierung der betroffenen ökosysteme soll dieser Trend umgekehrt werden (Harris und van Diggelen 2006). Vor diesem Hintergrund ist die ökosystemrenaturierung (ecological restoration) wichtiger Bestandteil der Planungs- und Naturschutzpraxis in Mitteleuropa und die Renaturierungsökologie (restoration ecology) zu einer eigenen wissenschaftlichen Arbeitsrichtung geworden.

  16. Design of a Miniaturized Meandered Line Antenna for UHF RFID Tags.

    PubMed

    Rokunuzzaman, Md; Islam, Mohammad Tariqul; Rowe, Wayne S T; Kibria, Salehin; Jit Singh, Mandeep; Misran, Norbahiah

    2016-01-01

    A semi-circle looped vertically omnidirectional radiation (VOR) patterned tag antenna for UHF (919-923 MHz for Malaysia) frequency is designed to overcome the impedance mismatch issue in this paper. Two impedance matching feeding strips are used in the antenna structure to tune the input impedance of the antenna. Two dipole shaped meandered lines are used to achieve a VOR pattern. The proposed antenna is designed for 23-j224 Ω chip impedance. The antenna is suitable for 'place and tag' application. A small size of 77.68×35.5 mm2 is achieved for a read range performance of 8.3 meters using Malaysia regulated maximum power transfer of 2.0 W effective radiated power (ERP).

  17. Design of a Miniaturized Meandered Line Antenna for UHF RFID Tags

    PubMed Central

    Islam, Mohammad Tariqul; Rowe, Wayne S. T.; Kibria, Salehin; Jit Singh, Mandeep; Misran, Norbahiah

    2016-01-01

    A semi-circle looped vertically omnidirectional radiation (VOR) patterned tag antenna for UHF (919–923 MHz for Malaysia) frequency is designed to overcome the impedance mismatch issue in this paper. Two impedance matching feeding strips are used in the antenna structure to tune the input impedance of the antenna. Two dipole shaped meandered lines are used to achieve a VOR pattern. The proposed antenna is designed for 23-j224 Ω chip impedance. The antenna is suitable for ‘place and tag’ application. A small size of 77.68×35.5 mm2 is achieved for a read range performance of 8.3 meters using Malaysia regulated maximum power transfer of 2.0 W effective radiated power (ERP). PMID:27533470

  18. Adaptation of primate vestibuloocular reflex to altered peripheral vestibular inputs. II Spatiotemporal properties of the adapted slow-phase eye velocity

    NASA Technical Reports Server (NTRS)

    Angelaki, D. E.; Hess, B. J.

    1996-01-01

    1. The ability of the vestibuloocular reflex (VOR) to undergo adaptive modification after selective changes in the peripheral vestibular system was investigated in rhesus monkeys by recording three-dimensional eye movements before and after inactivation of selective semicircular canals. In the preceding paper we showed that the horizontal VOR gain evoked by passive yaw oscillations after lateral semicircular canal inactivation recovers gradually over time in a frequency-specific manner. Here we present the spatial tuning of the adapted slow-phase eye velocity and describe its spatiotemporal properties as a function of time after canal inactivation. 2. The spatial organization of the VOR was investigated during oscillations at different head positions in the pitch, roll, and yaw planes, as well as in the right anterior/left posterior and left anterior/right posterior canal planes. Acutely after bilateral inactivation of the lateral semicircular canals, a small horizontal response could still be elicited that peaked during rotations in pitched head positions that would maximally stimulate vertical semicircular canals. In addition, the phase of horizontal slow-phase velocity abruptly reversed through 180 degrees at positions close to upright, similarly to torsional slow-phase velocity. These spatial response properties suggest that the small, residual horizontal response components that are present acutely after plugging of both lateral canals originate from vertical semicircular canal signals. 3. As the horizontal response amplitude increased over time, consistent changes were also observed in the spatiotemporal tuning of horizontal slow-phase velocity. 1) The spatiotemporal response properties of horizontal slow-phase velocity acquired noncosine tuning characteristics, primarily in the pitch plane, in the right anterior/left posterior and left anterior/right posterior canal planes. Accordingly, horizontal response amplitude was nonzero during rotation in any head

  19. Effects of digital altimetry on pilot workload

    NASA Technical Reports Server (NTRS)

    Harris, R. L., Sr.; Glover, B. J.

    1984-01-01

    A series of VOR-DME instrument landing approaches was flown in the DC-9 full-workload simulator to compare pilot performance, scan behavior, and workload when using a computer-drum-pointer altimeter (CDPA) and a digital altimeter (DA). Six pilots executed two sets of instrument landing approaches, with a CDPA on one set and a DA on the other set. Pilot scanning parameters, flight performance, and subjective opinion data were evaluated. It is found that the processes of gathering information from the CDPA and the DA are different. The DA requires a higher mental workload than the CDPA for a VOR-DME type landing approach. Mental processing of altitude information after transitioning back to the attitude indicator is more evident with the DA than with the CDPA.

  20. Flight evaluation of advanced navigation techniques for general aviation using frequency scanning

    NASA Technical Reports Server (NTRS)

    Jackson, C. T., Jr.; Denery, D. G.; Korsak, A. J.; Conrad, B.

    1976-01-01

    Experiments on an automatic multisensor navigation concept are being conducted in a Cessna 402B. The test system consists of VOR, DME, and air data sensors controlled by a Hewlett Packard 9820A electronic calculator which processes the data and, by means of a four-state Kalman filter, outputs position and ground and wind velocities to a map display. Novel features which make such a system potentially low-cost include frequency-scanning operation of a single VOR receiver and a single DME transceiver and use of a shed-vortex true airspeed sensor. Results obtained during flight in a local area where six to eight DME NAVAIDS were receivable yielded better than 1/4-mile accuracy.

  1. Effects of digital altimetry on pilot workload

    NASA Technical Reports Server (NTRS)

    Harris, R. L., Sr.; Glover, B. J.

    1985-01-01

    A series of VOR-DME instrument landing approaches was flown in the DC-9 full-workload simulator to compare pilot performance, scan behavior, and workload when using a computer-drum-pointer altimeter (CDPA) and a digital altimeter (DA). Six pilots executed two sets of instrument landing approaches, with a CDPA on one set and a DA on the other set. Pilot scanning parameters, flight performance, and subjective opinion data were evaluated. It is found that the processes of gathering information from the CDPA and the DA are different. The DA requires a higher mental workload than the CDPA for a VOR-DME type landing approach. Mental processing of altitude information after transitioning back to the attitude indicator is more evident with the DA than with the CDPA.

  2. Motor function in microgravity: movement in weightlessness

    NASA Technical Reports Server (NTRS)

    Lackner, J. R.; DiZio, P.

    1996-01-01

    Microgravity provides unique, though experimentally challenging, opportunities to study motor control. A traditional research focus has been the effects of linear acceleration on vestibular responses to angular acceleration. Evidence is accumulating that the high-frequency vestibulo-ocular reflex (VOR) is not affected by transitions from a 1 g linear force field to microgravity (<1 g); however, it appears that the three-dimensional organization of the VOR is dependent on gravitoinertial force levels. Some of the observed effects of microgravity on head and arm movement control appear to depend on the previously undetected inputs of cervical and brachial proprioception, which change almost immediately in response to alterations in background force levels. Recent studies of post-flight disturbances of posture and locomotion are revealing sensorimotor mechanisms that adjust over periods ranging from hours to weeks.

  3. Lack of effects of astemizole on vestibular ocular reflex, motion sickness, and cognitive performance in man

    NASA Technical Reports Server (NTRS)

    Kohl, Randall L.; Homick, Jerry L.; Cintron, Nitza; Calkins, Dick S.

    1987-01-01

    Astemizole was orally administered to 20 subjects in a randomized, double-blind design to assess the efficacy of this peripherally active antihistamine as an antimotion sickness drug possessing no central side-effects. Measures of vestibular ocular reflex (VOR) were made to evaluate the agent as a selective vestibular depressant. Following one week of orally administered astemizole (30 mg daily), a Staircase Profile Test, a VOR test, and a variety of tests of cognitive performance were administered. These tests revealed no statistically significant effects of astemizole. This leads to the conclusion that, although the drug probably reaches the peripheral vestibular apparatus in man by crossing the blood-vestibular barrier, a selective peripheral antihistamine (H1) action is inadequate to control motion sickness induced through cross-coupled accelerative semicircular canal stimulation in a rotating chair.

  4. Lack of effects of astemizole on vestibular ocular reflex, motion sickness, and cognitive performance in man

    NASA Technical Reports Server (NTRS)

    Kohl, Randall L.; Homick, Jerry L.; Cintron, Nitza; Calkins, Dick S.

    1987-01-01

    Astemizole was orally administered to 20 subjects in a randomized, double-blind design to assess the efficacy of this peripherally active antihistamine as an antimotion sickness drug possessing no central side-effects. Measures of vestibular ocular reflex (VOR) were made to evaluate the agent as a selective vestibular depressant. Following one week of orally administered astemizole (30 mg daily), a Staircase Profile Test, a VOR test, and a variety of tests of cognitive performance were administered. These tests revealed no statistically significant effects of astemizole. This leads to the conclusion that, although the drug probably reaches the peripheral vestibular apparatus in man by crossing the blood-vestibular barrier, a selective peripheral antihistamine (H1) action is inadequate to control motion sickness induced through cross-coupled accelerative semicircular canal stimulation in a rotating chair.

  5. Victim-Offender Relationship Status Moderates the Relationships of Peritraumatic Emotional Responses, Active Resistance, and Posttraumatic Stress Symptomatology in Female Rape Survivors

    PubMed Central

    Feinstein, Brian A.; Humphreys, Kathryn L.; Bovin, Michelle J.; Marx, Brian P.; Resick, Patricia A.

    2010-01-01

    This study examined whether the level of victim-offender relationship (VOR) moderated the relationship between peritraumatic fear and active resistance as well as the relationship between peritraumatic fear and posttraumatic stress symptom severity in a community sample of female rape survivors. One hundred thirty-five participants were interviewed about their emotional and behavioral responses during the rape and assessed for posttraumatic stress symptomatology within one month of the assault. Results indicated that peritraumatic fear was positively associated with active resistance, but only among survivors of acquaintance rape. Additionally, peritraumatic fear was positively associated with posttraumatic stress symptom severity, but only among survivors of intimate partner rape. These results suggest that VOR may be an important contextual factor that influences emotional and behavioral responses during rape as well as posttraumatic stress symptomatology in its aftermath. PMID:21731797

  6. "Das Konkrete ist das Abstrakte, an das man sich schließlich gewöhnt hat." (Laurent Schwartz) Über den Ablauf des mathematischen Verstehens

    NASA Astrophysics Data System (ADS)

    Lowsky, Martin

    Die im Titel genannte Aussage findet sich in den Lebenserinnerungen von Laurent Schwartz (1915-2002), einem der fruchtbarsten Mathematiker, Mitglied der Gruppe Bourbaki. Im Original lautet die Aussage: "un objet concret est un objet abstrait auquel on a fini par s'habituer." Schwartz erläutert sie am Beispiel des Integrals über {e^{-1/2{x^2}}} , das den Wert Wurzel aus 2π hat und in dem sich also die Zahlen e und π verknüpfen. Was Schwartz aber vor allem ausdrücken will, ist dies: Das mathematische Verständnisd geht langsam vor sich und es bedarf der Anstrengung. "Es ist eine Frage der Zeit und der Energie", sagt Schwartz, und gerade dies mache es so schwer, die höhere Mathematik unter das Volk zu bringen. Das Lernen und Lehren von Mathematik laufe eben mühevoll und langsam ab.

  7. SARCOPTERYGII, Fleischflosser

    NASA Astrophysics Data System (ADS)

    Schultze, Hans-Peter

    Unter den rezenten und fossilen Fischen sind die Sarcopterygier durch fleischige Loben an den paarigen Flossen charakterisiert. Fossil gehen sie bis in das Obere Silur (vor 420 Mio. Jahren) zurück. Einige Gruppen (†Onychodontida, †Porolepiformes, †Elpistostegalia) waren auf das Devon beschränkt, andere verschwanden gegen Ende des Paläozoikums (†Rhizodontida, †Osteolepiformes). Nur wenige Arten der Dipnoi (Lungenfische) und Actinistia (Hohlstachler) haben überlebt; aus einer ausgestorbenen Teilgruppe evolvierten die erfolgreichen Tetrapoda. Im Devon waren die Sarcopterygier weltweit verbreitet; ihre rezenten fischartigen Formen sind dagegen auf die Südkontinente bzw. den Indischen Ozean beschränkt. Ursprünglich waren alle Formen marin. Mehrmals unabhängig wurde von ihnen das Süßwasser und innerhalb der Tetrapoden vor allem das Land erobert.

  8. [Receptor function of the semicircular canals. Part 2: pathophysiology, diseases, clinical findings and treatment aspects].

    PubMed

    Blödow, A; Bloching, M; Hörmann, K; Walther, L E

    2012-03-01

    Perturbation of semicircular canal function may result in a pathological angular vestibulo-ocular reflex (aVOR). The resulting impairment in gaze stabilization is perceived as "vertigo" or "dizziness" and may occur following receptor function impairment of all three semicircular canals. The head impulse test reveals hidden (covert-catchup) or visible (overt-catchup) saccades in disturbances of semicircular function. Most peripheral vestibular disorders can be treated conservatively. There are surgical treatment options for some diseases, such as intractable benign paroxysmal positional vertigo and superior semicircular canal dehiscence. Vestibular training promotes central reorganization of the VOR. Impaired semicircular receptor function, in particular bilateral vestibulopathy, may affect spatial orientation and cognitive processes. Balance prostheses could serve as a replacement for receptors in the future.

  9. Adaptation of primate vestibuloocular reflex to altered peripheral vestibular inputs. II Spatiotemporal properties of the adapted slow-phase eye velocity

    NASA Technical Reports Server (NTRS)

    Angelaki, D. E.; Hess, B. J.

    1996-01-01

    1. The ability of the vestibuloocular reflex (VOR) to undergo adaptive modification after selective changes in the peripheral vestibular system was investigated in rhesus monkeys by recording three-dimensional eye movements before and after inactivation of selective semicircular canals. In the preceding paper we showed that the horizontal VOR gain evoked by passive yaw oscillations after lateral semicircular canal inactivation recovers gradually over time in a frequency-specific manner. Here we present the spatial tuning of the adapted slow-phase eye velocity and describe its spatiotemporal properties as a function of time after canal inactivation. 2. The spatial organization of the VOR was investigated during oscillations at different head positions in the pitch, roll, and yaw planes, as well as in the right anterior/left posterior and left anterior/right posterior canal planes. Acutely after bilateral inactivation of the lateral semicircular canals, a small horizontal response could still be elicited that peaked during rotations in pitched head positions that would maximally stimulate vertical semicircular canals. In addition, the phase of horizontal slow-phase velocity abruptly reversed through 180 degrees at positions close to upright, similarly to torsional slow-phase velocity. These spatial response properties suggest that the small, residual horizontal response components that are present acutely after plugging of both lateral canals originate from vertical semicircular canal signals. 3. As the horizontal response amplitude increased over time, consistent changes were also observed in the spatiotemporal tuning of horizontal slow-phase velocity. 1) The spatiotemporal response properties of horizontal slow-phase velocity acquired noncosine tuning characteristics, primarily in the pitch plane, in the right anterior/left posterior and left anterior/right posterior canal planes. Accordingly, horizontal response amplitude was nonzero during rotation in any head

  10. Regenerative Energieträger im Aufwind: Entwicklung der erneuerbaren Energien

    NASA Astrophysics Data System (ADS)

    Kohl, Harald

    2006-05-01

    2005 kam 4,6 % des deutschen Primär-Energieverbrauchs aus erneuerbaren Energiequellen, bei der Stromproduktion lag ihr Anteil bei 10,2 %. Wesentliche Ursache ist der Boom bei der Windkraft, die vor allem durch Offshore-Windparks auf See weiter ausbaubar ist. Die Wasserkraft lieferte in Deutschland traditionell einen großen Beitrag zur Stromerzeugung, doch ihr Ausbaupotenzial ist gering. Die Photovoltaik, die solar- und die geothermische Stromerzeugung spielen derzeit noch eine kleine Rolle. Den deutschen Bedarf an Wärmeenergie deckten 2004 die erneuerbaren Energien zu 5,4 %, vor allem aus Biomasse. Die solarthermische Wärmeerzeugung hat sich gegenüber 2000 mehr als verdoppelt. Im Straßenverkehr spielen biogene Kraftstoffe mit 5,4 % noch eine untergeordnete Rolle. Bis 2050 könnte in Deutschland der Anteil regenerativer Energien am Primär-Energieverbrauch die Fünfzigprozentmarke überschreiten.

  11. Development of the Roll-Induced Vestibuloocular Reflex in the Absence of Vestibular Experience in Salamander Tadpoles (Pleurodeles Waltl)

    NASA Astrophysics Data System (ADS)

    Horn, Eberhard R.; Gabriel, Martin; Frippiat, Jean-Pol

    2008-06-01

    The macula organ of the labyrinth is stimulated by body roll or translatory movements. Due to its slow development, the salamander Pleurodeles waltl is an excellent model to study the impact of microgravity on the development of the roll-induced vestibuloocular reflex (rVOR) in the absence of any macular stimulation. The experiment was performed during the Soyuz mission TMA8 (return flight TMA7) in 2006 as part of the experiment AMPHIBODY. It was supplemented by a 3g-hypergravity experiment. It was shown, that microgravity retards the over-all development of Pleurodeles tadpoles but not specifically functional development of the vestibular system; normalization took place within 3 to 4 weeks after landing. Hypergravity accelerated rVOR development in the long-term frame.

  12. Ein Organic Computing Ansatz zur Steuerung einer sechsbeinigen Laufmaschine

    NASA Astrophysics Data System (ADS)

    Auf, Adam El Sayed; Larionova, Svetlana; Mösch, Florian; Litza, Marek; Jakimovski, Bojan; Maehle, Erik

    Obwohl die Rechengeschwindigkeit von Computern und die Komplexität unserer Systeme ständig zunimmt, sind die heutigen Laufmaschinen nicht in der Lage, sich mit den Fähigkeiten von Landtieren wie zum Beispiel Insekten zu messen. Das Verständnis biologischer Konzepte und das Lernen von der Natur könnten zur Verbesserung der heutigen Maschinen beitragen und sie ein wenig “lebensähnlicher“ machen. Dieser Artikel stellt einen Kontrollarchitekturansatz basierend auf “Organic Computing“-Prinzipien vor, der die Nutzung von Dezentralisierung und Selbstorganisation an einer sechsbeinigen Laufmaschine demonstriert. Die vorliegende Arbeit erklärt die elementaren Mechanismen für das gerade Laufen, das Kurvenlaufen sowie das Drehen auf der Stelle und den Umgang mit strukturellen körperlichen Änderungen wie einer Beinamputation und stellt die Ergebnisse experimenteller Versuche vor.

  13. Multiple subclasses of Purkinje cells in the primate floccular complex provide similar signals to guide learning in the vestibulo-ocular reflex

    NASA Technical Reports Server (NTRS)

    Raymond, J. L.; Lisberger, S. G.

    1997-01-01

    The neural "learning rules" governing the induction of plasticity in the cerebellum were analyzed by recording the patterns of neural activity in awake, behaving animals during stimuli that induce a form of cerebellum-dependent learning. We recorded the simple- and complex-spike responses of a broad sample of Purkinje cells in the floccular complex during a number of stimulus conditions that induce motor learning in the vestibulo-ocular reflex (VOR). Each subclass of Purkinje cells carried essentially the same information about required changes in the gain of the VOR. The correlation of simple-spike activity in Purkinje cells with activity in vestibular pathways could guide learning during low-frequency but not high-frequency stimuli. Climbing fiber activity could guide learning during all stimuli tested but only if compared with the activity present approximately 100 msec earlier in either vestibular pathways or Purkinje cells.

  14. The Chinchilla's vestibulo-ocular reflex

    NASA Technical Reports Server (NTRS)

    Merwin, W. H., Jr.; Wall, Conrad, III; Tomko, D. L.

    1989-01-01

    The horizontal vestibulo-ocular reflex (VOR) was measured and characterized in seven adult chinchillas using 0.01 to 1.0 Hz angular velocity sinusoids. Gains were less than compensatory, and were variable from day to day, but phases were highly repeatable both within and between animals. The best fitting transfer function to the average data of all animals had a dominant time constant of 7.5 sec, and an adaptation operator with a time constant of 24.0 sec. There were certain nonlinearities in the horizontal VOR of this animal, and it was difficult to elicit a robust optokinetic response. Results are discussed in relation to similar measurements in other species.

  15. Motor function in microgravity: movement in weightlessness

    NASA Technical Reports Server (NTRS)

    Lackner, J. R.; DiZio, P.

    1996-01-01

    Microgravity provides unique, though experimentally challenging, opportunities to study motor control. A traditional research focus has been the effects of linear acceleration on vestibular responses to angular acceleration. Evidence is accumulating that the high-frequency vestibulo-ocular reflex (VOR) is not affected by transitions from a 1 g linear force field to microgravity (<1 g); however, it appears that the three-dimensional organization of the VOR is dependent on gravitoinertial force levels. Some of the observed effects of microgravity on head and arm movement control appear to depend on the previously undetected inputs of cervical and brachial proprioception, which change almost immediately in response to alterations in background force levels. Recent studies of post-flight disturbances of posture and locomotion are revealing sensorimotor mechanisms that adjust over periods ranging from hours to weeks.

  16. Loran-C flight data base

    NASA Technical Reports Server (NTRS)

    Lilley, R. W.

    1979-01-01

    Loran-C time-difference data were collected on January 9, 1979 during a flight from Athens, Ohio to Madison VOR in Connecticut, thence to Millville VOR in New Jersey, and a landing at Atlantic City NAFEC. Portions of the return trip to Athens, Ohio were also recorded. Loran-C GRI data frames were recorded using the 99600 U. S. Northeast Loran chain stations Seneca/Nantucket (TDA) and Seneca/Carolina Beach (TDB). The GRI sequence number TDA and TDB were recorded as integer numbers, with the TD's in integer microseconds. Actual time-of-day can be determined from the data start time, plus the time per GRI and the sequence number. The low cost Loran-C receiver was used to obtain the time-difference data for each GRI. Data was recorded on digital magnetic tape and post-processed into latitude and longitude using an IBM system/370 computer.

  17. Multiple subclasses of Purkinje cells in the primate floccular complex provide similar signals to guide learning in the vestibulo-ocular reflex

    NASA Technical Reports Server (NTRS)

    Raymond, J. L.; Lisberger, S. G.

    1997-01-01

    The neural "learning rules" governing the induction of plasticity in the cerebellum were analyzed by recording the patterns of neural activity in awake, behaving animals during stimuli that induce a form of cerebellum-dependent learning. We recorded the simple- and complex-spike responses of a broad sample of Purkinje cells in the floccular complex during a number of stimulus conditions that induce motor learning in the vestibulo-ocular reflex (VOR). Each subclass of Purkinje cells carried essentially the same information about required changes in the gain of the VOR. The correlation of simple-spike activity in Purkinje cells with activity in vestibular pathways could guide learning during low-frequency but not high-frequency stimuli. Climbing fiber activity could guide learning during all stimuli tested but only if compared with the activity present approximately 100 msec earlier in either vestibular pathways or Purkinje cells.

  18. Orientation adaptation of eye movement–related vestibular neurons due to prolonged head tilt

    PubMed Central

    Kolesnikova, Olga V.; Raphan, Theodore; Cohen, Bernard; Yakushin, Sergei B.

    2012-01-01

    Sixteen neurons, including vestibular-only (VO), eye–head velocity (EHV), and position-vestibular-pause (PVP) neurons sensitive to head tilt were recorded in the rostromedial and in superior vestibular nuclei. Projection of the otolith polarization vector to the horizontal plane (response vector orientation [RVO]) was determined before and after prolonged head orientation in side-down position. The RVO of VO neurons shifted toward alignment with the axis of gravity when the head was in the position of adaptation. PVP neurons had similar changes in RVO. There were also changes in RVO in some EHV neurons, but generally in directions not related to gravity. Modeling studies have suggested that the tendency to align RVOs with gravity leads to tuning of gravity-dependent angular vestibular ocular reflex (aVOR) gain changes to the position of adaptation. Thus, coding of orientation in PVP neurons would contribute significantly to the gravity-dependent adaptation of the aVOR. PMID:21950996

  19. 78 FR 16606 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-18

    ... (GPS) RWY 26, Amdt 1 Savannah, GA, Savannah/Hilton Head Intl, RNAV (RNP) Y RWY 28, Amdt 1 Le Mars, IA, Le Mars Muni, RNAV (GPS) RWY 18, Amdt 1 Le Mars, IA, Le Mars Muni, RNAV (GPS) RWY 36, Amdt 1 Le Mars, IA, Le Mars Muni, Takeoff Minimums and Obstacle DP, Amdt 2 Le Mars, IA, Le Mars Muni, VOR/DME RWY 36...

  20. Ontogenetic Development of Vestibulo-Ocular Reflexes in Amphibians

    PubMed Central

    Branoner, Francisco; Chagnaud, Boris P.; Straka, Hans

    2016-01-01

    Vestibulo-ocular reflexes (VOR) ensure gaze stability during locomotion and passively induced head/body movements. In precocial vertebrates such as amphibians, vestibular reflexes are required very early at the onset of locomotor activity. While the formation of inner ears and the assembly of sensory-motor pathways is largely completed soon after hatching, angular and translational/tilt VOR display differential functional onsets and mature with different time courses. Otolith-derived eye movements appear immediately after hatching, whereas the appearance and progressive amelioration of semicircular canal-evoked eye movements is delayed and dependent on the acquisition of sufficiently large semicircular canal diameters. Moreover, semicircular canal functionality is also required to tune the initially omnidirectional otolith-derived VOR. The tuning is due to a reinforcement of those vestibulo-ocular connections that are co-activated by semicircular canal and otolith inputs during natural head/body motion. This suggests that molecular mechanisms initially guide the basic ontogenetic wiring, whereas semicircular canal-dependent activity is required to establish the spatio-temporal specificity of the reflex. While a robust VOR is activated during passive head/body movements, locomotor efference copies provide the major source for compensatory eye movements during tail- and limb-based swimming of larval and adult frogs. The integration of active/passive motion-related signals for gaze stabilization occurs in central vestibular neurons that are arranged as segmentally iterated functional groups along rhombomere 1–8. However, at variance with the topographic maps of most other sensory systems, the sensory-motor transformation of motion-related signals occurs in segmentally specific neuronal groups defined by the extraocular motor output targets. PMID:27877114

  1. Quantifying Environmental Control on Tropical Cyclone Intensity Change

    DTIC Science & Technology

    2010-08-01

    levels in a pseudoadia- batic expansion step of the Carnot heat engine cycle . However, the instability itself depends on positive feed- back between...include eyewall replacement cycles , potential vor- ticity (PV) mixing between eye and eyewall, and con- vectively coupled vortex Rossby waves [see the...continued to lag track skill im- provement (e.g., DeMaria et al. 2007). Moreover, there is poor intensity guidance in multiple phases of the TC life cycle

  2. 76 FR 35098 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-16

    ..... 1/0894 5/13/11 RNAV (RNP) Z RWY 34, Orig-A 30-Jun-11 ME Sanford Sanford Rgnl........ 1/0969 5/6/11 VOR RWY 7, Amdt 4 30-Jun-11 ME Sanford Sanford Rgnl........ 1/0970 5/6/11 ILS OR LOC RWY 7, Amdt 4 30... Southwest Rgnl...... 1/9838 5/2/11 RNAV (RNP) Z RWY 4, Orig 30-Jun-11 MT Bozeman Gallatin Field...... 1/9840...

  3. Transrapid und Rad-Schiene-Hochgeschwindigkeitsbahn: Ein gesamtheitlicher Systemvergleich

    NASA Astrophysics Data System (ADS)

    Schach, R.; Jehle, P.; Naumann, R.

    Der Transrapid bietet im Hochgeschwindigkeitsbereich eine sehr interessante Alternative. Über Vor-und Nachteile des Transrapid im Vergleich mit konventionellen Rad-Schiene-Systemen, im Hochgeschwindigkeitsbereich auf Strecken zwischen 150 und 800 Kilometernund als peer-to-peer-Verbindung im Kurzstreckenbereich, wurden viele einze lne Aspekte behandelt, darunter sachliche wie politische Statements. Ein Systemvergleich muß aber alle technischen, wirtschaftlichen und ökologischen Faktoren einschließen.

  4. Causes of General Aviation Weather-Related, Non-Fatal Incidents: Analysis Using NASA Aviation Safety Reporting System Data

    DTIC Science & Technology

    2010-09-01

    ed A pp ro ac h- ca pa bl e au to pi lo t-e qu ip pe d Com Nav Avoidance De-ice A/P 18 For the sake of completeness, the last four rows of... DME ...H.21 Navigation In Use: [Localizer, ILS, FMS/FMC, GPS/Area Nav , INS, NDB, Pilotage, VOR, Other _____] H.22 Flight Phase: [Ground: Parked

  5. Implementation of palliative care as a mandatory cross-disciplinary subject (QB13) at the Medical Faculty of the Heinrich-Heine-University Düsseldorf, Germany.

    PubMed

    Schulz, Christian; Wenzel-Meyburg, Ursula; Karger, André; Scherg, Alexandra; In der Schmitten, Jürgen; Trapp, Thorsten; Paling, Andreas; Bakus, Simone; Schatte, Gesa; Rudolf, Eva; Decking, Ulrich; Ritz-Timme, Stephanie; Grünewald, Matthias; Schmitz, Andrea

    2015-01-01

    Einleitung: Im Rahmen der Novellierung der Ärztlichen Approbationsordnung (ÄAppO) im Jahr 2009 fand die Palliativmedizin als 13. Querschnittsbereich (QB 13) Eingang in die ärztliche Ausbildung als Pflichtlehr- und Prüfungsfach. Die Implementierung des neuen QB stellt nach wie vor Medizinische Fakultäten vor große Herausforderungen. Geringe Lehrressourcen und nur geringe Zahlen von Patienten stehen einer hohen Anzahl von Studierenden gegenüber. Neben der Vermittlung von Wissen und Fertigkeiten liegt in der Lehre der Palliativmedizin auch eine besondere Herausforderung in der Vermittlung einer ärztlichen Haltung gegenüber unheilbar erkrankten und sterbenden Menschen und deren Angehörigen.Projektbeschreibung: Vor diesem Hintergrund wurde an der Medizinischen Fakultät der Heinrich-Heine-Universität und dem Universitätsklinikum Düsseldorf ein evidenzbasiertes longitudinales Curriculum systematisch nach dem Kern-Zyklus [1] entwickelt und teilweise bereits implementiert sowie durch die Studierenden im Pilotprojekt evaluiert. Innovative Lehrmethoden (Virtuelle Schauspielpatienten, eLearning-Kurse, interprofessionelle Lehre und reflexive Selbstentwicklungsgruppe) wurden mit dem Ziel eingesetzt, palliativmedizinische Kernkompetenzen interdisziplinär und interprofessionell im klinischen Kontext zu vermitteln.Ergebnisse: Das gesamte in diesem Prozess entwickelte Curriculum Palliativmedizin (60 UE) wird nach einer nahezu 5-jährigen Entwicklungsphase ab dem Wintersemester 2014/2015 erstmalig in vollem Umfang durchgeführt. Die vorangestellten Pilotphasen wurden erfolgreich abgeschlossen. Bisher liegen Evaluationsergebnisse der Pilotierungsphasen (n=26), des Teilprojektes eLearning in der Palliativmedizin (n=518) und dem Blended-Learning Wahlpflichtfach „Kommunikation mit Sterbenden“ (n=12) vor. Schlussfolgerung: Alle durchgeführten Schritte und entwickelten Programme stehen anderen Fakultäten zur Umsetzung frei zugänglich zur Verfügung (Open Access

  6. Readaptation of the vestibulo-ocular reflex relieves the mal de debarquement syndrome.

    PubMed

    Dai, Mingjia; Cohen, Bernard; Smouha, Eric; Cho, Catherine

    2014-01-01

    The mal de debarquement syndrome (MdDS), a continuous feeling of swaying, rocking, and/or bobbing, generally follows travel on the sea. The associated symptoms cause considerable distress. The underlying neural mechanisms are unknown, and to date there have been no effective treatments for this condition. Results in monkeys and humans suggested that MdDS was caused by maladaptation of the vestibulo-ocular reflex (VOR) to roll of the head during rotation. We studied 24 subjects with persistent MdDS (3 males, 21 females; 19.1 ± 33 months). Physical findings included body oscillation at 0.2 Hz, oscillating vertical nystagmus when the head was rolled from side-to-side in darkness, and unilateral rotation during the Fukuda stepping test. We posited that the maladapted rocking and the physical symptoms could be diminished or extinguished by readapting the VOR. Subjects were treated by rolling the head from side-to-side while watching a rotating full-field visual stimulus. Seventeen of the 24 subjects had a complete or substantial recovery on average for approximately 1 year. Six were initially better, but the symptoms recurred. One subject did not respond to treatment. Thus, readaptation of the VOR has led to a cure or substantial improvement in 70% of the subjects with MdDS. We conclude that the adaptive processes associated with roll-while-rotating are responsible for producing MdDS, and that the symptoms can be reduced or resolved by readapting the VOR.

  7. Situationeel Bewustzijn en Vestibulaire Stimulatie: De Invloed Van Draaibewegingen op de Taakprestatie (Situational Awareness and Vestibular Stimulation: The Influence of Whole-Body Rotation upon Task Performance)

    DTIC Science & Technology

    1989-08-01

    of the vestibular-ocular reflex (VOR). These findings are of importance for the problem of "situational awareness’ because similar reactions might...ergonomic, training , seloctie en preventie. 1.1 Situatigneel bewustziin Do problemen rand do invlood van niet allodaagse bewegingen op hot functioneren...informatieverwerking. In dit ondorzoek is aandscht bestood aan do volgondo vorschijnselon: - Do vostibulo-oculaire reflex Stabilisatie van do blik op eon

  8. 78 FR 25384 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-01

    ..., ILS OR LOC RWY 21L, Amdt 8A Atlanta, GA, DeKalb-Peachtree, VOR/DME RWY 21L, Amdt 2A Burley, ID, Burly... Muni, ILS OR LOC/DME RWY 4, Orig-A Talladega, AL, Talladega Muni, RNAV (GPS) RWY 4, Amdt 1B Talladega... Intl, ILS PRM RWY 28L (SIMULTANEOUS CLOSE PARALLEL), Amdt 2A San Francisco, CA, San Francisco Intl,...

  9. 78 FR 48800 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-12

    ..., Manassas Rgnl/Harry P. Davis Field, RNAV (GPS) RWY 34R, Amdt 2 Palm Coast, FL, Flagler County, VOR-A, Amdt..., Amdt 7A St Louis, MO, Lambert-St Louis Intl, ILS PRM RWY 11, ILS PRM RWY 11 (CAT II), ILS PRM RWY 11 (CAT III) (SIMULTANEOUS CLOSE PARALLEL), Orig-C, CANCELED St Louis, MO, Lambert-St Louis Intl, ILS PRM...

  10. Modeling the vestibulo-ocular reflex of the squirrel monkey during eccentric rotation and roll tilt

    NASA Technical Reports Server (NTRS)

    Merfeld, D. M.; Paloski, W. H. (Principal Investigator)

    1995-01-01

    Model simulations of the squirrel monkey vestibulo-ocular reflex (VOR) are presented for two motion paradigms: constant velocity eccentric rotation and roll tilt about a naso-occipital axis. The model represents the implementation of three hypotheses: the "internal model" hypothesis, the "gravito-inertial force (GIF) resolution" hypothesis, and the "compensatory VOR" hypothesis. The internal model hypothesis is based on the idea that the nervous system knows the dynamics of the sensory systems and implements this knowledge as an internal dynamic model. The GIF resolution hypothesis is based on the idea that the nervous system knows that gravity minus linear acceleration equals GIF and implements this knowledge by resolving the otolith measurement of GIF into central estimates of gravity and linear acceleration, such that the central estimate of gravity minus the central estimate of acceleration equals the otolith measurement of GIF. The compensatory VOR hypothesis is based on the idea that the VOR compensates for the central estimates of angular velocity and linear velocity, which sum in a near-linear manner. During constant velocity eccentric rotation, the model correctly predicts that: (1) the peak horizontal response is greater while "facing-motion" than with "back-to-motion"; (2) the axis of eye rotation shifts toward alignment with GIF; and (3) a continuous vertical response, slow phase downward, exists prior to deceleration. The model also correctly predicts that a torsional response during the roll rotation is the only velocity response observed during roll rotations about a naso-occipital axis. The success of this model in predicting the observed experimental responses suggests that the model captures the essence of the complex sensory interactions engendered by eccentric rotation and roll tilt.

  11. National Positioning, Navigation, and Timing Architecture

    DTIC Science & Technology

    2008-09-01

    frequency (RF) aids: the Global Positioning System (GPS), TACAN, VOR/DME, etc., which evolved from RF navigation systems, such as Gee and LORAN ...solutions to enhance efficiency and exploit source diversity 3) Promote, where appropriate, fusion of PNT with new and evolving communications... enhancements will result in greater capabilities that will be more commonly available. 2. Monitor PNT signals to verify service levels, observe

  12. 75 FR 68701 - Establishment and Amendment of Area Navigation (RNAV) Routes; Alaska

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-09

    ... System (GNSS) equipment, or Distance Measuring Equipment (DME)/DME Inertial Reference Unit (IRU.../DME (Lat. 64[deg]44'17'' N., long. 156[deg]46'38'' W.) ANC VOR/DME (Lat. 61[deg]09'03'' N., long. 150... (Lat. 55[deg]46'00'' N., long. 161[deg]59'56'' W.) PDN NDB/DME (Lat. 56[deg]57'15'' N., long....

  13. 78 FR 76114 - 36(b)(1) Arms Sales Notification

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-16

    ... spares 16 AN/ARC-220 HF Radios 32 AN/ARC-186 VHF AM/FM Radios 16 AN/ARN 123 VOR ILS Marker Beacons 14 AN/ARN-154(V) Tactical Air Navigation (TACAN) Systems 16 AN/ARC-201D or AN/ARC-201E VHF FM Homing Radios... Report Delivered to Congress: 3 December 2013 * as defined in Section 47(6) of the Arms Export...

  14. Physiology of Developing Gravity Receptors and Otolith-Ocular Reflexes in Rat

    NASA Technical Reports Server (NTRS)

    Blanks, Robert H.

    1997-01-01

    This proposal had the long-term objective of examining the effects of microgravity on the physiology of the adult and developing mammalian gravity receptors. The grant outlined three-years of ground-based studies to examine. 1) the physiologic responses or otolith afferents in the adult rat and during postnatal development, and 2) the otolith organ contributions to the vertical vestibulo-ocular (VOR) and postural reflexes.

  15. Adaptability of the vestibulo-ocular reflex to vision reversal in strobe reared cats.

    PubMed

    Mandl, G; Melvill Jones, G; Cynader, M

    1981-03-23

    Optical reversal of vision brings about adaptive changes in the vestibulo-ocular reflex (VOR) tending to reduce retinal image slip during head movement. The present experiments investigated this form of adaptation in cats whose complement of direction sensitive central visual cells had been substantially reduced by rearing in 8 Hz stroboscopic light. Horizontal vision reversal was produced by dove prisms carried in a skull-mounted mask. A scleral eye coil was used to measure horizontal eye movements. VOR gain and phase were measured in the dark during sinusoidal rotation using test stimuli of 1/8 Hz and 5- or 20 degrees/sec velocity amplitude. Initially, strobe reared cats produced virtually normal VOR in the dark, except for slight but significant exaggeration of the normal phase advancement to be expected at 1/8 Hz. Addition of their familiar strobe illumination produced almost perfect oculomotor compensation. Maintained vision reversal in both strobe and normal illumination produced similar patterns of adaptive change in normal and strobe reared subjects, i.e. all animals exhibited an initial fast, and subsequent much slower, stage of gain attenuation, with similar changes in phase. Thus, strobe rearing did not prevent the development of an essentially normal VOR, nor did it interfere significantly with the ability to adapt in response to vision reversal. Since strobe rearing depletes direction selective visual movement detectors in the cortex and superior colliculi, it is inferred that signals responsible for activating the adaptive process are probably carried mainly in the accessory optic, rather than cortical and collicular, visual system.

  16. Eye Movements Are Correctly Timed During Walking Despite Bilateral Vestibular Hypofunction.

    PubMed

    Anson, Eric R; Kiemel, Tim; Carey, John P; Jeka, John J

    2017-08-01

    Individuals with bilateral vestibular hypofunction (BVH) often report symptoms of oscillopsia (the perception that the world is bouncing or unstable) during walking. Efference copy/proprioception contributes to locomotion gaze stability in animals, sometimes inhibiting the vestibulo-ocular reflex (VOR). Gaze stability requires both adequate eye velocity and appropriate timing of eye movements. It is unknown whether eye velocity (VOR gain), timing (phase), or both are impaired for individuals with BVH during walking. Identifying the specific mechanism of impaired gaze stability can better inform rehabilitation options. Gaze stability was measured for eight individuals with severe BVH and eight healthy age- and gender-matched controls while performing a gaze fixation task during treadmill walking. Frequency response functions (FRF) were calculated from pitch eye and head velocity. A one-way ANOVA was conducted to determine group differences for each frequency bin of the FRF. Pearson correlation coefficients were calculated to determine the relationship between the real and imaginary parts of the FRF and the Oscillopsia Visual Analog Scale (oVAS) scores. Individuals with BVH demonstrated significantly lower gains than healthy controls above 0.5 Hz, but their phase was ideally compensatory for frequencies below 3 Hz. Higher oVAS scores were correlated with lower gain. Individuals with BVH demonstrated ideal timing for vertical eye movements while walking despite slower than ideal eye velocity when compared to healthy controls. Rehabilitation interventions focusing on enhancing VOR gain during walking should be developed to take advantage of the intact timing reported here. Specifically, training VOR gain while walking may reduce oscillopsia severity and improve quality of life.

  17. Closing the Irregular Warfare Air Capability Gap. The Missing Puzzle Piece: Rugged Utility Aircraft and Personnel

    DTIC Science & Technology

    2010-01-01

    Pilatus PC-6 Turbo Porter and the Basler BT-67 (a reengineered Douglas DC-3), available virtually off the shelf, meet the aforementioned... Pilatus PC-6 and Basler BT-67, among oth- ers.18 Although acquisition of those planes proved politically unsustainable at the time, these types of...6th SOS fa- vor the Pilatus PC-6 Turbo Porter and the Basler BT-67. Pilatus PC-6 Turbo Porter A Swiss corporation founded in 1939, Pilatus

  18. Johannes Kepler

    NASA Astrophysics Data System (ADS)

    Bialas, Volker

    Johannes Kepler (1571 - 1630) gilt zurecht als einer der bedeutendsten Mathematiker und Astronomen der frühen Neuzeit, doch wurde das Philosophische in seinem Werk bislang kaum in angemessener Weise gewürdigt. Volker Bialas legt eine fundierte und anregende Einführung in Leben, Werk und Weltanschauung Keplers vor und setzt dabei durch die Akzentuierung des philosophisch-ganzheitlichen Denkens bewußt einen Kontrapunkt zum herkömmlichen Kepler-Bild.

  19. Measurement of $W$ -Boson Helicity-Fractions in Top-Quark Decays with the CDF II Experiment and Prospects for an Early $t\\overline{t}$ Cross-Section Measurement with the CMS Experiment

    SciTech Connect

    Chwalek, Thorsten

    2010-12-02

    Aus was besteht die Welt? Die Frage nach den fundamentalen Bausteinen der Materie beschaftigte Wissenschaftler und Gelehrte zu allen Zeiten. Ausgehend von abstrakten philosophischen Uberlegungen wurde das Konzept von kleinsten, nicht weiter zerteilbaren Grundbausteinen der Materie bereits einige Jahrhunderte vor Christus von indischen und griechischen Philosophieschulen entwickelt. Etwa 450 v. Chr. pragte Demokrit den Begriff ´atomos, das “Unzerschneidbare”, fur die diskreten Grundbausteine der Materie. Doch erst in der jungeren Vergangenheit konnte dieses philosophische Konzept auch experimentell uberpruft werden.

  20. Tandem Mass Spectrometric Analysis (MS/MS) of Jet Fuels. Part 2. Quantitative Aspects of Direct MS Analysis.

    DTIC Science & Technology

    1985-07-01

    for pubZi- cation. Paul C. HIayes Jr. A.V. c URCHILL, Chief Proiect Scientist Fuels Branch vOR THE COMMANDER "-*’. "𔃼:- PO IT!T 1). ,*1RRLL, Chief F...40 30 20 13 0 20 .-.- 1 2 3 4 5 6 fraction number o3 alkones U tetralins M monoctqclics R naphthalenes 0 dict4clics 8 acenaphthenes . benzenes U other