Practice makes efficient: Effects of golf practice on brain activity

This study employed a test-retest design to examine changes in brain activity associated with practice of a motor skill. We recorded EEG activity from twelve right-handed recreational golfers (mean handicap: 23) as they putted 50 balls to a 2.4m distant hole, before and after a 3-day practice. We measured changes in putting performance, conscious processing, and regional EEG alpha activity. Putting performance improved and conscious processing decreased after practice. Mediation analyses revealed that performance improvements were associated with changes in EEG alpha, whereby activity in task-irrelevant cortical regions (temporal regions) was inhibited and functionally isolated from activity in task-relevant regions (central regions). These findings provide evidence for the development of greater neurophysiological efficiency with practice of a motor skill

Eye quietness and quiet eye in expert and novice golf performance: an electrooculographic analysis

Quiet eye (QE) is the final ocular fixation on the target of an action (e.g., the ball in golf putting). Camerabased eye-tracking studies have consistently found longer QE durations in experts than novices; however, mechanisms underlying QE are not known. To offer a new perspective we examined the feasibility of measuring the QE using electrooculography (EOG) and developed an index to assess ocular activity across time: eye quietness (EQ). Ten expert and ten novice golfers putted 60 balls to a 2.4 m distant hole. Horizontal EOG (2ms resolution) was recorded from two electrodes placed on the outer sides of the eyes. QE duration was measured using a EOG voltage threshold and comprised the sum of the pre-movement and post-movement initiation components. EQ was computed as the standard deviation of the EOG in 0.5 s bins from –4 to +2 s, relative to backswing initiation: lower values indicate less movement of the eyes, hence greater quietness. Finally, we measured club-ball address and swing durations. T-tests showed that total QE did not differ between groups (p = .31); however, experts had marginally shorter pre-movement QE (p = .08) and longer post-movement QE (p < .001) than novices. A group × time ANOVA revealed that experts had less EQ before backswing initiation and greater EQ after backswing initiation (p = .002). QE durations were inversely correlated with EQ from –1.5 to 1 s (rs = –.48 - –.90, ps = .03 - .001). Experts had longer swing durations than novices (p = .01) and, importantly, swing durations correlated positively with post-movement QE (r = .52, p = .02) and negatively with EQ from 0.5 to 1s (r = –.63, p = .003). This study demonstrates the feasibility of measuring ocular activity using EOG and validates EQ as an index of ocular activity. Its findings challenge the dominant perspective on QE and provide new evidence that expert-novice differences in ocular activity may reflect differences in the kinematics of how experts and novices execute skills

Quiet eye and eye quietness: Electrooculographic methods to study ocular activity during motor skills

Camera-based eye tracking research has revealed that experts make longer fixations on the target of an action (e.g., the ball in golf putting) prior to and following movement onset, compared to novices. Yet it is not clear how ocular activity affects motor performance. It is possible that the limited temporal resolution of camera systems has held back progress on this issue. We analysed horizontal EOG (512 Hz, 0.1-30 Hz filtered) from ten expert and ten novice golfers as they putted 60 balls to a 2.4 m distant hole. We used multiple voltage thresholds to measure the duration of the final fixation (quiet eye; QE) with its pre- and post-movement onset components. We also measured ocular activity across time as the standard deviation of the EOG in 0.5 s bins, –4 to +2 s from movement onset (eye quietness; EQ): lower values correspond with greater quietness. Finally, we measured ball address and club swing durations using infrared and sound sensors. Total QE duration did not differ between groups. However, experts had shorter pre-movement QE and longer post-movement QE than novices. Experts had less EQ before movement onset and greater EQ after movement onset. EQ was inversely correlated with QE duration, concurrently validating EQ as an index of ocular activity. Experts had longer swing durations than novices. Swing duration correlated positively with post-movement QE and negatively with post-movement EQ. Our findings provide new evidence that expert-novice differences in ocular activity may reflect differences in the kinematics of how experts and novices execute motor skills

Conscious processing and cortico-cortical functional connectivity in golf putting

The Theory of Reinvestment argues that automated motor processes are disrupted when task-related declarative knowledge is used to control movement execution. Electroencephalographic (EEG) based high-alpha band (10-12 Hz) connectivity between the left temporal (verbal/analytic processing) area and the frontal (motor planning) area has been endorsed as a neurophysiological marker of the propensity for conscious processing of declarative knowledge during movement preparation. Our study investigated the utility of left temporal to frontal connectivity in characterizing optimal golf putting performance. Ten expert and ten novice right-handed male golfers putted 120 golf balls on a flat mat to a 2.4 m distant hole while the EEG was continuously recorded. Conscious processing was assessed by a putting-specific reinvestment scale. Functional connectivity in preparation to golf putts was computed as high-alpha inter site phase clustering (ISPC), and analyzed as a function of expertise (expert, novice), performance outcome (holed, missed) and psychological pressure (low, high). We found that left (but not right) temporal-frontal ISPC was lower in experts compared to novices (M experts = .39; M novices = .48). The experts also reported lower conscious processing compared to the novices (M experts = 2.80; M novices = 3.50). Furthermore, left temporal-frontal ISPC was higher in missed versus holed putts for experts (M holed= .37; M misses = .41) and novices (M holed = .44; M misses = .51). No pressure effect was revealed (M low = .42; M high = .45). Our findings suggest that experts engage in less conscious processing compared to novices, and, in line with the Theory of Reinvestment, suggest that errors in motor performance can be prompted by excessive conscious verbal/analytic interference with movement preparation and execution. Our study findings suggest that diminished communication between the left temporal (verbal/analytic) and the frontal (pre-motor) cortical areas during movement preparation and execution is a feature of skilled motor performance. This knowledge can now be used to design connectivity-based neurofeedback training protocols to expedite motor learning and improve motor skills

Suppression of left temporal cortical activity mediates improvements in golf putting: A neural signature of expertise in precision sports?

Background and Purpose. The study of electroencephalographic (EEG) activity in precision sports has revealed that oscillatory activity within the upper-alpha frequency (10-12 Hz) recorded in the last seconds preceding skill execution can distinguish experts from novices. The power of these oscillations provides an index of neuronal suppression by a thalamic mechanism that gates resources to task-related and away from task-unrelated cortical areas. Our study employed a test-retest training paradigm to examine changes in cortical alpha activity and performance. Method. Twelve right-handed experienced golfers (age: M = 21) underwent three 1-hour putting training sessions, sandwiched between a test and retest session, during which they putted 50 balls to a standard hole at a distance of 2.4 m. Outcome (number of holed putts) and performance (radial, angle, and length errors) measures were recorded in both sessions. EEG upper-alpha power was measured from 32 scalp electrodes before (-3 s) and after (+1 s) initiation of the backswing. Results. The change in outcome and performance measures indicated that participants improved across sessions (e.g., holed putts: 12.17 during test, 16.25 during retest, P = .05). Among the performance measures, angle error was the best correlate of putting outcome during both test (r = -0.92, P < .001) and retest (r = -0.89, P < .001). The improvement in performance across sessions was fully mediated by the reduction of angle (P = .008) and radial (P = .06), but not length error. A topographical analysis of the EEG revealed that upper-alpha power was lowest in central areas and highest in temporal-occipital areas (P < .001). The improvements in putting outcome (P = .02) and angle error (P = .03) across sessions were partially mediated by higher power in the left temporal area in the last second preceding backswing initiation. Conclusion. The present findings confirm that improvements in putting outcome are largely attributable to decreases in putter head angle at impact. The topographical pattern displayed by preparatory upper-alpha power is consistent with the gating of resources to central sensorimotor areas and away from temporal and occipital areas. Importantly, increased inhibition of cognitive (e.g., language) processes performed in the left temporal cortex partially accounted for improved putting outcome and performance. Finally, data on self-reported measures (e.g., conscious processing) as well as limitations and further directions will be presented and discussed in relation to alpha gating

Hepatosplenic Gamma/Delta T-Cell Lymphoma Masquerading as Alcoholic Hepatitis and Methadone Withdrawal

Hepatosplenic gamma/delta T-cell lymphoma is a rare neoplasm of mature gamma/delta T-cells with sinusoidal infiltration of spleen, liver, and bone marrow. Patients are predominantly adolescent and young adult males and usually present with marked hepatosplenomegaly. Pancytopenia is another common finding. Despite an initial response to treatment, patients have a median survival of one to two years. In this report, we document a case of alcoholic hepatitis and methadone withdrawal masquerading unsuspected, hepatosplenic gamma/delta T-cell lymphoma with unusual CD20 positivity

NASA-JSC antenna near-field measurement system

Work was completed on the near-field range control software. The capabilities of the data processing software were expanded with the addition of probe compensation. In addition, the user can process the measured data from the same computer terminal used for range control. The design of the laser metrology system was completed. It provides precise measruement of probe location during near-field measurements as well as position data for control of the translation beam and probe cart. A near-field range measurement system was designed, fabricated, and tested

Observation of magnetization reversal and negative magnetization in a double perovskite compound Sr2YbRuO6

Detailed magnetic properties of the compound Sr2YbRuO6 are presented here. The compound belongs to the family of double perovskites forming a monoclinic structure. Magnetization meas-urements reveal clear evidence for two components of magnetic ordering aligned opposite to each other, leading to a magnetization reversal, compensation temperature (T* = 34 K) and neg-ative magnetization at low temperatures and low magnetic fields. Heat capacity measurements corroborate the presence of two components in the magnetic ordering and a noticeable third anomaly at low temperatures (~15 K) which cannot be attributed the Schottky effect. The calcu-lated magnetic entropy is substantially lower than that expected for the ground states of the or-dered moments of Ru5+ and Yb3+, indicating the presence of large crystal field effects and/ or in-complete magnetic ordering and/or magnetic frustrations well above the magnetic ordering. An attempt is made to explain the magnetization reversal within the frameworks of available models.Comment: 15 pages text, 6 figures Journal-ref: J.Phys.:Condens.Matter 20(2008)23520

Long-term microparticle flux variability indicated by comparison of Interplanetary Dust Experiment (IDE) timed impacts for LDEF's first year in orbit with impact data for the entire 5.77-year orbital lifetime

The electronic sensors of the Interplanetary Dust Experiment (IDE) recorded precise impact times and approximate directions for submicron to approximately 100 micron size particles on all six primary sides of the spacecraft for the first 346 days of the LDEF orbital mission. Previously-reported analyses of the timed impact data have established their spatio-temporal features, including the demonstration that a preponderance of the particles in this regime are orbital debris and that a large fraction of the debris particles are encountered in megameter-size clouds. Short-term fluxes within such clouds can rise several orders of magnitude above the long-term average. These unexpectedly large short-term variations in debris flux raise the question of how representative an indication of the multi-year average flux is given by the nearly one year of timed data. One of the goals of the IDE was to conduct an optical survey of impact sites on detectors that remained active during the entire LDEF mission, to obtain full-mission fluxes. We present here the comparisons and contrasts among the new IDE optical survey impact data, the IDE first-year timed impact data, and impact data from other LDEF micrometeoroid and debris experiments. The following observations are reported: (1) the 5.77 year long-term integrated microparticle impact fluxes recorded by IDE detectors matched the integrated impact fluxes measured by other LDEF investigators for the same period; (2) IDE integrated microparticle impact fluxes varied by factors from 0.5 to 8.3 for LDEF days 1-346, 347-2106 and 1-2106 (5.77 years) on rows 3 (trailing edge, or West), 6 (South side), 12 (North side), and the Earth and Space ends; and (3) IDE integrated microparticle impact fluxes varied less than 3 percent for LDEF days 1-346, 347-2106 and 1-2106 (5.77 years) on row 9 (leading edge, or East). These results give further evidence of the accuracy and internal consistency of the recorded IDE impact data. This leads to the further conclusion that the utility of long-term ratios for impacts on various sides of a stabilized satellite in low Earth orbit (LEO) is extremely limited. These observations and their consequences highlight the need for continuous, real time monitoring of the dynamic microparticle environment in LEO