A Model of Movement Coordinates in Motor Cortex: Posture-Dependent Changes in the Gain and Direction of Single Cell Tuning Curves

Central to the problem of elucidating the cortical mechanisms that mediate movement behavior is an investigation of the coordinate systems by which movement variables are encoded in the firing rates of individual motor cortical neurons. In the last decade, neurophysiologists have probed how the preferred direction of an individual motor cortical cell (as determined by a center-out task) will change with posture because such changes are useful for inferring underlying cordinates. However, while the importance of shifts in preferred direction is well-known and widely accepted, posture-dependent changes in the depth of modulation of a cell's tuning curve, i.e. gain changes, have not been similarly identified as a means of coordinate inference. This paper develops a vector field framework which, by viewing the preferred direction and the gain of a cell's tuning curve as dual components of a unitary response vector, can compute how each aspect of cell response covaries with posture as a function of the coordinate system in which a given cell is hypothesized to encode its movement information. This integrated approach leads to a model of motor cortical cell activity that codifies the following four observations: 1) cell activity correlates with hand movement direction, 2) cell activity correlates with hand movement speed, 3) preferred directions vary with posture, and 4) the modulation depth of tuning curves varies with posture. Finally, the model suggests general methods for testing coordinate hypotheses at the single cell level and example protocols arc simulated for three possible coordinate systems: Cartesian spatial, shoulder-centered, and joint angle.Defense Advanced Research Projects Agency (N00014-92-J-4015); Defense Advanced Research Projects Agency and the Office of Naval Research (N00014-95-1-0409); National Science Foundation (IRI-90-00530, IRI-97-20333); Office of Naval Research (N00014-91-J-4100, N00014-92-J-1309, N00014-94-l-0940, N00014-95-1-0657)

The 1997 U.S.-Japan Defense Guidelines under the Japanese Constitution and Their Implications for U.S. Foreign Policy

The 1997 U.S.-Japan Defense Guidelines represent additional commitment by Japan to the U.S.-Japan security alliance, the primary source of Northeast Asian security and stability. Certain tasks within Japan\u27s enhanced role raise questions of whether the Guidelines are compatible with Article 9 of Japan\u27s Constitution. On its face, Article 9 renounces Japan\u27s right to wage war or maintain military force, yet it has been interpreted to allow a defensively-oriented, though massive, military. Based on the existing interpretation of Article 9, it is likely that Japan will declare its new role under the Guidelines constitutional. U.S. policy toward Japan in the short-term is to clarify the division of roles in the alliance to stabilize Northeast Asia. This Comment argues that the U.S. security guarantee prevents Japan from acting like a self-sufficient country. Consequently, U.S. long-term policy should be to withdraw from the role of Japan\u27s protector wherever possible to encourage Japan to act more like a leader internationally

A Hard Scientific Quest: Understanding Voluntary Movements

In this article we explore the complexities of what goes on in the brain when one wishes to perform even the simplest everyday movements. In doing so, we describe experiments indicating that the spinal cord interneurons are organized in functional modules and that each module activates a distinct set of muscles. Through these modules the central nervous system has found a simple solution to controlling the large number of muscle fibers active even during the execution of the simplest action. We also explore the many different neural signals that contribute to pattern formations, including afferent information from the limbs and information of motor memories.National Science Foundation (U.S.) (Grant IIS-0904594)National Institutes of Health (U.S.) (Grant NS44393)National Institutes of Health (U.S.) (Grant NS068103

Analysis Of Stray Radiation Produced By The Advanced Light Source (1.9 Gev Synchrotron Radiation Source) At Lawrence Berkeley Laboratory

The yearly environmental dose equivalent likely to result at the closest site boundary from the Advanced Light Source was determined by generating multiple linear regressions. The independent variables comprised quantified accelerator operating parameters and measurements from synchronized, in-close (outside shielding prior to significant atmospheric scattering), state-of-the-art neutron remmeters and photon G-M tubes. Neutron regression models were more successful than photon models due to lower relative background radiation and redundant detectors at the site boundary. As expected, Storage Ring Beam Fill and Beam Crashes produced radiation at a higher rate than gradual Beam Decay; however, only the latter did not include zero in its 95% confidence interval. By summing for all three accelerator operating modes, a combined yearly DE of 43 mRem/yr with a 90% CI of (0.04-8.63) was obtained. These results fall below the DOE reporting level of 10 mRem/year and suggest repeating the study with improved experimental conditions.Master of Science in Public Healt

Don’t Make a Scene: The Representation of the Arthurian Love Triangle in the ‘English Tradition’ of Text and Film

The Arthurian legend has been part of history through different mediums ranging from art to film. Though no one text can be identified as the origin of the Arthurian legend, several texts have come to the forefront of the Arthurian canon. The “English tradition” consists of texts Britain and America recognize as versions of the Arthurian legend: Sir Thomas Malory’s Le Morte D’Arthur, Lord Alfred Tennyson’s The Idylls of the King, and T.H. White’s The Once and Future King. All three texts have caused different subsequent adaptations of the Arthurian legend as each portrays the Arthur, Guinevere, and Lancelot love triangle differently. As film became introduced to popular culture, Arthurian legends have been frequently presented on the silver screen. Three films in particular, Richard Thorpe’s Knights of the Round Table (1953), Joshua Logan’s Camelot (1967), and John Boorman’s Excalibur (1981), have not only presented the Arthurian legend differently based on the interpretations of the director, but also focused on the love triangle in varying ways. By analyzing these select texts and films, an understanding of how, why, and to what purpose the Arthurian love triangle has been presented to audiences since the fifteenth century can be gained