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Tuesday, April 29, 2008

Hurricanes & Brains

The networks of nerve cells in our brain are often described as self-organizing. That is, intrinsic features of the nerve cells and the fashion in which the cells relate determine the shape the network. However, the mechanisms underlying the capacity of the neural population to shape itself are poorly understood. Better insight may be gained from the examination of other natural phenomena with self-organizing properties that emerge from complex interactions between the phenomenon and its environment. In meteorology, hurricanes and tornadoes constitute examples of self-organization.

While I was a postdoctoral fellow at the National Institutes of Health 15 years ago, I was privileged to witness the presentation of a team of Russian researchers who developed a method to image changes in temperature within 0.1°  C on the surface of the brain through the skull. Local increases in temperature were associated with increases in cortical blood flow. Local cerebral blood flow, in turn, is related to nerve cell activity. The Russians sought to present a novel method to indirectly map cortical activity. Data obtained with this method was eventually reviewed years later in the journal Progress of Neurobiology.

In their presentation, the Russians showed temporal sequences of neural activation racing across cortex in a rat. The rat's whiskers on the face were stimulated. About one fifth of the rat's cortex processes sensory input from the whiskers. The animation showed bands of activation racing across the expanse of cortex nose-ward similar in appearance to tropical storms before the clouds coil around the center. This similarity sparked my interest in the development of tropical cyclones.

The hurricane season is about to begin. Reuters reported a week ago that an active Atlantic season is forecast. The National Hurricane Center (NHC) provides access to geographic information system (GIS) data that can be used as a starting point to examine the conditions conducive to self-organization. I am using Apple Macintosh computers for much of my work and compiled two software applications that may be useful in this process. One is a custom build of GRASS version 6.3 for Tiger. Version 7.0 for Leopard will be working before June 1. A demonstration of this application can be viewed at slideshare. The other application is a build of version 1.9 of degrib for Tiger. Version 1.91 for Leopard will be ready at the completion of GRASS 7.0. Instructions for the use of degrib can be found on the NHC web site. The applications run only on the Intel architecture. They are going to be available for download on my Sourceforge.net project site known as "Software for Small Budget Science". Join the effort!

Addenda

  • In this informative and richly illustrated report with the title "Studying Storms: NASA Looks For Hurricane's Secrets" aired today on NPR's Morning Edition, Jon Hamilton describes a meteorological reconnaissance mission examining Hurricane Karl. The cyclone formed in the Caribbean Sea and strengthened to a category 3 storm in less than a day after reaching the Gulf of Mexico where it made landfall near Veracruz on Sep. 17 (09/28/10).



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