Although the reasons for the dissociation of aura and headache are unclear, several facts are worth noting: First, aura may occur with primary headache disorders besides migraine, and an aura can occur in patients with structural brain lesions. Second, the tendency to experience aura may be inherited as a trait that is distinct from the inherited tendency to experience recurrent attacks of migraine headache and its other associated symptoms.

The reason aura is more common in migraine sufferers (30 percent) than in the general population (1 to 2 percent) may be that the physiological consequences of one trigger the symptoms of the other when the two traits coexist. For example, cortical spreading depression (CSD) can activate trigeminal pain fibers and may trigger a migraine headache in migraine sufferers. In those not predisposed to migraine, CSD may lead to a mild nonmigraine headache or to no headache. Conversely, the putative brain stem generator for migraine may generate changes in metabolic activity of cortical neurons and glia, altering cerebral blood flow, which may trigger aura symptoms in an individual predisposed to CSD. The reason for aura symptoms’ connection with age is unknown. Future research will, we hope, unravel this mystery.

Benefits to Burning?
“The Puzzling Inferno,” by Keren Blank­feld Schultz [News Scan], discusses the finding that suppressing forest fires reduces carbon sequestering because frequent fires favor the growth of more mature trees, which store carbon more effectively. The story refers to prescribed fires as a solution, but other news media have reported the severe health effects of smoke from this year’s wildfires. Frequent harvesting of immature trees and dead debris would also promote growth of mature trees. A good, technical assessment on the costs and benefits of forest burnings is sorely needed.
Dick Windgassen
Venice, Fla.

Note: This article was originally printed with the title, "Letters".

3 Comments

1. 1. Bill Case 03:22 AM 12/12/08

   I couldn't help noticing that the authors coupled the fresh water supplies of Canada and the United States. It is a bad habit of American intellectuals which they should break. Canada's fresh water is not, let me repeat not, a source of water for the United States. Most Canadians have long rejected the idea, and would never support a Canadian Government that even contemplated routing water southward.

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2. 2. Laurasis2c in reply to Bill Case 02:09 PM 12/12/08

   Have you considered that there are purification systems that can be developed for individual use such as the STiri Straw and larger portable units that can purify water for entire communities. I'm just concerned that the issue of water becomes a fear based one rather than the real issue which is that local politics like to starve communities so there own power will be unchallenged. Keep it real all the way around. Water can be an issue to make people more fearful rather than exploring the solutions that already exist. Good luck.

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3. 3. shopa 06:00 PM 12/14/08

   Please see my website www.electric-fluid-pipeline.com
   to see my invention of a new way to move water. It can be used to fight wildfires, and to bring water, electric power, and communications to regions suffering from drought.

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