Simple brain mechanisms explain arbitrary human visual...( St. Louis Nov. 9 2007 Mark Twain a ...),Health

St. Louis, Nov. 9, 2007 Mark Twain, a skeptic of the idea of free will, argues in his essay "What Is Man?" that humans do not command their minds or the opinions they form.

"You did not form that [opinion]," a speaker identified as "old man" says in the essay. "Your [mental] machinery did it for youautomatically and instantly, without reflection or the need of it."

Twain's views get a boost this week from researchers at Washington University School of Medicine in St. Louis and University of Chieti, Italy. In Nature Neuroscience, scientists report that a simple decision-making task does not involve the frontal lobes, where many of the higher aspects of human cognition, including self-awareness, are thought to originate. Instead, the regions that decide are the same brain regions that receive stimuli relevant to the decision and control the body's response to it.

Other researchers had already demonstrated the same principle in primates. But many still assumed that the more complex human brain would have a more general decision-making module that involved the frontal lobe independently of the neural systems for perception and action.

"It is important to understand how the brain makes decisions under normal conditions to gain insight into diseases like Alzheimer's disease, traumatic brain injury or stroke in which decision-making is disrupted," says senior author Maurizio Corbetta, M.D., the Norman J. Stupp Professor of Neurology. "We like to think of our decisions as willful acts, but that may be an illusion. Many decisions may be much more directly and automatically driven by what our brain is sensing."

For the study, lead author Annalisa Tosoni, a graduate student at the University of Chieti, trained volunteers to perform a task that involved discriminating between an image of a face and an image of a building. Varying degrees of noise obscured the image during the brief time it was visible. Volunteers were
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