Insight from broken brains

Article Abstract:

A husband and wife team of neurologists, Antonio and Hanna Damasio, have developed a registry of case histories of 1,500 people with specific brain lesions, the largest of its kind in the world. The patients with these lesions have agreed to participate in experiments, which will shed light on many unsolved mysteries of the human brain. By looking at how a brain works when it is 'broken', and studying the manifestations in behavior, intellect and memory, valuable information is assembled on the workings of unbroken nervous pathways. Since there can be no experimentation on live human brains, much of what is already known about these pathways has been elucidated from animal studies. The patients who the Damasios have gathered for their work have specific brain lesions, not general or diffuse brain damage. Follow-up on these patients is extensive and continuous, with 99 percent coming in to see the Damasios whenever they are called. The study of brain lesions is not new, but with the availability of imaging techniques, such as the CT scan (computer-assisted tomography) and MRI (magnetic resonance imaging), these lesions can now be located with great accuracy. Previously, information could only be obtained with similar accuracy on autopsy, allowing only retrospective conclusions and insights into the functions of the brain. Now, specifically designed direct questioning and task performance results can help to acquire desired information. To date, Antonio Damasio's work has led him to develop several hypotheses, including his concept on convergence zones, which allow visual and intellectual information to converge with emotional reactions and create a larger understanding of what is being perceived. He feels that his convergence zone theories may help explain why some convicted murderers do not experience the wrongness of their actions, even though they understand them to be wrong. Several fascinating case histories demonstrate the distinctions in memory and consciousness that arise after specific brain damage occurs, and prompt an appreciation of the complex integration that is occurring when a normal neurological response is achieved. (Consumer Summary produced by Reliance Medical Information, Inc.)

Psychological aspects, Reports, Brain, Neurology, Registries (in medicine), Registries (Medicine), Localization (Brain function), Brain damage

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Why statistics may understate the risk of heart disease

Article Abstract:

Richard Peto, a statistician, has proposed a method of analyzing the vast amount of available data that exists concerning the relationship between blood cholesterol levels and heart disease. His method is called meta-analysis. It pools results from several studies, regardless of differences between them in methodology or subjects. Peto explains how his approach works by sketching out an imaginary country where everyone has either high (240 mg per deciliter of blood) or low (200 mg per deciliter) cholesterol. A study of 100,000 of the citizens of that country would show that half are high and half are low. If, however, the laboratory performing the blood chemistry makes random errors that add or subtract 20 mg from each score, the values obtained will differ. A true value of 200 will then be reported as either 220 mg or 180 mg, and a true value of 240 will be 260 or 220. Now half the people will appear to be in the middle range, one-fourth low, and one-fourth high and the relationship that exists between heart disease and cholesterol levels will seem less than it really is. Random errors, as well as other types of error, can influence data in many ways, and Peto and his colleagues have suggested solutions to these statistical problems as they concern cholesterol research. (Consumer Summary produced by Reliance Medical Information, Inc.)

Evaluation, Risk factors, Statistics, Coronary heart disease, Blood cholesterol, Medical statistics, Peto, Richard

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