, monitoring how the patients’ brains reacted to a series of auditory stimuli.
Clark’s team conducted neuropsychological tests, including memory tests, of research subjects and evaluated their scores to decide whether they were suited for the study.
Kounios and his team acquired the EEG data from the participants. They used a specific protocol, called the “oddball paradigm with novel sounds,” to collect the EEG signals, during which patients hear a series of low- and high-frequency tones as well as some novel sounds. Patients were asked to respond by pressing a button every time they heard the high frequency tone, also known as the “oddball” tone, which generates ERPs in the EEG. Generally, in the ERP of a person without Alzheimer’s, that response registers a peak, the P300, about 300 milliseconds after the “oddball” tone. People with dementia, particularly Alzheimer’s, may exhibit that peak much later than 300 milliseconds, show a much weaker peak or have no peak at all, according to Polikar. Kounios said the P300 signal is generated by areas of the brain that seem to be attacked at an early phase of Alzheimer’s disease, but the results are not always conclusive.
Polikar and his students analyzed the data using sophisticated signal processing, pattern recognition and artificial intelligence techniques to explore the hypothesis that the entire ERP signal, not just the P300 indicator, reveals markers that previously have not been associated with Alzheimer’s disease.
The teams conducted several experiments, ultimately evaluating the parietal and occipital regions of the brains of 71 patients, some already diagnosed with Alzheimer’s and some without Alzheimer’s. Their diagnostic accuracy rate was 82 to 85 percent using the EEGs (e.g., it matched evaluations conducted at Penn 82 to 85 percent of the time). Alzheimer’s disease cannot be confirmed until a patient has died and his or her brain has been examined. Gold standardPage: 1 2 3 4 Related medicine news :1
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