An attempt is made to elucidate the information processing activities in which the brain is engaged during cognitive task performance. The primary experimental objective is to demonstrate localization and temporal sequencing of the functional steps carried out by human and nonhuman primate subjects during performance of sensory discrimination tasks, i.e. to identify the locale and sequence of activation of those regions responsible for the steps of cognitive processing. Signal processing and multivariate statistical procedures are applied to evoked transcortical and scalp recordings to identify the location and order of occurrence of signals which are effective in discriminating task conditions and parameters. Results using multivariate template matching and a unique feature extraction technique based on canonical variate time series analysis are compared. This work not only provides information about the brain mechanisms responsible for cognition, but also demonstrates a set of powerful multivariate analytic tools for mapping the location and sequencing of brain functions.
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