Separating processes within a trial in event-related functional MRI I. The Method.

J M Ollinger; G L Shulman; M Corbetta

doi:10.1006/nimg.2000.0710

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Separating processes within a trial in event-related functional MRI I. The Method.

J M Ollinger·G L Shulman·M Corbetta

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Abstract

Many behavioral paradigms involve temporally overlapping sensory, cognitive, and motor components within a single trial. The complex interplay among these factors makes it desirable to separate the components of the total response without assumptions about shape of the underlying hemodynamic response. We present a method that does this. Four conditions were studied in four subjects to validate the method. Two conditions involved rapid event-related studies, one with a low-contrast (5%) flickering checkerboard and another with a high-contrast (95%) checkerboard. In the third condition, the same high-contrast checkerboard was presented with widely spaced trials. Finally, multicomponent trials were formed from temporally adjacent low-contrast and high-contrast stimuli. These trials were presented as a rapid event-related study. Low-contrast stimuli presented in isolation (partial trials) made it possible to uniquely estimate both the low-contrast and high-contrast responses. These estimated responses matched those measured in the first three conditions, thereby validating the method. Nonlinear interactions between adjacent low-contrast and high-contrast responses were shown to be significant but weak in two of the four subjects.

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Algorithms Evoked Potentials Functional Laterality Hemodynamics Humans Image Processing, Computer-Assisted Linear Models Magnetic Resonance Imaging Models, Neurological Time Factors Journal Article Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, P.H.S.

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J M Ollinger, G L Shulman, M Corbetta. 2001. Separating processes within a trial in event-related functional MRI I. The Method.. https://doi.org/10.1006/nimg.2000.0710

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