DETECTION OF CORTICAL ACTIVATION DURING AVERAGED SINGLE TRIALS OF A COGNITIVE TASK USING FUNCTIONAL MAGNETIC-RESONANCE-IMAGING

Functional neuroimaging studies in human subjects using positron emiss ion tomograph or functional magnetic resonance imaging (fMRI) are typi cally conducted by collecting data over extended time periods that con tain many similar trials of a task. Here methods for acquiring fMRI da ta from single trials of a cognitive task are reported, In experiment one, whole brain fMRI was used to reliably detect single-trial respons es in a prefrontal region within single subjects. In experiment two, h igher temporal sampling of a more limited spatial field Has used to me asure temporal offsets between regions, Activation maps produced solel y from the single-trial data were comparable to those produced from bl ocked runs. These findings suggest that single-trial paradigms a will be able to exploit the high temporal resolution of fMRI. Such paradigm s will provide experimental flexibility and time-resolved data for ind ividual brain regions on a trial-by-trial basis.