Effects of varying the experimental design of a cognitive control paradigm on behavioral and functional imaging outcome measures.

Abstract A number of experimental techniques are commonly used within the field of functional neuroimaging to measure successive cognitive processes within a single trial. This study evaluated three experimental techniques to assess the comparability of behavioral and functional outcome measures in a task involving higher-level cognitive processing while controlling for the task duration. Twelve participants completed a cognitive control paradigm using the three techniques. Each trial of the task consisted of a green or red cue followed by a "Left" or "Right" probe. Green cues indicated that participants should respond in the direction of the probe. Red cues indicated participants should overcome their automatic tendency and respond in the direction opposite to the probe. The "slow" technique involved a sufficiently long trial allowing the blood oxygenation level-dependent response to rise and return to baseline before the next trial. The "jitter" technique involved varying the interstimulus and intertrial intervals. The "catch" technique involved presenting some cue-only trials in the midst of cue-probe trials. Predicted brain regions were activated by all the experimental techniques combined including the middle frontal, anterior cingulate, and inferior parietal cortices. Although there were more commonalties than differences between the three experimental techniques, generally, it appeared that the slow technique was effective at detecting posterior activity; the jitter technique was effective at detecting probe-related activity; and the catch technique was effective at detecting cue-related activity, especially in prefrontal regions. Thus, experiments measuring successive cognitive processes may have differential detection power for every event in a trial.