Utilizing hemodynamic delay and dispersion to detect fMRI signal change without auditory interference: the behavior interleaved gradients technique.

A major problem associated with the use of functional magnetic resonance imaging (fMRI) is the attendant gradient noise, which causes undesirable auditory system stimulation. A method is presented here that delays data acquisition to a period immediately after task completion, utilizing the physiological delay and dispersion between neuronal activity and its resulting hemodynamic lag. Subjects performed finger movements with the gradients off, followed by a rest period with the gradients on. This resulted in task-related signals comparable to those obtained with concurrent task performance and image data acquisition. This behavior interleaved gradients technique may be particularly useful for the studies involving auditory stimulation or overt verbal responses.