Get access

Fast optical imaging of frontal cortex during active and passive oddball tasks


  • This work was funded by a DARPA grant (via NSF EIA 00-79800 AFK) to G. Gratton and M. Fabiani. We thank Charles L. Brown III for computer programming and technical assistance on the waveform display program and Dr. David Friedman for allowing us access to software developed in his laboratory.

Address reprint requests to: Gabriele Gratton, University of Illinois, 2161 Beckman Institute MC-251, 405 N. Mathews Ave., Urbana, IL 61801, USA. E-mail:


This study used the high spatial and temporal resolution of the event-related optical signal (EROS) to investigate the timing of neuronal activity in frontal cortex during auditory target detection and passive oddball tasks. Activation in right middle frontal gyrus (MFG) peaked approximately 350 ms following rare target tones. This corresponded closely to the latency of the simultaneously recorded electrical P3 component. In addition, we found activation in left lateral MFG peaking at approximately 130 ms following tone onset for conditions that may have required response inhibition. These results correspond with activation patterns observed in similar fMRI studies, but provide temporal tags for the activated locations. These data may help bridge the gap between electrophysiological and hemodynamic measures of target detection and contribute to our understanding of the spatiotemporal dynamics of brain activity during target processing.