The functional role of the frontal cortex in pre-attentive auditory change detection

Abstract

Accounts of the functional role of the frontal cortex in pre-attentive auditory change detection include attention switching, response inhibition, contrast enhancement, and activation of a predictive model. These accounts assume different sequential activation patterns between the temporal and frontal cortices: Change detection in the auditory areas of the superior temporal cortex (STC) followed by inferior frontal cortex (IFC) activation for attention switching and response inhibition; STC preceded by IFC activation for contrast enhancement; and an IFC–STC–IFC activation sequence for the predictive model. We used the event-related optical signal (EROS), which provides a temporal resolution of milliseconds and a spatial resolution of 5 to 10mm, combined with lagged correlation path modeling to examine the response of the right frontal and temporal cortices to auditory duration deviants of varying magnitude. Event-related potentials (ERPs) were also recorded, as was the slow optical (hemodynamic) brain response. The data analyses revealed temporal–frontal, frontal–temporal–frontal, and temporal–frontal activation patterns when the deviants represented relatively large, medium, and small changes from the standard stimulus, respectively. These results indicate that the degree of deviance modulates spatio-temporal dynamics within the STC–IFC auditory change detection network.