The right inferior frontal cortex (rIFC) is frequently activated during executive control tasks. Whereas the function of the dorsal portion of rIFC, more precisely the inferior frontal junction (rIFJ), is convergingly assigned to the attention system, the functional key role of the ventral portion, i.e., the inferior frontal gyrus (rIFG), is hitherto controversially debated. Here, we used a two-step methodical approach to clarify the differential function of rIFJ and rIFG. First, we used event-related functional magnetic resonance imaging (fMRI) during a modified stop signal task with an attentional capture condition (acSST) to delineate attentional from inhibitory motor processes (step 1). Then, we applied coordinate-based meta-analytic connectivity modeling (MACM) to assess functional connectivity profiles of rIFJ and rIFG across various paradigm classes (step 2). As hypothesized, rIFJ activity was associated with the detection of salient stimuli, and was functionally connected to areas of the ventral and dorsal attention network. RIFG was activated during successful response inhibition even when controlling for attentional capture and revealed the highest functional connectivity with core motor areas. Thereby, rIFJ and rIFG delineated largely independent brain networks for attention and motor control. MACM results attributed a more specific attentional function to rIFJ, suggesting an integrative role between stimulus-driven ventral and goal-directed dorsal attention processes. In contrast, rIFG was disclosed as a region of the motor control but not attention system, being essential for response inhibition. The current study provides decisive evidence regarding a more precise functional characterization of rIFC subregions in attention and inhibition.
Keywords: Attentional capture; Functional magnetic resonance imaging; Meta-analytic connectivity modeling; Right inferior frontal cortex; Right inferior frontal junction; Stop signal task.