Prefrontal orchestration: Cortical networks for rodent action control

Goal-directed action control relies on the prefrontal cortex (PFC), where distinct subsections collaborate in functional networks. The extent to which the network favors a hierarchical system, characterized by early convergence within the PFC, versus a shallow brain hypothesis, featuring numerous parallel circuits from the cortex to downstream targets, remains elusive (Suzuki et al. 2023). Employing optogenetic modulation, behavioral assessments, and fMRI, we investigate the impact of PFC subarea-stimulation on motor control and whole-brain activation patterns. We quantified error rate and reaction time as indicators of action control for rats performing in a response-preparation task. Contrary to prior findings of distinct effects during individual PFC subsection-inhibition (Hardung et al., 2017), optogenetic activation produced similar behavioral effects across these areas. To investigate potential network points underlying these similar effects, we utilized opto-fMRI to identify downstream activation regions shared by subsection-specific stimulation; this revealed a common activation region independent of the exact PFC stimulation site, spanning the prefrontal cortex, olfactory system, basal forebrain, and motor cortex. Stimulation of the infralimbic cortex (IL) unveiled activation areas that delineated the overlapping activation volume among all subsection-stimulations, highlighting IL as a hub for shared PFC local interconnectivity and action control. By further investigating connectivity within this region through multisite in-vivo recordings, we uncovered dynamic synchrony between the prelimbic cortex (PL) and IL during correct trials. Together, our findings reveal task-specific and performance-dependent synchrony and identify primarily cortical shared activation regions among separate PFC subsections, emphasizing the importance of local network convergence for motor control.