Fig. 2: Cortical input/output organization of the DPs, DPd and other MPF areas.
a, Distribution map of cortical neurons projecting to the DPs, DPd and other MPF areas from retrograde tracing experiments, revealing diverse cortical inputs (left). Right, quantified cortical inputs to the DPs and DPd (representative CTB-labelled neurons are shown; the full datasets and connectivity map are shown in Extended Data Figs. 9 and 10 and Supplementary Fig. 7; all MPF cases are available at https://brain.neurobio.ucla.edu/mpf/; validation of the connections is provided in Extended Data Fig. 11a,b). b, Summary of inputs to the DPs and DPd from cortical, amygdalar and hippocampal regions. c, Anterograde tracing confirmed distinct ENTl inputs: Cux2-positive L2/3 neurons project to the DPs, while L5/6 neurons target the DPd. d, Quantitative comparison of DPs outputs to, and inputs from, other MPF (ILA, PL, ACAv, ACAd) and cortical (medial orbitofrontal area (ORBm), MOp, MOs) areas (top). Middle, PHAL-labelled axons from the DPs travel through layer 1 and deep layer 5, terminating densely in the MPF, MOp, MOs and association cortices (for example, PTLp, RSPd, visual areas; Extended Data Fig. 11e). Bottom, by contrast, retrograde CTB labelling reveals sparse DPs input from these regions (see Extended Data Figs. 5a,b and 10a for PHAL and CTB injections). These data highlight the primarily unidirectional DPs to cortex connections. e, Schematic of the DP as a network hub relaying inputs from cortical areas within the lateral cortical network28, olfactory cortex (OLF), amygdala (AMY) and hippocampus (HPF) to other MPF and cortical areas within the medial cortical network28 and somatic sensorimotor cortices. f, 2D hierarchical clustering of the MPF to cortex projection fraction matrix reveals distinct clusters of cortical targets for the DPs, DPd and other MPF areas (based on anterograde tracer injections made into each MPF area). Prefrontal (PFC) regions are grouped to the left of the grey line; additional clusters are boxed in colour. Further details are provided in the Supplementary Results. Scale bars, 200 μm (d (right)), 300 μm (c (top)) and 500 μm (a, c (bottom) and d (left and middle)). A full list of abbreviations is provided in Supplementary Table 1.
