Mediodorsal and ventromedial thalamus engage distinct L1 circuits in the prefrontal cortex

Interactions between the thalamus and prefrontal cortex (PFC) play a critical role in cognitive function and arousal. Here we use anatomical tracing, electrophysiology, optogenetics, and 2-photon Ca2+ imaging to determine how ventromedial (VM) and mediodorsal (MD) thalamus target specific cell types and subcellular compartments in layer 1 (L1) of mouse PFC. We find thalamic inputs make distinct connections in L1, where VM engages NDNF+ cells in L1a, and MD drives VIP+ cells in L1b. These separate populations of L1 interneurons participate in different disinhibitory networks in superficial layers by targeting either PV+ or SOM+ interneurons. NDNF+ cells also inhibit the apical dendrites of L5 pyramidal tract (PT) cells, where they suppress AP-evoked Ca2+ signals. Lastly, NDNF+ cells mediate a unique form of thalamus-evoked inhibition at PT cells, selectively blocking VM-evoked dendritic Ca2+ spikes. Together, our findings reveal how two thalamic nuclei differentially communicate with the PFC through distinct L1 micro-circuits.