The Dentate Gyrus (DG) receives rich multimodal inputs from the entorhinal cortex through the perforant path, and it translates them into a sparse code for the CA3. During the exploration of new environments, groups of DG granule cells (GCs) become active and form new memories. The activity of GCs is strongly modulated by a large network of inhibitory interneurons (INs) that allow the sparsification and orthogonalization of cortical inputs. Recently, a novel population of GABAergic INs expressing the Neuron-Derived Neutrophic Factor (NDNFIs) has been identified as a key component in the modulation of cortical networks and CA1 hippocampal region. We found that NDNFIs are also integral part of the DG network where they provide distal dendritic inhibition to GCs. We investigated their distribution, morphology, electrophysiological properties, and functional connectivity. We distinguished 2 subpopulations of DG NDNFIs based on their soma location: molecular layer NDNFIs (ML-NDNFIs) and hilar NDNFIs (hNDNFIs). ML-NDNFIs and hNDNFIs show different morphological and electrophysiological characteristics, and they receive synaptic inputs prevalently from the perforant path and mossy fibers’ collaterals, respectively. Thus, we propose they differently contribute to feedforward and feedback control of GCs. Using in-vivo 2-photon calcium imaging and optogenetic manipulations we are currently investigating the activity dynamics of NDNFIs during spatial navigation and their contribution to the DG function. Combining ex-vivo and in-vivo approaches, we will provide the first functional characterization of DG NDNFIs, and we will address their impact on DG network dynamics and memory formation.