Spatially modulated tuning and sequential activity in the CA1 region of the hippocampus is essential for the formation of new memories. Because cells within CA1 do not have local excitatory projections, it is currently presumed that most of the computations that support this complex spatial activity occur upstream of CA1, and that CA1 merely reflects tuning from its upstream partners – area CA3 of the hippocampus, and the medial entorhinal cortex (mEC). During the first two years of my postdoc, I addressed this question by performing simultaneous reversible silencing of both mEC and CA3 as mice performed a hippocampus-dependent memory task. While each manipulation had unique effects of local field oscillations and unit firing, the proportion of place cells and cell assemblies in CA1 was unaffected despite complete silencing of the major synaptic inputs. These results suggest that excitatory-inhibitory connections within CA1 are sufficient to generate cell assemblies with minimal reliance on upstream inputs (Zutshi et al, 2022). These results were further supported as part of a collaboration where we determined that place fields emerge due to a lack of inhibition, rather than an increase in excitation (Valero et al, 2022).