Memories have been suggested to be stored in groups of neurons known as neuronal ensembles, or “engrams”, and neuroplasticity is believed to be the underlying mechanism that allows the formation or remodeling of these ensembles, thus allowing memory modifications. Critically, the hippocampus has been described as a central hub for neuronal ensembles. In the context of fear memory, the representation of the hippocampal neuronal ensemble has been characterized, while little is known about the neuronal ensemble within the hippocampus and the upstream circuits in spatial learning and memory. With the recent development of whole-brain imaging, it is now possible for the identification of previously unidentified, or understudied, circuitry by monosynaptic tracing. In this study, we will first establish a spatial learning task that requires coordinated activities of dorsal (d)CA1 neurons. We will then examine the functional importance of the dCA1 subregion in this learning task using chemogenetics, activity-dependent marker measurement, and calcium recording via fiber photometry. We will also examine the real-time dynamics of neuronal ensembles using miniature microscopy and investigate the molecular signatures and transcriptional landscapes of ensemble neurons. Our working hypothesis is that CA1, as a major output region of the hippocampus, integrates inputs from multiple brain regions to generate task-relevant outputs to downstream region in spatial learning and memory. The study will characterize novel and understudied upstream inputs to a subregion of the CA1, and will provide a deeper understanding of the functional importance of this corticohippocampal circuit in spatial learning and memory.