Hippocampal and Neocortical Dynamics During Long-term Memory in Macaques

Memory is one of the most important faculties of the mind. Memory keeps a record of our experiences which enriches our sense of self, enables us to make adaptive decisions in the present and informed plans for the future. Historically, memory research has focused on the hippocampal formation in the medial temporal lobes which is critical in the initial stages of memory formation. More recently, memory research expanded to include neocortical areas especially with regards to remote memory. An open question in neuroscience is what happens to memory representations in the brain with time. It remains unclear whether the contribution of the hippocampus to memory decreases with time in favour of the neocortex, or if both their contributions stay the same. In this dissertation, I use the non-human primate model to examine the neural mechanism underlying memory formation in the hippocampus, as well as the contribution of neocortical areas during remote memory. In the first study, I present findings that the neural mechanism underlying memory is heterogenous; varying by waking state and underlying spiking of different neuronal types. In the second study, I focus on two neocortical areas alongside the hippocampus and present findings that support a greater role for neocortical areas during remote memory. These findings support the idea that memory dependence shifts to areas outside the hippocampus with time.