The science of memory: A comprehensive analysis of declarative and non‑declarative memory mechanisms and updates (Review)

Memory is a vital cognitive process of the acquisition, storage and retrieval of sensory information, which is essential for understanding and learning. It is classified as sensory, short‑term and long‑term memory. A particular type of memory may be associated with different areas of the brain, such as navigational memory, which may be regulated by the basal ganglia, cerebellum, hippocampus, entorhinal cortex, as well as associated parahippocampal and retrosplenial cortices. Emotional learning is associated with the auditory cortex and amygdala. Memory is also regulated by epigenetic mechanisms; for example, hypomethylation enhance memory by enhancing the expression of memory‑associated genes. The present review provides a comprehensive overview of memory mechanisms and updates, as well as the molecular mechanisms involving the procedure of memory formation. The molecular mechanisms involve long‑term potentiation and the cyclic AMP signalling pathway. The role of nitric oxide in memory formation is also discussed. The present review also expands to the cellular level, exploring how dopamine neurons orchestrate the balance of memory formation and forgetting. Neurogenesis is associated with the formation of new memory. The hippocampus is associated with learning and memory formation. The dentate gyrus is a unique area of the hippocampus that can generate new neurons throughout adulthood, a process known as adult neurogenesis. Memory modulation is a high‑priority research topic for future research, as modern research reveals that memory can be modulated by specific receptor agonists, such as glutamate receptor agonists and deep brain stimulation techniques. However, the exact mechanisms involved need to be further elucidate and validated by clinical evidence in human studies.