Memory: from its formation to its loss

Abstract

Memory is the process by which learning experiences are stored and retained through associative, conscious, and non-conscious mechanisms and it is susceptible to change over time. Memory can be classified in several ways, one of them according to the permanence of the information, considers a short- and long-term memory, mainly determined by the initial process of memory formation. This process involves four fundamental stages: encoding, consolidation, store and retrieval, involving modification of the synaptic strength between neurons of an engram, with participation of specific neurotransmitters and receptors, giving rise to Long-Term Potentiation (LTP); the interaction of various brain areas is also required, mainly hippocampus and cerebral cortex. Memory storage is the result of dynamic processes between engrams, which represent a permanent but fragmented storage of memories, while memory retrieval involves an interaction between a stimulus and a previously stored engram set, being largely dependent on the repetition of the original engram connectivity pattern. Memory can be affected by toxic environments that alter communication between neurons and/or brain structures, leading to memory loss. The most common pathologies where memory is affected are Alzheimer’s disease, Parkinson’s disease and Lewy body dementia.