The psychobiology of learning and memory: Fundamentals and recent advances

Aim. This review describes the concepts, temporal dynamics and main features of learning and memory systems from a comprehensive molecular, neuroanatomical, neurophysiological, cognitive and behavioural approach. Development. Starting with molecular mechanisms of synaptic plasticity we describe the memory stages, implicit and explicit memory systems, working memory, remembering and forgetting. Each process is illustrated with examples of recent experimental and clinical research. Conclusions. Learning and memory are closely related brain processes which give rise to adaptive changes in behaviour. Implicit memory is a kind of unconscious and rigid memory for habits, which is based on brain regions processing perceptions and motor and emotional information, like the neocortex, the neostriatum, the cerebellum or the amygdala. Explicit or declarative memory is a conscious and flexible memory, hippocampus-dependent. Working memory is actually a system of executive cognition, based on interactions between the prefrontal cortex and other brain regions. The retrieval of complex memories consist of an active process of reconstruction of the past which incorporates new experiences of the subject who is remembering. The reactivation of memories can initiate genuine processes of reconsolidation and extinction. Forgetting could depend on alterations in the neural networks storing the information or, otherwise, on active processes which hinder consolidation or block the expression of the memories. © 2005, Revista de Neurología.