Plain-language explanation.
Memory allows us to store and recall information and experiences. Different types of memory are stored in different brain regions. The hippocampus is crucial for forming new memories of facts and events. Working memory is like a mental scratchpad. Damage to different brain areas can cause very specific types of memory loss.
Core concepts and standard treatment.
Memory systems are distinguished by type: declarative (explicit) memory — episodic (personal experiences, hippocampus-dependent) and semantic (general knowledge, neocortical storage); and non-declarative (implicit) memory — procedural (skills, basal ganglia and cerebellum), priming, and classical conditioning (cerebellum for motor responses, amygdala for fear). The case of H.M. (Henry Molaison) defined the hippocampus's role in declarative memory formation.
Deeper theory, debates and edge cases.
Memory consolidation transforms labile new memories into stable long-term representations through synaptic consolidation (hours — protein synthesis, LTP/LTD) and systems consolidation (years — hippocampo-neocortical dialogue, especially during slow-wave sleep). Reconsolidation (Nader) — finding that reactivated memories return to a labile state — has implications for trauma treatment. The Standard Model of systems consolidation is challenged by Multiple Trace Theory: hippocampus remains involved in contextually rich episodic memory indefinitely.
How it is applied in practice.
Applied memory research: spaced repetition (Ebbinghaus forgetting curve) optimises educational learning. Sleep's role in memory consolidation has prompted sleep prioritisation in athletic training and educational policy. Post-traumatic stress disorder involves abnormal fear memory — prolonged exposure therapy and EMDR target reconsolidation and extinction. Alzheimer's disease pathology preferentially affects hippocampal and entorhinal circuits, causing episodic memory failure. Neuroprosthetic memory devices using multi-input multi-output models to decode and reinstall hippocampal patterns are in early clinical trials.