Expansion
Declarative memory needs the hippocampus; procedural memory does not
Expansion
Declarative (explicit) - conscious recall, requires the hippocampus and medial temporal lobe
- Episodic: personal events
- Semantic: facts and knowledge
Non-declarative (implicit) - unconscious
- Procedural skills: basal ganglia and cerebellum
- Priming, classical conditioning (amygdala for emotional conditioning)
Working memory is a separate short-term system dependent on the prefrontal cortex.
The cellular mechanism of consolidation is long-term potentiation, a persistent strengthening of synapses involving NMDA receptor activation, calcium entry and insertion of additional AMPA receptors.
Clinical patterns:
- Bilateral hippocampal damage (herpes encephalitis, hypoxia, surgery) causes dense anterograde amnesia with preserved procedural learning and preserved remote memory
- Korsakoff syndrome from thiamine deficiency damages the mammillary bodies and dorsomedial thalamus, causing anterograde and retrograde amnesia with confabulation
- Alzheimer disease begins in the entorhinal cortex and hippocampus, which is why episodic memory fails first