Long term memory

Long term memory

1. Explicit/declarative memory:

   • Ability to recall what you know, e.g. facts, consciously retrieve, including semantic and episodic
   • Encoded: top down, conceptually driven, subject able to recognise info, active role
   • Retrieval: conscious recollection
   • Test categories: free recall, cued recall, forced choice recognition, yes/no recognition
   • Neural structures: MTL - HC, amygdala, entorhinal cortex, parahippocampal cortex, perirhinal cortex and frontal cortex

2. Non-declarative/implicit memory:

   • Ability to recall how to perform something, unconscious memory like skills, conditioned response, includes: procedural knowledge, priming, conditioning
   • Encoded: processed bottom up, data driven, so encoded same way as seen, passive role
   • Retrieval: not conscious, hardly any attention
   • Tests: lexical decisions, word fragment completion, word stem completion
   • Neural structures: BG, ventral thalamus, substantia nigra, premotor cortex

3. Amnesia = loss of memory, caused by: viruses, Parkinsons, brain treatment, accidents, Korsakov syndrome

   • Cohen and Squire - mirror reading - learning effect normal across list, however repeated words norms did better as involved explicit memory too
     • Patient JK - impaired implicit, intact explicit - couldn't perform basic task, Parkinson's -> damage to BG

4. Dissociating memory circuits: severity of memory disturbance related to size rather than location

5. Patient HM: resection of MTL - impairment in episodic, couldn't recall anything after surgery, had an above IQ, recall childhood events, could learn new skills, e.g. mirror drawing