Memory & Amnesia

Memory & Amnesia

1. Memory

   • Sensory
   • LTM/ STM
   • Stages : Encoding> storage>retrieval
   • Serial position effect
   • Working memory: central executive
     • Phonological loop
     • Visuospatial sketchpad
     • Episodic buffer
   • LTM
     • Declarative: Episodic/semantic
     • Non-declarative: Implicit/procedural
   • Papez's circuit

2. Memory Consolidation Theories

   • System consolidation (Squire & Bayley, 2007)
     • New memories consoildated in hippocampus, moved to neurocortext
     • Explains temporal gradient in retrograde amnesia
   • Multiple trace theory (Nadel & Moscovitch, 1997)
     • Different types of memories encoded/decoded in different areas
     • Change over lifespan as recalled, stored in multiple locations
   • Reconsolidation theory (Tronson & Taylor, 2007)
     • Self explanatory & multiple trace

3. Hippocampus & Spatial representation

   • London Taxi Drivers
     • Bilateral hippocampal lesion damage (Maguire et al., 2006)
       • Still navigate by only mainroads
     • Increase in posterior hippocampus grey matter (Woolett & Maguire, 2011)
   • Scene Construction theory (Hollingsworth & Henderson, 2002)
     • Visuospatial representations stored in LTM
   • Developmental topographic disorientation

4. Amnesia

   • Psychogenic vs Organic amnesia
   • Material vs Global
   • Retrograde vs Anertograde
   • Degen/non-degen
   • Causes: Damage, Viral disease (e.g. encehpalitis), Tumor/treatment, Ischemia, Anoxia, Low thiamine (Korsakoff's), Alzheimers (amnesia symptom)
   • Hippocampal amnesia
   • HM (Milner & Scoville, 1957): Anterograde amnesia
     • Same IQ & implicit learning e.g. motor skills
     • vague memory of major news
     • Temporsl lobectomy, removed most of the hippocampus
   • Long term, Declarative memory disorder
     • Intact implicit learning
       • Intact repetition priming & fragment completion
   • No double dissociation evidence for distinctdeclarative & non-declarative systems
   • Anertograde still some retro
   • Semantic memory system link is debatable
   • STM impariment when task requires forming relational memories (Hannula et al., 2006)
     • BUT - relational memory only uses hippocampus when task exceeds working memory capability
   • Confabulation with extra FL lesions (Pauly-Takacs, Moulin & Estlin, 2011)
   • Temporal gradient: Recent LT memory more than LT in retrograde amnesia
     • Evidences multiple memory systems