16. Amnesia

16. Amnesia

1. Amnesia

   • controversial area
   • anterograde = encoding, storing and retrieving information deficits
   • Dual-Process model (Aggleton & Brown, 1999) suggested hippocampus involved in recollection, PRC familiarity
   • HM = removed medial temporal lobes to treat seizures
   • retrograde amnesia = deficit in accessing events that occurred before truama
   • disorders of memory = forgetfulness, but preserved intellect and language
   • some dispute where familiarity is just a weaker version of recollection
   • BJ = snooker cue up nostril, delayed memory
   • PB = stroke damaged H, anterograde amnesia
   • NA = penetrating brain injury, deficits in verabl and memory
   • Baddeley et al (2001) info enters semantic, held in recognition system
   • causes of amnesia = alzheimers, korsakoff, surgery, truamtic brain injury and herpes

2. Amnesic Issues

   • Jon: damage to hippocampus, had issues with remember/know tasks. When he got the task, he couldnt explain the basis of his remember decisions. Locked remember component in ERP study (left-parietal old/new)
   • Hypoxic patients: relativley presevred semantic memory, but hippocampal role in semantic is unclear. For example, functional re-organisation may occur where extra- hippocampal regions take on the role of the hippocampus
   • Recollection and Familiarity, Aggleton & Shaw (1996) pathology confined to hippocampal-related regions have recall impairments. Memory familarity intatc, suggested other strucutres involved here, e.g. PRC
   • Episodic memory:
     • baddeley et al (2001) Jon and 2 patients, jon performs same as controls on recognition, but badly on recall (recollection issue)
     • recall = recollection. Recognition = familairty/recollection
     • modal model of amnesia (Baddeley, 1990) consolidation = learning in episodic memories involves associating with context. Recall and recognition same processes, semantic separate based on long-term memory, But Jon shows model is incorrect

3. Retrograde Amnesia

   • test items learned beofre amnesia onset
   • confabulation = information false, but not misleading. Can be provocked to fill in the gaps, or spontaneous
   • Temporal RA gradient
     • memoris from earlier life easier to remember than those later
     • steepness of gradient differs across patients
     • Ribbot (1882) memories early in life reserved more than later, suggests Hippocampus has time-limited role in memories
     • butter & Cermak 91986) acute amnesia, early life recalled betetr than later
     • saunders & Warrington (1971) no evidence of sparing early memories on famous faces test
     • zola-Morgan et al (1993) particiapnts retrieved memroies with cue-word. korsakoff patients had to retirve information from 30.4 years, while controls only 12.7 = gradient
   • explanations of RA
     • multiple trace hypothesis (Nadel & moscovitch, 1988) hippocampus alwaysa involved in stroage and retirval, long-term consolidation results in redundant traces, but older memories have more traces, so complete H damage results in pure RA
     • cermak (1984) episodic memories rehersed from semantic memory
   • test news, TV shows = but knolwedge likely to vary across patients
   • standard consolidation (Alvarez & Squire, 1994) information consolidation by transfer from cortex > hippocampus > neocortex. Ribots law = older memories dont require H
   • Koppelman, Wilson & baddeley (1990) developed autobiographical memory interview. remember infor from range fo time periods, then recall sepcific events from the periods

4. Preserved Abilities

   • Short term memory = but must constantly reherse to remember (Baddeley & Warrington, 1970)
   • Cohen-Squire (1980) korsakoff syndrome vs controls on mirror tracing task = korsakoff slower to understand task
   • implicit memory
     • behaviour influenced by rpevious experience despite not being cosnciosuly aware
     • Graf et al (1984) list of words, either recall (explicit) or generate 1st word that comes to mind (implicit) = amnesic patients had difficulties with explicit recall
     • Clarparede (1911) shook hands with pateints 1 morning he had a pin in his hand, the next, they didnt want to shake his hand but they couldnt explain why
     • Warrington & Weiskrantz (1968) degraded pictures and words taks, after trainign amnesic pateints (HM) could improve
   • Semantic memory
     • some evidence deficit in acquiring new semantic information, e.g. HM unable to define words introduced after damage
     • SKotko et al (2004) HM could learn new information when it linked to acquired knowledge
     • Tulving 91989) amnesics have selective deficit in episodic memory, semantic dementia have issues with semantic
     • kensinger et al (2001) HM, lexical knwoledge, picture naming spelling no deficit, knwoeldge early in life ebtter that later (ribot)
     • generally retian vocab and word knowledge