Download Disorders of memory overview

Disorders of memory overview
AMNESIA
 Amnesia is a partial or total loss of memory
o Retrograde vs anterograde
o HM and Clive Wearing
 Explanation 1: loss of explicit memory
o Schacter (1987): Amnesiacs have normal implicit/procedural memory, but impaired
explicit/declarative memory
 Warrington & Weiskrantz (1968): HM and the Gollin test
 Milner (1962): HM and mirror drawing
 Stickgold (2000): Tetris
o However, this is a descriptive rather than explanatory explanation
 Ryan et al (2000): Relational memory binding
 Explanation 2: Inability to consolidate new memories
o Issac and Mayes (1999): amnesiacs could retrieve but not consolidate memories
 The temporal gradient: evidence for consolidation
o Consolidation issues caused by damage to hippocampus
 HM and Clive Wearing
 Gabrieli (1998): damage to CA1 (hippocampus) causes anterograde amnesia.
 Reed and Squire (1998): MRI scans on amnesiacs
 Remondes & Scman (2004): damage to rats’ hippocampus
ALZHEIMER’S
 Progressive form of dementia. Causes problems with memory
 Explanation 1: β-amyloids, plaques and tangles
o Amyloid precursor protein broken down into β-amyloid protein 42 causing the build up of
plaques
 Selkoe (2000): causes damage to cerebral cortex and hippocampus
 Berntson et al (2002): causes damage to basal forebrain
 Murphy & LeVine (2010): β-amyloid starts chain of events which leads to alzheimer’s
o β-amyloid interferes with normal brain function
 Synder (2005): β-amyloid interferes with NDMA neurotransmitter
 Cleary et al (2005): rats injected with β-amyloid have memory disruption
o Tangles: structure of cell body disintegrates sue to build up of tau protein
 Explanation 2: Genes
o Alzheimer’s can be explained by a genetic predisposition. These genes play a role in producing
β-amyloid
 Lott (1982): Early onset Alzheimer’s linked to chromosome 21 (down’s syndrome)
 Levy-Lahad eta al (1995): Early onset Alzheimer’s gene found on chromosome 1
 Schellenberg et al (1992): Early onset Alzheimer’s gene found on chromosome 14
 Ertekin-Taner et al (2000): Gene for later onset Alzheimer’s found on chromosome 10
o Genes do not provide a full explanation
 St George-Hislop (2000): Half of all Alzheimer’s patients have no relatives with the
illness
 Hendrie (2001): Yoruba people have Alzheimer’s genes, but much lower rates of the
illness.