Essay 5: Outline and Evaluate Disorders of Memory
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- Created on: 05-02-14 12:05
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- Essay 5: Outline and Evaluate Disorders of Memory
- AMNESIA
- There are 2 types of Amnesia: Retrograde (forgetting OLD info) and Anterograde (forgetting NEW info)
- 1) Damage to Hippocampus
- Damaging the hippocampus can cause amnesia
- Infection
- Case Study= Clive Wearing
- STM intact but unable to lay down new LTM
- LTM for events prior to illness
- Procedural memory was intact
- But declarative and episodic memory was affected
- Procedural memory was intact
- Viral encephalitis damaged his hippocampus and adjoining areas of temperal lobes
- Case Study= Clive Wearing
- Surgical Brain injury
- Case study=HM (Scoville and Milner):
- HM also improved in mirror drawing skills with successive trails even though he couldnt recall doing it before
- HM's Hippocampus surgically removed in order to reduce epileptic fits.
- STM intact and LTM for events prior to surgery intact, However, HM is unable to lay down new LTM
- HM improved in the Golen test ( recognising incomplete line drawings) with successive trails even though he couldnt remember having done the test before
- Case study=HM (Scoville and Milner):
- Evaluation of Brain Danage Theory
- However studies dont specify which area leads to memory loss
- Case studies of BD patients infer that BD to specific areas causes specific memory loss.
- It appears that areas within or close to the Hippocampus are involved in semantic and episodic memory loss.
- 2) Explicit V.S Implicit memory ( Schachler)
- Can used HM and Clive Wearing as case studies
- Explicit memory requires conscious recollection, whereas Implicit doesnt.
- Contrlled experiments
- Graf et al (1984)
- Lab experiment. Word list was presented to amnesiac patients with an immediate recall test
- Amnesiac's recall was much worse than controls for explicit memory tests but equal on the implicit test
- 3 out of 4 tests were conventional explicit memory, where the 4th involved implicit memory
- Lab experiment. Word list was presented to amnesiac patients with an immediate recall test
- Stickgold (2000)
- People with normal memory can learn tetris in a few hours and describe it. whereas peo+
- People with normal memory can learn tetris in a few hours and describe it. whereas people with Amnesia can improve, showing implicit memory but have no explicit memory of having done so
- Graf et al (1984)
- Evaluation: All of the previous sugests that amnesisa may be caused by impairment in explicit/ declarative memory
- This explanation is descriptive rather than explanatory
- Ryan et al (2000)
- Through relational memory binding suggested that amnesiac lack the function which makes a link between implicit and explicit memory which is also known as consolidation
- 3) Impairment of consolidation of information
- Ryan et al (2000)
- Through relational memory binding suggested that amnesiac lack the function which makes a link between implicit and explicit memory which is also known as consolidation
- Issac and Mayers (1999)
- They suggested that Anterograde Amnesia might be due to problems with consolidation or retrieval of memories.
- They found that Amnesia performed as well as controls on cued recall and recognition
- This suggests that the main explanation for anterograde amnesia is impairment of consolidation of information rather than retrieval
- Retrograde Amnesia may also be caused by impaired consolidation as recvall for events occuring closest to onset of amnesia is worst
- The greater the time between old memories being formed and the onset of Amnesia the better the recall
- The Temporal Gradient suggests that the greater the consolidation the better the recall
- This process is associated with damage to the hippocampus suggesting that this brain area plays a key role in forming LTM
- What causes problems with consolidation?: problems with consolidation may be due to damage to the hippocampus
- Clive Wearing had a virus which affected his brain, damaging the hippocampus amongst other parts
- E.g HM, His amnesia was caused by surgery that removed his hippocampus, amygdala and parts of the temporal lobes
- What causes problems with consolidation?: problems with consolidation may be due to damage to the hippocampus
- Reed and Squire (1998)
- It also suggests that other structures are important
- This supports the role of the hippocampus in consolidating memory
- MRI scans of patients with retrograde amnesia showed hippocampus damaage
- Those with the worst sympotms aslo had damage to the temporal lobe
- Animal studies.
- Case studies of humans with naturally occurring brain damage are problematic in that the extent of brain damage varies and so do sympotms
- Remondes and Schuman (2004)
- It also suggests that the hippocapmus is associated with consolidation
- This suggests the rats could make new memories but couldn't consolidate them.
- Rats with damage to the hippocampus could learn a maze but forgot it quickly.
- Surgical lesianing of animals' brains offers researchers control in the area of brain being studied.
- Evaluation
- Case studies
- Face Vadlity
- Use of animals
- Ryan et al (2000)
- ALZHEIMERS
- Tau Protein
- Tangles
- These were formed from a build up of Tau Protein.
- Tangles arise when the structure of the neurons' cell body degenerates.
- This normally provides support for the structure with in a neuron.
- Tangles are seen in other diseases but have a distinct form in AD.
- Tangles
- B amyloid
- Individuals with Alzheimer's don't break down Amyloid precursor protein (APP) properly
- B-amyloid Plaques
- Plaques cause damage to cerebral cortex, hippocampus and basal forebrain
- Plaques interfere with NMDA
- Cleary et al (2005)
- Injecting rats with B-amyloid disrupts memory
- Unable to learn maze
- Shows cause and effect although can't generalise rats to humans
- Injecting rats with B-amyloid disrupts memory
- Snyder (2005)
- B-Amyloid protein 42 interferes with NMDA, a Neurotransmitter which produces changes in neurons when we learn
- Cleary et al (2005)
- Berntson et al (2002)
- Alzheimer's effects memory is because of damage to the basal forebrain which is involved with alertness and attention
- MSM says that in order to commit things to memory you first have to pay attention to them
- Alzheimer's effects memory is because of damage to the basal forebrain which is involved with alertness and attention
- Selkoe (2000)
- Plaques start to form before symptoms of Alzheimer's. Progressive damage causes cerebral cortex to shrink
- So suggests that plaques cause Alzheimer's.
- Previous studies have suggested that the hippocampus is involved in LTM e.g. Clive Wearing
- Previous studies have suggested that the hippocampus is involved in LTM e.g. Clive Wearing
- So suggests that plaques cause Alzheimer's.
- Plaques start to form before symptoms of Alzheimer's. Progressive damage causes cerebral cortex to shrink
- Evaluation of B-Amyloid Plaque Theory
- The explanation that the basal forebrain is damaged usefully explains why people with AD are less alert and find attending to stimuli more difficult
- The basal forebrain is involved in increasing arousal in cerebral cortex
- MSM attention= memories
- The basal forebrain is involved in increasing arousal in cerebral cortex
- Dogs develop more B-amyloid with age and also develop associated cognitive dysfunction. However, they don't lose neurons or develop plaques and tangles
- Primates have the same B-amyloid as human but don't develop nerve damage or cognitive symptoms in old age
- Studies have mainly been carried out on animals even though no single species had all the same physiological and psychological symptoms as human AD patients
- Generlisability?
- However the link between the build up of plaque and AD is weak and hard to explain
- Murphy and LeVine (2010)
- The presence of B-amloid protein 42 early in the disease starts a chain of events that leads to the illness
- This has yet to be tested
- The presence of B-amloid protein 42 early in the disease starts a chain of events that leads to the illness
- Murphy and LeVine (2010)
- The explanation that the hippocampus ids damaged usefully explains memory loos in AD
- Use studies showing a link between memory and hippocampus.
- E.G Clive Wearing
- Use studies showing a link between memory and hippocampus.
- The explanation that the basal forebrain is damaged usefully explains why people with AD are less alert and find attending to stimuli more difficult
- Alzheimer's is the gradual deterioration in cognitive abilities including mempory
- Compared to Amnesia which is a sudden loss due to brain damage
- Genetics
- Lott (1982)
- Most individuals with Downs syndrome (DS) Who reach middle age develop early onset Alzheimer's
- As DS is caused by having an extra copy of chromosome 21, this led researchers to look for and find genes associated with AD on Chromosome 21
- Levy-Lahad et al (1995)
- Early onset AD's gene found on Chromosome 1
- All found different Genes so less reliable
- Schellenberg et al (1992)
- Early onset AD's gene found on chromosome 14
- Ertekin et al (2000)
- Gene for later onset AD's found on chromosome 10
- Ertekin et al (2000)
- Gene for later onset AD's found on chromosome 10
- AD is a complex disorder, so it's only right that its got a complex cause
- Schellenberg et al (1992)
- Schellenberg et al (1992)
- Early onset AD's gene found on chromosome 14
- Lott (1982)
- Tau Protein
- AMNESIA
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