Introduction to cognitive neuropsychology Flashcards
What are the two causes of Amnesia
Organic: Damage from injury or damage from disease
Psychogenic: purely psychological
What are the two forms of Amnesia
Retrograde: Can’t recall memories formed in the time leading up to the injury but can sometimes remember childhood memories
Anterograde: Not able to form new memories after the onset of amnesia
What are the main features of Amnesic Syndrome
(relatively pure amnesia meaning there are no other problems i.e. no language problems)
- Retrograde amnesia
- Anterograde amnesia
- In tact short term memory
- Skills such as driving are not affected
- Preserved general intelligence (IQ)
- Some residual learning capacity for motor skills usually
What are some causes of Organic Amnesia
(organic amnesia means biological so damage to the brain)
- Amygdala - episodic memories
- Basal Ganglia - Learning of motor skills
- Cerebellum - Storage of motor skills
- Frontal Lobes - Working memory
- Occipital lobes - Visual perception and memory
- Hippocampus - long term memories
Effects of damage to the hippocampus
- Patient HM had hippocampus and amygdala removed
- His epilepsy improved and his personality did not change
- Unable to form new episodic memories
- Severe anterograde amnesia
- He could learn new procedural memories
Korsakoff’s Syndrome
- Happens because of thiamine deficiency
- A thiamine deficiency occurs as a result of alcoholism
- The thiamine deficiency causes damage to diencephalon
- Patients seem as though they are drunk and have no coordination, they are also confused
- Retrograde amnesia going back years or even decades
- Short term memory is normal
Viral Encephalitis
- Caused by herpes virus
- Causes damage to the temporal lobe
- Clive Wearing suffered with Severe amnesic disorder
- Problems with facial recognition also dyslexia
Non Pure Amnesia as a result of Dementia
- Most common type of dementia is Alzheimer’s disease
- Dementia is very common
- Progressive neural disorder
- Growth of neural plaques
- Alois Alzheimer, described his patient as having memory loss, hallucinations ‘unusual disease of the cerebral cortex’
Contextual Cues in Amnesia
Oliver Sacks, Music and memory in Alzheimers
- People Alzheimers are able to remember songs
- Listening to music also brings back memories from that stage in their life
Medication and Amnesia
- Viagra, had been shown to cause amnesia
What is Transient Global amnesia
- Sudden onset of anterograde and retrograde amnesia
- No loss of personal identity, still recognise family
- Resolves within 12 hours
- More common in men over 50
- May be as a result of emotional distress or extreme exercise
Amnesia and dissociations between different types of memory
- Amnesia provides evidence that there should be a separation between long and short term memory
- Amnesia also helps with the distinction between episodic memory and semantic memory
- Amnesics show recency effect because they can still use short term memory
Theories of Anterograde Amnesia
Why can’t amnesics store or code new memories:
- Faulty encoding
- Accelerated forgetting
- Faulty retrieval
- Faulty encoding/ storage of contextual information
Problems with initial encoding
Cermak (1979)
- Lack of deep encoding
- ## Not very good at learning word pairs such as ‘hungry’ and ‘thin’ - levels of processing theory
Accelerated Forgetting
Huppert & Piercy, (1979)
- People who have lesions on their hippocampus forget things a lot quicker than controls even after they have learnt the material properly
Retrieval Deficit
(Aggleton & Shaw, 1996)
- Recognition is sometimes unimpaired in amnesics
- Recall is always impaired
A Test of contextual deficit theory
Huppert and Piercy (1976):
- Amnesic (korsakoff) patients and control patients
- Presented set of pictures on day on and day two, some were present on both days
- Recognition task, participants had to say if they had seen image at all (regardless of day) and also if they had seen certain pics only on day two.
- Results showed no diff between groups on if they had seen picks
- However, Amnesic patients were poorer at recognising if the picture had been seen on day two but they also though that many pictures they had seen on day one were seen on day two.
Contextual Deficit Theory Problems
- Semantic memories can be impaired and these aren’t contextual
- Context definition is vague
- Context-processing deficits vary substantially across patient groups (e.g., Parkin & Hunkin, 1997; Squire, 1982).
Temporal gradient in retrograde amnesia
- Butters and Cermak (1986), Amnesic patient had written a autobiography so could use this to ask questions.
- Couldn’t remember anything 20 years prior although could remember from childhood.
- This is because of a consolidation process
Consolidation Theory of retrograde amnesia
(Dudai, 2004; Squire, 1992)
- Initially episodic memories are stored in the hippocampus
- To access these memories the hippocampus has to be reactivated
- Overtime, the cortex can retrieve these memories without the hippocampus
- Thus, older memories aren’t affected by amnesia
Two types of Psychogenic Amnesia
- Fague states
- Dissociative Amnesia
Fugue states
- Patients usually found wondering a long way from home
- Triggers are stress and depression
- Can last from a few hours to a few days
- When recovered, memories from the fugue state are lost
- Very rare
Dissociative type
- Loss of memory for specific events as a result of trauma
- Very rare
- 25-45% of murder suspects claim amnesia for the crime
