Neuropsychology of Memory (1) Flashcards
What is the neuropsychology of memory?
- The study of neural networks that enable us to record, retain and retrieve information
- the first aim is to understand normal functional architecture of human memory
- the second aim is to explain why damage to specific memory systems cause specific patterns of memory impairment
What Explicit VS Implicit memory?
Explicit memory:
- deliberate attempt to remember previously experienced event, free recall, recognition, cued recall
Amnesia and Memory
patient HM
- bilateral medial temporal lobectomy (removed both lobes)
- intact immediate memory
- retained knowledge of earlier life
- profound anterograde amnesia
- 3-year retrograde amnesia (proceeding/leading up to surgery)
- normal implicit memory
What are some other causes of temporal lobe dysfunction?
- Korsakoff’s syndrome
- Alzheimer’s disease
- Stroke
- Head injury
- Temporal lobe epilepsy
Explain Zola-Morgan et al’s., (1986) study
- Case R.B. identical to cognitive profile to HM but damage was localised to the hippocampus
- in humans we await for lesions to occur naturally and usually very precise
- in animals systematic and precise lesions can be made
What did Zola-Morgan et al., (1993) used animal Models for?
- Used delayed NST to identify critical structures within MTL essential for memory formation
Hippocampus (H)
Amygdala (AMY)
Perirhinal Cortex (PRC)
Parahippocampal Cortex (PHC)
Explain Zola-Morgan et al’s., findings of their 1993 study
if there is a lesion in these different combinations of areas of the brain it will lead to:
- H+PHC+AMY+PRC = severe deficit in performance
- H = poor performance
- AMY = normal performance
- PRC+PHC = severe deficit in performance
Reasons why:
- H is essential for memory formation
- AMY isn’t involved in memory formation per se
- PRC+PHC are also essential (for memory formation)
What are the conclusions from the amnesia studies?
- Explicit memory is mediated by neural structures compromised in amnesia
- Implicit memory mediated by neural structures other than those compromised in amnesia
(Important that both points are based on single dissociation)
What is single dissociation?
- Observed when performance on task A is impaired but performance on task B is normal
- the deficit isn’t due to general impairment
- one reason for this impairment may be that different processes aren’t involved or task A may be more demanding
What is double dissociation?
- Observed when a patient is impaired on task A but normal on task B
- whereas a different patient performs normally on task A but is impaired on task B
- this pattern can’t be explained by task difficulty
What was Gabrieli et al’s., study into?
- Compared M.S. (occipital lesion) with amnesiac patients (MTL/H)
- Implicit (perceptual-identification); Explicit (recognition)
Group - Implicit - Explicit
Amnesic - Intact - Impaired
M.S. - Impaired - Intact
What are the problems with lesion studies?
- lesion studies can provide clues about which brain regions are involved in memory processing
Caveats:
- generalising from primates
- lesion studies don’t identify specific processes
- lesions can disrupt multiple neural systems
- compensatory operations
- individual variation
What are imaging studies and what/how are they used?
- Based on assumption that mental activity correlates with regional cerebral blood flow (rCBF)
- increased mental effort increases rCBF and therefore regional hemodynamic response
- subtraction methods allow task specific changes in activation to be observed
Explain, in brief Squire et al’s., (1992) study (method)
- Study: 15 words e.g. peach
- Test: stem completion e.g. pea__
- 4 conditions selected to isolate changes related to specific mnemonic processes
Explain, in brief Schott et al’s., (2005) study
- Study: 160 words - indicating number of syllables by finger press
- Test: 240 3-letter word stems - complete stem with studied word or first word that comes to mind
- Indicate if word had been previously studied
- Explicit: target completion remembered
- Implicit: target completion NOT remembered
