Introduction to the neuropsychology of memory & perception Flashcards
What does the fact that types of memory can be dissociated from each other mean?
They can be disrupted independently by lesions.
What’s episodic memory for?
Specific events
What is stored in semantic memory?
Facts
What is working memory?
Short term, requires rehearsal.
What’s procedural memory?
Motor.
What’s declarative memory?
Explicit (episodic and semantic)
Describe anterograde amnesia.
- Poor ability to acquire new information.
- Information acquired before damage is relatively spared
- Information in working memory is spared
- Impaired declarative memory
- Non-declarative memory relatively preserved.
What is non-declarative memory?
Implicit:
- Perceptual memory (stimuli)
- Procedural memory (motor skills and habits)
Where does damage cause anterograde amnesia?
Hippocampus and related structures in the medial temporal lobe.
What is the cause of Korsakoff’s syndrome?
- Thyamine (vitamin B1) deficit
- Due to alcoholism, poor diet and impaired absorption of thiamine from intestine.
What symptoms does Korsakoff’s syndrome cause to happen to the brain?
Bilateral degeneration of mammilary bodies
What are the memory-related symptoms of Korsakoff’s syndrome?
- anterograde amnesia
- retrograde amnesia, severe memory loss
- confabulation, (invented memories which - are then taken as true due to gaps in memory sometimes associated with blackouts)
Describe the temporal lobotomies carried out in the 1950s.
- For patients with intractable seizures.
- Bilateral removal of temporal lobes.
What was surgically removed in HM’s case?
Anterior hippocampal regions (bilateral)
What deficits did HM suffer from?
- Inability to form new memories - complete absence of episodic memories, no new semantic memories.
- Temporally graded retrograde amnesia
What remained unaffected in HM after the surgery?
IQ, personality, working memory (digit span, rate of forgetting - although had to rehearse constantly), ability to hold a conversation, procedural memory (Milner, mirror tracing task).
What is the role of the hippocampus in memory?
- HM suggests memories aren’t stored there.
- Perhaps enables consolidation of memories for transfer elsewhere?
How did Marsien-Wilson and Teuber (1975) test HM’s retrograde amnesia?
Photos of celebrities - spanned decades, most distant preserved.
What are double dissociations?
- Two patient groups with different lesion sites and impairments.
- Suggest tasks rely to some extent on different brain structures.
Why are double dissociations particularly useful?
- Solve problem of task difficulty from dissociations.
Define agnosia.
- Lack of knowing/perception - inability to recognise objects.
- Can be visual, auditory, somatosensory.
- Is modality-specific.
- Not due to deficit in ‘early’ perception.
What is apperceptive agnosia?
- Inability to perceive a whole object.
- Intact low-level perception, but unable to extract global structures.
- Evidenced by impairments in drawing, copying and recognition.
What is associative agnosia?
- Ability to perceive and copy a shape but not name it.
- Inability to draw from verbal instruction or to recognise object using vision.
- Man who mistook his wife for a hat.
What is the theoretical explanation for associative agnosia?
- Disconnection between visual representation and language
- Damage includes left occipital cortex and white matter
- Patients can use visual representations to guide non-speech movements, e.g. gestures.
What is prosopagnosia?
Inability to recognise faces visually - can tell it’s a face and describe it but not identify.
Can still identify people through other features.
What sort of brain damage is usually associated with prosopagnosia?
Right sided damage to the fusiform gyrus in the inferior part of the occipital/temporal lobe.
What is the Fusiform Face Area (FFA)?
- Specific area activated by faces (Kanwisher et al., 1997 - imaging).
In what ways are we experts at processing faces?
- Can detect subtle emotions
- Can identify individuals despite radically different conditions etc.
- Can identify people despite all faces being pretty similar.
What does face processing involve?
Perception of both configuration and features. Holistic processing = FFA?
What is the inversion effect?
Upside-down faces are more difficult to recognise - it’s difficult to process feature configuration.
Perhaps upside-down faces don’t use the specialised face-processing system.
Only notice distortion right way up e.g. Thatcher effect.
Prosopagnosia suggests that faces are special, but this is a dissociation. In fact,…
Prosopagnosics tend to have difficulty recognising other things too (pure prosopagnosics are rare), faces are just difficult. This suggests that The FFA isn’t only concerned with faces.
What did Gauthier et al (1999; 2000) find about the FFA?
It’s activated when experts observe the object of their expertise.
Why are pure prosopagnosics so rare if faces are special?
- Accidental lesions are rarely high focal.
- Imaging provides converging evidence and can only say an area’s active during, not necessary for, a function.
The idea that faces are special, with dedicated processing systems, is…
Controversial.
