Neuropsychology of Memory (2) Flashcards
What is Consolidation?
- Process by which changes in brain activity are translated into permanent structural changes e.g. (Ward, 2010)
- required for explicit memory
- binding different types of information in memory trace/setting index e.g. (Moscovitch)
- Huppert & Piercy, (1987) - amnesia as a failure of context when, where, what etc.)
What are the types of recognition memory?
Familiarity (F):
- context-free memory, recognised items feel familiar
Recollection (R):
- context-dependent memory remembering specific details of the event
- Typical recognition judgements involve both familiarity and recollection mechanisms
False-fame paradigms: - allows separate estimates of F/R
What are independent processes?
- Stronger recollection and weak familiar forms of the same processes e.g. Wixted & Stretch (2004)
- Ranganath et al., (2004) - fMRI dissociable responses for recollection/familiarity within MTL
- H+ activity correlates with R
- Perirhinal activity correlates with F (enhanced activity when people give familiarity judgements)
- Stronger hippocampal activity
What evidence is there for for lesions?
Patient YR - studied by Mayes et al:
- Patient became amnesic following selective H+ (hippocampus) lesion
- FINDINGS: intact familiarity with intact recollection
Patient NB - studied by Bowles et al., (2007)
- Had a selective resection of perirhinal cortex in the brain, sparing of the H+ (hippocampus)
- FINDINGS: impaired familiarity with intact recollection
What is meant by consolidation over time in this topic?
Butters and Cermark (1986) - Case PZ:
- PZ became amnesic after writing his biography
- 50 years before he was amnesic = 70% remembered memories with accuracy, less for memories from more recent years
- 40 years = 50%
- 30 years = 40%
- 10 years = 0%, could hardly remember any of what happened/memories within 10 years before having amnesia
- demonstrated clear temporal gradient (in the brain)
What is Ribot’s Law?
Retrograde:
- Poor for events before the onset of amnesia
- can remember old memories well
Anterograde:
- Poor for events following onset of amnesia
- can remember old and recent memories
- anterograde = OPPOSITE to retrograde
What is the neuropathy of Alzheimer’s Disease?
- Cortical and subcortical changes
- neuronal loss - particularly large neurons with long fibres
- neurotic plaques and amyloid deposits
- neurofibrillary tangles
- neurotransmitter depletion
What is semantic dementia?
- Form of ‘frontotemporal dementia focal atrophy’ to neocortex early sparing of H+ (hippocampus)
- progressive deterioration of memory of people, objects, facts, word meaning and conceptual knowledge
Nestor et al., (2002): - Reversed temporal gradient - better for recent events (e.g. 4 years ago), than for remote, older events and general knowledge
- recent events haven’t been transferred from H+ (hippocampus) to the neocortex (yet), so are in tact (person with semantic dementia can still remember recent events but are severely impaired for older events)
Memory and the frontal lobes
- MTL plays an associative role in memory formation
- classical (older) studies didn’t emphasise memory impairment in the frontal lobes pts (recognition)
- frontal lobes control coordinating, elaborating and interpreting MTL associations
- patients with frontal lobe problems tend to have more coordinated problems
- frontal lobe patients are particularly deficit when ‘working with memory’
What is HERA?
- Hemispheric Encoding/Retrieval Asymmetry model of memory (Tulving et al., 1994)
- Encoding: Left . Right
- Retrieval: Right . Left
What is encoding?
- Frontal lobes have deeper levels of processing
- they establish relations between elements
- and engage in more semantic processing
- left lateral prefrontal cortex increased activity, predicts successful encoding (Dickerson et al., 2007)
- left dominance for verbal material (Golby et al., 2011)
What is retrieval?
- Right lateral prefrontal cortex is activated and active during retrieval
- integrates retrieved material to form an episodic representation - verifies activity
- frontal lobes detect errors, lesions increase the probability of false recognition
- incorrect identification can cause delusional symptoms (capgras)
- capgras syndromes are common in people with right frontal love lesions
- reduplicative paramnesia: thinks a familiar place is a duplicate of a real place (Devinsky, 2009)
Explain frontal lobes and executive control
- Working with memory
Prospective: setting a future external cue to trigger an appropriate memory
Sequential: attributing a temporal order to acquired memories
Context: temporal-spatial context (source) which memory occurred (source memory problem)
Confabulations: production of fabricated, distorted or misinterpreted (getting things mixed up, not lying)
