Next in the current series of understanding more about how we store memories and types of memory disorders occur this article is focusing on retrograde amnesia. Exploring different theories behind what exactly occurs cognitively and different theories behind this.
RETROGRADE AMNESIA (RA)
- Retrograde amnesia is the inability to recall memories prior to trauma
- Cause: severe head trauma, electroconvulsive therapy (ECT), drug abuse, etc
- Location: Most exhibit Hippocampus damage, if HC damage extensive may show anterograde amnesia too
- Recovery: Gradually regain more recent memories, so the amnesia “shrinks”
RETROGRADE AMNESIA: DISRUPTION OF CONSOLIDATION?
- Shows a temporal gradient; recent memories effected more than older memories (Ribot’s Law, 1882)
- Yarnell & Lynch (1970)– study of concussed American football players
- Players questioned immediately after incident – able to recount what happened
- Asked same questions 3- 20 minutes after incident where they were unable to give any information
- Suggests blow to head disrupts physiological consolidation process for memory to be permanently retained
RETROGRADE AMNESIA: DESTRUCTION OF MEMORIES?
Squire and Cohen (1982)
- Electroconvulsive therapy (ECT) for depression
- Tested recognition of TV shows before and after ECT
- Memory was worse for most recent memories
- Suggesting memories with less consolidation are damaged
But they may not be destroyed…
RETROGRADE AMNESIA: RETRIEVAL DEFICIT?
The return of memories suggests they exist but cannot be accessed.
Warrington & McCarthy (1988)
- R.F.W. suffered severe retrograde amnesia after encephalitis
- Vague autobiographical memory and public events
- Recognition of personal and famous photographs poor
- But, can use name cue to recognise photographs
- And define recent terms such as ‘Thatcherism’ without memory for Margaret Thatcher!
- Evidence suggests:
- Damage to HC interrupts consolidation of recent memories
- Older memories are already consolidated and can be retrieved from other brain regions (entorhinal cortex in temporal lobe)
- If damage is more severe, may suffer continued problems with consolidation (i.e. Anterograde)
- Over time, memory returns because consolidation returns via different cues, rehearsal via retrieval.
OTHER CAUSES OF AMNESIA
- Close Head Injury: PTA, Anterograde/Retrograde
- Infantile Amnesia
- Psychological trauma/stress
- Destructive surgery
- Electroconvulsive therapy (ECT)
- Virus e.g. Encephalitis
- Poisoning (e.g. Failed suicide)
- Hypoxia (=lack of oxygen)
- Alcohol Abuse = Blackout
- Alcohol abuse + malnutrition = Korsakoff’s syndrome
- Progressive dementia: Alzheimer’s disease
Read next: ‘Memory Disorders: Anterograde Amnesia‘