Model of Memory
RETRIEVAL
Atkinson & Shifrin
ATTENTION
Sensory
Signals
Sensory
Memory
Short-Term
Memory
Long-Term
Memory
REHEARSAL
Long-term Memory
• How long is it?
- persists indefinitely (from seconds to decades)
- persists without active rehearsal
• What types of LTM are there?
Long-term Memory
Where does the distinction between LTM types come
from?
Long-term Memory
Where does the distinction between LTM types come
from?
Patient H.M.
• “Loss of Recent Memory After Bilateral Hippocampal
Lesions”, Scoville and Milner (1957)
•onset of epilepsy at age ten, perhaps due to bike
accident (wear a helmet!)
• 1953 - underwent temporal lobectomy to reduce
seizure activity
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Patient H.M.
• severe anterograde amnesia
• temporally graded retrograde amnesia
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Patient H.M.
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Patient H.M.
1. Memory and perceptual skills are dissociable.
2. Lesions of the MTL produce amnesia for recent but not
remote events.
3. There are multiple long-term memory systems in the brain.
Patient H.M.
What’s new with Patient H.M.?
• Suzanne Corkin et al. (1997)
• used MRI to assess lesion extent
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Patient H.M.
• perhaps H.M.’s lesion is not as big originally thought, at
least in terms of hippocampal damage
• most of amygdala, entorhinal cortex (major input to HPC),
and large portion of HPC gone or atrophied
• mammillary nuclei shrunken
• cerebellar atrophy
Patient H.M.
• So what can H.M. do?
Patient H.M.
• So what can H.M. do?
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Patient H.M.
• fMRI of H.M. during novel picture encoding
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• caudal parahippocampal gyrus activation (same as controls)
Patient K.C.
• developed amnesia after motorcycle accident (really, wear a
helmet!)
• damage to MTL, frontal, parietal and occipital cortices
• suffered from source amnesia - remember the info, just not
where/when you learned it
Long-term Memory
• so we have a single dissociation
• what about people that have an intact declarative
memory system yet present with difficulties in nondeclarative tasks?
Patient M.S.
• opposite pattern of results from H.M./K.C.
• intact declarative memory
• problems with priming tasks
Patient M.S.
Long-term Memory
• there are multiple memory systems in the brain.
• explicit (declarative) and implicit (non-declarative) memory
can be doubly dissociated
• can anyone see a problem with using human subjects?