1. Model of Memory RETRIEVAL Atkinson & Shifrin ATTENTION Sensory Signals
Sensory Memory
Short-Term Memory
Long-Term Memory
REHEARSAL

2. Long-term Memory How long is it?
- persists indefinitely (from seconds to decades)
- persists without active rehearsal
What types of LTM are there?

4. Long-term Memory
Where does the distinction between LTM types come from?

5. Long-term Memory
Where does the distinction between LTM types come from?
Brenda Milner
Turns 89 this year.
Last publication was in 2005!

6. 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!)
underwent temporal lobectomy to reduce seizure activity
Wear a helmet!
First study to localize memory to a specific structure
The surgery was experimental!

10. The imaging technology that was available at the time…

11. Patient H.M. severe anterograde amnesia
temporally graded retrograde amnesia

12. Patient H.M.

13. Patient H.M. Memory and perceptual skills are dissociable.
Lesions of the MTL produce amnesia for recent but not remote events.
There are multiple long-term memory systems in the brain.

14. Patient H.M. What’s new with Patient H.M.?
Suzanne Corkin et al. (1997)
used MRI to assess lesion extent
First “experimental” brain surgery, then “experimental” MRI (clips used in surgery may be magnetic)

17. 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
Textbook suggests that Scoville was way off.
Don’t forget Korsakoff’s syndrome.
Pretty good, considering the tools available.

18. Patient H.M.
So what can H.M. do?

19. Patient H.M.
So what can H.M. do?

20. Picture of house before and after surgery, H. M
Picture of house before and after surgery, H.M. recalls the layout of the newer house. Acquired this info after his surgery.

21. Patient H.M. fMRI of H.M. during novel picture encoding
Some of the surrounding tissue is functional…
caudal parahippocampal gyrus activation (same as controls)

22. 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

24. Priming tasks, can retain info for up to 12 months, similar to controls (as can H.M.)

25. Other examples of priming tasks that MTL patients can do…
No memory of episode during which task was learned.
You can train someone on sequence task, they will get better although not necessarily aware of the pattern (can’t tell you the pattern explicitly)

26. Long-term Memory so we have a single dissociation
what about people that have an intact declarative memory system yet present with difficulties in non-declarative tasks?

27. Patient M.S. opposite pattern of results from H.M./K.C.
intact declarative memory
problems with priming tasks
Problem with implicit perceptual priming task

28. Patient M.S. Extrastriate cortex.
Visual association area, shape recognition, attention?

29. 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?
Lack of control of size/location of the lesion.