1. Memory & the Medial Temporal Lobe Lesson 21

2. Memory n Storage of information l perceptions l learning l personality n Information processing approach l RAM vs. hard drive n Multiple memory stores l different characteristics n Clive Wearing ~ Clive Wearing

3. Multiple Memories n Sensory memory l capacity: large; sensory receptors l duration: < 1 sec. n Short-term memory (STM) l capacity: 7 ± 2 chunks l duration: < 1 min. l maintenance: rehearsal ~

4. Multiple Memories n Long-term memory (LTM) l capacity: functionally unlimited l duration: minutes - years n Working memory l intermediate to STM & LTM l information needed longer than 1 min, but not permanent ~

5. Sensory Memory stimuli STMLTM transfer retrieval attention forgetting A Model of Memory rehearsal

6. Subdivisions of LTM 1. Declarative - Explicit n Episodic: l autobiographical l time-tagged, automatic n Semantic: l generic l not time-tagged, effortful ~

7. Subdivisions of LTM 2. Procedural – Implicit l non-declarative, unconscious n Motor learning n Nonassociative Learning l modulation of reflexes n Associative Learning l Classical & Operant Conditioning ~

8. Neural Mechanism of STM n Donald Hebb n Change in neural activity l not structural l temporary n Reverberatory Circuits l cortical loops of activity l activity persists for short period of time ~

9. Reverberating loops n Maintains neural activity for a period

10. Neural Mechanism of LTM n LTM relatively permanent l structural change required n Hebbian Synapse l use strengthens synaptic efficiency l requires simultaneous activity l pre- and postsynaptic neurons l Long-term potentiation (LTP) ~

11. Where are memories stored? n Engram l physical change representing learning and memory n Lashley l Mass Action & Equipotentiality n Classical Conditioning: Eye-blink l lateral interpositus nucleus of cerebellum n Memories stored locally l in different parts of brain ~

12. H.M. n Greatest contribution to study of memory l can’t remember any of it l similar to Clive Wearing n Bilateral medial temporal lobectomy l to control seizures l hippocampus (HC) ~

13. Hippocampus Mid-sagittal View

14. Spared some memory n Personality n Intelligence n LTM n Verbal STM memory OK n Motor skills

15. Memory Deficits n Some retrograde amnesia l but many old memories intact n Severe anterograde amnesia l unable to form new memories ~ Trauma time RetrogradeAnterograde

16. Evidence of deficits n Digit Span + 1 n Block tapping memory span n Delayed-matching-to-sample l verbal OK - rehearsal l nonverbal impaired – ellipses ~

17. Evidence of Spared Abilities n Performance improved with practice l Procedural memory l but no conscious memory of it n Mirror Drawing n Tower of Hanoi ~

18. Conclusions: Role of Hippocampus n Removal of HC  deficits n Memory Storage? l STM not in HC l LTM not in HC n HC transfers info STM  LTM? l Declarative memories: YES l Procedural: NO n H. M. anterograde amnesia for declarative memories ~