1. Last Lecture Frontal Lobe Anatomy Inhibition and voluntary control
A model task: working memory +

2. This Lecture Long Term Memory role of hippocampus in consolidation
role of frontal regions in encoding and retrieval
right frontal regions and representation of self...

3. Announcements FINAL EXAM: 182 Dennison Wednesday, 4/19
4:00 pm - 6:00 pm.
Please contact us immediately if this poses a conflict.

4. Long Term Memory and its Dysfunction
Memory: the ability to retain & recollect the contents of our experience
typically multimodal
rich in associations
The ability to acquire new skills & demonstrate improved performance as a result of experience.

5. Human Amnesia Anterograde: Inability to acquire NEW memories.
Retrograde: Inability to recollect OLD memories.

6. Human Amnesia
Scoville & Milner (1957) H.M. bilateral removal of hippocampus (medial temporal lobes).
Wada testing to avoid bilateral hippocampectomies.
Unilateral removals: material-specific deficit: (Right- nonverbal; Left: verbal)

7. Case H.M.-- PROFOUND ANTEROGRADE AMNESIA
High Average intelligence
STM: normal- digit span 7 forward; 5 backward
Can converse normally, perform mental math
No post-operative personality changes
Unable to acquire new memories...
all modalities
all material (verbal, nonverbal)
names, people, places, events, route finding
all are affected.
surgery
Retrograde
Anterograde

8. Early animal models of HM were unsuccessful
WHY? (Hint: remember what happened with blindsight)
Testing the wrong type of memory
What Amnesics can learn:
Milner (1962) mirror drawing
Warrington & Weiskrantz (1968) perceptual learning (degraded cues, priming)
Weiskrantz & Warrington (1979) classical conditioning

9. Types of Long Term Memory

10. Declarative/Explicit
consciously accessible
Episodic: personal/public episodes
Semantic: facts, events, routes
Tested with recall / recognition:
"Have you seen this before?"; "Can you remember...?"; "Is this one of the items you studied...?”

11. Nondeclarative/Procedural/Implicit
Does not require conscious recollection
Examples:
conditioning
skills (motor skills, mirror reading)
priming (e.g. stem completion)

12. Skill Acquisition
Mirror drawing improves
Amnesics = Controls

13. An example of the dichotomy...
Phase 1
Read & rate words (living/non):
Lead
Bear
Fear
Work...
Phase 2
EXPLICIT TEST:
"Complete stem with a word you just read"
lea_
bea_
OR IMPLICIT TEST: "Complete stem with first word that comes to mind"
lea_ > lead or leaf
bea_ ---> beat or bear

14. Priming is spared in Amnesia
Amnesics cannot recall study items.
But stored representation is accessed automatically.

15. The Hippocampal circuit & Explicit Memory
Hippocampus - part of a circuit with input to & from parietal, temporal, frontal lobes & limbic system (amygdala).

16. Hippocampus

17. The Hippocampal circuit & Explicit Memory
Hippocampus - part of a circuit with input to & from parietal, temporal, frontal lobes & limbic system (amygdala).
CA1 , CA2 , CA3 layers of HPC form a circuit allowing access to cortex
CA1 layer - sensitive to anoxia & epileptic activity (CASE R.B.)
Damage to HPC or its inputs/outputs --> LTM impairment

18. Role of Hippocampus in Explicit Memory
NOT the location of LTM
NOT necessary for retrieval of LTM
NOT the location of STM
HPC: immediate experience --> LT memories CONSOLIDATION
Explicit memory - stores single events w/ context.
Learning is fast (one-trial learning-- but forgetting endures).
Representations are
accessible by various cognitive systems
modality-general
give rise to sense of familiarity.

19. Implicit memory...
Reactivation of the processing structures engaged during learning.
Learning is incremental, gradual, slow
Representations are specific to a task and or the learning modality.
Involves multiple systems (cortex, basal ganglia)
More on the encoding and retrieval of explicit LTM...

20. Frontal Contributions to LTM
Recency Judgments
knowledge of temporal context
give a list of items
probe w/ two items asking:
“Which one of these items came most recently?”

21. Frontal Contributions Source Memory
ability to identify (remember) the context in which a memory was acquired
task: judge which of two characters uttered a particular fact.
Marco Polo
was Venetian
Mt. Everest
Keeps growing
Hypno
Psyduck

22. HERA: Hemispheric Encoding/Retrieval Asymmetry (Tulving et al., 1994)
PET studies w/normal subjects show
Left Hem. is critical to encoding into LTM
Lateral Prefrontal areas
all materials: verbal & nonverbal
Why? associating meaning with events
Right Hem. is critical to retrieval from LTM
Why? memory requires reflection about self / personal experience

23. Right Frontal Lobe & Self
Craik et al., PET study with 4 conditions
How well does the word stubborn describe...
You?
Lee Bollinger?
How socially desireable?
How many syllables?
RESULT: Only self-referential instruction activated Right prefrontal cortex ( same areas activated by memory retrieval)
Conclusion: Right frontal regions are important for representation of self.

24. Memory Summary WM vs. LTM LTM: IMPLICIT vs. EXPLICIT
Explicit (personal episodes, semantics/facts)
Amnesia -- anterograde or retrograde
Establishing new explicit memories requires
encoding, consolidation, retreival
hippocampus -- consolidation (HM & RB)
HERA:
Left frontal- encoding (context info)
Right frontal- retrieval (self)