1 / 24

Last Lecture

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

calliope
Télécharger la présentation

Last Lecture

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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. 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 An example of the dichotomy...

  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. Marco Polo was Venetian Mt. Everest Keeps growing 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. 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 retrievalfrom LTM • Lateral Prefrontal areas • all materials: verbal & nonverbal • Why? memory requires reflection about self / personal experience

  23. Right Frontal Lobe & Self Craik et al., 1999 - 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)

More Related