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Fronto Limbic and Mem

Fronto Limbic and Mem. Parallel Memory Systems. Episodic Memory- Hippocampal based Procedural and “ Habit ” learning system: Basal Ganglia Reward system effects on learning-ventral striatum Frontal lobe contributions Retrieval systems Organization of input Priming

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Fronto Limbic and Mem

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  1. Fronto Limbic and Mem

  2. Parallel Memory Systems • Episodic Memory- Hippocampal based • Procedural and “Habit” learning system: Basal Ganglia • Reward system effects on learning-ventral striatum • Frontal lobe contributions • Retrieval systems • Organization of input • Priming • Repetition priming/sensory based traces • Frontal contributions to effortful learning/priming

  3. Memory systems • Hippocampal • New associations • Episodic - temporal signature • Case examples • Tests • Paired associate learning • Effect of retrieval cues

  4. Hippocampal System • H.M. first model of episodic memory • Bilateral medial temporal lobectomy for epilepsy surgery • Cured of epilepsy • No new episodic encoding since surgery • This memory deficit is the classic amnesia syndrome • Other good ways to get this deficit: • Repeated temporal lobe seizures (mesial temporal sclerosis • Anoxia- at birth or acquired- HC especially sensitive to anoxic damage • Herpes encephalitis (limbic encephalitis). Herpes loves the HC.

  5. Neuropsych patterns in HC-based memory impairment • Difficulty forming new associations • E.g. Unrelated paired associate learning • Face-name associations • Steep forgetting curve • Delayed recall specifically impaired • Minimal to no benefit from retrieval cues • Minimal to no benefit from recognition format • Some evidence for content specificity • left vs right, verbal vs spatial dissociation

  6. Wada testing of HC function • Anterior 2/3 HC fed by the anterior choroidal artery which comes of the ICA • During Wada testing, anesthetize 1 HC • Present new information to learn (eg 6 objects) • Wait 12 minutes (with distraction) • Test for Memory for Episode (did we show you anything?) • Test for cued recall; finally, test recogntion • ***Important assess for Episodic recall

  7. Memory without episodic recall: feeling of knowing • HC memory is episodic: remember the encoding episode (eg the objects I just showed you 10 minutes ago) • Distinguish from Explicit, but non-episodic memory (eg, yes I have seen this before, don’t remember the exact episode: “feeling of knowing”

  8. Recollection versus Familiarity • (R) Recollection - re-experiencing the encoding event at the time of recall, true episodic memory • (K) - Know - the feeling of familiarity that you’ve seen something before, but not remembering the exact encoding event • Not implicit because it is conscious

  9. Eldridge et al 2001, 2005: Remember- Know Distinction in HC

  10. R vs. K • Eldridge et al have shown the HC is selectively involved in R, not with K.

  11. Novelty Encoding Paradigm Alternating Blocks of Novel and Repeat Pictures New New New Rest Repeat Repeat Rest Outdoor Indoor

  12. Time Series for Subregions Sustained Late Activation No Activation CA 2, 3, DG CA 1 Parahippocampal Fusiform Subiculum Entorhinal

  13. Non-episodic Memory:Habit Learning System

  14. Striatum Hippocampus

  15. Patient H.M. can learn….. • Was able to navigate around his (new) environment, eventually. • Could learn new skills: initially, motor skills; ultimately found to include cognitive skills • Eg mirror reading (see next slide) • Could perform the tower of Hanoi in the optimal number of moves; but had to be explained the directions repeatedly; no memory of having seen it before • Thus there was some unconscious, implicit learning that was conceptual in nature

  16. Imaging the striatal learning system:Learning a new skill • Mirror-reading: (Poldrack et al) • College students were taught to read mirror-reversed text for ~5 hours • Scanned before and after learning using fMRI • Activity in striatum during learning • Normal in HC lesioned patients ambitious bedraggle plaintiff

  17. Knowlton and Squire • Performed a probabilistic learning task in Parkinson’s patients and amnestic patients: Weather Prediction Task • In this task subjects learn an association between a stimulus (a playing card) and an outcome (rain or shine) • Relationship was probabilistic, not deterministic; 66% probability of an outcome • Subjects could not memorize the associations, and ultimately guessed • However their behavior showed a learning curve despite no explicit knowledge of learning

  18. Learning concepts without consciousness

  19. Amnesic patients learned the associations (without awareness) • Parkinson’s patients did not • Requires hundreds of trials • Testing of explicit memory results in chance • Behavior shows learning • Considered an implicit, habit based learning system • What other skills do you learn this way?

  20. Implicit learning

  21. Basal Ganglia and learning • What else is learned implicitly? • Language learning and grammar: based on probabilistic word boundaries and repetition to learn syntactic structures • Social skills: how close to stand to people, how loud to talk, where to stand in an elevator, how much eye contact, etc

  22. (14,6,0) Striatum is Involved in Language & Communication • Artificial grammar learning (Lieberman et al., 2004) • Subjects given sequences of letters with probabilistic sequences • Presented novel sequences that follow the same rules • Subjects can correctly classify them as right or wrong without knowing the rules or having learned the specific examples! Grammatical > Non-Grammatical Lieberman et al., 2004 J Cog Neuro

  23. Implicit learning and dorsal striatum • Dorsal striatum (Ca/Pu) is implicated in implicit or “habit” learning (Knowlton and Squire) • Language acquisition and social learning are thought to rely on implicit learning mechanisms • Probabilistic learning tasks (vs. deterministic) are implicit, subconscious, and rely on dorsal striatum

  24. Implicit Learning and Reward • Probabilistic Classification Task • Reported by Knowlton and Squires- impaired in PD, intact in amnesia • Inversely related to hippocampal activity • Reward variant- social vs. monetary • Stimuli predict a given outcome (1 or 2); 50% deterministic, 50% random • Reward and Cognitive (Correct / Incorrect) feedback Adults: BG activity during probabilistic learning Source: D. Ghahremani

  25. Response to Rewards Every occurrence of a reward (any type) vs. no-reward

  26. Effect of rewards on implicit learning

  27. R L Dorsal Striatum deficits in ASD during implicit learning Typical children > ASD children

  28. R Variation in VS activity in typical children predicts social reciprocity

  29. Word Segmentation & Language Learning • Identifying word boundaries is one of the earliest steps in language learning (Kuhl 2002) • Infant studies suggest heavy reliance on statistical learning for word segmentation (Saffran et al., 1996; Aslin et al., 1998) • Prosodic cues (e.g., stress) aid speech parsing (Johnson & Juscyzk, 2001; Thiessen & Saffran, 2003) • Adapt well-established paradigm from infant literature

  30. Unstressed Language Stressed Language Random Syllables po vu ba novuka pofimu vikoga bafugi gi pabiku daropigolatu tibudo no ko fu ro do ga go la fi mu ka ku da Transitional Probabilities Only Transitional Probabilities + Prosodic Cues No Transitional Probabilities No Prosodic Cues vi bi bu ti pi pa li ni tu lidura vorifamanuto nimolu vo lu to fa ma du ri mo nu ra nimoluvorifaliduramanuto… pabikugolatudaropitibudo… kagipovuganomubakafufibako… Implicit Language Learning Study

  31. Implicit Language Learning Paradigm Unstressed Language Stressed Language Random Syllables 144s 30s 144s 30s 144s TIME (seconds)

  32. RH LH LH RH Comparisons with Baseline (Rest) in typical adults Random Syllables RH LH Unstressed Language Stressed Language McNealy et al., 2006

  33. U S R TD > ASD Children TD kids show significantly greater signal increases in striatum than ASD RH LH Language learning compared to Rest: indexed by signal increases over exposure Stressed Unstressed Random

  34. Implicit Learning and Reward • Rewards augment implicit learning • Probabilistic Classification Task • Reward variant- • Stimuli predict a given outcome (1 or 2) either 17% 50% or 83% • Reward and Cognitive (Correct / Incorrect) feedback • Reward type varied: Monetary Rewards or Social Rewards • Equal number of reward and cognitive feedback trials Source: D. Ghahremani

  35. Frontal contributions to memory • Attention to incoming information • Organization of incoming information • Pre-organized • Semantic categorization • Working memory capacity • Organized memory retrieval (Brodmanns area 10 found to be involved in controlled retrieval)

  36. Frontal lobe memory deficits • Information size effects (supraspan) • LM story 2 second rep; • Interference (proactive) • Eg: CVLT 5,7,10,9,8 • Benefit from cues • Reduced spontaneous categorization • Confabulation • Prospective memory impairment

  37. Some examples to discuss • Patient 1: • CVLT: 4,7,12,15,9 2 I, 4 P • List B: 4 • SF: 7 cued 9 • LF: 9 cued 12 • Recognition 15/16 3 FP • What does this pattern suggest? • What would WMS LM look like?

  38. Example 2 • CVLT 8,10,12,13,14 • B 8 • Sdfree 8 cued 8 • Ldfree 4 cued 5 • Recognition 10/16 0 FP • What else would you be likely to see? What would WMS LM look like?

  39. Emotion effects on memory • Flashbulb memory: where were you on 9/11? • Most can remember exquisite details of highly emotionally charged events • Close contact between amygdala and HC facilitate strong emotional memories • Interestingly, these memories are modifiable- details are altered with retelling, easily tampered with • People retain their emotional traces, which includes a strong conviction of the accuracy of their memory for emotional events • This is exactly why eyewitness testimony is so poor.

  40. Neuroanatomy of psychiatric conditions • Eg schizophrenic auditory hallucinations: strong activity in TTG and A2 during hallucinations • Many studies of psychiatric disorders have used emotional faces as stimuli

  41. “Match” “Label” Facial Emotions: ExperimentalParadigm Control MatchExpressions: Perception only; implicit emotional processing Label Expressions: Explicit cognitive analysis

  42. Match Affect- normal adults -seeing negative face expressions activates Face and Fear brain centers amygdala face area Hariri et al., 1999

  43. Label Affect -interpreting negative face expressions activates Face center … down regulates the amygdala amygdala Hariri et al., 1999

  44. Cortical Influence During “Label” -this frontal lobe region regulates and controls Fear brain centers Hariri et al., 1999

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