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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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parallel memory systems
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
memory systems
Memory systems
  • Hippocampal
    • New associations
    • Episodic - temporal signature
    • Case examples
    • Tests
    • Paired associate learning
    • Effect of retrieval cues
hippocampal system
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.
neuropsych patterns in hc based memory impairment
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
wada testing of hc function
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
memory without episodic recall feeling of knowing
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”
recollection versus familiarity
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
r vs k
R vs. K
  • Eldridge et al have shown the HC is selectively involved in R, not with K.
novelty encoding paradigm
Novelty Encoding Paradigm

Alternating Blocks of Novel and Repeat Pictures

New

New

New

Rest

Repeat

Repeat

Rest

Outdoor

Indoor

slide15

Time Series for Subregions

Sustained

Late Activation

No Activation

CA 2, 3, DG

CA 1

Parahippocampal

Fusiform

Subiculum

Entorhinal

patient h m can learn
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
imaging the striatal learning system learning a new skill
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

knowlton and squire
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
slide22
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?
basal ganglia and learning
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
striatum is involved in language communication

(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

implicit learning and dorsal striatum
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
implicit learning and reward
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

response to rewards
Response to Rewards

Every occurrence of a reward (any type) vs. no-reward

word segmentation language learning
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
implicit language learning study

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
implicit language learning paradigm
Implicit Language Learning Paradigm

Unstressed

Language

Stressed

Language

Random

Syllables

144s

30s

144s

30s

144s

TIME (seconds)

comparisons with baseline rest in typical adults

RH

LH

LH

RH

Comparisons with Baseline (Rest) in typical adults

Random Syllables

RH

LH

Unstressed Language

Stressed Language

McNealy et al., 2006

language learning compared to rest indexed by signal increases over exposure

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

implicit learning and reward1
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

frontal contributions to memory
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)
frontal lobe memory deficits
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
some examples to discuss
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?
example 2
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?
emotion effects on memory
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.
neuroanatomy of psychiatric conditions
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
facial emotions experimental paradigm

“Match”

“Label”

Facial Emotions: ExperimentalParadigm

Control

MatchExpressions: Perception only; implicit emotional processing

Label Expressions: Explicit cognitive analysis

match affect normal adults
Match Affect- normal adults

-seeing negative face expressions activates Face and Fear brain centers

amygdala

face area

Hariri et al., 1999

label affect
Label Affect

-interpreting negative face expressions activates Face center … down regulates the amygdala

amygdala

Hariri et al., 1999

cortical influence during label
Cortical Influence During “Label”

-this frontal lobe region regulates and controls Fear brain centers

Hariri et al., 1999

mirror neurons and autism
Mirror Neurons and Autism
  • A dysfunctional mirror neuron system (MNS) in autism? (Williams et al 2001)
  • Mirror neurons: class of neurons first discovered in ventral premotor cortex (area F5) of the macaque (Gallese et al 1996; Rizzolatti et al 1996); Pars opercularis (BA 44), inferior frontal gyrus, is human homologue.
  • Neurons fire during both the performance and observation of motor behavior; respond to intention: only fire for meaningful actions
slide58

faces

+

2 s

+

2 s

+

2 s

Mirror Neuron function in autism: Imitating and Observing emotions

Watch faces

Imitate expressions

Angry

Fearful

Happy

Sad

Neutral

2 Separate Functional Runs

“Just look at the expression on each face”

“Imitate the expression you see on each face”

slide59

TD Imitate

L

R

6

5

4

t

3

ASD Imitate

2

1

L

R

0

Imitate:

TD > ASD

p<.05, corrected at cluster level

L

R

Activity During Imitation

Motorareas

Visual areas

Mirror neuron area

slide60

z: -12

z: 8

L

R

R

L

Amygdala: fear centers

Negative faces

Imitation: TD > Autism

Anterior Insula

Connection from mirror centers to emotion centers

Ventral striatum:

Reward Centers

(happy faces)