implicit learning and dorsal striatum

Implicit learning and dorsal Implicit learning and dorsal striatumstriatum

• Dorsal striatum (Ca/Pu) is implicated in Dorsal striatum (Ca/Pu) is implicated in implicit or “habit” learning implicit or “habit” learning (Knowlton and Squire)(Knowlton and Squire)

• Language acquisition and social Language acquisition and social learning are thought to rely on implicit learning are thought to rely on implicit learning mechanismslearning mechanisms– Probabilistic learning tasks (vs. deterministic) are Probabilistic learning tasks (vs. deterministic) are

implicit, subconsciousimplicit, subconscious, , and rely on dorsal striatumand rely on dorsal striatum

Implicit Learning and RewardImplicit Learning and Reward• Probabilistic Classification TaskProbabilistic Classification Task• Reported by Knowlton and Squires- impaired in PD, Reported by Knowlton and Squires- impaired in PD,

intact in amnesiaintact in amnesia• Inversely related to hippocampal activityInversely related to hippocampal activity• Reward variant- social vs. monetaryReward variant- social vs. monetary

– Stimuli predict a given outcome (1 or 2); 50% deterministic, Stimuli predict a given outcome (1 or 2); 50% deterministic, 50% random50% random

– Reward and Cognitive (Correct / Incorrect) feedbackReward and Cognitive (Correct / Incorrect) feedback

Source: D. GhahremaniSource: D. Ghahremani

Adults: BG Adults: BG activity during activity during probabilistic probabilistic learninglearning

Response to RewardsResponse to Rewards

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

Reward response in VS

0

0.05

0.1

0.15

0.2

0.25

Social Monetary

Magnitude (mean %)

TDASD

Effect of rewards on implicit Effect of rewards on implicit learninglearning

Total Performance

0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.00

90.00

100.00

1 2 3

Time

Percent Correct

ASD Money Total

TD Money Total

ASD Social Total

TD Social Total

Dorsal Striatum deficits in Dorsal Striatum deficits in ASD during implicit learningASD during implicit learning

R L

Typical children > ASD childrenTypical children > ASD children

Variation in VS activity in typical Variation in VS activity in typical children predicts social reciprocitychildren predicts social reciprocity

R

Social Responsiveness Scale Score

403020100

PE Social Deterministic Rewards

600

400

200

0

- 200

- 400

- 600

- 800

Implicit Language Learning M. Dapretto, A. Scott

• 3 Miniature Artificial Languages– Unstressed (Transitional Probabilities only)

– Stressed (Transitional Probabilities & Prosodic Cues)

– Random (No Transitional Probabilities OR Prosodic Cues)

pabiku daropigolatu tibudo

novuka pofimuvikoga bafugi

lidura vorifamanuto nimolu

Implicit Language LearningImplicit Language Learning

StressedStressed

LanguageLanguage

UnstressedUnstressed

LanguageLanguage

RandomRandom

SyllablesSyllables

TIME (seconds)TIME (seconds)

144 s 30 s 144 s 30 s 144 s 30 s 144 s 144 s 30 s 144 s 30 s 30 s

Implicit Language LearningImplicit Language Learning

TD ASD

• 2 languages (Stressed & Unstressed) vs. rest2 languages (Stressed & Unstressed) vs. rest• Absence of activity in caudate, mPFC and left IFG in Absence of activity in caudate, mPFC and left IFG in

ASDsASDs