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Beatriz Luna, PhD Laboratory of Neurocognitive Development University of Pittsburgh

LNCD. Vulnerabilities in Neurocognitive Processes in Adolescence. Beatriz Luna, PhD Laboratory of Neurocognitive Development University of Pittsburgh. Control of Behavior. Exo genous Elicited by “external” guides External Stimuli, Emotional States Not guided by a planned response

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Beatriz Luna, PhD Laboratory of Neurocognitive Development University of Pittsburgh

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  1. LNCD Vulnerabilities in Neurocognitive Processes in Adolescence Beatriz Luna, PhD Laboratory of Neurocognitive Development University of Pittsburgh

  2. Control of Behavior • Exogenous • Elicited by “external” guides • External Stimuli, Emotional States • Not guided by a planned response • Reflexive Behavior • Endogenous • Voluntary • Guided by internal plans • Overrides exogenously-guided behavior • Cognitive Control of Behavior / Decision Making • Can be adult like in adolescence

  3. Conclusions: Adolescence • Adolescents can demonstrate adult-level cognitive control of behavior • Behavioral Studies • Brain mechanisms that support adult-level behavior in adolescence are immature • fMRI studies • Adolescent cognitive control of behavior is immature and vulnerable to error • Conclusions

  4. Brain Maturation in Adolescence Synaptic Pruning Myelination • Improved Brain Function • Increased efficiency of local computations • Increased speed of neuronal transmission

  5. Cognitive Development: Core Processes • Voluntary Response Inhibition (Paus 1990, Levin 1991, Ridderinkhof 1997, Fischer 1997, Munoz 1998, Luna 2004) • Working Memory (Zald 1998, Demetriou 2002, Luna 2004)

  6. Oculomotor Studies of Cognition • Direct Measure of Cognitive Control • Minimal strategy formation • Well-delineated Neural System • Anatomically & Physiologically • Simple Cognitive Tasks • Appropriate for Developmental Studies

  7. Behavioral Studies

  8. Methods • 245 subjects • 8-30 yo (93 Female/152 Males) • Tasks • Speed of Processing • Response Inhibition • Working Memory Child Development 2004

  9. Direct current electro-oculography (EOG) -24 deg -16 deg -8 deg 1 meter 0 deg 8 deg 16 deg 24 deg Darkened Room 20

  10. Non-visible Target Locations Illuminated Targets Correct Gaze Location Visually Guided Saccades Central Fixation (1.5-2.5s) Saccade Saccade to Target (1.5s) -30 -20 -10 0 10 20 30 Degrees of Visual Angle

  11. Antisaccade Task 3 - 5 sec Central Fixation Saccade away from 1.5 sec Peripheral Target Feedback 1.5 sec -24 -16 - 8 0 8 16 24 Illuminated Targets Degrees of Visual Angle Correct Gaze Location 19

  12. ODR/ Memory Guided Saccade Task 1.5-2.5s Central Fixation 0.1 s Target Location to be Remembered 1,2,4,8 s Delay Period Saccade to Remembered Location 1.5 s 2.0 s Feedback Illuminated Targets -27 -18 - 9 0 9 18 27 Correct Gaze Location Degrees of Visual Angle

  13. Response Inhibition Working Memory Visually Guided Saccades Speed of Processing

  14. Voluntary Response Inhibition

  15. Working Memory: Accuracy Initial Saccade Final Saccade

  16. Conclusions • Cognitive control of behavior matures in adolescence • What develops is the sophistication of responses not the appearance of an ability

  17. Brain Imaging Studies

  18. + + + + + + + + + + + + + + + + + + + + + + + + + + + + + fMRI Capillary Bed - - - - baseline - - - - - - - activation - -

  19. Response Inhibition

  20. MR Imaging Methods: • Subjects (N=36) • 8-13y (N=11) • 14-17y (N=15) • 18-30y (N=10) • fMRI Studies • 3.0 Tesla GEMS scanner • Gradient-Echo EPI, TR = 5000 • In-plane resolution 3.125 mm2 • 23 - 3 mm slices, 2 mm gap • Standard anatomic imaging (SPGR)

  21. Antisaccade: Block Design 36 sec. 36 sec. Antisaccades Prosaccades 36 sec. • Tasks Repeated for 7.5 cycles Prosaccade Trial Antisaccade Trial Fixation Fixation 15

  22. Adults > Adolescents and Children Adults Children Adolescents R L FEF PEF Sup Coll Lat Cer 14

  23. Adolescents and Children > Adults Adults Children Adolescents PPC R L DLPFC 13

  24. Response Inhibition: Planning

  25. Event Related Antisaccades Saccade Fixation + + Prosaccade Trials Antisaccade Trials + Cue + + 10

  26. Preparation to Inhibit a Response: Adults Children Adolescents FEF R L 9

  27. Antisaccade Preparation: FEF • Children • Adolescents • Adults • Adolescents, like children, do not reach adult-level activation for correct responses. • Adolescents, like adults, do show a second peak of activation. 7

  28. Preparation to Inhibit a Response: Adults Children Adolescents DLPFC VLPFC R L 9

  29. Antisaccade Preparation: DLPFC • Children • Adolescents • Adults • Adolescents, like children, show a delayed peak of activation. • Adolescents, like adults, show a similar magnitude of activation. 6

  30. Conclusions: Response Inhibition • Maturation is characterized by the emergence of an integrated collaborative brain system. • Adolescents are not as efficient at activating brain regions supporting response planning • Adolescents compensate for immature brain systems by recruiting PFC 12

  31. Working Memory

  32. Methods: ODR task VGS Trials Saccade Saccade Delay 4s Fix 1250 ms time Cue 75 ms + + Fix 2425 ms 30 sec. 30 sec. + + Memory Guided Visually Guided 30 sec. • Tasks Repeated for 10.5 cycles Working Memory Trials 15

  33. Working Memory Children Adolescents Adults Basal Ganglia: Caudate & Putamen DLPFC Superior Temporal Gyrus

  34. Working Memory: Encoding and Maintenance

  35. Methods: ODR task + + + + Spatial Working Memory Trials Saccade Delay 2.5 or 10 time + VGS Trials Saccade Cue 75 ms Baseline Fix 2425 ms Fix 1250 ms Jittered 2.5-12.5s

  36. Prefrontal Cortex: Maintenance LNCD Children 8-12yo Adolescents 13-17yo Adults 18-30yo 2.5s Delay BA9 10s Delay BA10 BA9 PFC supports WM maintenance and is on line at all ages

  37. Hippocampus: Encoding Children 8-12yo Adolescents 13-17yo Adults 18-30yo 2.5s Delay 10s Delay • The hippocampus supports encoding and is only recruited by adults

  38. Conclusions: Working Memory • Adolescents are not efficient at recruiting regions that support encoding information in working memory. 12

  39. Take Home Message • While adolescents behave similarly to adults the brain processes supporting cognitive control of behavior are not mature • Adolescence is a still unstable stage that is vulnerable to immature processing 2

  40. Why? • Adolescence is a crucial and necessary period of plasticity when brain circuitry and behavior is beginning to be established. • Risk-taking behavior and novelty seeking may provide a mechanism for increasing exposure to the environment necessary for successful sculpting of the system. end

  41. Laboratory of Neurocognitive Development Dr. Bea Luna PI Dr. Miya Asato Dr. Suzy Scherf Matt Costello MA Krista Garver BA Chuck Geier MA Emi Yasui BA Melanie Wilds BA

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