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

2. Control of Behavior Exogenous Endogenous 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. electro-oculography (EOG) -24 deg -16 deg -8 deg 1 meter 0 deg
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. Visually Guided Saccades
Central Fixation
( s)
Saccade
Saccade to
Target (1.5s)
Degrees of Visual Angle
Illuminated Targets
Correct Gaze Location
Non-visible Target Locations

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

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

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

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) fMRI Studies 8-13y (N=11)
3.0 Tesla GEMS scanner
Gradient-Echo EPI, TR = 5000
In-plane resolution mm2
mm slices, 2 mm gap
Standard anatomic imaging (SPGR)

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

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

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

24. Response Inhibition: Planning

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

26. Preparation to Inhibit a Response:
Children
Adolescents
Adults
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:
Children
Adolescents
Adults
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 Memory Guided Visually Guided 30 sec. time
Working Memory Trials
Saccade
VGS Trials
Saccade
Delay 4s +
Cue 75 ms
Fix 2425 ms +
Fix 1250 ms
Memory Guided
30 sec.
Tasks Repeated for 10.5 cycles
Visually Guided 15

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

34. Encoding and Maintenance
Working Memory:
Encoding and Maintenance

35. Spatial Working Memory Trials
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 s

36. Prefrontal Cortex: Maintenance
Children
8-12yo
Adolescents
13-17yo
Adults
18-30yo
2.5s Delay
BA9
10s Delay
BA10
-La parte dorsal lateral de la cortesa prefrontal.
-What I am showing you here are the structure of a representative subject with the group averaged activation for each age group overlaid on top of it. The columns indicate age group and the rows the two delay periods.
-Prefrontal activation was present in the short delay for younger subjects and in all subjects and more robustly for the longer delay. This confirms that DLPFC underlies maintenance aspects of working memory and that it is on-line by childhood.
BA9
PFC supports WM maintenance and is on line at all ages
LNCD

37. Hippocampus: Encoding
Children
8-12yo
Adolescents
13-17yo
Adults
18-30yo
2.5s Delay
10s Delay
The hippocampus was only evident in the adult subjects and more so for the short than the long delay suggesting that the hippocampus underlies encoding aspects of maintenance, since the shorter delay incorporates less maintenance relative to long delay, and that these processes are not being recruited by younger subjects.
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