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Beatriz Luna, PhD

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Cognitive control of behavior matures in adolescence ... Adolescence is a crucial and necessary period of plasticity when brain circuitry ... – PowerPoint PPT presentation

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Title: Beatriz Luna, PhD


1

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
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
Speed of Processing
14
Voluntary Response Inhibition
15
Working Memory Accuracy
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 (N36)
  • 8-13y (N11)
  • 14-17y (N15)
  • 18-30y (N10)
  • 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
Prosaccade Trial
Antisaccade Trial
Fixation
Fixation
15
22
Adults gt Adolescents and Children
Adults
Children
Adolescents
R
L
FEF
PEF
Sup Coll
Lat Cer
14
23
Adolescents and Children gt Adults
Adults
Children
Adolescents
PPC
R
L
DLPFC
13
24
Response Inhibition Planning
25
Event Related Antisaccades
Prosaccade Trials
Antisaccade Trials

Cue


10
26
Preparation to Inhibit a Response
Adults
Children
Adolescents
FEF
R
L
9
27
Antisaccade Preparation FEF
  • 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
  • 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
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 1250 ms
Jittered 2.5-12.5s
Fix 2425 ms
36
Prefrontal Cortex Maintenance
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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