From the event "From Troubled Teens to Tsarnaev: Promises and Perils of Adolescent Neuroscience and Law." Part of the Project on Law and Applied Neuroscience, cosponsored by the Center for Law, Brain and Behavior at Massachusetts General Hospital and the Petrie-Flom Center for Health Law Policy, Biotechnology, and Bioethics at Harvard Law School. For more information, visit our website at http://petrieflom.law.harvard.edu/events/details/from-troubled-teens-to-tsarnaev.

1. Adolescent brain development
& psychological functioning
Leah Somerville
Department of Psychology & Center for Brain Science
Harvard University
Affective
Neuroscience
&
Development
Laboratory
HLS 2015

2. Studying brain development

3. • The adolescent brain is different from the adult
brain.
Lessons learned about the adolescent brain

4. The adolescent brain is different from the adult brain
Gray Matter: Computation CentersWhite Matter: Connection Pathways
Brain Dev Cooperative Group (2013)
The gross structure of the adolescent brain is less
metabolically efficient and less integrated
than the adult brain.

5. Mills et al. (2014)
The prefrontal cortex is
critical for planning,
decision making, and self-
control.
The prefrontal cortex is
continuing to develop well
past age 18.
The adolescent brain is different from the adult brain

6. • The adolescent brain is different from the adult
brain.
• The maturational state of the adolescent brain
‘tunes’ it to rewards and learning opportunities.
Lessons learned about the adolescent brain

7. The adolescent brain is tuned to rewards and learning opportunities.
Dopamine
Dopamine pathways
Replotted from Andersen et al (2000)
DopamineReceptorDensity
0
30
60
90
120
Age (days)
20 40 60 80 100
Dopamine, the
“currency” of
rewards and
learning in the
brain, is uniquely
potent during
adolescence.

8. Galvan et al., 2006
Adolescents > Children & Adults
Striatum Signaling
“registering” learning opportunities
Cohen et al., 2010
Arbitrary Cue
The adolescent brain is tuned to rewards and learning opportunities.

9. The adolescent brain is tuned to rewards and learning opportunities.
Adolescents rely on
learning from direct
experience more than
adults, and outperform
adults in experience-
based learning.
%timerewardfound
20
30
40
50
60
70
Time —>
1 2 3 4 5 6
Adults Adolescents
Replotted from Decker et al (2015)
False Instruction

10. • The adolescent brain is different from the adult
brain.
• The maturational state of the adolescent brain
‘tunes’ it to rewards and learning opportunities.
• Neurodevelopmental trajectories are molded by
the environment.
Lessons learned about the adolescent brain

11. Neurodevelopmental trajectories are molded by the environment.
Sheridan et al, 2012
Institution Typical env. Institution Typical env.
Adverse environments impact brain health
8-11 year olds
Deprived environments hijack neurodevelopment.

12. “Moving parts get broken”
Neurodevelopmental trajectories are molded by the environment.
Hippocampus
Prefrontal
cortex
Adversity
at age
3-5
Adversity
at age
14-16
Negative
impact
Negative
impact
Andersen et al., (2008)

13. “Moving parts get broken”
Neurodevelopmental trajectories are molded by the environment.
Hippocampus
Prefrontal
cortex
Adversity
at age
3-5
Adversity
at age
14-16
Negative
impact
Negative
impact
Andersen et al., (2008)
The developmental trajectory of PFC is tenuous during adolescence.

14. “Moving parts get broken”
Neurodevelopmental trajectories are molded by the environment.
Hippocampus
Prefrontal
cortex
Adversity
at age
3-5
Adversity
at age
14-16
Negative
impact
Negative
impact
Andersen et al., (2008)
These effects are not temporary.

15. Neurodevelopmental trajectories are molded by the environment.
Social & identity development
- modeling peers
Stress
- deprivation
- violence
- chaos
Learning opportunities
Nelson et al. (2005); Crone & Dahl (2012); Somerville (2014); Casey (2015)

16. Concluding points
The adolescent brain is still developing
It is a ‘sponge’ for rewards and for learning
It needs to be treated with care
- Avoid the explicitly negative inputs
- Provide suite of expected inputs
- Maximize positive influence
CAREER
Award