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Inventing ourselves: the secret life of the teenage brain
Sarah-Jayne Blakemore
Developmental Cognitive Neuroscience GroupUCL Institute of Cognitive Neuroscience
www.icn.ucl.ac.uk/sblakemore
Twitter: @sjblakemore
A unique period of biological, psychological and social development.
Some adolescent-typical behaviours are common across species, culture and history
Adolescence
Adolescent (but not adult) mice drink more alcohol when with other mice
Logue et al. Dev Science (2014)
Adolescent-typical behaviour across 11 cultures
Sensation-seeking
Self-regulation
Steinberg et al. Dev Science (2017)
Peer influence on risk taking
Gardner & Steinberg (2005)
13-16
17-24
25+
Cyberball: an experimental social exclusion manipulation
Williams et al. (2000) JPSP
Cat Sebastian
2
Adolescents are hypersensitive to social exclusion
Sebastian et al. (2010) Brain & Cognition* P<0.05
*
** **
SHALL I DRIVE REALLY FAST?
SOCIAL
Blakemore & Mills (2014) Annual Review of Psychology
�KICK� LAW`
NOYES
HEALTHUSEFUL
Kate Mills
Social influence on risk perception
Lisa Knoll Lucia MagisMaarten Speenkenbrink
N = 563 (313 female), aged 8-59
Teenagers rated
crossing a street on a red light
Adults rated
crossing a street on a red light
Rating 1
crossing a street on a red light
Rating 2
crossing a street on a red light
Provided rating
Please rate again!
Social influence on risk perception
N = 563 (313 female), aged 8-59
All age groups show social influence effect
Knoll et al (2015) Psych Science
0
10
20
30
40
8-11 12-14 15-18 19-25 26-59Children Young
adolescentsMid-
adolescentsYoung adults Adults
Percent change between rating 1 and rating 2
**
**
**
****
** P<0.001
Knoll et al (2015) Psych Science
Young adolescents’ risk perception is influenced more by other teenagers than by adults
-0.08
-0.04
0
0.04
0.08
8-11 12-14 15-18 19-25 26-59Children Young
AdolescentsMid
AdolescentsYoungAdults
Adults
Influenced more by teenagers
Influenced more by adults
****
**
*
*** P<0.001** P<0.01* P<0.05
Replicated in a new cohort (N = 590; Knoll et al. 2017)
3
Summary
Peer influence is an important determinant of adolescent-typical behaviour
Magnetic Resonance Imaging (MRI)
Functional MRI
Structural MRI
White mattercontains axons
Grey mattercontains cell bodies and synapses
Structural brain development in four cohorts
NIH PITTSBURGH
OSLOLEIDEN
Total N = 391 participantsTotal MRI scans = 852
Kate Mills
Christian Tamnes
MeganHerting
RosaMeuwese
N = 391 participants; 852 scans
Mills et al. (2016) Neuroimage
Cortical grey matter volume
Grey matter volume decreases around 1.5% annually during adolescence
Cor
tical
gre
y m
atte
r vol
ume
age
NIMHPittsburgh
OsloLeiden
N = 391 participants; 852 scans
Mills et al. (2016) Neuroimage
Cerebral white matter volume
White matter volume increases up to 1% annually during adolescence.
Cer
ebra
l whi
te m
atte
r vol
ume
age
Why does grey matter decrease and white matter increase during adolescence?
Myelination
Axonal growth
Synaptic pruning
à Neuroplasticity during adolescence
4
Summary
Peer influence is an important determinant of adolescent-typical behaviour
Grey matter decreases and white matter increases in adolescence
Social deprivation in adolescent rats has more damaging effects on behaviour and brain development than deprivation in juvenile or adult rats
Einon & Morgon (1977); Van Hoeve et al. (2013); Burke et al. (2017)
Do plasticity and learning decline across development?
Plastic
ity
Age
Fuhrmann et al. (2015)
“Brain plasticity and the ability to change behavior decreases over time” (National Scientific Council on the Developing Child, 2014).
Are there sensitive periods for learning in adolescence?
Lisa KnollAshok
SakhardandeDelia
Fuhrmann
N = 663, aged 11-33 years
Knoll et al. (2016) Psych Science
Does learning decline across development?
T1NumerosityReasoning
Face perception
Pre-trainingN=663
Numerosity training
Reasoning training
Face training
Training 20 days
Younger adolescents
11-13 years
Mid-adolescents
14-15 years
Older adolescents
16-17 years
Adults 18-33 years
T2NumerosityReasoning
Face perception
Post-trainingN=602
Knoll et al. (2016) Psych Science
Does learning decline across development?
T1NumerosityReasoning
Face perception
Pre-trainingN=663
Numerosity training
Reasoning training
Face training
Training 20 days
Younger adolescents
11-13 years
Mid-adolescents
14-15 years
Older adolescents
16-17 years
Adults 18-33 years
T2NumerosityReasoning
Face perception
Post-trainingN=602
N = 663, aged 11-33 years
5
Non-verbal relational reasoning
based on Raven’s matrices (Raven, 1960)
c
The ability to learn non-verbal reasoning improves over adolescence
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
Younger adolescents11-13
Midadolescents14-15
Older adolescents16-17
Adults18-33
Impr
ovem
ent a
fter t
rain
ing
(T2-
T1)
******
******
Knoll et al. (2016) Psych ScienceLearning does not always decline with age
*** P<0.001
Summary
Peer influence is an important determinant of adolescent-typical behaviour
The brain develops structurally and functionally in adolescence
Adolescence may be a sensitive period of brain development?
Individual differences are huge (Foulkes & Blakemore, Nature Neuroscience, in press)
Funding
Developmental Cognitive Neuroscience labPost-docsSaz AhmedGuillaume BarbalatGabriele ChierchiaKathrin Cohen KadoshIroise DumontheilLucy FoulkesLisa KnollLara MenziesStefano PalminteriSusanne Schweizer
PhD studentsJack AndrewsJessica BoneZillah BorastonStephanie BurnettSuparna ChoudhuryJennifer CookDelia FuhrmannAnne-Lise GoddingsHauke HillebrandtEmma KilfordKathryn MillsCatherine SebastianStephanie ThompsonLaura Wolf www.icn.ucl.ac.uk/sblakemore
Research assistants and masters students Hanneke den OudenHugo FlemingAnnie GauleCait GriffinBano HassanRachael HoultonElina JacobsSarah JensenOlivia KüsterAlberto LazariJovita LeungLucia MagisAlex MoscickiEmily GarrettAshok SakhardandeMaximilian ScheupleinFabian StampLeonora Weil
Royal Society University Research Fellowship
