Wesley College Institute Colloquium
1st November, 2006
Gender and the Developing
Brain
Don Cameron
Centre for Neuroscience
Flinders University
Girls, Boys, Brains and Learning
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What makes boys and
girls different?
Do boys and girls have
different brains?
Do boys’ and girls’
brains develop
differently?
What does it all mean?
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Remarkable Insight #1
Boys and
girls think
differently
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In a nutshell…
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There are a myriad of cognitive gender differences
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Although statistically significant, most of these
differences are very small
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InterInter-individual differences are far greater
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Differences don’t imply that one cognitive property or
strategy is necessarily better than another
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There are gender differences in learning difficulty
identification
Remarkable Insight #2
Boys and
girls are
biologically
different
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Medline Listed Publications
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Brain + Learning
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So what IS the difference...?
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Increasing numbers
of structural gender
differences have been
reported
Scientific publishing
favours difference
The significance of
these differences is
largely unknown
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Is neuroscience any use at all?
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What we do know…
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Important differences
emerge between boys
and girls in the nature
and timing of
adolescent brain
changes.
Prefrontal Cortex (PFC)
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The special role of the prefrontal
cortex
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Behavioural inhibition
Planning
ShortShort-term memory
Abstract thought
Emotional processing
Reward integration
Social perception
Selective attention
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Adolescent changes in the PFC
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Grey matter (neuron) density increases just
before puberty
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A new round of “synaptic pruning” starts
during puberty
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New neurons migrate into the PFC
This “pruning” is activity dependent
Myelination of connections (“fast links”) to the
PFC completes at ~18~18-24 years
Synaptic Pruning ages 5-20
(Thompson, Giedd et al, 2004)
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Synaptic Pruning ages 5-20
(Thompson, Giedd et al, 2004)
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Grey matter
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The increase in PFC
neuron density occurs
earlier in girls
Oestrogen delays
synaptic pruning in girls
Boys’ neuron density
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starts off bigger
reduces faster
“shrinks” to adult size
Implications?
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Synaptic pruning
occurs more rapidly in
boys
This may make boys
more vulnerable to an
excess or inappropriate
elimination of synapses
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White matter
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Boys’ “fast” connections
between neurons
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grow later
grow more rapidly
stop growing more quickly
end up smaller
Myelination reaches adult
levels earlier in girls
Implications?
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In particular, the
frontal cortex (PFC) is
not “wired in” until
later in development
Extended period of
“executive” lability
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Functional Consequences
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Some abilities go backwards
n Studies on emotional
processing
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mutism”
What is this person feeling?
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Adults vs. Adolescents
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Adults:
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100% said fear
Adolescents
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50% said fear
50% said shock,
shock,
confusion,
confusion, sadness or
don’t know
Yergelun-Todd et al, 2002
Girls vs. Boys
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Adolescent Girls:
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Most said fear
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Dependent on age
Adolescent Boys
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Most said shock,
shock, confusion,
confusion,
sadness or don’t know
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Independent of age
Yergelun-Todd et al, 2002
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I just can’t talk about it...
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The planum temporale
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larger in women
denser packed neurons
in women
greater left/right
asymmetry in women
assymetry becomes
more pronounced at
puberty
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Other differences
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The female cerebellum
and subcortical grey
matter and are at adult
size by 9 years
Earlier coco-ordination
So why are girls different?
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“Adolescent” brain changes
occur much earlier in girls
The female brain attains
much of it’s adult form by
the onset of sexual maturity
These changes are more
gradual and occur in a very
different social and
hormonal milieu to boys
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So what can we conclude?
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Differences in brain structure are only likely to account for a
very small difference in abilities between boys and girls
Adolescent brain changes are vastly out of sync between
boys and girls – this may have important implications
beyond education
What we do now know is that the brain responds to the
environment much more than we ever realised
Constructing an educational environment
for the brain to grow into that reflects
positive values is likely to be more
important than any gender differences
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