brain neuroscience and learning

7/30/2019 Brain Neuroscience and Learning

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Educating a Brain..

How does the brain develop

and how do we know what it

does?

Whats special about the

adolescent brain ?

How does memory work?

What do we know aboutintelligence and ability?

Summary


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Building a brain


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The brain builds itself Other than a basic floor plan there is no map

per se of brain structure

A set of social guidelines for neurons are

genetically encoded Connections between neurons (synapses) are

formed and broken in response to neural activity

An estimated 10,000 synapses are made (andbroken) every minute

This process starts in utero and continues until

death


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How does the brain

mature?


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The First Years Fallacy

Pioneering studies on vision

Smarter rats from enriched environments

The first 3 years

Hollywood, politics & the Head Start programme


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Maturation occurs back-to-front

Experience-expectantdevelopment

Vision

Hearing Gross movement

Some elements oflanguage

Experience-dependentdevelopment

Environmentally specific

Eg Taxi drivers


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Changes in structure & function

Progressively more efficient neuronal circuitsGrey matter (neuron density) peaks at 3-5y and

again, pre-pubertally.

Following these peaks, neuron density declinesrapidly (synaptic pruning)

Faster connectionsMyelination (white matter) of the connections between

cells increases rapidly until 20y - then levels off

Better communication between hemispheres The corpus callosum increases in size until 20y.


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How do we know

how the brainworks?

Giving function to structure


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The traditional approach


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Revolution in the 1800s


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Revolution in the 1900s/2000s


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Whats special

about theadolescent brain?


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Prefrontal Cortex (PFC)


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The special role of the prefrontal

cortex Behavioural inhibition

Planning

Short-term memory

Abstract thought

Emotional processing

Reward integration Social perception

Selective attention


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Adolescent changes in the PFC

Grey matter (neuron) density increases (again)just before puberty

Neurons migrate from the basal forebrain

A new round of synaptic pruning starts duringpuberty

Myelination of connections to the PFCcompletes at ~18-20 years


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What is this person feeling?


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Adults vs. Adolescents

Adults:

100% said fear

Adolescents

50% said fear 50% said shock,

confusion, sadness or

dont know

Yergelun-Todd et al, 2002


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Functional Consequences

Some abilities go

backwards

Studies on emotional

processing benign adolescent

mutism

Executive functions arentplugged in until late teens

Interaction with sexual

maturity


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Gender differences

Increases in PFC grey

matter density occur earlier

in girls

Oestrogen inhibits pruning

Myelination reaches adult

levels earlier in girls

Boys and girls undergo PFC

maturation in a vastly

different social milieu


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Thinking About MemoryHow does the brain learn?


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Develops (very) early nondeclarative, procedural

Doesnt requireconcentration

No feeling of recall

Behavioural, emotional,perceptual, somatosensory

Implicit memory involves the

basal ganglia & cerebellum


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Explicit memory involves the

hippocampus Develops late

declarative (verbal),episodic, semantic, spatial

Requires concentration

Aha! feelings

I remember when I was

Facts & figures


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Consolidation

Implicit and explicit memoryuse the same encoding factorsand perceptual processes

Repetition Gordons Rule!!

Sleep (dreaming)

Procedural (Implicit) memory

Stress

Explicit Memory


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Retrieval

Retrieval of perceptual knowledge relies

on the same brain regions used to mediate

sensory experiences

Depends on prefrontal cortex maturation

foreffective retrieval strategies


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Memory

involves physical synaptic changes

is influenced by experience, context

dynamic, not fixed

is dependent on implicitand explicitsystems

is heavily influenced by repetition, arousal, sleepand stress


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Intelligence &

Ability


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The Need for Speed!

Information is stored multiplecortical areas.

Ensembles of synchronisedneurons emerge and fade A neuronal choir hums in unison to

rivet the brains attention

The same neurons may be

involved in numerous ensemblessimultaneously!

Consequently the brain has a needfor speed!


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Developing intelligence

Processing Speed (especially

between the hemispheres).

myelination (white matter) within

and between hemispheres.

Intelligence is correlated with a

large cross-sectional area of the

corpus callosum

Similar heritability to intelligence

Increased inter-hemispheric

transfer rates?


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Focus, focus, focus!

Maturation of executive

functions.

Selective attention - focus.

A meta-analysis of imaging

studies of academic-type

learning points to the PFCas a central mediator in

this process.


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A talented bit of the cortex?

The PFC drives complexactivation patterns across thewhole brain in response to

complex stimuli

The PFC seems particularlyinvolved in challengingtasks.

As well as executivefunctions, the PFC directlyinfluences memory systems.


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Individual talents

Established individualdifferences in thestructure of the PFCmay underlie differentabilities.

This property of the PFChas a high populationvariance


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What differentiates ability?

Developmental environment The brain builds itself in response to the particular

world around it based on a broad genetic foundation(myelination, corpus callosum)

Maturation of reward processes High sensitivity during adolescent brain development

Differences in PFC structure/function This central brain structure shows the greatest

variation between individuals


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In summary

Building a brain with a unique set of talents


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Research suggests that

The plasticity of the brain is far greater than previouslyrealised this is sustained throughout life

Recent research has shown adolescence to be a time ofextensive brain remodeling

Two structurally and functionally distinct memorysystems have been identified, with a range of factors

influencing their function

Abilities continue to emerge and differentiate in responseto new environments and ongoing brain development

brain neuroscience and learning

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