Brain Development in

Children

Genes vs. Environment

Development of the human

brain is crucial in the first 2 years of a person’s life.

Genes + Environment = Full development

The Development of the Brain

The Brainweighs 3 lbs 100

billion neurons60 trillion connections

Trees in the Amazon Rainforest

Right Hemisphere & Left Hemisphere connected by a fibre bundle

Grey Matter Cell Bodies of Neurons

White Matter Axons

Surface of the Brain = Neocortex

47 sub-areas of the Neocortex

Development Foetus Adult

Almost all of neurons are generated during the first half of pregnancy

Produce 200 000 Neurons / minute during early pregnancy

Until first year of life, baby has almost

2x amount of Neurons & Connections as an adult

Cells that are part of functioning networks have access

to nerve growth factor.

Cells compete to survive.

Make Connections survive. No Connection Die

Peak varies with Each area of the brain, but same pattern

Nature vs. Nurture

Fight between Nature vs. Nurture.

Actually, Nature + Nurture

Nature Interaction Nurture

Brain : -Plan governed by genetic expression

-Influenced by experience of the organism

Genes

Structure Base Compound= Letter in alphabet

in the genetic code

4 Letters (A,C,G,U)Some have few letters. Some are very long

Function

Genes Contribute to talent, language, eye color, disease, etc.

Very rare that a gene is solely responsible for a

particular structure or function

Pax6 & Emx2Pax6 and Emx2: genes that control regionalization of the Pre-neuronogenic Cortical Primordium

Pax6: high concentration in Back &

Middle of brain

Emx2: high concentration in Front & Sides of brain.

Gene Mutation

Expressed in the embryonic neo-cortex region very early in development. (First 2 months of pregnancy) Compete

with each other suppressing the

one with mutation

Environment

Plays an essential role in determining which cells

& connections are lost or stabilized.

Big effect on the brain’s development

Effects on the Brain’s Development

Rat Study2 different settings

1- One rat/cageNo activity, contact, input or companionship

2- Many rats/cageToys, nicely decorated, visitors

Some rats started as babies & some as adults

Results

Rats in CEs had more synapses per neuron than those in ICs in both cases

Auditory Study2 types of kids

1- Kids deaf since birth

2- Kids with good hearing

Deaf kids: Something visual and respond

Regular kids: Something auditory and respond

ResultsWhen deaf kids did the visual task, they activated the auditory cortex

This happens when people have never heard anything before.

Doesn’t work with someone

Normally, in the beginning of who became deaf later in life

development, the structures of the body fight for the response from certain parts of the brain.

Eyes and ears fight for the response from

the auditory cortexIn these cases, the ear

doesn’t activate a response because no sound is heard,

so the eyes take over the function of this area