Early childhood sees several areas develop:

1. the brain stem or the survival brain
2. the cerebellum where coordination develops, and
3. the sensory regions of the cerebrum that rule visual, auditory, touch, and movement

The brain is divided vertically intohemispheres, the right and the left,each with a different set of functionsthat myelinate (forming an insulating sheath of white, fatty substance about certain nerve fibers) and mature during different stages of life.

When puberty hits, the brain develops the limbic system which is referred to as the feeling brain. 

During late adolescence the prefrontal cortex (anterior or front part of the frontal lobes which are situated in the front portion of the brain) of the frontal lobes develop, which fine tune the higher level thinking and emotional regulation of the brain.

There are at least 100 billion neurons in the adult human brain.  There are support cells, called glial cells that number 10 times more than neurons.  The neurons communicate with each other through billions of tiny web connections in an electrochemical process. There are about 500 trillion connections in the adult brain.  When you do the math the minimum number of possible thought patterns in the brain is the number 1 followed by over 6 miles of typed zeros.  

Your brain is about the size of a cantaloupe and wrinkled like a walnut.  You brain weighs between 3 and 3.5 pounds and has the consistency of jello.  This lump of matter is the best organized most functional awesome three pounds of matter in the known universe.

Dendrites

Dendrites receive information in the brain. The number of dendrites on a neuron varies from a few hundred to thousands. They are covered with tiny 'spines' that are neurotransmitter receptor sites.

Cell Body

The cell body and its DNA genetic system use the nutrients that the blood brings to maintain the cell and to synthesize neurotransmitter molecules (chemical messengers).

Axons and Terminals

Axons send information.  Neurons generally have one axon branching out into many terminals.  Axons vary in length:  some can be up to 3 feet long.  Mature axons are covered in an insulated coating called myelin. Neurons don’t actually touch each other, there is a gap between the terminals. This is called a synaptic gap. The neurotransmitters are released into the gap that acts as a chemical messenger for the receiving neuron.

How do neurons transmit information? The axon sends a message through a series of electrical impulses.  When the impulses reach the end of the axon, the electrical activity ceases.  A chemical process then takes place at the synaptic gap.

Although the process is complex, the end result is chemicals released by Neuron #1 turn Neuron #2 on or off, telling it to "transmit" or "don't transmit" the message.  Neuron #2's dendrite receives the message and sends it electrically through the axon to Neuron #3.  This process repeats until the message has reached its destination.  A single neuron can fire up to 50,000 times a minute if necessary.

Let’s break it down- 

The cell body (that's easy enough) has dendrites (the receivers) and axons (the senders). The axons are covered in an insulation layer called myelin.The neurons send information from the cell body down the axon to the next cell's dendrite across a synaptic gap.  The information goes through as many neurons as it takes to get the message to the appropriate place.

Let’s think of this whole process in another context.    Think of your brain as a phone system in a very large city.   The city is “alive” with calls being made between millions of senders (axons) and dendrites (receivers) all day and all night.  And this city is a completely wireless system, which explains the gap between the axons and dendrites, no phone cords.  Sometimes the “call” is made directly, but most of the time it is like calling your local phone company's main office.  It takes many connections for the message to get to the correct place!

Myelinization

This helps explain why infants can’t see very well, and don’t have good motor coordination, among other things.  Their neurons just aren’t working fast enough, so they can’t coordinate very well.  

Wrapped around many of the axons are cells which form myelin sheaths, composed mainly of fat.  These sheaths serve to insulate the axon, letting its signal travel about 100 times faster than in an unmyelinated axon.  Why is this important?Well, if you have more myelinated axons in your brain, then your circuits are working much faster, and certain activities may be easier for you to learn.  This myelinizationis extremely important in children, because as newborn infants, we have very few myelinated axons.

The chemicals released into the synaptic gap are called neurotransmitters. 

FAS: Fetal Alcohol Syndrome is a serious medical condition due to exposure to high levels of alcohol during pregnancy. Recent research has discovered that alcohol interferes with the development of the cerebellum (controls coordination), the hippocampus (controls memory and learning), and the migration of neurons up to the cortex of the brain resulting in a severe deficiency in the prefrontal lobes which control executive functions of the brain.

FAE:  Fetal Alcohol Effect is similar to FAS, but involves children exposed to a lesser amount of alcohol during the mother’s pregnancy.  They are usually smaller at birth, and can have lower than average IQ’s.  

A healthy brain must have the right conditions in the womb to develop.  The mother's general health, stress level, nutrition and exposure to external and internal toxins all dramatically impact the developing brain.

According to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-V) children must show at least 6 symptoms in one domain prior to age 12.

Inattentive-type symptoms are:

• lack of close attention to details
• difficulty sustaining attention
• does not appear to listen
• does not follow through on instructions
• struggles difficulty with organization
• avoids or dislikes tasks requiring sustained mental effort
• loses things
• easily distracted
• orgetful in daily activities

Hyperactivity-impulse type symptoms:

• fidgets with hands or feet or squirms in chair
• has difficulty remaining seated
• runs about or climbs excessively
• difficulty engaging in activities quietly
• acts if driven by a motor
• talks excessively
• blurts out answers before questions have been completed
• difficulty waiting or taking turns
• interrupts or intrudes upon others

Combined-type symptom is:

• individual that meet both sets of inattention and hyperactive/impulsive criteria