Brain Development from Child to Adolescent

CTP EU EDU 1 Lecture notes on Brain Development

Prepared by Prof. Claire Medina, RN

What makes up our Brain?

  • Forebrain– largest and highly developed (cerebrum and structures beneath it)
  • Midbrain- upper part of the brainstem (reflex, voluntary movements and eye movement)
  • Hindbrain- upper part of the spinal cord (cerebellum)

Controls heart rate and respiratory functions and coordinates movement

  • The Inner Brain is our limbic system it is composed of a network of nerves and networks in the brain that controls our basic emotions and drive.
  • Hypothalamus (sadness, excitement, body’s alarm clock)
  • Thalamus (“The Control Freak” controls info going to and from the spinal cord)
  • Hippocampus (responsible for “stock knowledge”.)
  • Amygdala (controls emotions,fear/anger, arousal,hormonal secretions)
  • Lateralization is the term used for the specialization of function in one hemisphere.

(reading and playing musical instruments use both hemispheres.

 

There are two hemispheres:

lobes3 lobes2

Meet the lobes:

lobes

 lobes1

 

Nerve Cells

nerves

  • Follows genetic code to run its own programming
  • Process info at a cellular level
  • Sends both electrical and chemical signals to communicate with one another.

Dendrites- receives information

Axons-transmits information away

 

  • Myelination is the process of encasing axons in fat cells, this occurs prenatally and through adolescence.
  • Myelin sheath– covers axons and helps speed up info transmission.
  • Terminal buttons releases neurotransmitters (chemicals) into synapses
  • Synapses are gaps between neural fibers.
  • Synaptogenesis forming of synapses
  • Receptors binds with substances

What is blooming and pruning?

pruning-and-blooming

The connections that are frequently used become strong and survive while the ones that are unused are replaced or disappears eventually.

 

Brain development key points: It takes time to have a big fat brain!

  • Increase in size (mostly in the cerebrum)
  • Increase in number of folds in the cerebral surface. Increase in the cerebral cortex volume

 

Welcome to the “Main Event” in our lecture! 

 

 

Neural Tube

      Neurulation- forming of neural tubes

Starts at 2-3 weeks

Closes the top(brain) and bottom(spinal cord) 24 days after conception

Neurons from neural tube                     brain

 

Neurogenesis

(5th week)

200-500,000 neurons per minute
Neuronal migration (6th-24th weeks)       Neurons move to specific location and wait for instructions.

Genes starts to hardwire or direct the brain’s wiring process.

Connections begin at 23 weeks.

Myelination       Begins in the spinal cord                  subcortical regions

Cortical regions myelinate  from posterior to anterior region

Frontal and parietal lobes are completed last

 brain

Brain Development from Birth to Two Years of Age:

 

0-1 year

      Weighs about 1000 grams (2 lbs) at 1 year

Approximately: 970g male/940g female

From 7-12 months prefrontal cortex develops dramatically.

At 3-6 months the visual pathways are complete.

 

 

Visual Development

 vision
Temporal Lobe       4th month- responds to sounds

10th month able to distinguish and produce sounds of their own language.

Does not respond to sounds of foreign language.

 

Lateralization Left hemisphere is more active when listening to sounds/voices
Amygdala Matures at 8 months
Dendrite Connections       Experiences help in making connections

8-9 months starts to form specific memories based on experience.

Blooming and Pruning More activities or use of language strengthens the pathways of neurons.

 

 

2 Years Old

Brain is at 75% of its adult size

1,120g (2.5 lbs) male

1,040g (2.3 lbs) female.

 

Early Childhood (3-5 years old)

 

 

3 years old

      Rapid growth spurts

Continues increase in dendrite connections and myelination.

Experience shapes one’s mind, blooming and pruning

¾ of adult size

1,270( 2.8 lbs) male

1,090 (2.4 lbs) female

 

4 years old

      Parietal- developed gross and fine motor skills due to myelination

Auditory myelination and hand-eye coordination is complete

 

5 years old

      Brain is at 95% of its adult size

Visual acuity reaches adult level

 

Middle/Late Childhood (6-12 years old)

 

6-7 years old

      Occipital lobe matures

Contrast sensitivity and peripheral vision is at adult levels

8 years old Temporal lobe matures
Cerebral Cortex       Temporal and frontal lobe area thickens

Language abilities like reading is improved

Prefrontal Cortex       Pathways and circuitry is increased

Improved cognitive control, attention and reasoning

Blooming and Pruning       Some brain areas are used more frequently while others are not

from broader areas to more focal and smaller areas

 

Adolescence (13-18 years old)

 

12 years old

      During this period of adolescence the brain undergoes structural changes

The parietal lobe matures

Corpus Callosum       The hemispheres becomes connected by nerve fibers

Thickens and improves one’s ability in processing information

Amgdala Matures earlier than the prefrontal cortex
Synapses Are at their adult density
At 18 years- 25 years old Both the frontal lobe and the prefrontal cortex mature at this time.

 

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