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:
Meet the lobes:
- 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?
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!
| 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
|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 Development from Birth to Two Years of Age:
| 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.
|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.|