Neuro and Neurolinguistic Development (Locke)

Question 1

How and when does the neural system form during pregnancy?

Answer 1

Begins as thickening of the ECTODERM.
Neural plate forms
Folds eventually touch (Day 22) - Neural Tube
Day 26: Tube is fully formed

Question 2

How does the brain develop prenatally?

Answer 2

Upper end of neural tube forms brain/cranial nerves
Gyri & sulci only appear ~ 7 months into gestation
Huge amount of neural development occurs in first year of life

Question 3

Timing of development - what can happen if there is a prenatal injury?

Answer 3

First 8 weeks = major congenital defects (defectively designed structure or system)
After the 8th week = failure of growth/development/refinement of the neural system

Question 4

Neural tube defects

Answer 4

Incomplete development of the neural tube

E.g. spina bifida - related to folic acid deficiency, genetics, maternal diabetes

Question 5

1. Cell birth (Neurogenesis)

Answer 5

Populating the brain with neurons
Born with 100 billion neurons
Hippocampus is the only area to produce NEW neurons

Question 6

2. Cell migration

Answer 6

Occurs prenatally

Question 7

3. Cell differentiation

Answer 7

The location to which the cell migrates determines its function

Question 8

4. Cell maturation

Answer 8

Dendrite and axon growth
More dendrites - highly connected to other cells (cognitive processes become more efficient)
Cell maturation correlates with cognitive and intellectual development, and is dependent on experience (stimulation)

Question 9

5. Synaptogenesis

Answer 9

CELLS THAT WIRE TOGETHER FIRE TOGETHER
Mostly occurs after birth
Success is dependent on experience - synapses form from learning and practising and CONNECTIONS STRENGTHEN

Question 10

6. Synaptic pruning

Answer 10

Building more efficient/refined neural pathways
Synapses that aren’t needed/activated are “pruned”
- therefore brain areas necessary for language must be activated through stimulation EARLY, or else they may be pruned.
Born with 1000 trillion synapses - by adolescence we have 500 trillion.

Question 11

7. Myelogenesis

Answer 11

Myelinated cells transmit messages much faster
Occurs firstly at life-supporting regions of the brain (heart and respiratory centres)
Pre-frontal cortex is not myelinated until adolescence/early 20s

Question 12

Locke’s theory of neurolinguistic development

Answer 12

• Considers the interaction between the child and their environment in shaping language development
• Explains the neural mechanisms that support language development

Question 13

Locke’s Phase 1

Answer 13

VOCAL LEARNING

• Listening and attending to vocal activity of others
• Superficial characteristics of language (prosody)
• Genetic bias toward language learning
• Onset: prenatal

Question 14

Characteristics of Phase 1

Answer 14

• Mimicking gesture, intonation, prosody
• Turn-taking
• Eye contact

Question 15

Brain areas involved in Phase 1

Answer 15

RIGHT HEMISPHERE functions are critical for this social/emotional side of language

Question 16

Locke’s Phase 2

Answer 16

UTTERANCE ACQUISITION

• Onset: 5 months
• “Starter Phrases”
• Child stores (and eventually produces) utterances exactly as they hear them - picking up on emotional prosody/length
• Utterances stored as WHOLE CHUNKS

Question 17

Characteristics of Phase 2

Answer 17

• Increased use of words/phrases
• Comprehension increases (indicating increased storage)
• Correct grammar in these phrases although this doesn’t develop until much later

Question 18

Brain areas involved in Phase 2

Answer 18

RIGHT HEMISPHERE storage

- limited in efficiency of storage. Need to be analysed and sorted by the left hemisphere

Question 19

Locke’s Phase 3

Answer 19

ANALYSIS AND COMPUTATION

• Onset: 18-20 months
• Storage of enough starter phrases activates pathways to the left hemisphere. CRITICAL FACTOR = number of starter phrases in storage.
• Learn and apply rules of language

Question 20

Characteristics of Phase 3

Answer 20

• Rapid increase in expressive and receptive vocabulary
• Overextension of grammatical rules - “went” becomes “goed”
• Child generates/combines NEW utterances
• LONGER utterances

Question 21

Brain areas involved in Phase 3

Answer 21

LEFT HEMISPHERE functions - much more efficient storage

Question 22

Locke’s Phase 4

Answer 22

SYNAPTIC PRUNING occurs

• Increases speed
• Decreases number of errors
• Processes become more automatic - less cognitive resources are needed to attend to language

Question 23

Characteristics of Phase 4

Answer 23

More sophisticated linguistic structures are used e.g. embedded clauses

Question 24

Brain areas involved in Locke’s Phase 4

Answer 24

Both the left and right hemispheres - social/pragmatic skills are continually refined

Question 25

Critical Periods and Inactivation

Answer 25

• Each phase enables succeeding phases
• Inactivation has the same effects as damage
• If too few starter phrases are stored, neural pathways won’t activate at the optimal moment (because the left hemisphere has nothing to grammatically analyse/store)
• After this optimal moment, grammar capabilities decline.