Neurodevelopment (3)

Question 1

What happens to neurons with incorrect connections during development?

Answer 1

They are more likely to die during the period of cell death.

Question 2

How does neuron death affect synapses?

Answer 2

Vacant postsynaptic spaces are filled by axon terminals of surviving neurons, rearranging synaptic connections.

Question 3

How does synapse rearrangement affect neuron output?

Answer 3

It focuses output on fewer postsynaptic cells, increasing selectivity of transmission.

Question 4

Which cells contribute to synapse rearrangement?

Answer 4

Microglia play a role in reorganizing synapses during development.

Question 5

What causes postnatal brain growth if not the creation of new neurons?

Answer 5

Growth is due to synaptogenesis, myelination of axons, and increased dendritic branching.

Question 6

How does synaptogenesis vary across cortical regions?

Answer 6

Visual and auditory cortex: peak in 7–8 months. Prefrontal cortex: steady rate, peak in second year.

Question 7

How does myelination progress postnatally?

Answer 7

Sensory areas: first few months. Motor areas: soon after sensory. Prefrontal cortex: continues into adulthood. Myelination speeds up axonal conduction and parallels functional development.

Question 8

What is dendritic branching, and how does it develop postnatally?

Answer 8

Dendritic branching follows the inside-out pattern of migration, progressing from deep to superficial layers. Dendritic spines can rapidly change shape based on experience.

Question 9

Are there regressive changes in the postnatal brain?

Answer 9

Yes, periods of synapse and gray-matter loss occur after maximum density is reached, first in sensory/motor areas, then association areas.

Question 10

How do modern technologies help study postnatal brain development?

Answer 10

Infant MRI and fMRI track structural and functional changes. Proteome mapping catalogs proteins in different cell types, revealing postnatal neural development.

Question 11

Why is the prefrontal cortex important in human development?

Answer 11

It has the longest development period of any brain region and largely drives cognitive development from infancy through adolescence.

Question 12

What are four main cognitive functions associated with the adult prefrontal cortex?

Answer 12

1. Working memory (holding information short-term)
2. Planning and executing sequences of actions
3. Inhibiting inappropriate responses
4. Following social rules

Question 13

When do prefrontal cortex cognitive functions typically mature?

Answer 13

During adolescence, roughly 10–24 years of age, alongside growth of dopaminergic axons and maturation of the GABAergic system.

Question 14

What is perseveration in infants?

Answer 14

The tendency to repeat a previously correct response even when it is currently incorrect, seen in infants 7–12 months old.

Question 15

How is perseveration linked to prefrontal cortex development?

Answer 15

It occurs due to immature prefrontal cortex function; the region is responsible for suppressing old responses and maintaining working memory.

Question 16

What evidence supports the link between prefrontal cortex development and perseveration?

Answer 16

1. Patients with prefrontal damage show perseveration in task-switching 2. Prefrontal cortex is needed for working memory 3. Synapses in the prefrontal cortex peak around the second year of life

Question 17

What is the difference between a critical period and a sensitive period in development?

Answer 17

Critical period: An experience must occur within a specific interval to influence development; otherwise, it won’t happen.

Sensitive period: An experience has the greatest effect during a specific interval but can still influence development outside that time, though less strongly.