cogneuro wk 4- the developing brain

Question 1

What is a challenge in using fMRI across age groups?

Answer 1

groups? Brain structure and blood flow change with age, making cross-age comparisons difficult.

Question 2

At what age is the hemodynamic response function relatively stable?

Answer 2

after 7 yrs

Question 3

What issues do young children face during fMRI scans?

Answer 3

Difficulty keeping still, which can introduce motion artifacts in the MR signal.

Question 4

What are the advantages of fNIRS over fMRI in children?

Answer 4

More movement tolerance, infant can sit upright, and greater portability.

Question 5

What are the limitations of fNIRS?

Answer 5

Poorer spatial resolution and limited whole-head coverage.

Question 6

What limits EEG/ERP use in young children? practically

Answer 6

Discomfort with electrodes, attention span, and task tolerance.

Question 7

Why do ERP patterns differ between children and adults?

Answer 7

Due to both cognitive (strategy differences) and non-cognitive (e.g., skull thickness, myelination) factors.

Question 8

Is single-pulse TMS safe for children?

Answer 8

Yes, it’s considered low risk, but repetitive TMS is generally avoided unless for clinical purposes

Question 9

What is tES, and is it safe for children?

Answer 9

Transcranial electrical stimulation; it is considered as safe as in adults.

Question 10

What has tES been used for in children?

Answer 10

Used with cognitive training to help treat learning difficulties.

Question 11

What is predetermined development (Gottlieb, 1992)?

Answer 11

A model where genes determine brain structure → function → experience.

Question 12

What is probabilistic development (Gottlieb, 1992)?

Answer 12

A model where genes, brain structure, brain function, and experience all influence each other bidirectionally.

Question 13

How do genes influence brain structure probabilistically?

Answer 13

They specify approximately how many neurons to grow and where to grow them, but not exactly how or where neurons will grow

Question 14

How long is the human gestation period from conception?

Answer 14

Around 38 weeks.

Question 15

From what structure does the nervous system develop?

Answer 15

The neural tube, a hollow cylinder of cells.

Question 16

What happens by around 5 weeks of gestation?

Answer 16

The neural tube forms bulges and convolutions that will become major brain structures (e.g., cortex, thalamus, hypothalamus, midbrain).

Question 17

How many neurons per minute does the fetal brain add during early development (Purves, 1994)?

Answer 17

250,000 neurons per minute.

Question 18

How do neurons reach their destination in the developing brain?

Answer 18

Through passive migration (older cells pushed outward) and active migration (newer cells guided by radial glial cells).

Question 19

Which brain structure is formed by passive migration?

Answer 19

The hippocampus.

Question 20

What role do radial glial cells play in brain development?

Answer 20

They act like climbing ropes, guiding neurons to their correct location (Rakic, 1988).

Question 21

How do molecular signals affect neuron development?

Answer 21

Regional variations in signal dose determine the neuron’s structure, migration, and survival (Sur & Rubenstein, 2005).

Question 22

How do signal doses influence lobe development?

Answer 22

Higher doses may lead to frontal lobe characteristics; lower doses may result in parietal lobe features (Fukuchi-Shimogori & Grove, 2001).

Question 23

What is Hebbian learning?

Answer 23

The strengthening of a synapse when both the presynaptic and postsynaptic neurons are active at the same time — often summarized as “what wires together fires together.”

Question 24

What causes the folding of the human cortex?

Answer 24

Likely caused by packing more neurons into limited space and axonal tension, rather than being directly coded in the genome.

Question 25

How do axons shape the cortex?

Answer 25

Axons exert tension like elastic bands, pulling the cortical surface to create gyri and sulci (Van Essen, 1997).

Question 26

What influences axon guidance?

Answer 26

Regional molecular signals attract or repel axons, guiding where they form and connect.

Question 27

What enables brain network formation before sensory input?

Answer 27

Spontaneous electrical activity supports Hebbian learning and early network formation even before birth.

Question 28

What is synaptic density?

Answer 28

A measure of how interconnected neurons are, not the number of neurons or activity leve

Question 29

What is the pattern of synaptogenesis in the developing cortex

Answer 29

Synaptogenesis = formation of connections (synapses) between neurons. Follows a rise-and-fall pattern during development Synapse decline reflects pruning of unused connections, fine-tuning the brain based on experience

Question 30

How does synaptogenesis differ between sensory cortex and prefrontal cortex?

Answer 30

Primary sensory areas (visual & auditory cortex): Peak synaptic density: 4–12 months Returns to adult levels by 2–4 years Prefrontal cortex: Peak synaptic density: after 12 months Returns to adult levels by 10–20 years

Question 31

Why is more gray matter not always better?

Answer 31

More gray matter does not always indicate better function or ability Examples: Congenitally blind people → more gray matter in visual cortex People with congenital amusia → more gray matter in auditory cortex Interpretation depends on underlying cause: Developmental pruning: fewer synapses → more efficient → thinner cortex is better Experience-dependent plasticity: learning strengthens connections → thicker cortex is better

Question 32

What structural changes could explain increased gray matter in MRI studies?

Answer 32

Growth of dendrites, synapses, or axon collaterals; changes in glial cell size, number, or structure; or changes in blood vessels.

Question 33

Why is neurogenesis considered an unlikely explanation for MRI-visible structural changes (outside the hippocampus)?

Answer 33

Because neurogenesis is limited in most adult brain regions, except the hippocampus

Question 34

What cellular changes underlie experience-related brain plasticity detectable with imaging?

Answer 34

Changes in dendritic branching, synapse formation, glial activity, or myelination rather than neurogenesis

Question 35

What is the Kennard Principle?

Answer 35

The idea that brain damage sustained earlier in life generally leads to better functional outcomes due to greater neural plasticity.

Question 36

What do studies with goslings and chicks suggest about imprinting?

Answer 36

Imprinting occurs in a narrow time window and is hard to reverse, though preferences can shift slightly with experience—suggesting a sensitive rather than strictly critical period.

Question 37

What evidence is there for sensitive periods in vision

Answer 37

In cats, depriving one eye of input in early life causes permanent changes in primary visual cortex—only the non-deprived eye is represented (Hubel & Wiesel, 1970b).

Question 38

Is language acquisition governed by a critical period

Answer 38

Not strictly; different components (like phoneme discrimination or grammar) have their own sensitive periods that occur at different developmental stages.

Question 39

How does age of acquisition affect second language processing?

Answer 39

Later acquisition leads to more neural activity (i.e., less efficiency) for syntactic tasks; proficiency mainly affects semantic processing.

Question 40

What neural mechanism might underlie sensitive periods?

Answer 40

Neurons may be readied for learning via synaptogenesis and later "fossilized" through pruning; sensitive periods may be genetically timed or self-terminating based on experience.

Question 41

What is prepared learning?

Answer 41

The idea that evolution has biologically primed us to more easily learn certain fears (e.g., snakes) than others (e.g., flowers).

Question 42

How can innate be interpreted in neuroscience?

Answer 42

(1) As evolved dispositions shaped by natural selection, or (2) as behaviors that develop without experience—though most abilities involve both genes and environment

Question 43

What is the Nc component in infant ERP?

Answer 43

A negative central peak found in infants, occurring 300–700 ms after stimulus onset; linked to attentional processing.

Question 44

What is the N290 in infant ERP studies?

Answer 44

An infant ERP component related to face processing; considered a precursor to the adult N170

Question 45

How does fNIRS work in developmental research?

Answer 45

It uses near-infrared light to detect changes in oxygenated blood, offering a portable and movement-tolerant alternative to fMRI.

Question 46

Why is fNIRS better suited than fMRI for infants

Answer 46

It allows for more motion, is more portable, and infants can sit upright on a caregiver’s lap during testing.

Question 47

What is a limitation of fNIRS compared to fMRI?

Answer 47

It has lower spatial resolution and cannot image deep brain structures—limited to cortical surface.

Question 48

What brain imaging methods can be used prenatally

Answer 48

Ultrasound and MRI can be used to measure structural brain development based on tissue density.

Question 49

What is a preferential looking paradigm?

Answer 49

A behavioral method used with infants that measures looking time to infer perceptual or cognitive abilities.

Question 50

What does the case of AH (born without right hemisphere) show?

Answer 50

That the brain can develop bilateral visual field maps in one hemisphere, showing extreme functional plasticity