the developing brain

Question 1

Describe the stages involved in prenatal brain development.

Answer 1

Prenatal brain development includes stages such as cell division (1-2w), cell specalisation, neural tube formation, and neuronal migration to their final locations

Question 2

Explain the ‘neural tube formation’ stage of prenatal development

Answer 2

Proliferative zones produce neurons and gial cells (specalised)
250k neurons produced per minute
Nervous system comes from a set of cells arranged in a neural tube
neurons will migrate to their final location

Question 3

What structural features of the brain emerge in prenatal development?

Answer 3

Folded cortex - emerges due to having lots of neurons within a restricted space
Pattern of gyri/sulci pulled into shape by tension of axon bundles (white matter tracts)

Question 4

Outline the 3 mechanisms which contribute to postnatal brain development

Answer 4

Newborn baby brain weighs around 450g - synaptogenisis makes it grow
Synaptogenisis involves the formation of new synapses, contributing to the increase in brain connectivity and facilitating learning and memory processes during postnatal brain development
Myleination - increase communication efficacy
Gial cell proliferation

Question 5

Explain the concept of plasticity and its role in brain development.

Answer 5

Plasticity refers to the brain’s ability to change and adapt in response to experience.
Allows the formation of new neuronal connections in development and the reorganisations of existing ones.
Increased grey matter - new synapses, dendrites, axons, glia cells

Question 6

What are critical and sensitive periods?

Answer 6

Critical and sensitive periods are specific time frames where learning and developing are particularly susceptible to influence. They provide optimal learning windows for skills and knowledge.

Question 7

Outline the 2 main features of critical and sensitive periods.

Answer 7

Learning takes place in a limited window (can be extended in lack of experience)
Learning is hard to reverse (preferences can be changed through generalisation)

Question 8

Discuss the differences between the blueprint analogy, predetermined development, and probabilistic development in brain development theories.

Answer 8

The blueprint analogy = that genes determines brain structure and function
(Gottlieb) predetermined development = genes -> brain structure -> brain function -> experience,
(Gottlieb) probabilistic development = genes <-> brain structure <-> brain function <-> experience

Question 9

What is the difference between the empiricist and nativist views on innate knowledge?

Answer 9

Empiricism holds that the newborn mind is a blank state, suggesting that all knowledge is acquired through experience. In contrast, nativism asserts that humans are born with some innate knowledge or predispositions.

Question 10

How does the modern view reconcile empiricism and nativism regarding innate knowledge?

Answer 10

The modern view acknowledges both perspectives. There are innate components, such as a readiness to learn (as seen in imprinting) and certain knowledge or behaviors that exist even without specific experiences. For example, preferences for sweet tastes or recognizing faces are considered innate. Additionally, in the first three weeks of development, we observe numerous innate learning mechanisms being employed.

Question 11

What is Hebbian learning, and how does it relate to early brain development?

Answer 11

Hebbian learning: Spontaneous electrical activity (just happens, no need for external stim – by the time the baby is born essential networks like sight are formed) enables networks to form (e.g. electric activity from the retina helps to form the visual pathways)

Question 12

How much does a newborn’s brain weigh? How does this compare to an adult’s brain?

Answer 12

Newborn brain weighs 450g
Adult brain weighs 1400g

Question 13

Explain the pattern of plasticity in postnatal development.

Answer 13

In all cortical areas there is a characteristic rise and then fall in synapse formation (synaptogenesis) - primary visual and primary auditory cortex, the peak density is between 4 and 12 months, at which point it is 150 percent above adult levels, but falls to adult levels between 2 and 4 years. In the prefrontal cortex, the peak is reached after 12 months, but does not return to adult levels until 10–20 years old.

Question 14

Give an example of where functional brain activity lead to the reorganisation of major neuronal tracts. How does this relate to development?

Answer 14

Functional brain plasticity: prenatal brain damage can lead to major reorganisation of tracts
Case study: AH – no right hemisphere, only here left hemisphere developed in the womb
Information from both VFs was sent to her left hemisphere – how plasticity allows you to develop and adapt to environment/constraints (easier when younger )

Question 15

Outline how brain development is studied.

Answer 15

Structure - prenatal ultrasound/prenatal MRI can distinguish between different types of tissue to create STATIC maps
Functional Behavioural methods - understanding inferred from preferential looking paradigm
Functional Neuroscience methods - temporary changes in brain physiology associated with cognitive processing (e.g infant EEG, fMRI)

Question 16

What are the issues with using fMRIs to study infants? What alternatives have been introduced?

Answer 16

fMRI - struggle to perform necessary tasks, won’t stay still (fMRI sensitive to motion), loud and restrictive procedure
Infant EEG - infant friendly stimuli, quick installation , more breaks

Question 17

Outline the findings from infant ERP studies.

Answer 17

Some adult ERP are delayed in infants e.g N170 adult ERP equiv to N290 in infants - face processing component
But there are some ERP components that are exclusive to infants - e.g Negative central peak which occurs between 300-700ms after stimulus onset and its peak is determined by level of attention

Question 18

Describe the limits of functional brain plasticity. Outline Lorenz’s research into this.

Answer 18

Opportunities for major reorganization are time-limited due to critical or sensitive periods (e.g Lorenz study, ducklings had a sensitive period of 15hrs-3 days)

Question 19

Discuss the limitations and advantages of using fNIRS compared to fMRI.

Answer 19

Both measure BOLD signal but fNIRS has lower spatial resolution compared to fMRI but is more portable and tolerates movement better and it better for studying brain activity related to cognitive tasks. However, it can only image the surface of the cortex and is limited to a smaller number of sensors.

Question 20

What are the two explanations for critical and sensitive periods?

Answer 20

1. Genetically programmed synaptogenesis (readies brain for learning), followed by reduced plasticity (learned information is then “fossilized”) - strict maturational timetable allows for removal of weaker connections/consolidation of knowledge
2. Closure of window could be initiated by learning itself, i.e. an environmental cue
   * E.g. particular gene plays a role in filial imprinting, it is switched off after exposure

Question 21

What is Glial cell proliferation?

Answer 21

Glial cell proliferation is the process in which non-neuronal cells in the central nervous system, such as astrocytes, oligodendrocytes, and microglia, rapidly reproduce or divide.

Question 22

Outline how fNRIs is used to study developing brains.

Answer 22

Uses infared light - absorbed by Hb and deoxyHb
Difference in levels between emitted and detected NIR we can compute the BOLD response - more absorbed = more active the region

Question 23

Outline the pros and cons of using fNIRS over fMRI for infant brain imaging.

Answer 23

Pros
Portable and more tolerant to movement
Cons
lower spatial res
only surface of cortex can be imaged and only a few sensors can be used above an area