The Developing Brain, Lecture 4

Question 1

What does nature mean?

Answer 1

Genetic blueprint (things we are born with).

Question 2

What does nurture mean?

Answer 2

Role of experiences

Question 3

What did Piaget consider development as?

Answer 3

A cyclical process of interactions between the child and their environment, leading to a progression through stages

Question 4

What is genetic contribution?

Answer 4

Developing a brain that is ready to learn in certain ways

Question 5

What is neuroconstructivism?

Answer 5

Interaction between environment and genetic factors. The cognitive system matures and transforms as the brain goes through developmental changes.

Question 6

What is the blueprint analogy?

Answer 6

Each connection in the brain is pre-determined.

Question 7

What were the two types of development suggested by Gottlieb, 1992?

Answer 7

Deterministic development means the structure is the same for everyone.
Probabilistic development, meaning each stage influences the other.

Question 8

What are the features of prenatal brain development?

Answer 8

Cell division; cell specialisation; neural tube formation. Proliferation zones: neurons and glial cells are produced
Early development - 250,000 neurons are produced per minute
Neurons then migrate to their final location

Question 9

What structural features of the brain emerge from other constraints?

Answer 9

• Folded cortex emergences from having lots of neurons
• Pattern of gyri/sulci pulled into shape by tension of axon bundles (white matter tracts)

Question 10

What is hebbian learning?

Answer 10

Spontaneous electrical activity enables networks to form

Question 11

Postnatal Brain Development

Answer 11

Majority of neurons formed prior to birth.
Newborn brain weights 450g (vs. 1400g adult brain).
Postnatal increase in brain size: synaptogenesis, myelination, glial cell proliferation.
Plasticity: experience-dependent change in neural functioning.
Increased grey matter: new synapses, dendrites, axon collaterals, glia cells.
Functional brain plasticity: prenatal brain damage can lead to major reorganization of tracts.

Question 12

Postnatal Brain Development - CONT

Answer 12

Spontaneous electrical activity enables networks to form intrauterine – these connections won’t be fully lost.
Opportunities for major reorganization are time-limited = critical or sensitive periods.
Konrad Lorenz studied filial imprinting in birds (recognition of parents), happens between 15h – 3 days, and movement is crucial.
Learning takes place within a limited window, but opportunity can be extended in lack of experience.
Learning is hard to reverse by later experiences, but preference can be changed after the sensitive period.

Question 13

Critical and Sensitive Periods

Answer 13

Examples of critical and sensitive periods: phonemic discrimination, accents, etc.
Two possible explanations for critical and sensitive periods: genetically programmed synaptogenesis or closure of window initiated by learning itself.

Question 14

Innate knowledge

Answer 14

Empiricist vs. Nativist view.
Empiricism: newborn mind is a blank state.
Nativist: we are born with some knowledge.
Innate = readiness to learn (e.g., imprinting).
Knowledge or behaviour that arises in the absence of appropriate experience.
Development of cat visual cortex; Preferences – sweet taste, visual pattern.

Question 15

Structural Methods for Inferring Brain Development

Answer 15

Structure is “easy” - Prenatal Ultrasound.
Structural: different types of tissue (skull, grey matter, white matter, CSF fluid) have different physical properties – used to create STATIC maps.
Structure is “easy” - prenatal MRI.

Question 16

Behavioural Methods for Inferring Brain Development

Answer 16

Behavioural Methods – we can infer brain development from their behaviour.
Preferential looking paradigm; Habituation paradigm.
Robert L. Fantz, 1961: The origin of form perception.
“Is man’s ability to perceive the form of objects inborn or must it be learned? What goes on in the infant’s mind as he stares, blinks, looks this way and that? Does he sense only a chaotic patchwork of colour and brightness or does he perceive and differentiate among distinctive forms?”.
If an infant consistently turns its gaze toward some forms more often than toward others, it must be able to perceive form.

Question 17

Fantz (1961): The visual interest tes

Answer 17

“looking chamber”.
Pairs of test objects attached to the ceiling of the chamber.
Through a peephole in the ceiling, experimenters could see tiny images of the objects mirrored in the subjects’ eyes.
When the image of one of the objects was at the centre of the eye, infant looks directly at it.
Time infant spends looking at each object was recorded on a time.

Question 18

Form Perception

Answer 18

1-week-olds – 3.5 month olds, differential interest within pairs was based on pattern differences. Infants consistently turn their gaze toward some forms more often than toward others, it must be able to perceive form.

Question 19

Preferential looking:

Answer 19

Visual acuity threshold: the finest pattern width preferred to grey provides an index to visual acuity. Finest stripes width distinguishable decreases with increasing age (0 to 6 months).
The eye, visual nerve pathways, and visual brain regions are poorly developed at birth.
Modern use: eye-tracking, which uses non-collimated infrared light to measure participant gaze location. This method is more precise for measuring looking times and fixations.
Problems: infants must both find a screen more interesting than another and discriminate between screens for a significant difference in looking time. Infants may equally find both screens interesting or fail to discriminate.

Question 20

Habituation paradigm:

Answer 20

Infants prefer novelty (Fantz, 1964): pairs of stimuli are shown simultaneously, one of which remains constant while the other changes across trials. There is decreasing fixation on the familiar pattern and increasing fixation on the novel pattern.
Modern use: infants are made bored with one stimulus (A) and then paired with another (B). If the infant looks more at the new stimulus, then they have discriminated between the two stimuli.
Overcomes the problems of the preferential looking paradigm.

Question 21

Functional Neuroscience Methods:

Answer 21

Functional neuroscience methods involve measuring temporary changes in brain physiology associated with cognitive processing. However, these methods typically require participants to perform tasks or remain still, which can be challenging with infants and young children. To address this challenge, researchers can use methods that are more suitable for these populations.

Question 22

Electrophysical response:

Answer 22

One method that can be used with infants is electrophysical response, which involves measuring the electromagnetic fields generated in the brain. Electroencephalography (EEG) is a commonly used electrophysical response method. EEG analysis involves examining event-related potentials (ERPs), which are averaged EEG segments that are time-locked to a specific event. Different ERP peaks reflect different cognitive functions.

Question 23

Infant ERPs:

Answer 23

Some adult ERP peaks are present in infants but are delayed, such as visual ERPs. N290 in infants reflects the same perceptual and/or face-specific component as N1 or N170 in adults. By comparing visual processes in adults and infants, we can assume that the underlying brain networks and/or processing mechanisms are similar if the ERP patterns are similar. Some ERP components are only present in infants and toddlers, such as the Negative Central Peak (Nc), which reflects attention. A larger Nc peak indicates higher attention. For example, when presented with their mother’s face compared to a stranger’s face, infants show a larger Nc for their mother’s face, indicating that they recognize their mother’s face.

Question 24

FMRI and FNIRS

Answer 24

Functional magnetic resonance imaging (fMRI) is another method used in functional neuroscience but is not ideal for use with infants due to motion artifacts, loud and restrictive movements. Researchers can use functional Near-Infrared Spectroscopy (fNIRS) instead, which is more tolerant of movement and can measure the concentration changes of oxyhemoglobin (oxyHb) and deoxyhemoglobin (deoxyHb) related to brain activity. fNIRS emits NIR light, and the emitter and detector measure the absorption of oxyHb and deoxyHb, which are related to blood oxygen-level dependent (BOLD) contrast. While fNIRS has lower spatial resolution and can only image the surface of the cortex, it is a portable and appropriate substitute for fMRI for studying brain activity related to cognitive tasks.