The developing brain

Question 1

nature vs nurture

Answer 1

extent to which cognition and behaviour (and brain development) can be attributed to genes or the environment

Question 2

nature

Answer 2

genetic blue brint

Question 3

nurture

Answer 3

roles of experiences

Contemporary notion of environment is much broader than commonly understood
-includes biological circumstances (e.g. Exposure to toxins, diet), personal and social circumstances

Question 4

galton

Answer 4

nature- geniuses are born, not made

first person to realise heredity could be estimated by comparing identical and non identical twins

Question 5

piaget

Answer 5

considered development as a cyclical process of interactions between the child and his or her environment leading to a progression
through stages

Genetic contribution = developing a brain that is ready to learn in certain ways

Environment = assimilating evidence via experience and then developing new
mechanisms in light of the feedback obtained

Question 6

neuroconstructivism

Answer 6

A process of interaction between environment and brain based constraints that leads to the mature cognitive system emerging out of transformations of earlier ones (but does not assume discrete stages)

Question 7

blue print analogy

Answer 7

each connection in the brain is pre-determined

at some gross level must be true: human brains are similar to each other but differ from other species

-inconceivable that genome contains detailed wiring diagram of the brain, misleading that this suggests structural details of our brain are specifies at a fine level of detail

Question 8

deterministic development

Answer 8

genes dictate the structure of the brain, which enables the particular functions of the brain, which determines the experiences we have

Question 9

probabilistic development

Answer 9

brain structure and expression of genes can be influenced by expression of genes and visa versa

effects of genes on the brain are probabilistic- they specify approximately how many neurons will grow but not exactly how/where they will grow

Question 10

human gestation period

Answer 10

about 38 weeks from conception

Question 11

prenatal brain development

Answer 11

Cell division

Cell specialization
*
Neural tube formation
o Proliferative zones: neurons and
glial cells are produced
o During early development 250,000
neurons are produced per minute
o Neurons migrate to their final
location

Question 12

prosencephalon to

Answer 12

telencephalon and diencephalon

Question 13

mesencephalon to

Answer 13

midbrain

Question 14

rhombencephalon to

Answer 14

metencephalon
myelencephalon

Question 15

telencephalon to

Answer 15

cerebrum

Question 16

diencephalon to

Answer 16

eyecup, thalamus, hypothalamus and epithalamus

Question 17

metencephalon to

Answer 17

pons and cerebellum

Question 18

myelencephalon to

Answer 18

medulla oblongata

Question 19

prenatal brain development

Answer 19

Highly folded cortex is highly distinguishable feature of human brain
-visible in last few months before birth and shows further small changes over the fist 2 years of life

Folding likely to be a outcome of packing more neurones within a restricted space together with stretching the cortical surface by axonal tension
-rather than it being specified by genome

Gyri and fissures very similar for everyone
-emerges from constraints

Spontaneous waves of electrical activity emanating from the retina before birth are important in setting up synaptic pathways from the retina to the LGN and the V1 in readiness for processing of visual stimuli
-this is the beginning of individual experience/ differences

Question 20

what is the beginning of individual experience/ differences?

Answer 20

Spontaneous waves of electrical activity emanating from the retina before birth are important in setting up synaptic pathways from the retina to the LGN and the V1 in readiness for processing of visual stimuli

Question 21

hebbian learning

Answer 21

Spontaneous electrical activity enables networks to form

Question 22

postnatal brain development

Answer 22

Majority of neurons formed
prior to birth

Newborn brain weights 450 g
(vs. 1400 g adult brain)

Postnatal increase in brain
size:
o Synaptogenesis
o Myelination
o Glial cell proliferation

plasticity

increased grey matter: new synapses, dendrites, axon collaterals, glia cells

Question 23

synaptogenesis

Answer 23

-there is a characteristic rise and fall in the synapse formation

-synapses fall during the course of development because the process of fine tuning the brain to the environment renders some connection redundant

-more synapses do not necessarily reflect more efficient functioning

Question 24

myelination

Answer 24

-increase in fatty sheath that surrounds the axons and increases speed of information transmission

-prefrontal cortex = one of the last areas to reach adult levels of myelination

Question 25

plasticity

Answer 25

experience dependent change in neural functioning, alterations in the pattern of synaptic connections

Question 26

adults who learn to juggle over a 3 moth period show increased grey matter density

Answer 26

assessed with MRI, in a region, V5/MT, specialized for detecting visual motion as well as the occipitoparietal region implicated in hand–eye coordination

We might expect a positive relationship between individual difference in ability and local increases in grey matter, this isn’t always the case

congenitally blind people have more grey matter in V1 than sighted people

One cant take grey matter density as a simple proxy of cognitive ability as it depends on the underlying mechanisms
-developmental pruning of synapses -thinner is better
-experience-dependent changes -thicker is better

Question 27

what can increase grey matter density?

Answer 27

new synapses

Glia cells can divide or change in size which could contribute to changes in grey and white matter volume

More dendritic branches, synapses or axon collaterals

Question 28

functional brain development

Answer 28

prenatal brain damage can lead to major reorganisation of tracts

Question 29

extreme plasticity

Answer 29

In the face of major insult, the brain may be capable of reorganising itself in some fundamentally different ways

In non human animals it is possible to surgically transplant a region of the cortex or sever pathways such that novel ones emerge

Question 30

AH

Answer 30

10 year old girl- failed to develop a right hemisphere and right eye prenatally

Only has minor visual impairment

fMRI showed visual information could be rerouted into the intact ipsilateral hemisphere
-neurons coding left and right sides of space in the same cortical map where they are normally segregated into separate hemispheres

Question 31

functional brain plasticity limitations

Answer 31

Spontaneous patterns of activity prior to birth are already shaping neural activity and parcellating them into different networks - these connections will not be fully lost

Major reorganisation seems to be strictly time limited

Question 32

Lorenz imprinting - critical and sensitive periods

Answer 32

Once imprinted, the gosling is unable to learn to follow a new foster parent

happens between 15h and 3 days, movement is key

Intermediate and medial of the hyperstriatum ventrale (IMHV) in chick forebrain, which may correspond to mammalian cortex, is critical for enabling imprinting

Question 33

two main features of critical and sensitive periods

Answer 33

1. Learning takes place within a limited window
   o But opportunity can be extended in lack of experience
2. This learning is hard to reverse by later experiences
   o But chicks imprinted to one object can generalize to similar objects
   (colour or shape)
   o Preference can be changed after sensitive period

Question 34

language sensitive and critical periods

Answer 34

Each basic skill involved in language may have its own sensitive period rather than a fixed cut off point at puberty

e.g. Sensitive period for phonemic discriminations - occurs during infancy and is resistant to subsequent exposure

In contrast, accents are ore fluid during childhood and but become notoriously hard to change from onset of adulthood

Question 35

possible explanations of critical and sensitive periods

Answer 35

Genetically programmed synaptogenesis (readies brain for learning),
followed by reduced plasticity (learned information is then “fossilized”)

2. Closure of window could be initiated by learning itself, i.e. an environmental
   cue

Question 36

empiricist view

Answer 36

newborn mind is a blank slate

Question 37

natiavist view

Answer 37

we are born with some knowledge