Chapter 8 : Development

Question 1

Neural plate and neural tube

Answer 1

Neural plate : thickened region of the ectodermal layer that gives rise to the neural tube

Neural tube : structure in the early stage of brain development from which the brain and spinal cord develop

Question 2

Neuroblast and Glioblast

Answer 2

Neuroblast : product of a progenitor cell that gives rise to different types of neurons

Glioblast : product of a progenitor cell that gives rise to different types of glial cells

Question 3

How do stem cells know what to become?

Answer 3

Chemical signal - Turns genes on - Specific proteins are made - Specific cells

Question 4

Stages of brain development

Answer 4

1. Cell birth (a chemical compound acts to support growth and differentiation in developing neurons, begins at 7 weeks)
2. Cell migration and 3. Cell differentiation (begins 8 at weeks, damage has more serious consequences)
3. Cell maturation (begins at week 20, continues long after birth, 2 methods of maturation : dendritic growth - increases surface area for synapses with other cells & axonal growth - extend axons to appropriate targets intiate synapse formation) Filipod : process at end of developing axon that reaches out to search for potential target or to sample intercellular environment
4. Synaptic development (combination of genetic programming and environmental cues and signals)
5. Cell death and synaptic pruning (born with overabundance of neurons and synaptic connections) like natural selection
6. Glial development (oligodendria form myelin in CNS, myelination provides a useful rough index of cerebral maturation)

Question 5

Piaget’s 4 stages of cognitive development

Answer 5

0-2 : Sensorimotor (experiences world through senses, i.e. object permanence and stranger anxiety)
2-6 : Preoperational (represents things with words and images but lacks logical reasoning, i.e. pretend play and egocentrism)
7-11 : Concrete operational (thinks logically about concrete events; grasps concrete analogies, i.e. conservation & maths)
12+ : Formal operation (reasons abstractly, i.e. mature moral reasoning)

Question 6

Problem-solving ability : Overman

Answer 6

Children can learn concurrent-discrimination task (basal ganglia, 12 months)
Children can learn nonmatching-to-sample task (temporal lobe, 18 months)

Question 7

Experience and cortical organization : Hebb

Answer 7

Cognitively stimulating environments help maximize intellectual development (stimulating environment = more connections & more synapses)

Question 8

Experience and neural connectivity (prenatally and postnatally)

Answer 8

Prenatally : neurons are drawn toward signaling chemical that indicates correct pathway
Postnatally : fine-tuning of connections proceeds in an activity-dependant manner (ex. amblyopia : vision in one eye is reduced as result of disuse, visual input from lazy eye doesn’t contribute to fine tuning of neural connections)

Question 9

Challenging experiences

Answer 9

Early deprivation of sensory experience : opposite effect of cognitively stimulating environments : atrophy of dendrites
Early deprivation of social experience : profoundly negative effect on later intellectual and social behaviours
*If deprivation is relatively short, child may be able to overcome some of negative effects (stress early life associated with : increased amygdalar volumes, decreased hippocampal volumes, later development depression & anxiety)

Question 10

Hormones

Answer 10

Testosterone and estrogen can both affect development of brain, can alter : # neurons formed, # neurons that die, cell growth, dendritic branching, synaptic growth, activity of synapses

Question 11

Abnormal brain development

Answer 11

Spina bifida : spinal cord abnormality, failure of neural tube to close completely, serious motor problems
Anencephaly : failure of forebrain to develop, front end of neural tube doesn’t close, infants die soon after birth
Abnormal cell migration and differentiation : faulty connections may produce a range of problems (ex. schizophrenia)
Too many synapses (failure of pruning) can produce neural dysfunction
Behavioural effects of brain damage to certain area often not seen until time area matures (frontal lobe damage = adolescence)
Brain has some capacity to repair minor abnormalities that can occur during development (plasticity)