Genetics, Environment, and Human Development

Question 1

When does an embryo become a foetus?

Answer 1

8 weeks

Question 2

What is the last area of the cortex to be myelinated and what is its role?

Answer 2

Prefrontal cortex

Decision-making, planning, inhibition

Question 3

Name some genetic factors that can affect brain development

Answer 3

Improper cell division
Single gene defect
Recessive gene defect
Gene variant that predispose to diseases

Question 4

Name some environmental factors that can affect brain development

Answer 4

Teratogens - cause birth defects
Retinoic acid
Epigenetics
Alcohol/drugs of abuse

Question 5

What are the positive symptoms of schizophrenia?

Answer 5

Delusions
Hallucinations
Thought disorder

Question 6

What are the negative symptoms of schizophrenia?

Answer 6

Social withdrawal
Anhedonia
Lack of drive and speech

Question 7

Which pathway is implicated in the negative symptoms of schizophrenia?

Answer 7

Mesocortical

Question 8

Which pathway is implicated in the positive symptoms of schizophrenia?

Answer 8

Mesolimbic

Question 9

What are the neurological symptoms of schizophrenia?

Answer 9

Catatonia
Eye tracking problems
Problems with blinking and eye focusing

Question 10

What are the brain abnormalities in schizophrenia?

Answer 10

Enlarged ventricles - loss of brain cells
Abnormal prefrontal cortex
Abnormal medial temporal lobes
Medial diencephalon

Question 11

What is the evidence for the heritability of schizophrenia?

Answer 11

Adoption studies - scz adults adopted as children more likely to have scz biological relatives
Twin studies - concordance rate higher for MZ twins than DZ - not 100% - environmental component
Certain mutations predispose - mutagenic disease

Question 12

What is the role of the Disc1 gene?

Answer 12

Maturation and integrations of neurons in NS

Binds to microtubules along axon and synapse - prevents arborisation

Question 13

What are the effects of Disc1 downregulation?

Answer 13

Accelerated neuronal integration - neuron mis-positioning - aberrant morphology
Accelerated dendritic development and synapse formation - larger spines
Increased neuronal excitability

Question 14

Name 3 other genes that may be involved in schizophrenia

Answer 14

Neuregulin-1
Reelin
Neurexin-1

Question 15

How does lack of early maternal care affect later stress response in rats and humans?

Answer 15

Methylation of promoter for Nr3c1 - encodes glucocorticoid receptor (GR) - NGF1-A TF cannot bind
Decreased GR expression into adulthood

Question 16

How does lack of early maternal care affect later synaptic connectivity in mice?

Answer 16

Decreased REST expression
Decreases Grin2B expression - promoter for GluN2B subunit
Decreases GluN2B - changes NMDAR subunit composition

Question 17

What is the role of REST?

Answer 17

Transcriptional repressor - of GluN2B - NMDAR subunit - via epigenetic remodelling

Question 18

How do high doses of alcohol affect the brains of young people?

Answer 18

Permanent decrease in pre-frontal cortex volume
Inhibits neurogenesis
Affects pruning of connections
Affects myelination
Affects synaptic maturity

Question 19

What are the symptoms of foetal alcohol syndrome?

Answer 19

Small head
Characteristic facial features
Developmental and mental retardation
Poor memory
Attentional deficits
Impulsive behaviour

Question 20

What is the direct effect of alcohol in FAS?

Answer 20

Cytotoxic - causes superoxide production

Question 21

What is the effect of alcohol on cell adhesion in FAS?

Answer 21

Inhibits L1 protein - inhibits cell adhesion

Question 22

What are the effects of an L1 mutation?

Answer 22

Mental retardation, developmental abnormalities

Question 23

What are the effects of alcohol on retinoid metabolism in FAS?

Answer 23

Inhibits retinal dehydrogenase - reduced conversion of retinol to retinal to retinoic acid
Retinoic acid regulates developmental genes