Genetics, Environment, and Human Development Flashcards
When does an embryo become a foetus?
8 weeks
What is the last area of the cortex to be myelinated and what is its role?
Prefrontal cortex
Decision-making, planning, inhibition
Name some genetic factors that can affect brain development
Improper cell division
Single gene defect
Recessive gene defect
Gene variant that predispose to diseases
Name some environmental factors that can affect brain development
Teratogens - cause birth defects
Retinoic acid
Epigenetics
Alcohol/drugs of abuse
What are the positive symptoms of schizophrenia?
Delusions
Hallucinations
Thought disorder
What are the negative symptoms of schizophrenia?
Social withdrawal
Anhedonia
Lack of drive and speech
Which pathway is implicated in the negative symptoms of schizophrenia?
Mesocortical
Which pathway is implicated in the positive symptoms of schizophrenia?
Mesolimbic
What are the neurological symptoms of schizophrenia?
Catatonia
Eye tracking problems
Problems with blinking and eye focusing
What are the brain abnormalities in schizophrenia?
Enlarged ventricles - loss of brain cells
Abnormal prefrontal cortex
Abnormal medial temporal lobes
Medial diencephalon
What is the evidence for the heritability of schizophrenia?
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
What is the role of the Disc1 gene?
Maturation and integrations of neurons in NS
Binds to microtubules along axon and synapse - prevents arborisation
What are the effects of Disc1 downregulation?
Accelerated neuronal integration - neuron mis-positioning - aberrant morphology
Accelerated dendritic development and synapse formation - larger spines
Increased neuronal excitability
Name 3 other genes that may be involved in schizophrenia
Neuregulin-1
Reelin
Neurexin-1
How does lack of early maternal care affect later stress response in rats and humans?
Methylation of promoter for Nr3c1 - encodes glucocorticoid receptor (GR) - NGF1-A TF cannot bind
Decreased GR expression into adulthood
How does lack of early maternal care affect later synaptic connectivity in mice?
Decreased REST expression
Decreases Grin2B expression - promoter for GluN2B subunit
Decreases GluN2B - changes NMDAR subunit composition
What is the role of REST?
Transcriptional repressor - of GluN2B - NMDAR subunit - via epigenetic remodelling
How do high doses of alcohol affect the brains of young people?
Permanent decrease in pre-frontal cortex volume Inhibits neurogenesis Affects pruning of connections Affects myelination Affects synaptic maturity
What are the symptoms of foetal alcohol syndrome?
Small head Characteristic facial features Developmental and mental retardation Poor memory Attentional deficits Impulsive behaviour
What is the direct effect of alcohol in FAS?
Cytotoxic - causes superoxide production
What is the effect of alcohol on cell adhesion in FAS?
Inhibits L1 protein - inhibits cell adhesion
What are the effects of an L1 mutation?
Mental retardation, developmental abnormalities
What are the effects of alcohol on retinoid metabolism in FAS?
Inhibits retinal dehydrogenase - reduced conversion of retinol to retinal to retinoic acid
Retinoic acid regulates developmental genes
