Lecture 21 Flashcards
Is human brain development complicated?
Yes extremely
What is mutation selection balance?
Mutations get eliminated over time, but new ones keep coming
What are the many insults that the human genome have buffered?
Environmental variation, genetic variation and molecular noise
What does the robustness of the human genome allow?
Genetic variation to accumulate in the population if the individual mutations are not too severe
What can slightly bad gene mutations that do not directly cause a disease can collectively compromise?
What does it do?
The evolved interactions of everything in the brain.
It reduces the overall robustness of brain development and functions
Does much of brain development depend on chance?
Yes
What makes it so that identical twins that can have very different brains?
The unavoidable randomness at the molecular level that impacts brain developmeny
What do people argue that body symmetry is indicative of?
The robustness of the underlying genetic instructions
What does the robustness of the underlying genetic instructions have to contend with?
Environmental variation and molecular noise
Do the two sides of the body develop independantly from the same set of genomic instructions?
Yes
What happens if the genomic instructions are clear?
Not clear?
The body should be symmetrical.
The person may be more assymetric
Is body symmetry heritable?
What does it correlate with?
It’s partially heritable
It slightly correlates with intelligence, physical attractiveness and physical health
What correlates with a very small statistical increase in intelligence?
Hundreds of gene variants
Do some of the gene variants that are associated with intelligence overlap gene variants associated with physical attractiveness, physical health and longevity?
Yes
Have genetic studies identified gene variants that correlate with a very small statistical increase in intelligence?
Yes
Can you identify gene variants that confer an increased risk of developing psychiatric illness?
No, it has not been particularly helpful with regards to prevention or treatment
Are there preventive measures that can be taken to prevent psychiatric disroders?
No, besides avoiding trauma
What is the best advice for maintinating a healthy brain and healthy body?
-stay active, physically and metally
-eat well
-reduce stress
-maintain good sleep habits
-limit alchohol intake and avoid tobacco and hard drugs
What is characterized by social withdrawl, disorganized thinking, abnormal speech and an inability to understand reality?
Schizophrenia
What percentage of the population is affected by schizophrenia?
1%
How do to the symptoms of schizophrenia typically come on?
They begin in young adulthood, and in many cases never cease
- 20% of people eventually do quite well
What percentage of people with schizophrenia don’t believe they have an illness or don’t comply with their recommended treatment?
30-50%
What are the 3 groups of schizophrenia symptoms?
Negative
Cognitive
Positive
Describe negative behaviours in schizophrenia patients?
The absence of behaviours, social withdrawal, reduced emotional expression, poverty of speech and reduced motivation
Describe cognitive behaviours in schizophrenia patients?
Disorganized and irrational thinking, deficits in learning and memory, poor abstract thinking, and poor problem solving
Describe positive behaviours in schizophrenia patients?
The presence of delusions and hallucinations
What type of symptoms usually emerge first in schizophrenia patients?
negative then cognitive then positive
What do patients with schizophrenia also exhibit?
Such as?
Neurological symptoms, such as poor control of eye movements and unusual facial expressions
Is schizphrenia associated with differences in brain structure?
Yes, subtle
What do the causes of schizophrenia include?
Environmental and genetic factors
What is the estimate of the heritability of schizophrenia?
Around 80%
What does heritability measure?
The fraction of phenotype variability that can be attributed to genetic variability
What is the risk of developping schizophrenia if…
both of your parents/identical twin have it?
one of your parents has it?
your sibling has it?
50%
13%
8%
What percentage of cases of schizophrenia are attributed to rare gene copy number variations?
What are they frequently comorbid with?
5%
They are frequently comorbid with autism and intellectual disabilities
What are the environmental factors of schizophrenia?
-mother’s nutrition during pregancy
-mother’s stress during pregnancy
-certain infections (particularly during pregnancy)
-birth month
-being raised in a city
-childhood trauma
-social isolation
-perinatal hypoxia / brain damage
What is schizophrenia related to?
Several environmental factors that could affect development in utero
What is the seasonality effect?
Why is this?
A large number of schizophrenic patients are born in february, march, april and may
People are more likely to stay inside and catch a viral illness
Why is schizphrenia about three times more prevalent in people who live in the middle of large cities as compared to those who live in rural areas?
The transmission of infectious illnesses is facilitated by increased population density
Are monochroinic twins more similar are dichorionic twins more similar?
monochorionic, they share one placenta
What does behavioural and anatomical evidence suggest about abnormal prenatal development?
It is associated with schizophrenia
What was seen in kids who go on to develop schizophrenia?
behavioural: less sociability and deficient psychomotor functionning
anatomical: minor physical abnormalalties
Is there a cure for schizophrenia?
No
What is the main treatment for schizophrenia?
medication that is often combined with psychological and social supprots
What do drugs that relieve the positive symptoms of schizophrenia do?
What are they called
Block dopamine D2 receptors
Antipsychotics or neuroleptics
What type of drugs tend to temporarily elicit certain aspects of the positive aspects of the positive symptoms of schizophrenia?
Dopamine receptor agonists like cryal meth and cocaine
What is the dopamine hypothesis?
Excessive dopamine D2 receptor activity, particularly in the nucleus accumbens (striatum), underlies the positive symptoms of schizophrenia
What do dopamine D2 receptors antagonist typically do?
Reduce the positive symptoms of schizophrenia, but not the negative symptoms
What does some evidence suggest that the negative symptoms of schizphrenia result from?
Abnormal activity in the prefrotal cortex
Or hypofrontality
What is hypofrontality?
Descreased activity of the frontal lobes, partciularly the dorso lateral preforntal cortex, which may relate to hypoactivity of local dopamine D1 receptors
What is reduced dopamine signaling in the prefrontal cortex been associated iwth?
The negative symptoms of schizophrenia
What has the atypical antipsychotic clozapine been found to do in monkeys?
Decrease dopamine levels in the striatum and increase dopamine levels inthe prefrontal cortex
What are atypical antipsychotic medications?
Recently discovered medications which aim to reduce both the positive symptoms and negative symptoms of schizphrenia.
They typically influence the activity of several neurotransmitter receptors (beyond blocking the dopamine D2 receptor)
What is the first of the atypical antipsychotic medications? What does it block?
Clozapine
Dopamine D2 and serontonin 2A receptors
What is aripiprazole?
An atypical antipsychotic. It acts as partial agonist at the dopamine D2 and D3 receptors. It is thought to reduce dopamine receptor activity in the striatum but boost it in the prefrontal cortex
What is the atypical antipsychotic aripiprazole?
A partial dopamine D2 receptor agonist
What is a partial agonist?
a drug with very high affinity for a receptor but it activates it less than the normal ligand does
What does a partial agonist act as in regions of low concentration of normal ligand?
In regions of high concentrations?
Agonist
Antagonist