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Lecture 1- The genetic basis
70’s: environment (violent) behavior
90’s: genes (violent) behavior
Today: genes environment (violent) behavior
Today: interaction between genes and environment causes behavior
Gene: meaningful section of the DNA molecule.
Gene expression: whether a gene is turned “on” or “off”; the extent to which a gene is transcribed into
a sequence of amino acids (protein). In each cell, some genes are expressed at any point in time and
others are not. This is controlled by the biochemical environment inside the cell.
The biochemical environment inside the cell is influenced by for example the environment
outside the cell, timing in development, the overall environment, experience and behavior.
Genotype: an organism’s specific set of genes
Phenotype: an overt traits and behaviors of an organism. (determined by genotype and environment)
Each gene is paired with another gene
Pairs are located at corresponding positions on pairs of chromosomes.
Allele is one specific variant of a gene. You have dominant or recessive.
Homozygote: alleles on locus are the same.
Heterozygote: alleles on locus are different.
A specific trait or behavior is determined by the interaction between the environment (past and
present) and:
- One gene pair or multiple gene pairs. Multiple gene pairs: Polygenetic inheritance.
The genome is shaped by evolution over the years: Darwin
- Evolution by natural selection
Key mechanism of evolution is natural selection. Requires 3 conditions:
- There is variation among individuals of a populations
- Individuals with a certain trait survive and reproduce at higher rate than others
- The trait associated with this advantage is passed to offspring
This specific trait will be better represented in the next generation.
Organisms differ in genotype and variations in genotype are passed from generation to generation.
What matters is the survival of genes and NOT the survival of individuals.
,Evidence for modern evolutionary theory comes from many sources. For example: fossil, resemblance
between genomes of various organisms, pseudogenes (inactive genes), distribution of species across the
world.
- Genes and behavior
Nature (genes) always interact with nurture (environment).
Who we are is determined by how our genes are expressed in distinct environments.
Nature and nurture can work together to affect human behavior.
Behavioral genetics: the study of how genes and environment interact to influence psychological
activity.
Heritability (H) = Genetic Variance/Phenotypic Variance
Epigenetics: the study of how environment affects genetic expression.
Lecture 2: the brain and the nervous system
- Introduction
Genes x environment phenotype
- Building blocks of the nervous system
The nervous system consists of: Glia (supportive function myelinescheden) and Neurons (cells which
receive info and send info by electrical pulses). White matter consists stuff with myeline and grey matter
consists stuff without myelene
Electrical signal goes from the dendrite along the axon.
Different types of neurons:
Sensory receptors (physical signal electric signal)
sensory (afferent) neurons (information from sensory receptors spinal core etc.)
interneurons (between sensory neurons and motor neurons)
motor (efferent) neurons (form brain muscles).
- Communication among neurons
Semi-permeable membrane and can be stimulated. Neuron is negatively charged relative to the outside
(~-70mV). This is the rest potential. Action potential: inside of the neuron is briefly positive relative to
outside (~40mV). Action potential goes along axon.
1. Na+ inside the cell causes depolarization. (inside becomes positively); passive
2. K+ leave the cell (repolarization); active
3. Rust potential!! (refractory period) = hyperpolarization.
Excitation threshold = ~-55mV above: action potential, below: nothing happens.
, You have an action potential, or you have NOT! There is no other way.
All-or-none law: intensity variations by:
Variations in the number of neurons firing.
Variations in firing rate.
Neurons interact
Via synapses (the place where a signal passes from one nerve cell to another)
Through chemical substances.
You have a presynaptic membrane and a postsynaptic membrane. Goes from pre synaptic gap
post by releasing neurotransmitter(substances). Neurotransmitters leads to opening sodium channels
which can lead to an action potential.
Neurotransmitters works with lock-and-key model. The effect is terminated by auto receptors or
synaptic reuptake (re-absorption by pre-synaps) or enzymes. The binding of a neurotransmitter with a
receptor produces an excitatory or inhibitory signal. Na+ goes in the cell (excitatory) or Cl- goes in the
cell (inhibitory).
Probability if a neuron fire depends on many neurons (not just 1).
Drugs: Agonists
1. Increase of precursor
2. Counteracting the cleanup enzymes
3. Blocking the re-uptake
4. Mimicking the transmitter’s action
Antagonists
1. Decrease precursor (or neurotransmitter)
2. Increase effectiveness cleanup enzymes
3. Enhance the re-uptake
4. Blocking of receptors
- Communication of the brain with the body
Nervous system: central nervous system and the peripheral nervous system. SEE THE PIC ON THE SLIDE
Somatic nervous system: muscle etc.
Autonomic nervous system: breath etc. consists of sympathetic (adrenaline!) and parasympathetic
(calm).
Endocrine system: responsible of the regulating release of hormones in our bloodstream.
- Studying the brain
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