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Biological level of approach - Coggle Diagram
Biological level of approach
The brain
Research divided into areas related to their function
Outer layer - cortex
Cerebral lobes = outer layer of brain = cortex
Temporal lobe
Learning and memory
Occipital lobe
Visual processing
Frontal lobe
Executive function
decision making
Personality
Foreseeing consequences
Prefrontal cortex:
Part of frontal lobe
Inhibits impulsive behaviour
Executive functions - planning, problem solving and decisions
Damage = reactive, impulsive aggression
Parietal lobe
Processing sensory info
Inner core: brain stem/inner core
Inner systems: limbic system
Only fully developed in mammals - key areas includes:
Hippocampus - transferral of STM to LTM
Amygdala - fear, social threat perception, emotional centre
Hypothalamus - fight or flight, feeding, sex, emotion, thirst, hunger,...
Localisation
Theory that specific parts of the brain is responsible for specific behaviours or cognitive processes. There are three perspectives on the extent of localisation
Strict localisation: states that every part of the brain is directly responsible for specific functions
Holism/distributed functioning - states that functions of the brain are due to the brain working as a whole and not specific parts
Principle of mass action: proportion of brain damage is directly proportional to decreased cognitive ability
Principle of equipotentiality: ability of intact brain areas to carry out the function of damaged areas
Relative localization/ weak localization: Specific parts maybe responsible for the specific functions but not exclusively and other areas can also assist in those functions
Relevant studies
Phineas Gage
Maguire 2000
Grafman
Neuroplasticity
Neurons and neural networks
Neurons - nerve cells that transmit electrical impulses to other neurons and to the brain to respond to a stimuli
Neurotransmission
Electrical impulses = action potential
The action potential travels down the body of the neutron (Axon, which is wrapped by myelin sheets that help increase speed of the action potential), it releases neurotransmitters that are stored in the terminal button of the neuron
Neurotransmitters are then released into the gap between two neurons, called the synapse
After passing through the synaptic gap, the neurotransmitters binds to the receptor sites on the post-synaptic membrane on the next neuron which causes another action potential going through the next neuron.
When the action potential has been passed, neurotransmitters are either broken down by enzymes , reabsorbed by the terminal buttons (Reuptake) or float away to bind with other neuron's receptor sites
Synapses are the gap between the axon tip of the sending neuron and the dendrites of the receiving neuron, where there are neurotransmitters' receptor sites
Neurotransmitters are chemical messengers that transmit information between neurons
Excitatory neurotransmitters: Increasing the likelihood of the neuron firing an action potential
Acetylcholine: Consolidation of memory in the hippocampus
Inhibitory neurotransmitters: Decrease the likelihood of the neuron firing an action potential
Serotonin can be argued to be inhibitory neurotransmitters
Metabotropic neurotransmitters indirectly affect the neuron and are not considered excitatory or inhibitory
Dopamine: Controls the brain's reward and pleasure centers, plays key role in motivation, low levels linked with addictive behaviour - can be both excitory and inhibitory
Norepinephrine: Arousal and alertness
Serotonin: Sleep, arousal level and emotion
Agonists: If its internal, it is called endogenous, if external, called exogenous agonists - they prevent the removal of neurotransmitters from the synaptic gap, increasing the effect of the neurotransmitter
Nicotine for acetylcholine
Antagonists: Mimic neurotransmitters and block the receptor site, inducing faster removal of neurotransmitter from synaptic gap, reducing the effect
E.g. scopolamine on acetylcholine
The ability of the brain to change and adapt to internal or external stimuli
This is done through the brain's ability to rearrange connection between its neurons
High level of stimulus and repetition can lead to increase in the density of neural connections
When we learn something new, neurons connect to create a new trace - process called dendritic branching - dendrites of the neurons grow in number and connect with other neurons
Through repeated uses of synaptic connection, the synapses become stronger, called long term potentiation
This leads to greater level of response on the post-synaptic membrane
Over time, this leads to protein synthesis and gene expression that will be the building block for dendritic branching - Neural aborization
When a synapse is not used or is under-stimulated, that synaptic connection is destroyed through synaptic pruning
Process:
Stimulus in the environment
Causes neurons to fire continually - synapse become stronger with continuous use = long term potentiation
Causing dendritic branching where neurons sprout new dendrites to form connection with other neurons
Number of available synapse for the behaviour increases = neural network
When a synapse is not used, it leads to synaptic pruning, which is the removal of unused synapses
Brain imaging technology
Magnetic Resonance Imaging (MRI) - gives a three dimensional image of the brain's structure, image can be viewed as 2d slices of the brain or used to form a 3d image
Functional Magnetic resonance imaging - shows brain activity and show which areas of the brain are active in when performing a behavior or cognitive process - measures changes in blood flow in the active brain
Hormones: Chemical messengers secreted by glands and travel in the blood to cause long term changes to organs
Features:
Secreted by glands in the endocrine system
Travel in the blood
Take longer to produce changes to human
Produce effects that last longer than neurotransmitters
Can only produce effect in specific cells - called target cells
Some hormones act as neurotransmitters, meaning that they target receptor sites on the neuron's synaptic gap even though they are secreted by an endocrine gland
Adrenaline - responsible for arousal and fight or flight response, plays a role in emotional memory formation - also called epinephrine
Fight or flight response = hormone cascade - hormone triggering hormones
When a stimulus threatens us, hypothalamus responds by activating pituitary glands, pituitary glands then release a hormone that activates the adrenal glands = cortisol and adrenaline both released into the bloodstream
Cortisol release glucose into bloodstream
Adrenaline increases heart rate, blood pressure and respiration
Cortisol - Control blood sugar levels, regulate metabolism, reduce inflammation and assist in memory formation
Oxytocin - Acts as a neurotransmitter, plays a role in mother-child attachment, believed to play a role in social bonding and trust between people
Testosterone - facilitative role in aggression and competition - male sex hormone (male androgen)
Determines sex of embryo in the womb
Determines secondary sex characteristics such as increased muscle mass, body hair and deeper voice
In men produced in testes, lesser extent in adrenal gland
In woman produced in ovaries
Pheromones: chemicals produced and released into the environment by an animal and causes a change in behavior or physiology of others of the same species
Primer pheromones: found in animals and some evidence of being in humans - causes slow, long-lasting physiological changes
Androstadienone: Found in male semen and sweat
Estratetraenol: found in female urine
Major histocompability complex (MHC) set of genes that play important role in the immune system, may be encoded within body odour
Signaling pheromones - present in animals - produce rapid behavioral effects
Pheromones are usually detected by vomeronasal organ(VNO) and processed by accessory olfactory bulb (AOB)
Human adults lack accessory olfactory bulb and it is unclear whether humans have a VNO
Limitation:
Human sense of smell is complex - 400 odour receptors and each with different genetic variations
Many odours are not caused by bodily secretion but by bacteria mixing with secretion
Different culture can perceive each smells differently, namely durians
Behavioral genetics - deals with understanding how genetics and environmental differences contributes to individual variations in human behaviour
Inherited behaviour - the inheritance of genetic materials from previous generations that give rise to specific psychological processes that leads to certain traits and behaviours
Methodology in genetic research
Twin studies
They share common genetic materials
Monozygotic twins (MZ) - Genetically identical
Dizygotic twins (DZ) - have about 50% of genes in common
Should be that the higher the genetic relationship, the more similar the individuals will be if the specific characteristic is inherited
Correlation found = Concordance rate - based on systematic analysis of similarity based on assumption that heritable traits will be more concordant in MZ twins than in DZ twins and would be even higher than siblings
If concordance rate for MZ twins significantly higher than DZ twins, likely that there is genetic factor to the behavior
If concordance rate is high in both types, likely that environment play a large role in the behaviour
Concordance rate - probability that the same trait can be found within both member of a twin
Equal environment fallacy - twins are often raised together so are exposed to similar environment so it is hard to isolate the genetic component and the environmental component of the observed behavior.
Monozygotic twins raised apart
This method minimize the influence of equal environment fallacy since they are growing up in different environment and if the same characteristics are observed in both members of the twin to a significant extent, the observed characteristic could have a genetic component
Family/kinship studies - more representative of the general population than twin studies
Degrees of genetic relatedness is compared with respect to specific traits or behaviours - concordance will increase if heritability is high and vice versa - so parent-child should have higher concordance rate than grandparents-grandchildren
Adoption studies - direct comparison of genetic and environmental influences of behaviour
Adopted children share none of their genes with adopted parents but share 50% of their genes with their biological parents.
If behaviour is highly genetic-based then the adopted child should have higher concordance rate with biological parents and vice versa for environment
Adoptive placement - genetic and environmental influence might be difficult to isolate since adoption agencies usually put children with families that have as many similarities with their biological family as possible
After human genome project, one way of researching heritability is through genetic mapping (also called linkage analysis), which indicates which chromosome contains the gene associated with the behavior, researchers examine the DNA for polymorphism - presence of genetic variation = genetic markers
Association studies - see if there is a correlation between the presence of a genetic marker and a behaviour
Genome-wide association studies (GWAS) - Compare the DNA of two groups of participants, people with the behavior and similar people without. if the genetic marker is more present in people with the behaviour , it is said that the gene is 'associated' with the behaviour
Epigenetics and depression (major depressive disorder)
Epigenetics - in order for behaviour to occur, genes must be 'expressed' as a result of stimuli like experience, diet, exercise
Gene-environment interaction
Diathesis stress model in explaining depression - psychological theory that attempts to explain behaviour as a predispositional genetic vulnerability expressed as a result of stress from life experiences - so individuals that have a specific set of genes that predisposes them to depression will be more likely to have depression when exposed to stressful life experiences than those who don't
Depression - mood disorders tend to run in families
Evolutionary psychology - As genes mutate, those that are advantageous are more likely to be passed down to following generations due to natural selection
Natural selection: theory states that the environment presents challenges to individuals and those who best adapt and best suited for the environment will be able to live longer to have offsprings and pass on their genes - therefore, later generations will acquire adaptive characteristics that allows them to best survive in the changing environment
Species will develop characteristics that make them more competitive in the environment - Adaption
Sexual selection - Subset of natural selection that arises from the preferences of specific characteristics in the genetics of a mate that would ensure the greatest survival odds for the offspring, for the species and ensuring that own good genes are passed on to following generations, so organisms are driven to reproduce as much as possible
Differential reproduction: The forces of natural and sexual selection ensure that those with 'good genes' will be able to live longer and attract mate to reproduce and pass on their genes while those who have 'bad genes' might not live as long, unable to attract mate to reproduce so their 'bad genes' will slowly be displaced by the 'good genes' since those with 'good genes' reproduce at a higher rate
Basis of attraction