Content - biological psychology Flashcards
What are the two functions of the CNS?
-Collects, processes and responds to information in the environment
-Coordinates the working of different organs and cells in the body
What is the CNS made up of?
Spinal cord - passes messages to and from the brain, responsible for reflex actions such as pulling your hand away from a hot plate
Brain - left hemisphere controls activity, cerebral cortex is highly developed in humans and is what distinguishes our mental functioning from other animals
What is lateralisation and localisation?
Lateralisation - Where each hemisphere has different functions
Localisation - Certain areas of each hemisphere are responsible for a specific function
The components of the cerebral cortex and their functions
Frontal lobes - Controls high level cognitive functions, contains a motor cortex which controls voluntary movements
Parietal lobes - processes sensory information from the skin
Temporal lobes - contains an auditory cortex which deals with sound information and have a role in understanding language
Occipital lobes - Contains a primary visual cortex
What are the language areas of the brain?
Broca’s area - identified a small area in the left frontal lobe responsible for speech production
Wernicke’s area - Identified damage in left temporal lobe causing fluent but meaningless speech
What is a neuron and its function?
A neuron is a nerve cell
-They allow the nervous system to fullfill its communication function by transmitting signals electronically
-When a neuron is sufficiently activated by a stimulus, the inside of the cell becomes positively charged. This rapid switch is called depolarisation and creates an electrical impulse that travels down the axon towards the terminal buttons of the neuron
What are the functions of components of the neuron?
Axon - carries impulses away from the cell body
Dendrites - carries impulses from neighbouring neurons towards cell body
Cell body - contains nucleus where genetic material is stored
Myelin sheath - Fatty layer that insulates the neuron and speeds up rate of reaction
What are the functions of each neuron?
Sensory neuron carries messages from receptors to the CNS
Motor neuron carries messages from the CNS to effectors
Relay neuron connects sensory neuron and motor neuron together
What is the process of synaptic transmission?
Synaptic transmission is a chemical process using substances called neurotransmitters. When the AP reaches the end of a neuron it triggers the release of neurotransmitter from tiny sacs called synaptic vesticules
-Neurotransmitters are chemicals that diffuse across the synapse to the next neuron in the chain. The chemical signal carried by the neurotransmitter is converted back into the postsynaptic neuron
What is inhibition and excitation?
Inhibition - makes something negatively charged. If the net effect on the postsynaptic neuron is inhibitory then its less likely to fire
Excitation - makes something positively charged. If the net effect on the postsynaptic neuron is positively charged, depolarisation takes place and the AP travels down the dendrite towards the cell body along the axon
What is the limbic structure?
-A key structure involved in aggression is the amygdala. This has a central role in how an organism accesses and responds to environmental threats and changes.
Coccaro et al (2007) studies people with IED. IED participants showed high levels of amygdala activity when viewing images of angry faces, a response not found in non - IED controls. The evidence of an association between amygdala reactivity and aggression is meaningful.
What is the role of the prefrontal cortex?
-Research indicates the amygdala functions in tandem with OFC. The OFC plays an important role in higher cognitive functions such as rational thinking and decision making. In patients with psychiatric disorders that feature aggression, activity in OFC is reduced.
Raine et al used PET scans to study murderers whose crimes include an overwhelming level of aggression. They found greater glucose metabolism in the amygdala but abnormally low metabolism in prefrontal cortex.
Role of Serotonin
Serotonin is a neurotransmitter with widespread inhibitory effects on transmission between neurons in the brain. Low levels of serotonin may reduce self control leading to impulsive behaviours.
Virkunnen et al compared levels of serotonin breakdown product in fluid of violent impulsive and non-impulsive offenders. The levels were significantly lower in impulsive offenders.
What is the role of dopamine?
Dopamine is a neurotransmitter that has inhibitory effects in some areas of the brain. Involved in regulating motivated behaviour and our experience of reward.
According to Seo et al (2008) serotonin underactivity stimulates dopamine overactivity
Evaluation of the structure of our brain and aggression
-Strength is powerful research evidence for the role of amygdala in aggression. Pardini et al (2014) identified 56 males who’d been part of a study 20 years ago. Over the 20 years these man had behaved aggressively. Researchers found a strong negative correlation between levels of aggression and amygdala volumes. This is strong support for influence of amygdala, especially as it shows the explanation has predictive validity.
-Weakness is research into neural influences on aggression is often correlational. It’s impossible to establish whether a particular structure of function is a cause/effect of aggressive behaviour or a third party was involved.
However, some researchers have attempted to overcome this problem by using drugs known to increase serotonin activity. For example, participants given paroktene gave less intense shocks to others. This is evidence of a link between serotonin and aggression that goes beyond usual correlational findings
-Practical benefits to understanding neural influences on aggression. For example, one goal of research is to discover a drug that affects the brain’s serotonin system, reducing aggressive behaviour with minimal effects. This may be invaluable given human aggression is at the root of personal and social costs.
What is natural selection?
Due to survival of genes
occurs when there is competition for scarce resources
What is sexual selection?
Explains why some characteristics that might appear disvantageous actually confer a survival advantage because the characteristics are attractive to potential mates
Evaluation of evolution, natural selection and aggression
-Strength of evolutionary theory is it can explain why males are more aggressive than females. Females who are cooperative are likely to be naturally selected because cooperation helps them protect themselves and offspring. Therefore, reduced aggression is selected in females. Males are better hunters shown in studies of chimpanzees (Manson and Wrangham). This is a strength because it explains gender differences in aggression today, increasing validity
However, any evolutionary theory is uncertain as its impossible to test evolution directly. Variables are just measured and not manipulated, so correlational research can never rule out effects of other factors of aggressive behaviour
-Weakness is there are differences between cultures in aggressive behaviour. For example, people of the Kalahari are discouraged from aggression since childhood and is rare. In contrast, Yanomani of Brazil accepts aggression. These differences in aggression aren’t universal and suggest innately determined behaviour can be outraged by cultural norms.
-Evolutionary theory helps us understand human relationships as it predicts we should choose partners who’ll enhance reproductive success shown in Buss’s study. This shows predictions from the theory are upheld by evidence.
What are hormones?
Endocrine glands manufacture a variety of hormones and secretes them into the bloodstream. Hormones are biochemical messengers.
Hormones act much slower than the nervous system but have widespread and powerful effects
What is testosterone?
Animal studies have demonstrated that experimental increases in testosterone are related to more aggressive behaviour in males
Dolan et al (2001) found a positive correlation between testosterone levels and aggressive behaviours in a sample of 60 male offenders in maximum security hospitals
What is dual-hormone hypothesis?
Cortisol helps the body deal with effects of stress. This suggests there is an interaction between the systems responsible for regulating aggression and stress response
Carre and Mehta claim high levels of testosterone lead to aggressive behaviour when cortisol is low
Evidence for female aggression
Eisenegger et al (2011) found women given a dose of testosterone behaved more generously and socially in a lab based negotiating game
Evaluation of hormones
-Strength is evidence of testosterone effects in females. Dabb and Hargrove measured testosterone in saliva of 87 female inmates. The level of violence correlated with testosterone level. This was replicated in the study of males, increasing validity.
However, we can’t establish a casual relationship between aggression as other hormones could be affecting it
-Weakness is its difficult to determine testosterone levels. Carre et al (2011) argues baseline testosterone plays a less important role in human aggression than it does in animals. However, baseline measure used in many studies may not provide a valid indicator of testosterone level in relation to aggression
-Understanding the effects of hormones on aggression could lead to practical benefits. As there is a close link between aggression and serious crimes, anti - testosterone drugs may have positive effects on individuals and society
What is the id?
-Exists from birth
-In the unconscious mind
-Contains instincts, impulses and drives that are socially unacceptable
-Obeys the pleasure principle - demands the immediate gratification of our desires. This makes aggression unavoidable
What is the ego?
-Logical, rational and mostly conscious part developed shortly after birth
-Follows reality principle - the interface between unrealistic desires of id and social reality
-Satisfies the id by fulfilling urges indirectly
What is the superego?
-Emerges later in development, around 5 or 6 years old
-Superego opposes the id’s aggressive drive through guilt and shame when we fail to meet the highest moral standards
-Just as irrational and punishing in its demands as the id
What is catharsis?
Expressing aggression through releasing psychic energy, reducing aggressive drive
What happens if you prevent catharsis?
A build up of energy which will eventually produce a destructive aggressive outburst
How is catharsis achieved?
-Through displacement - where aggression towards one person is redirected against a less powerful and more available substitute
-Observing others behaving aggressively
Evaluation of Freud’s explanation of aggression
-Strength is it can explain the distinction between “hot blooded” and “cold blooded” aggression. “Hot blooded” aggression is impulsive, angry and has no purpose other than its own satisfaction. This is domain of the id. “Cold blooded” aggression is deliberate. It is the outcome of the ego’s successful control of its impulses. This matches reality of behaviour and gives us confidence in validity of the theory
-Weakness is “letting off steam” may lead to more aggression rather than less. Bushman’s 2002 study produced opposite results to Freud’s theory.
However, there’s evidence expressing anger can be cathartic. Graham et al suggests we should rant rather than vent. Ranting involved consideration of reasons why one is angry. Venting is uncontrolled expression of anger
-Catharsis can be used practically to prevent aggression. Can feature in therapy .
What is cocaine and its effects?
Cocaine has an impact on activity of dopamine
Cocaine blocks the reuptake of dopamine as dopamine receptors will be down-regulated. Few receptors are active after so level of dopamine produced declines
Cocaine is a stimulant so causes depression and anxiety
What is heroin and its effects?
Slows down CNS activity
Heroin produces morphine which binds with receptors. Downregulation is caused as opioid receptors on the postsynaptic neurons bind with morphine molecules
Heroin is a depressant which can lead to deficits in motor and cognitive ability
Evaluation of recreational drugs
-Strength is supported by research with non-humans. The findings of Weinshenker’s 2007 study on mice supports the view that cocaine’s effects are due to the activity of dopamine in the brain
-Weakness is problems with using non-human studies to understand drug effects on human CNS transmission. The human brain is different to a mouse’s brain thus extrapolation from non-human animals to humans is risky and should be undertaken very cautiously. However, evidence of drug effects on CNS transmission come from studies of humans as well e.g. Volkow et al used PET scans to find out subjective experience intensified as more dopamine transporters were occupied by cocaine and declined when less active
-Strength is application as more treatments for addiction become available. e.g. Naxolane was created once heroin was identified as an agonist that binds to opiate receptors
