Biopsychology Flashcards
Define brain scanning
Used to investigate localisation, to determine which parts of the brain do what.
Explain fMRI (functional magnetic resonance imaging)
- Works by using large magnets to detect changes in oxygenated (active area) and deoxygenated blood (inactive area) as well as blood flow, as a result of neural activity.
- HAEMODYNAMIC RESPONSE = When a brain area is more active it consumes more oxygen, and so to meet this increased demand, blood flow is directed to the area.
- fMRI’s then produce three-dimensional images that appear brightly coloured when highly active areas absorb the signal produced by the scan.
Explain EEG (electroencephalogram)
- Works by measuring electrical activity within the brain via electrodes that are fixed to an individual’s scalp, using a skull cap.
- The activity is displaced as brainwave patterns (a series of lines) that are generated from the action of thousands of neurons.
- The amplitude shows the brain intensity and the frequency shows the speed of activation.
Explain ERPs (event-related potentials)
- Works the same as EEGs but the key difference is that a stimulus is presented to the participant, this could be in the form of a sensory, cognitive or motor event.
- Then using a statistical averaging technique, all extraneous brain activity from the original EEG recording is filtered out, leaving only the responses to stimulus.
Explain PME (post-mortem examinations)
- A technique involving the examination of person’s brain after they die.
- Individuals who are subject to a PME are likely to be those who have a rare disorder and have experienced unusual deficits in cognitive processes or behaviour during their lifetime.
- Areas of damage are examined to establish the likely cause of affliction experienced.
- Their brain is also compared with someone who had a neurotypical brain, in order to ascertain the extent of the difference.
Define the nervous system
A specialised network of cells in the body and is our primary internal communication system. It’s based on electrical and chemical signals and has two main functions:
State the two subsystems of the nervous system
The CNS (central nervous system) and the PNS (peripheral nervous system).
Outline the CNS
The central nervous system is the main control system of the body. It consists of two parts: the brain and spinal cord.
THE BRAIN
- The centre of all conscious awareness
- Responsible for higher psychological processes such as perception.
- Regulates bodily processes and maintaining homeostasis, based on the info sent from the PNS.
The SPINAL CORD
- Connects the brain with the PNS
- Responsible for some unconscious movements, such as reflexes.
Outline the PNS (peripheral nervous system)
Transmits messages via millions of neurons to and from the CNS. It’s subdivided into the ANS (autonomic nervous system) and the SNS (somatic nervous system).
Outline the SNS (somatic nervous system)
= Transmits information between the CNS and the sensory receptors.
- Responsible for voluntary muscle movement (e.g. walking) and reflex actions.
- Under conscious control.
Outline the ANS (autonomic nervous system)
= Transmits information between the CNS and the internal organs, to govern vital functions in the body.
- Involuntary and not under conscious control.
- It’s subdivided into the sympathetic and parasympathetic nervous systems.
Outline the sympathetic nervous system
Sympathetic functions increase bodily activity (increased heart rate, breathing rate, decrease digestion and dilate pupils) to prepare for an action, for e.g. the flight or fight response.
Outline the parasympathetic nervous system
Parasympathetic functions decrease bodily activity that were increased by the actions of the sympathetic system. This is to return the body back to its resting state.
Describe the endocrine system
= A system of glands that are responsible for the release of hormones.
- Transmits information chemically, and operates much slower than the nervous system.
Describe the pituitary gland
The master gland which is linked to the nervous system via the hypothalamus, co-ordinating and regulating the release of hormones from all the other glands.
Outline the role of adrenaline in the fight or flight response
1) The body detects a stressor in the environment.
2) The sensory receptors and neurons in the PNS sends information to the hypothalamus.
3) The hypothalamus then coordinates
a response and triggers increased levels of
activity in the sympathetic nervous system.
4) This sends a message to the adrenal medulla, in the adrenal glands, to release adrenaline.
5) Adrenaline increases physiological changes to either fight or flee from the threat. For e.g. heart rate increases to improve blood flow, and the pupils dilate to increase vision.
6) Other bodily activities that aren’t essential for the response are reduced, such as digestion and saliva production being inhibited.
7) Once the brain senses that the threat has passed, the parasympathetic nervous system reduces these activities and returns the body to a resting state.
Define a neuron
Nerve cells that process and transmit messages through electrical and chemical signals, to and from the CNS.
Define motor neuron
Transmits information from the CNS (away from relay neurons) to the organs and muscles.
Define relay neuron
Connects sensory neurons to motor neurons and transmits information within the CNS.
Define sensory neuron
Transmits information from sensory receptors to the CNS, which is then converted into electrical impulses. When they reach the brain, they are translated into sensations (heat, pain).
Explain the structure of a neuron
1) The dendrite (receptor) receives a signal (nerve impulse).
2) It carries this signal from neighbouring neurons towards the cell body (which contains the nucleus).
3) The signal travels along an axon which is protected by the myelin sheath. It speeds up the electrical transmission of the impulse.
4) Terminal boutons at the end of the axon pass the electrical signal to the next neuron in the chain (across a gap known as the synapse).
State the two main functions of the nervous system
- To collect, process and respond to information in the environment.
- To co-ordinate the working of different organs.
Explain the electrical transmission of a neuron
- At rest, the neuron is negatively charged.
- When a neuron is activated by a stimulus, it becomes positively charged causing an action potential to occur.
- This sends an electrical impulse through the axon.
Explain the process of synaptic transmission
= The process by which neighbouring neurons communication with each other by sending chemical signals across the synapse.
1) Electrical impulse reaches the end of a neuron, the pre-synaptic terminal.
2) Triggers a release of neurotransmitters from the vesicles.
3) These diffuse across the synapse, where it’s taken up by a postsynaptic receptor site, on the dendrites of the next neuron.
4) The chemical message is converted back into an electrical impulse and the process repeats.
Explain the excitatory effect of neurotransmitters
Excitation occurs when receptor stimulation results in an increase in the positive charge of the postsynaptic neuron, which increases the likelihood of the neuron firing.
Explain the inhibitory effect of neurotransmitters
Inhibition occurs when receptor stimulation results in an increase in the negative charge of the postsynaptic neuron, which decreases the likelihood of the neuron firing.
Explain summation
= Whether a postsynaptic neuron passes on the electrical impulse is decided by this process.
- The positive and negative postsynaptic potentials are summed. If the net effect on the postsynaptic neuron is inhibitory, the neuron will be less likely to fire, and if the net effect is excitatory, the neuron will be more likely to fire.
Explain 2 strengths of fMRIs
1) SAFER - Doesn’t rely on the use of ionising radiation. If administered correctly it’s virtually risk-free, non-invasive and straight forward to use.
2) HIGH SPATIAL RESOLUTION (unlike EEGs) - fMRI scans are able to identify activity in the brain to within 1mm. This provides a highly detailed and accurate picture of how brain activity is localised.
Explain 2 limitations of fMRIs
1) EXPENSIVE (unlike EEG) - to buy and maintain. This limits their use as research tools as studies that use fMRIs often consist of small sample sizes to reduce costs.
2) LOW TEMPORAL RESOLUTION (unlike EEG) - It takes several seconds between recording brain activity using fMRI and converting it into an image. This means fMRI generates fewer images per minute and brain activity between each image is not recorded.
Explain 2 strengths of EEGs/ERPs
1) HIGH TEMPORAL RESOLUTION (unlike fMRIs) - Can record several pictures of the brain per second. This means they’re frequently used to measure cognitive functions & deficits.
2) The limitations of EEG are partly addressed through the use of ERPs - They bring much more specificity to the measurement of neural processes, than could ever be achieved using raw EEG data.
Explain a limitation of EEG
LOW SPATIAL RESOLUTION (unlike fMRIs) -
The electrodes of EEG only measure general electrical activity and are unable to pinpoint the exact source of neural activity. For example, neurons associated with feeling in the hands may be next to neurons associated with hearing, but the EEG will not be able to differentiate between the two.
Explain a strength of PME
USEFUL FOR ADVANCING MEDICAL KNOWLEDGE - For example, Broca used a PME on his patient Tan, which led to the identification of Broca’s area and was the foundation for further research into the theory of the localisation of brain function.
Explain a weakness of PME
NO BRAIN ACTIVITY - As the person is dead, it doesn’t enable researchers to measure dynamic brain activity (unlike fMRI and EEG). As such, researchers may have to speculate about (rather than measure) connections between the person’s physical brain and their psychological conditions when they were alive.
Define localisation of function
Refers to identifying specific areas of the brain that are responsible for certain processes, behaviours and activities. The cortex of both hemispheres is subdivided into four centres.
Explain the motor cortex
WHERE: Found in the frontal lobe of each hemisphere.
WHAT: Responsible for regulating and coordinating voluntary movements.
- Lesions in this area result in an inability to control fine motor skills. For example, difficulty holding a pen
- Contralateral: The RH controls movement on the left side of the body and vice versa.
Explain the auditory cortex
WHERE: Found in the temporal lobe of each hemisphere.
WHAT: Responsible for processing sound (speech/auditory information).
- Contralateral: The RH processes sound from a person’s left ear and vice versa.
Explain the visual cortex
WHERE: Found in the occipital lobe of each hemisphere.
WHAT: Responsible for processing visual information.
- Contralateral and ipsilateral: Each eye receives light from the the left visual field and right visual field.
Explain the somatosensory cortex
WHERE: Found in the parietal lobe of each hemisphere.
WHAT: Responsible for sensing physical sensations on the skin, like pressure and heat and touch.
- The number of neurons in the somatosensory cortex differs according to body part. For instance, receptors for our face and hands occupy over half of the area, as we use them more often.
State the two language centres of the brain
Broca and Wernicke’s area
Explain Broca’s area
WHERE: Found in the frontal lobe of the left hemisphere.
WHAT: Responsible for speech production
HOW: Paul Broca treated patient ‘Tan’ who could only express that syllable. He was able to understand spoken language but couldn’t speak or express thoughts in writing.
FINDINGS:
- Damage to this area causes Broca’s aphasia = A condition characterised by slow speech, lack of fluency, and an inability to find the right words i.e. generating meaningful language.
- Despite difficulties producing speech, people with Broca’s aphasia often have normal language comprehension.
Explain Wernicke’s area
WHERE: Found in the temporal lobe of the left hemisphere.
WHAT: Responsible for language comprehension.
HOW: Karl Wernicke was describing people who had no problem producing language but several difficulties understanding it.
FINDINGS: Damage to this area causes Wernicke’s aphasia = Produce nonsense words i.e. meaningless.
Outline a strength of localisation of function in the brain (Gage)
POINT - There’s several case studies to support localisation of function. The most famous being Phineas Gage.
EVIDENCE - Gage had an iron bar shot straight through his head during an accident while working, which damaged the left frontal lobe of his brain. Before the accident, Gage was calm and polite, but after the accident Gage was violent and rude.
EXPLAIN - Gage’s doctor believed the damaged area was responsible for regulating mood, which was confirmed by later research into localisation of function.
LINK - Therefore, this show’s that there’s direct real life application of the theory
COUNTER - However, the problem with case studies is that it’s difficult to make meaningful generalisations from the findings of single individuals.
Outline a weakness of localisation of function in the brain (Lashley rat’s)
POINT - The work of Lashley challenges the theory.
EVIDENCE - Lashley removed areas of the cortex in rats that were learning the route through a maze. No area was proven to be more important than any other area in terms of the rats’ ability to learn the route.
EXPLAIN - This means that the process of learning seemed to require every part of the cortex rather than being confined to a particular area.
LINK - Therefore, this suggests that higher cognitive processes are seemingly too complex to be localised but rather they’re distributed in a more holistic way in the brain.
Define hemispheric lateralisation
The idea that two halves of the brain are functionally different and that certain mental processes and behaviours are mainly controlled by one hemisphere rather than the other. As in the example of language, it’s localised as well as lateralised.
Define split-brain research
A series of studies which involved people who had epilepsy experience separation of their hemispheres, by cutting the corpus callosum. This enables researches to test lateral functions of the brain.
Outline a strength of research into hemispheric lateralisation (split-brain research - sperry )
FINDING 1: When split-brain patients were shown an image to their RVF, they were able to describe in words what they saw. However, when they were shown the same image to their LVF they couldn’t.
EXPLANATION 1: TIB in the connected brain, messages from the RH are relayed to the language centres in the LH, but this isn’t possible in the split-brain.
FINDING 2: However, the patients could use their hands to pick an object associated with that image. For example, if they were shown a cigarette to their LVF they could use their left hand to pick an ashtray.
EXPLANATION 2: TIB images in the LVF are processed by the RH which coordinates movement from the left side of the body, as the motor cortex is contralateral.
Link - This therefore supports hemispheric lateralisation
Explain why nerve impulses can only travel in one direction
Due to the specific function of different parts of the neuron.
Neurotransmitters are ONLY RELEASED from the vesicles at the end of the pre-synaptic membrane, carrying the signal over the synaptic gap. It is then the binding to specific receptor sites that are ONLY PRESENT on the post-synaptic membrane which then enables the signal to be transmitted.
Diffusion of the neurotransmitters mean they can only go from HIGH TO LOW concentration, so they can only travel in this direction.
Outline the first methodological issue of research into hemispheric lateralisation (confounding variables)
POINT - Causal relationships between the IV and DV are hard to establish
EVIDENCE - TIB the split-brain patients underwent the procedure because they suffer from epileptic fits. There was no control group to compare to.
EXPLAIN - But we can’t be sure that the effects seen in the experiment are a result of splitting the hemispheres rather than the epilepsy itself or the drugs used to treat it. This therefore a major confounding variable.
LINK - TMT this methodological concern raises questions about the validity of the conclusions drawn.
Outline a second methodological issue of research into hemispheric lateralisation
POINT - Split-brain patients are rare.
EVIDENCE - Just 11 participants took part in Sperry’s experiments.
EXPLAIN - TMT, we should be cautious about applying findings from them to the entire population.
LINK - Therefore, generalisability may be an issue.
Define neuroplasticity
The ability of the brain to change its physical structure to perform different functions, as a result of experience and new learning
Define functional recovery
A form of plasticity, following damage through trauma, in which the brain is able to redistribute or transfer functions from, damaged areas to undamaged.
Describe the brains plasticity in childhood vs adulthood
- during infancy the brain experiences a rapid growth in the number of synaptic connections, 2x as much as adults brain
- as we age, rarely-used connections are eliminated and frequently used ones are strengthened = SYNAPTIC PRUNING
Outline a strength of research into brain plasticity
(taxi drivers)
POINT - Research support
EVIDENCE - An MRI scan found larger volumes of grey matter in the posterior hippocampus of ldn taxi drivers than a control group.
EXPLAIN - This part of the brain is associated with the development of spatial and navigational skills. Psychologists found that this learning experience (memorising ldn routes) altered the structure of their brains as well as a positive correlation between the length of working and the extent of structural difference.
LINK - This therefore supports the idea that areas of our brain are adapted to support our life experiences.
Outline a strength of research into brain plasticity and functional recovery (patient eb + golf)
POINT - Research shows that neuroplasticity and the ability of the brain to recover function after damage differs depending on several factors, such as age.
EXPLAIN - The brain tends to lose neuroplasticity with age.
EVIDENCE - Psychologists found patient EB who had almost all of her LH removed after discovering a tumour at age 3, with all her linguistic abilities disappearing. By age 17, the RH was found to compensate for the loss, as her brain activity was almost identical to the activity in normal controls.
LINK - This demonstrates that young people can recover function even after extensive damage to the brain, but it’s highly unlikely that an older patient could recover from such extensive damage.
COUNTER - However, psychologists found evidence of neural changes (reduce motor cortex activity in the novice group) in participants aged 40-60 following 40 hours of golf training. This suggests that plasticity may be a life-long ability.
Outline research into functional recovery (neuronal unmasking)
- Psychologist Wall found that the brain restructures itself by recruiting unused neural pathways.
- The brain contains many dormant neural connections. When healthy neural connections are damaged, these previously dormant synapses activate and form new connections to compensate for the damaged ones.
