Biopsychology

• Brain

  The limbic system is involved in the processing of emotion and memory. It is made up of many different structures, but the main ones are the hippocampus, the amygdala and the hypothalamus.
• Localisation of the brain

  Sperry (1968) investigated the lateralisation of brain function in split-brain patients

  
  

  Method:

  • A natural experiment (participants had already had their corpus callosum severed due to severe epilepsy).
  • There were 11 participants (10 men and 1 woman).
  • Participants took a range of visual and tactile tests.
  • In the visual tests, images were flashed into their left or right visual field for a 1/10 of a second and they were asked to name, describe or draw the objects.
  • In the tactile test, objects were placed in either their left or right hand behind a screen.
• Localisation of the brain

  Sperry's split-brain research

  Findings

  • Information presented to the right visual field could be described in speech and writing. If the same information was presented to the left visual field, the participant could not remember seeing anything and could not describe it.
  • Objects placed in the right hand could be described in speech or writing. If the same objects were placed in the left-hand, participants guessed and sometimes seemed unaware they were holding anything.
• localisation of the brain

  Sperry's split-brain research

  Conclusion:

  • in split-brain patients, perception and memory are independent
  • info from one visual field or hand only passes to one hemisphere and cannot be exchanged
  • if info is in the right hemisphere only (from the left visual field) then the individual cannot respond in speech or writing because language is processed in the left hemisphere
  • info from one visual field or hand is remembered only by that hemisphere and cannot be accessed by the other
• Localisation of the brain

  Sperry's split-brain research

  EVAL

  Strengths

  • case study - detailed qualitative data about each participant - did lots of tests which increases the validity of the research
  • highly controlled and standardised environment - high internal validity

  Weaknesses

  • small sample size - only 11 patients - unrepresentative and difficult to generalise
  • individual differences - eg time since the patient's surgeries - may be different parts of their brains that are affected by the hemispheric disconnection
• Localisation of the brain

  Sperry

  some people with epilepsy undergo surgery where their corpus callosum is severed - this is a collection of fibres that connect the two hemispheres of the brain together

  Sperry's experiment was a natural experiment because participants already had their corpus callosum's severed due to epilepsy

  • the IV varied naturally
• Localisation of function

  Specific parts of the brain

  Visual cortex: in the occipital lobe

  • processes visual information
  • the right eye sends information to the left visual cortex, and vice-versa.
  • damage to left hemisphere = blindness in the right visual field of BOTH eyes
  • main visual centre = Area V1 - necessary for visual perception - any damage to this leads to no vision of any kind - eg conscious vision or visual imagery while awake or in dreams
• Localisation of function

  Specific parts of the brain - language centres

  • language is an example of a cognitive ability which is both localised and lateralised (to the left hemisphere).

  Wernicke's area

  only the left hemisphere

  • helps with understanding speech
  • damage = Wenicke's/fluent aphasia - characterised by the use of nonsensical words (called syllogisms), no awareness of using incorrect words, but no issues with pronunciation and intonation. - their speech is fluent but has no meaning for atypical people
• Localisation of function

  Specific parts of the brain - language centres

  • language is an example of a cognitive ability which is both localised and lateralised (to the left hemisphere).

  Broca's area:

  only in the left hemisphere

  • deals with speech production
  • damage = Broca's aphasia - difficulty forming complete and understandable sentences, as well as failing to say words in the right order in a sentence and who they are directed towards - eg him, her, you, I - stuttering
• Localisation of function is the idea that different parts of the brain are responsible for different functions.
• Localisation of function

  Specific parts of the brain - language centres

  Broca's area:

  only in the left hemisphere

  deals with speech production

  
  

  Evidence - Case study of Victor Leborgne: Broca

  • an educated man who suffered with epilepsy - he later lost the ablity to speak
  • post-mortem found a lesion on his left temporal lobe - area responsible for speech production

  EVAL:

  • case study - individual differences - generalisability
  • post-mortem - issues with establishing cause and effect
• Localisation of function

  Specific parts of the brain - hemispheric lateralisation

  • when a function seems to only be carried out by one hemisphere - either the right or left

  Fink et al

  • when participants were asked to identify small/ specific details of a picture, their left hemisphere was more active
  • when participants were asked to look at a picture more holistically, their right hemisphere was more active
  • shows that different hemispheres of the brain are localised for different things - left vs right - details vs overall patterns
• Localisation of function

  Visual cortex: in the occipital lobe

  Research evidence - Overgaard

  case study on a 31-year-old woman who experienced 'blindsight'

  she experienced headaches and CT scanning showed a haemorrhage in the left occipital lobe and after surgery her visual cortex was damaged leaving her cortically blind

  • in tests 3 weeks after operation when askes to detect a letter shown on a screen she could not identify the letter but she did report an 'awareness of something' despite seeing nothing
  • shows that there can be two types of vision: conscious and unconscious
• Localisation of function

  Somatosensory cortex

  in the parietal lobes in both hemispheres

  • perceives touch and other sensory info - sensitivity
  • the amount of neuronal connections needed dictates the amount of somatosensory cortex needed for that specific area of the body - eg face requires a larger proportion of the somatosensory cortex than other areas - higher level of sensitivity
• Localisation of function

  Auditory - in the temporal lobe

  one primary auditory cortex in each hemisphere

  • receives and processes sound info from both ears and transmits info about what the sound is and how far away it is
  • sound from the right ear primarily goes to the left hemisphere buts some is transmitted to the left primary auditory cortex too
  • damage doesn't lead to total deafness - but sounds like music that requires complex processing are not able to be heard
• Localisation of function

  Plasticity and Functional recovery

  Following a trauma such as a stroke or physical damage to the brain, unaffected areas are able to compensate for the injury by ‘taking over’ the functions of the damaged areas.

  Neural regeneration

  • growth of new neurons and connections to compensate for damaged areas - axonal sprouting, where new nerve endings grow to make connections with undamaged nerves; reformation of blood cells
  • neural reorganisation - functions that would be normally be localised are transferred to undamaged areas - eg case study of EB
• Localisation of function

  Plasticity and Functional recovery

  After damage to the brain, unaffected areas are able to compensate for the injury by ‘taking over’ the functions of the damaged areas.

  Evidence - case study of EB

  • 2 and a half year old boy EB had the majority of his left hemisphere removed due to a benign tumour - lost all speech capabilities
  • went into intensive rehabilitation and language started to improved at age 5 until there were no problems with language abilities 3 years after that

  example of plasticity and functional recovery
• Localisation of function 


  Factors affecting the likelihood of recovery

  Gender:

  Ratliffe et al

  325 patients with a brain trauma tested for their cognitive skills to rehabilitation

  • women had better performance in attention and in working memory tests and language tests
  • men had better performance in visual analytical skills
  • overall results suggested better recovery for women

  HOWEVER, the results did not account for performance pre-injury so we can't compare results before and after - makes it difficult to know the extent to which the brain has recovered to pre-trauma levels
• Plasticity


  The ability of the brain to change and adapt in response to experience
• Localisation of function

  Plasticity

  Maguire study

  
  

  1. Natural experiment

  2. Using an MRI scanner, researchers calculated the amount of grey matter in the brains of taxi drivers and a set of control participants

  • high amounts of grey matter in the posterior hippocampus - associated with the development of spatial and navigation bias

  
  

  shows the structure of the brain can change depending on the demands placed on it - plasticity
• Endocrine system


  System made up of glands that secrete hormones, or chemical messengers that create long-lasting effects all around the body
• Endocrine system

  Hormones

  Chemical messengers secreted into the blood stream that must bind to a receptor in order to send their signals
• Pituitary gland


  • Descends from the hypothalamus at the base of the brain and acts in close association with it
  • Messenger hormones control all the other glands in the endocrine system (although it mostly carries out instructions from the hypothalamus)
  • Secretes growth hormone, endorphins for pain relief, and a number of important hormones that regulate fluid levels in the body
• Thyroid gland


  • Located in the neck
  • Releases hormones that regulate growth, metabolism, and appetite
  • Thyroid disorders such as hyperthyroidism or Grave's disease can cause symptoms such as weight loss and agitation
• Endocrine system

  Adrenal glands

  • Located on top of the kidneys
  • Secrete hormones involved in the stress response, such as epinephrine (adrenaline) and norepinephrine (noradrenaline)
• Endocrine system

  Pancreas

  Secretes hormones that regulate blood sugar levels: insulin, which lowers levels, and glucagon, which raises them
• Endocrine system

  Gonads

  • Secrete sexual hormones, which are important in reproduction
  • Mediate both sexual motivation and behaviour
  • Female gonads are the ovaries which secrete oestrogens and progesterone
  • Male gonads are the testes that secrete androgens
• Neurons


  Neurons are nerve cells that process and respond to stimuli in our environment and communicate and send messages using electrical and chemical signals

  There are three main types of neuron:

  • Sensory neurons- carry messages from PNS to the CNS; carry messages to the CNS/brain about the environment by processing information from the senses.
  • Relay neurons- connect sensory neurons to motor and other relay neurons; carry messages from one part of the CNS to another.
  • Motor neurons- connect the CNS to effectors such as muscles/glands; helps organs and muscles function and move.
• Neuron


  Function

  Reflex arc: - burnt hand

  1. (PNS) sensory neurons recognise the pain in the hand and send messages to the relay neurones in the spinal cord
  2. (CNS) relay neurones in the spinal cord receive the sensory neuron's messages and pass these messages to the motor neurons with instructions for the hand to move
  3. (PNS) motor neurons receive these messages and cues the effectors in the arm to move to stop the feeling of pain - brings about a response - the hand moves as a result
• Neuron

  Structure: name the neuron

  A) sensory

  B) relay

  C) motor

  
• Neurons - structure and function

  Synaptic transmission

  1. an electrical impulse (action potential) moves down the axon of the presynaptic neuron until it reaches the axon terminal
  2. once it reaches the axon terminal the synaptic vesicles release neurotransmitters - electrical to chemical message
  3. these neurotransmitters diffuse across the synapse towards the post-synaptic neuron
  4. the neurotransmitters bind to the receptor sites in the post-synaptic neuron
  5. the post-synaptic neuron uses the process of summation to decide what to do next
• Neuron - structure and function

  Synaptic transmission - pt 2

  6. summation: if there are more excitatory neurotransmitters then an electrical impulse is generated - this is called excitatory postsynaptic potential

  7. summation: if there are more inhibitory neurotransmitters then no electrical impulse is generated - this is called inhibitory postsynaptic potential

  8. if there are any neurotransmitters left over in the synapse after summation then they will go back to the synaptic vesicles in the presynaptic neuron - this is called reuptake
• The endocrine system


  a series of glands which release chemicals called hormones throughout the body through the bloodstream and other bodily fluids - communicating messages to the organs in the body

  • slower than the nervous system - messages via bloodstream

  Pituitary gland - descends from the hypothalamus at the base of the brain - master gland - its messager hormones control and regulate the other glands

  Adrenal gland - on top of the kidneys - releases adrenaline - fight or flight response

  Testes - release testosterone

  Ovaries - release progesterone and oestrogen
• Fight or flight response 


  The sympathomedullary pathway - process

  1. the hypothalamus recognises that there is a threat and activates the sympathetic division of the autonomic nervous system
  2. this sympathetic division activates the adrenal glands, triggering the release of adrenaline
  3. the adrenaline travels through the endocrine system and noradrenaline goes to the brain
  4. this prompts physical changes - eg increased heart rate and blood flow, pupils dilate, reduced functioning of the digestive and immune systems
• Fight or flight 


  EVAL

  Male bias - Taylor (2006): females = 'tend and befriend' approach

  • tend to offspring and befriend other females - evolutionary
  • therefore fight or flight does not apply to female behaviour

  Oversimplified concept

  • freeze response - waiting and doing nothing rather than taking action

  reductionist - oversimplifies a complex process

  • reducing our response to threats to simply an interaction between the endocrine and nervous systems doesn't help us to fully understand the phenomenon of fear
• Biological rhythms


  Infradian rhythms last more than 24 hours.

  • for example, the menstrual cycle on average, takes place over 28 days.
• Biological rhythms



  Infradian rhythms last more than 24 hours.

  • eg the menstrual cycle lasts for 28 days

  McClintock and Stern

  women wiped a pad under their armpits and gave it to other woman who wiped this pad on their upper lip - containing 'odourless compounds'/ pheromones

  • if the woman received a pad from a woman who was at the beginning of her cycle, her menstrual cycle lengthened
  • if the woman received a pad from a woman who was at the end of her cycle, her menstrual cycle shortened

  shows that the menstrual cycle of a woman can be altered by communication via pheromones
• Biological rhythms

  Circadian rhythms - lasts within 24 hours

  • eg the sleep/wake cycle

  Siffre - French man in a cave with no natural light or cues to the time of day

  • stayed for 6 months - 179 days
  • his internal body clock settled into a sleep/wake cycle of about 25 to 30 hours
  • lost track of time - he thought he had stayed in the cave for 5 months rather than 6

  shows that natural light resources are vital for keeping individuals to a 24 hour cycle
• Biological rhythms

  Circadian - sleep wake cycle

  Superchiasmatic nucleus (SCN) = influential endogenous pacemaker - in the hypothalamus - affects production of melatonin - too much bright light disrupts melatonin production making it harder to sleep

  Endogenous pacemakers - internal body clock

  Ralph et al - genetically abnormal hamsters with a circadian cycle of 20 hours had their SCN removed and transplanted into hamsters without the abnormality (their circadian cycle was 24hrs)

  • "normal" hamsters' cycle changed to 20 hours
• Split-brain research


  Sperry

  Task 2:

  Participants were able to describe the items they had seen in the right visual field when asked

  When asked to describe what they saw in the left visual field, they were not able to do so

  • what they saw in the LVF is processed by the right hemisphere which cannot communicate with the left hemisphere which is responsible for speech - meaning they could not describe what they had seen in the LVF