Biopsychology

• Parts of the brain

  Frontal lobe

  Parietal lobe

  Occipital lobe

  Temporal lobe

  (Cerebellum)
• Frontal lobe

  Motor cortex - location for awareness of what we are doing within our environment (consciousness) and responsible for generation of some voluntary motor movements, such as walking or running
• Parietal lobe

  Somatosensory cortex - location for sensory information from the skin
• Occipital lobe

  Visual cortex - location for visual information
• Temporal lobe

  Auditory cortex - location for auditory ability which analyses speech-based information (language comprehension)
• Symptom of damaged frontal lobe

  Loss of control of fine movements
• Symptom of damaged temporal lobe

  • Unable to understand a question
  • Impairment in ability to group meaning of spoken words (Wernike's aphasia)
• Symptom of damaged parietal lobe

  • Difficulty identifying a sensation's location and type
  • Difficulty recognising objects by touch
  • Lack of awareness of own body, limbs and positioning in space
• Symptom of damaged occipital lobe

  Cannot see even though the eyes themselves are functioning normally - cortical blindness (some people with cortical blindness are unaware they cannot see)
• Wernike's area

  In the left temporal lobe - language comprehension
• Broca's area

  In the left frontal lobe - speech production
• Cerebellum

  • Receives information from sensory systems, spinal cord and other parts of the brain - regulates motor movements
  • Coordinates voluntary motor movements, such as posture, balance, coordination and speech
• Localisation of function

  Theory that there are specific areas of the cerebral cortex associated with particular cognitive functions.

  • Argued for by Broca and Wernike due to their research in brain damage and post-mortems
  • Phineas Gage case study
  • Prior to this (19th century), the brain was considered to work in a holistic way
• Phineas Gage (1823-1860)

  Iron tamping pole went through his head when he was fixing a railroad

  • Led to a personality change where he became more irritable and rude
  • Dr Bigelow thought there was no localisation and believed that the rest of Phineas' brain had compensated for the parts destroyed in the accident
  • Dr Harlow believed that there was localisation in the brain and that areas involved in planning, reasoning and control had been damaged
• Peterson (1958)

  • Used brain scans to demonstrate how Wernike's area was active during a listening task and Broca's area was active during a reading task
  • Suggests that listening is localised in Wernike's area and reading is localised in Broca's area - supported by evidence from fMRI and ERP scans
• Plasticity application

  • Could be applied to neurorehabilitation where physical therapy is used with brain-damaged patients to help recover lost functions
  • Lashley's law of equipotentiality suggests that surviving brain circuits work together to achieve the same neurological action
• Completeness - higher cognitive functions are not localised

  • Lashley (1950) suggests that the basic motor and sensory functions were localised but higher mental functions were not
  • Claimed that intact areas of the cortex could take over responsibility for specific cognitive functions following injury to the area normally responsible for that function
  • This view suggests that the effects of damage to the brain would be determined by the extent rather than the localisation of damage
• Phineas Gage case study for localisation of the brain

  • Iron tamping pole went through his head
  • Before the accident, he had been kind and reserved but after, his personality changed to being boisterous, rude and grossly blasphemous
  • Damasio et al found that his frontal lobe had been damaged
  • This suggests that personality and emotions may have been localised to the frontal lobe
  • However, does not account for environmental factors such as loss of job or feelings about accident and excruciating pain rather than actual localisation of the brain - unique - low generalisability
• Functional Magnetic Resonance Imaging (fMRI)

  • Works by detecting changes in both blood oxygenation and flow that occurs as a result of neural activity in specific parts of the brain
  • When a brain area is more active, it consumes more oxygen and, to meet this increased demand, blood flow is directed to the active area (haemodynamic response)
  • Produces 3D images showing which parts of the brain are involved in a particular mental process and this had important implications for our understanding of localisation of function
• Strengths of fMRI

  • Does not rely on use of radiation, unlike other scanning techniques, such as PET
  • Is virtually risk-free, non-invasive and straightforward to use - if administered correctly
  • Produces images that have very high spatial resolution, depicting detail by the millimetre, and providing a clear picture of how the brain is localised - means it can safely provide a clear picture of brain activity
• Limitations of fMRI

  • Expensive compared to other neuroimaging techniques
  • Poor temporal resolution as there is around a 5 second time-lag behind the image on screen and the initial firing of neuronal activity - may not represent moment to moment brain activity
• Electroencephalogram (EEG)

  • Measures electrical activity within the brain via electrodes that are fixed to an individual's scalp using a skull cap
  • The scan recording represents the brainwave patterns that are generated from the action of thousands of neurons, providing an overall account of brain activity
  • Often used by clinicians as a diagnostic toll as unusual arrhythmic patterns of activity may indicate neurological abnormalities such as epilepsy, tumours or some sleep disorders
• Strengths of EEGs

  • Has been useful in studying the stages of sleep and in the diagnosis of conditions such as epilepsy
  • Has extremely high temporal resolution - can accurately detect brain activity at a resolution of a single millisecond - shows real-world usefulness of this technique
• Limitations of EEGs

  • The generalised nature of the information received
  • EEG signal is not useful pinpointing the exact source of neural activity - does not allow researchers to distinguish between activities originating in different but adjacent locations
• Event-related potentials (ERPs)

  • Isolated neural responses associated with specific sensory, cognitive and motor events that are averaged statistically - all extraneous brain activity from original EEG recording is filtered out leaving only those responses that relate to the specific thing being studied
  • Specifically types of brainwave that are triggered by particular events
  • Research has revealed many different forms of ERP and how those are linked to cognitive processes such as attention and perception
• Strengths of ERPs

  • Partly addresses limitations of EEGs
  • Bring much more specificity to the measurement of neural processes that could ever be achieved using raw EEG data
  • Excellent temporal resolution, especially when compared to neuroimaging techniques such as fMRI - means ERPs are frequently used to measure cognitive functions and deficits such as the allocation of attentional resources and the maintenance of working memory
• Limitations of ERPs

  • Lack of standardisation in ERP methodology between different research studies which makes it difficult to confirm findings
  • In order to establish pure data in ERP studies, background 'noise' and extraneous material must be completely eliminated - not always easy to achieve
• Post-mortem examinations

  • Involves analysis of a person's brain following their death
  • Likely conducted on individuals who had a rare disorder and experienced unusual deficits in cognitive processes or behaviour during their lifetime
  • Areas of damage examined after death as a means of establishing the likely cause of the affliction the person experienced - may involve comparison with a neurotypical brain in order to ascertain the extent of difference
• Strengths of post-mortems

  • Was vital in providing a foundation for early understanding of key processes in the brain
  • Broca and Wernike both relied on post-mortems in establishing links between language and behaviour decades before neuroimaging became a possibility
  • Also used to study HM's brain to identify areas of damage, which could be associated with his memory deficits - they continue to provide useful information
• Hemispheric lateralisation

  The fact that the same mental processes in the brain are mainly specialised to either the left or right hemisphere
• Split-brain research

  Research that studies individuals who have been subjected to the surgical separation of the 2 hemispheres of the brain as a result of severing the corpus callosum
• Corpus callosum

  A bundle of nerve fibres which joins two halves of the brain
• Sperry (1968)

  • Quasi-experiment involving a unique group of 11 individuals who had all undergone a commissurotomy (cutting the corpus callosum and other tissues connecting the 2 hemispheres down the middle to separate the hemispheres and control frequent and severe epileptic seizures)
  • Meant that for these patients, the main communication line between the 2 hemispheres was removed, allowing Sperry to see the extent to which the 2 hemispheres were specialised for certain functions
• Sperry conclusions

  • The left hemisphere was the primary hemisphere for the processing of language - understanding
  • The right hemisphere was able to recognise words, make mental associations, process emotional reactions and solve simple arithmetic - better than the left hemisphere at spatial skills
• Plasticity

  The brain's tendency to change and adapt as a result of experience and new learning - generally involves the growth of new connections
• Functional recovery

  A form of plasticity - following damage through trauma, the brain's ability to redistribute or transfer functions usually performed by damaged areas to other undamaged areas
• Plasticity AO1

  • During infancy, brain experiences rapid growth in the number of synaptic connections it has - twice as many as there are in the adult brain
  • Cognitive pruning happens where unused connections are deleted and frequently used connections are strengthened in the process
  • Bridging occurs where new links are made between neurons - shows brain in a continual state of change from growth in early years to change and refinement in adulthood as we learn and experience
  • However, can be negative (e.g. prolonged drug use leading to poorer cognitive functioning)
• Functional recovery AO1

  • Following physical injury or other forms of trauma, unaffected areas are sometimes able to adapt or compensate for those areas that are damaged - an example of neural plasticity
  • Can happen quickly after trauma (spontaneous recovery) and then slow down after several weeks or months
  • The brain is able to rewire and reorganise itself by forming new synaptic connections close to the area of damage
  • Secondary neural pathways that would not typically be used to carry out certain functions are 'unmasked' to enable functioning to continue - supported by structural changes
• Structural changes that support functional recovery

  • Axon sprouting
  • Denervation supersensitivity
  • Recruitment of homologous areas
• Axon sprouting

  New nerve endings grow and connect with undamaged areas