week 6 brain

• Neuroscience is an essential part of modern psychology
• How behaviour is related to the nervous system

  • Behaviour is initiated by the nervous system
  • Behaviour is the thread which ties all domains of Psychology together
  • Dysfunctional behaviour
• Brain studies are an important part of neuroscience
• Brain study case studies

  • Phineas Gage
  • Louis Victor Leborgne "Tan"
  • Auguste Deter
  • HM
• These are all case-studies, not examples of experimental brain lesions. Post-mortem dissection often carried out in such cases.
• Phineas Gage (1848)


  • Iron rod driven through his head
  • Much of left frontal lobe of brain destroyed: 'the balance between his intellectual faculties and animal propensities seems to have been destroyed'
  • Not aggressive, sexually deviant or a drifter
  • 'conceived a great fondness for pets, and souvenirs, especially for children, horses and dogs'
• Auguste Deter


  • Progressive cognitive impairment, hallucinations, disorientation, paranoia and psychosocial impairment
  • Autopsy revealed arteriosclerotic changes, plaques, neurofibrillary tangles
  • Condition was named after her Dr, Alois Alzheimer
• Disciplines concerned with the brain in the 20th century

  • Neuropsychology – development of behavioural principles
  • Medicine – treatments, e.g. brain tumours, epilepsy, schizophrenia
• Karl Lashley 'Mass Action' (1951)


  • Biological psychologist; found that rats trained to obtain food rewards in mazes retained memories even after progressive brain lesions
  • Concluded that memories were not localised, but distributed throughout the brain
  • Developed the principle of 'mass action'– amount of memory loss proportionate to the amount of brain tissue loss
• Wilder Penfield and the 'Montreal Procedure' (1954)

  • Pioneering neurosurgeon: used electrical brain stimulation in awake patients
  • Produced 'vivid memories', smell, auditory and déjà vu experiences
  • Results consistent with localisation of brain function
• Methods of modern neuroscience

  • Histology
  • Experimental ablation
  • EEG
  • Imaging (CT, MRI, PET, fMRI)
• Histology


  1. Visualise particular brain region

  2. Fixation, sectioning and staining of the brain + microscopy

  3. Identify, quantify and localise cells (e.g. using a particular neurotransmitter or receptor)

  4. Tracing neural connections

  5. Efferent neurons via anterograde labelling

  6. Afferent neurons via retrograde labelling

  7. Establish the wiring diagram of the brain
• Experimental ablation


  1. Stereotaxic surgery

  2. Brain tissue is destroyed, and alterations in behaviour observed (lesion studies)

  3. Allows identification of neural circuits and localisation of behaviour
• Stereotaxic surgery


  • Stereotaxic atlas help researchers locate areas of the brain through images and software etc.
  • Stereotaxic apparatus - device maintains skull in proper orientation and can also be used on humans eg, to reduce symptoms of Parkinson's
• Lesion studies


  • Alterations in brain function are inferred
  • Behavioural results of naturally occurring lesions (eg, from accidental injuries or strokes) can also be studied in human participants
  • Rationale - function of an area of the brain can be inferred from the behaviours that are affected after damage to the area
  • Interpreting results is challenging because all regions of the brain are interconnected
• How are lesions created?

  1. Electrical stimulation

  2. Chemical stimulation (excitotoxic lesions)

  3. Sham lesions - insert electrode into brain but don't turn electrode on
• Measuring electrical activity


  • Chronically implanted - over extended period of time after animal recovers from surgery
  • Acutely implanted - relatively short period of time during which animal is kept anesthetised
  • Using microelectrodes: single-unit recordings based on stereotaxic coordinates
  • Using macroelectrodes: scalp recordings e.g. EEG/MEG - represent activity of many neurons
• Studying the structure of the brain

  • CT: Computerised Tomography
  • MRI: Magnetic Resonance Imaging
• CT: Computerised Tomography


  • Measures x-rays passed through brain
  • Used to image progressive 'slices' through tissues of the body, including the brain and skull
• MRI: Magnetic Resonance Imaging


  • Measures magnetic field passed through brain
  • Different molecules in brain have different frequencies eg, grey and white matter (density)
  • Distinguish between regions of grey and white matter so major fibre bundles can be seen
  • More detailed than CT scan
• Measuring metabolic activity


  • PET: Positron Emission Tomography
  • SPECT: Single Positron Emission Computerised Tomography
  • fMRI: functional Magnetic Resonance imaging
• PET: Positron Emission Tomography

  • Receive radioactive injection (2-DG)
  • When decay - emit particles called positrons which meet nearby electrons
  • Sensors around individuals head allow us to trace the location of the emission, which are plotted onto a computer image (shows us activity levels of different regions of the brain)
  • Uptaken but not metabolised
• fMRI: functional Magnetic Resonance imaging

  • Uses magnetic fields to detect oxygen levels in blood
  • Deoxygenated haemoglobin is more magnetic than oxygenated haemoglobin
  • Brain activity requires oxygen
  • Identifies brain activity by detecting changes in cerebral blood flow
• fMRI is used to examine brain activity during psychological tests, and identify the brain area which 'lights up' showing greater blood flow, to conclude that that area is associated with that cognitive activity
• Optical dynamic laser/electron microscopy

  • Uses light from lasers
  • Precision images of cellular processes and metabolism
  • Real Time dynamic images
  • In-vivo
  • 3 dimensional images
  • Limited to animal studies
  • Extremely time consuming
• The brain has been understood as the physical location of psychological phenomena since the late 16th century, and all of psychology (learning, memory, personality, psychomotor performance, motivation, emotion, mental health) is mediated by the brain
• Measuring neural activity: EEG


  1. Brain activity can be detected by measuring voltage fluctuations within neurons

  2. EEG, combined with eye-movement (electro-oculogram EOG ) and muscle tension (electromyogram EMG) measures can be combined to measure sleep – polysomnography (PSG)
• EEG sleep stages


  • Stage N1: drowsiness not quite fully awake
  • Stage N2: 'true' sleep, but light (spindles)
  • Stages N3: 'deep sleep'
  • REM: Rapid Eye - Movement Sleep
• Polysomnogram (PSG) can be used to measure sleep onset and REM sleep
• PSG v subjective experience (Adam, Tomeny and Oswald, 1986)

  • In general, people over-estimate Sleep Latency (we think it takes longer to get to sleep than it really does)
  • In general, people underestimate Total Sleep Time (we think our sleep is shorter than it really is)
• Borkovec et al (1981)


  • Compared the sleep of 25 insomniacs and 10 good sleepers
  • Each woken up in the 5th minute of first episode of Stage 2 (N2)
  • Most good sleepers said "asleep"; most insomniacs said "awake"
  • Despite identical electrophysiology, people "experience" their sleep differently
  • Sleep onset is an experiential, as well as an electrophysiological phenomenon
• Knowledge of neural activity is not always relevant to explaining experiential elements of psychology, such as intelligence, inter-personal relationships, mental illness, and consciousness
• The problem of mind and body remains unresolved even in the context of neuroscience, as neuroscience cannot fully explain conscious experience
• Neuroscience is founded on objective measurement, but much of psychology is concerned with people's subjective experience, which cannot be fully captured by objective measures
• Psychological science will continue to develop alongside neuroscience, but there remains more to 'psychology' than just brain function