The brain

• What is localisation?

  The idea that specific areas of the brain are associated and controlled by specific functions and behaviours
• What did Broca and Wernicke do?


  Discovered specific parts of the brain are associated with specific physical and psychological functions and different parts of the body
• What was the holistic theory and what caused that theory to shift?


  • Holistic theory - brain functions are not restricted to certain areas of the brain and that all parts of the brain are involved in all thinking and action processes
  • Phineas Gage changed that
• What happened to Phineas Gage and what was its impact?

  An iron rod went through his brain but he survived.

  The injury caused damage to his frontal lobe and limbic system - involved in emotional and behavioural processes

  Gage became rude, irritable, impatient and had a lack of restraint with anything that conflicted with his desires
• What is lateralisation?


  The idea that the two hemispheres of the brain have different functions and control different behaviours
• Identify different parts of the brain

  A) Precentral gyrus

  B) Central Sulcus

  C) Postcentral gyrus

  D) Parietal lobe

  E) Wernicke's area

  F) Occipital Lobe

  G) Cerebellum

  H) Spinal Cord

  I) Brain Stem

  J) Temporal Lobe

  K) Sylvian Fissure

  L) Frontal Lobe

  M) Broca's Area

  
• How is the cortex divided?


  It is subdivided into 4 lobes named after the bones they lie on
• What does the back of the frontal lobe control?


  Motor area controlling the voluntary movements in the body
• What does the front of both parietal lobes control?


  Somatosensory area that processes all sensory information from the skin.
• What is the valley separating the motor area and somatosensory area called?


  The central sulcus
• What does the back of the occipital lobe control?

  Visual area

  • Eyes send information from the right visual field to the left visual cortex and vice versa
  • Damage to the left hemisphere would mean blindness in parts of the right visual field in both eyes and vice versa
• Where is the language area of the brain located?


  Restricted to the left side of brain in most people
• What is Broca's area responsible for and where is it found?

  Broca's area is responsible for speech production

  It can be found in the left frontal lobe
• What is it called when there is damage to Broca's area?


  Broca's aphasia
• Where is Wernicke's area and what is its function?

  Found in the left temporal lobe

  Wernicke's area is responsible for speech comprehension
• What is it called when there is damage to Wernicke's area?


  Wernicke's aphasia
• What are the strengths of brain localisation?


  1. Brain scan evidence of localisation:

  • Wealth of evidence of localisation especially for language and memory, Petersen et al (1988) used brain scans and demonstrated Wernicke's area was active during listening and Broca's area was active during reading.
  • Tulving et al (1994) study on long-term memory showed that semantic and episodic memories are in different parts of the prefrontal cortex
• What are the strengths of brain localisation (cont)?

  2. Neurosurgical evidence:

  • Surgically removing/destroying areas of the brain to control behaviour was developed in the 1950s
  • Lobotomy (pioneered by Walter Freeman) was brutal but involved destroying the frontal lobe to control aggression
  • Neurosurgery is still used today in extreme cases of OCD and depression
• What are the weaknesses of brain localisation?


  1. Reductionist:

  • Some say this theory reduces complex human behaviours to a single brain region

  1. Does not take into account the brain's plasticity
  2. Does not take into account individual differences:

  • Harasty et al (1997) found that women had larger Broca's and Wernicke's areas than men which could account for their differences and greater use of language by the former
• What is brain plasticity and when can it occur?

  When does it peak?

  Brain changes throughout life and existing neural connections can change or new ones can be formed via learning at any time.

  It peaks by 3 years old according to Gopnick et al 1999
• What was originally thought about brain plasticity?


  All brain changes occurred in childhood only
• What is synaptic pruning?


  Neural connections which have not been used and thus strengthened are deleted
• What did the Maguire et al (2000) study and what was the outcome?


  • Studied the brains of London taxi drivers
  • They found that the cab drivers had a higher volume of grey matter in the posterior hippocampus (associated with development of spatial and navigational skills) than the matched control group
  • Cabbies take 'Knowledge' test which alters the structure of the brains of taxi drivers
• What did Draganski et al (2006) do and find?


  • They imaged the brains of medical students 3 months before and 3 months after their final exams
  • They found changes in the posterior hippocampus and parietal cortex
• What did Mechelli et al (2004) find?


  They found the parietal cortex in bilingual people was larger compared to the matched monolingual control group
• What is functional recovery?


  Functional recovery is when unaffected parts of the brain adapt and take over for the damaged parts after physical injury or trauma (e.g. stroke)
• What is it called when recovery occurs quickly?

  Spontaneous recovery
• What is needed when functional recovery slows down?


  Rehabilitation
• What does Doidge (2007) say?


  Brains can rewire and form new synaptic connections close to the damaged area
• How does the brain structurally change after trauma?

  1. Axonal sprouting
  2. Reformation of blood vessels
  3. Recruitment of homologous areas
• What is axonal sprouting?


  New routes are created around the broken area - new nerve endings grow that connect with other undamaged nerve cells (new neuronal pathway)
• What is the reformation of blood vessels?

  It supports and reinforces the new neuronal pathways
• What is a denervation supersensitivity?

  It occurs when the axons doing similar jobs become aroused at a higher level to compensate for the lost neuronal pathways. This can cause oversensitivity and pain
• What is a possible side effect of axonal sprouting?


  Denervation supersensitivity
• What is the recruitment of homologous areas?


  The recruitment of homologous areas refers to using the neuronal pathways of corresponding regions in the opposite hemisphere of the brain during a specific task or function.
• What are the strengths of brain plasticity and functional recovery?


  1. Practical application:

  • neurohabilitation, movement therapy, electrical stimulation of brain
• What are the weaknesses of brain plasticity and functional recovery?


  1. Negative plasticity:

  • Ability to rewire brain can have maladaptive behavioural consequences
  • Prolonged drug use shown to result in poorer cognitive functioning and increased risk of dementia (Medina et al 2007)
  • 60=80% of amputees have phantom limb syndrome
• What is the relationship between age and plasticity?


  • Plasticity reduces with age - harder to learn when older
  • There is a higher propensity for reorganisation of brain in childhood
  • Ladina Bezzola et al (2012) said 40 hours of golf training led to changes in neural representation of movement in pps 40-60
  • fMRI was used and researchers saw reduced motor cortex activity in novice golfers versus control group, suggesting there is more efficient neural representation after training - proves new neural connections are made and strengthened