Hemispheric lateralisation and split brain research

• Hemispheric lateralisation is the idea that the two halves of the brain are functionally different and the certain mental processes and behaviours are mainly controlled by one hemisphere rather than the other.
• split brain research is a series of studies which began in the 1960s involving people with epilepsy who had experienced a surgical separation of the hemispheres of their brain to reduce the severity of their epilepsy. this enabled researchers to test lateral functions of the brain in isolation.
• Where are Broca's and Wernicke's areas located?

  Broca's area is in the left frontal lobe
• What does it mean that language is lateralised?

  It is performed by one hemisphere
• What is the role of the right hemisphere in language?

  It produces rudimentary words and emotional context
• How do the left and right hemispheres differ in language processing?

  LH is the analyser; RH is the synthesiser
• Which functions are not lateralised in the brain?

  Vision, motor, and somatosensory areas
• What is contralateral wiring in the brain?

  RH controls left body movement; LH controls right
• How does vision work in terms of lateralisation?

  It is both contralateral and ipsilateral
• Which visual fields connect to the right and left hemispheres?

  LVF connects to RH; RVF connects to LH
• What is the benefit of having both eyes connected to both hemispheres?

  It aids depth perception through comparison
• How does auditory input function in the brain?

  It helps locate sound sources through disparity
• What is the relationship between visual and auditory processing in the brain?

  Both involve comparing inputs for perception
• What is the function of Broca's area?

  It is responsible for speech production
• What is the function of Wernicke's area?

  It is responsible for language comprehension
• What does the left hemisphere dominate in most people?

  Language processing
• How does the right hemisphere contribute to language?

  By adding emotional tone
• How does the brain's motor area control body movement?

  Through contralateral wiring
• How do both eyes contribute to depth perception?

  By providing slightly different perspectives
• What is the role of auditory processing in locating sounds?

  It compares inputs from both ears
• What does a 'split-brain' operation involve?

  Severing connections between the RH and LH
• Why is a split-brain operation performed?

  To reduce epilepsy
• What happens during an epileptic seizure?

  The brain experiences excessive electrical activity
• How does severing the corpus callosum affect brain function?

  It prevents communication between hemispheres
• What is the focus of split-brain research?

  • Studies how hemispheres function independently
  • Investigates communication loss between hemispheres
  • Examines effects on speech and vision
• Who devised a system to study split-brain patients?

  Roger Sperry
• What was the setup used in Sperry's study?

  An image projected to RV and LVF
• What does RVF stand for in the context of the study?

  Right Visual Field
• What does LVF stand for in the context of the study?

  Left Visual Field
• What happens in a normal brain when an image is presented?

  The corpus callosum shares information between hemispheres
• What could participants describe when an object was shown to their RVF?

  They could describe what was seen
• What was the response when an object was shown to the LVF?

  Participants said there was 'nothing there'
• Why could participants not label objects shown to the LVF?

  Messages from the RH can't reach LH
• What could participants do with objects shown to the LVF?

  Select a matching object using their left hand
• What was the emotional reaction to a pinup picture shown to the LVF?

  Participants giggled but reported seeing nothing
• What conclusions can be drawn from the split-brain research findings?

  • Functions are lateralized in the brain
  • LH is verbal; RH is emotional but 'silent'
  • Communication loss affects perception and response