Lateralisation split brain

• What is hemispheric lateralisation?

  • Some mental processes are specialised to either the left or right hemisphere.
  • The left hemisphere is often associated with language.
  • The right hemisphere is associated with other functions like object recognition.
• Who suggested that different hemispheres of the brain had specialisations in the early 1800s?

  Dax
• What did Dax study in his research?

  Patients who had lost speech due to brain damage
• What did Dax find regarding the location of brain damage in patients who lost speech?

  All had damage in the left hemisphere but not in the right
• What did Broca suggest about left hemispheric damage?

  It led to language difficulties
• What was the significance of damage in the right hemisphere according to Broca?

  It did not cause the same language issues
• How do the two hemispheres of the brain communicate?

  • They are connected via the corpus callosum.
  • The corpus callosum allows information to be sent from one hemisphere to the other.
• What treatment was developed for severe epilepsy involving the corpus callosum?

  A surgical procedure to cut the corpus callosum
• What are patients who have undergone the corpus callosum surgery known as?

  Split-brain patients
• What are the advantages of hemispheric lateralisation?

  • Lateralisation may enhance immune system functioning.
  • Lateralisation can change with age.
• What activity is suggested to illustrate hemispheric lateralisation?

  Drawing a lion with the left hand and an elephant with the right hand
• What is split-brain research?

  • It studies individuals who have had their brain hemispheres surgically separated.
  • This is done by severing the corpus callosum.
• Who conducted significant research on split-brain patients in 1967?

  Sperry and Gazzaniga
• Why did patients report seeing nothing when a picture of a cat was flashed to the left visual field?

  Because the information could not be processed by the right hemisphere
• What is a counterargument to the idea that language is restricted to the left hemisphere?

  • Gazzaniga suggested that old research does not support new findings.
  • Case studies like Patient J.W. show speech can develop in the right hemisphere.
• What did Patient J.W. demonstrate regarding hemispheric function?

  He developed the capacity to speak from the right hemisphere
• What are some limitations of split-brain research?

  • The split-brain procedure is rarely performed today.
  • Many studies have small sample sizes, leading to unreliable conclusions.
  • Confounding physical disorders may affect results.
• Why is the small sample size in split-brain research an issue?

  It can lead to unreliable conclusions
• What happens when results of split-brain studies fail to be replicated?

  Confounding physical disorders may only be identified later
• What is a potential exam question related to split-brain research?

  Briefly outline and evaluate research using split-brain patients to investigate hemispheric lateralisation of function (8 marks)