Hemispheric Lateralisation

• What is hemispheric lateralisation?

  2 halves (hemispheres) of the brain are functionally different and that certain mental processes and behaviours are mainly controlled by one hemisphere rather than the other
• How does hemispheric lateralisation differ from localisation?

  Lateralisation refers to hemisphere dominance, localisation to specific brain areas
• What is split-brain research?

  Studies on patients with surgically separated hemispheres due to epilepsy to reduce their severity
• Why do neuroscientists study split-brain patients?

  To test lateral functions of the brain in isolation
• What are the two main centres for language in the brain?

  Broca's area and Wernicke's area
• In which hemisphere are Broca's and Wernicke's areas located and in what regions ?

  Both are located in the left hemisphere

  Broca= Left frontal lobe

  Wernicke= Left Temporal lobe
• What does the right hemisphere contribute to language?

  Emotional context to verbal communication
• What is contralateral wiring in the brain?

  Each hemisphere controls opposite body sides
• How does vision demonstrate both contralateral and ipsilateral wiring?

  Each eye connects to both hemispheres and receives light for depth perception
• What is the corpus callosum's role in the brain?

  Connects the left and right hemispheres
• What happens during a split-brain operation?

  The corpus callosum is severed to reduce seizures
• What was the main finding of Sperry's research on split-brain patients?

  Each hemisphere processes information independently

  Certain functions are lateralised and support the view that the LH Is verbal and the RH is ‘silent’ but emotional
• If an object is shown to the LVF of a split-brain patient, what can they do?

  They can select a matching object with their left hand
• What emotional response occurs when a pinup picture is shown to the RVF?

  Participants may giggle but report seeing nothing
• What does the research by Gereon Fink et al. (1996) suggest about hemispheric processing?

  Visual processing= hemispheric lateralisation is a feature of the connected brain as well as the split brain
• What research did Fink et al carry out?

  Used PET Scans to identify which brain areas were active during visual processing tasks

  • when ppts with connected brains were asked to attend to wider elements of the image regions of the RH were more active
  • When required to focus on finer details, the specific areas of the LH dominate
• What is neural plasticity in relation to brain function?

  Non-specialised areas can take over functions after damage
• What did Gazzaniga's research supporting split brain research find about split-brain participants?

  They performed better on certain tasks than connected controls

  • they were faster at identifying the odd one out in similar objects
• What is a limitation of Sperry's research regarding control groups?

  Control group participants did not have epilepsy

  = Causal relationships hard to establish, any differences observed may have been the result of epilepsy rather than the split brain
• What ethical considerations are raised by Sperry's research?

  Ppts consented and the operation was not performed for the purpose of the research= ppts not deliberately harmed

  HOWEVER, the trauma from the operation might mean that ppts did not later fully understand the implications of what they had agreed to- they were subjected to repeated testing over a lengthy period and this may have been stressful
• What are the key terms related to hemispheric lateralisation?

  • Hemispheric lateralisation: Functional differences between hemispheres
  • Split-brain research: Studies on surgically separated hemispheres
• What are the strengths and weaknesses of lateralisation in brain function?

  Strengths:

  • Enables simultaneous task performance
  • Supports efficient processing of information

  
  

  Weaknesses:

  • May not indicate a dominant side for personality
  • Can lead to misconceptions about brain function
• What are the implications of split-brain research findings?

  • Supports the idea of lateralised functions
  • Highlights differences in processing between hemispheres
  • Suggests limitations in communication between hemispheres