Hemispheric lateralisation and split-brain research

• What is hemispheric lateralisation?


  The idea that the two halves of the brain are functionally different.
• How does hemispheric lateralisation relate to mental processes?


  Certain mental processes and behaviours are mainly controlled by one hemisphere rather than the other.
• What is an example of a function that is localised and lateralised in the brain?


  Language.
• What is split-brain research?


  A series of studies involving people with epilepsy who had their brain hemispheres surgically separated.
• Why was split-brain research initiated?


  To reduce the severity of epilepsy in patients.
• What does split-brain research enable researchers to do?


  Test lateral functions of the brain in isolation.
• What happens when two words are presented simultaneously in split-brain research?


  • One word is presented on the left side of the visual field.
  • The other word is presented on the right side of the visual field.
• What does the term "localisation" refer to in the context of brain functions?


  It refers to the fact that some functions are governed by very specific areas in the brain.
• What is meant by "hemispheric lateralisation"?


  It means that the brain has two sides, called hemispheres, which govern different functions.
• In which areas of the brain are vision functions localised?

  The visual area is located in the left and right occipital hemispheres.
• Where are the two main centres for language located in the brain?

  Broca's area is in the left frontal lobe and Wernicke's area is in the left temporal lobe.
• How does the right hemisphere contribute to language?


  The right hemisphere can produce rudimentary words and phrases and contributes emotional context.
• What is the suggested role of the left hemisphere compared to the right hemisphere in language processing?


  The left hemisphere is considered the analyser while the right hemisphere is the synthesiser.
• Are many functions in the brain lateralised?


  No, many functions such as vision, motor, and somatosensory areas appear in both hemispheres.
• What is meant by "contralateral wiring" in the brain?


  It means that the right hemisphere controls movement on the left side of the body and vice versa.
• How does the visual processing differ between the left and right visual fields?


  The left visual field is connected to the right hemisphere, while the right visual field is connected to the left hemisphere.
• What is the significance of the arrangement of visual input from both eyes?


  It enables the visual areas to compare perspectives from each eye and aids depth perception.
• How does auditory input relate to hemispheric lateralisation?


  There is a similar arrangement for auditory input, where disparity from two inputs helps locate the source of sounds.
• When a neuron receives enough excitatory input, it will depolarize, meaning its membrane potential changes from -65 mV to +30 mV. When this happens, voltage-gated Na+ channels open up, allowing Na+ ions to rush into the cell. This influx of positive charges further increases the membrane potential until it reaches about +40 mV.
• What is one strength of research on lateralisation in the connected brain?


  It shows that the two hemispheres process information differently.
• What did Gereon Fink et al. (1996) use to identify active brain areas during a visual processing task?


  They used PET scans.
• In the study by Gereon Fink et al. (1996), which hemisphere was more active when participants focused on global elements of an image?


  The right hemisphere (RH) was more active.
• What does the activation of the right hemisphere during global processing suggest about hemispheric lateralisation?


  It suggests that hemispheric lateralisation is present in connected brains as well.
• When participants were required to focus on finer details, which hemisphere tended to dominate?


  The left hemisphere (LH) tended to dominate.
• What are the implications of hemispheric lateralisation in visual processing for connected brains?

  • Hemispheric lateralisation occurs in connected brains.
  • Different hemispheres process different aspects of visual information.
  • Right hemisphere is more active for global processing.
  • Left hemisphere is more active for detailed processing.
• What is the common belief about the left hemisphere (LH) and right hemisphere (RH) of the brain?


  The LH is thought to be the analyser and the RH the synthesiser.
• What does research suggest about brain dominance and personality?


  Research suggests that people do not have a dominant side of their brain that creates a different personality.
• Who conducted a study analyzing brain scans from over 1000 people, and in what year?

  Jared Nielsen et al. conducted the study in 2013.
• What did the study by Jared Nielsen et al. find regarding brain hemispheres and tasks?


  The study found that people used certain hemispheres for certain tasks, providing evidence for lateralisation.
• What does the absence of evidence for a dominant side of the brain imply?


  It suggests that the notion of right- or left-brained people is incorrect.
• What is the difference between lateralisation and plasticity in brain function?

  • Lateralisation: Enables two tasks to be performed simultaneously with greater efficiency.
  • Plasticity: Allows non-specialised areas to take over functions after damage.
• How did Lesley Rogers et al. (2004) demonstrate the concept of lateralisation in chickens?


  They showed that lateralised chickens could find food while watching for predators, unlike 'normal' chickens.
• What can happen to language function following brain damage, according to Holland et al. (1996)?


  Language function can literally 'switch sides' to the opposite hemisphere.
• What are the adaptive advantages of lateralisation and plasticity in brain function?

  • Lateralisation: Increases efficiency in performing simultaneous tasks.
  • Plasticity: Allows recovery and reallocation of functions after brain damage.
• What recent research supports the concept of split-brain functionality?


  Recent split-brain research shows that split-brain participants perform better on certain tasks.
• What was the sample size in the study conducted by Jared Nielsen et al.?


  The sample size was over 1000 people.
• What is a 'split-brain' operation?


  It involves severing the connections between the right hemisphere (RH) and left hemisphere (LH), mainly the corpus callosum.
• Why is a split-brain operation performed?


  To reduce epilepsy by preventing excessive electrical activity from traveling between hemispheres.
• What happens during an epileptic seizure in the brain?


  The brain experiences excessive electrical activity which travels from one hemisphere to the other.
• What does split-brain research study?


  It studies how the hemispheres function when they can’t communicate with each other.