Week 9; Split Brain Research Flashcards
Split Brain
A condition that occurs when the corpus callosum is surgically cut and the two hemispheres of the brain do not receive information directly from one another
When does Split Brain surgery Occur
- Very Rare
- In patients with intractable epilepsy
- Designed to stop the spread of neural activity from one hemisphere to the other
Impact of Split Brain Surgery
- Hemispheres operate independently to one another
- Essentially an individual has two separate brains within one body
- Sensory mechanisms, motor systems and memories no longer appear to exchange info
Michael Gazzaniga
Spent several decades conducting split brain research
Primary Visual Areas
- Located in occipital lobe at back of brain
- Receives visual sensory info travelling from eyes
- Visual world divided into left/ right visual field which is processed by opposite hemisphere
Contralateral Arrangement
Occurs due to crossing over of optic nerve fibres at optic chiasm
Research on Split Brain
- Patient shown two photos; a spoon on the left and a fork on the right
- When asked what he sees verbally, the response is controlled by the left hemisphere (fork)
- When asked to pick up the object shown in the picture with his left hand, person picks up spoon
Takeaways from Fork/Spoon Experiment
- Right hemisphere cannot verbalise the word spoon but can pick it up
Left Hemisphere
Dominant for Language
Right Hemisphere
Dominant for Spatial Relationships
Splitting the Brain and the conscious mind
- Splitting the brain splits the conscious mind
Challenges for Split Brain Patients
- Intermanual Conflict
- ‘Alien Hand’ Syndrome
Intermanual Conflict
Contradictory activities of left and right hands
- i.e. woman complained that when she went to select a dress with her right hand, her left hand reached for a different one
Alien Hand Syndrome
Patients often report their left hand as ‘having a mind of their own’
- A functional disentanglement between thought and action
Interpreter
- The left hemispheres propensity to construct a world that makes sense
Study on interpreter phenomenon
- Patient presented with different images flashing simultaneously on left/right side of screen
- Below screen, there was a row of other images
- Patient asked to point with each hand to a bottom image that most related to the image flashed on that side of screen above
Purpose on Interpreter Experiment
- To test the left hemispheres capacity to explain behaviour produced by the right hemisphere
Result of Study
- In one trial, a picture of a chicken claw was flashed to the left hemisphere and a picture of a snow scene was flashed to the right
- Left hemisphere pointed the right hand to a photo of a chicken head
- The right hemisphere pointed the left hand to a photo of a snow shovel
