Split brain research into hemispheric lateralisation Flashcards
What is hemispheric lateralisation?
The ability to produce and understand language is controlled by the left hemisphere of the brain - the specialised areas for language are in one rather than both hemispheres of the brain
What was Sperry’s research into split brain?
His RPS’s were a group of individuals who had undergone the same surgical procedure - a commissurotomy
What is a commissurotomy?
Where the corpus callosum and other tissue that connects the two hemispheres were cut down the middle in order to control seizures meaning that for these split brain patients their main communication lines were cut off - allowing Sperry to see to which extent the two hemispheres were specialised and if they performed tasks independent of eachother
What was Sperry’s procedure?
An image or a word is presented to the patients right visual field (processed by the left hemisphere) in the normal brain the corpus collosum would share the information between both hemispheres giving a complete picture. Presenting the image to one hemisphere meant that info cant be conveyed from that hemisphere to the other
What was the ‘describe what you see finding’?
When an object was shown to a patients right visual field they could easy describe it but when shown to left visual field they claimed there was no object present
What caused the patients inability to describe objects?
Language is processed in the left hemisphere but the langug3 centre is in the left hemisphere. In a normal brain messages from the right could be relayed to the language centre in the left hemisphere
What was the recognition by touch finding?
Although patients couldn’t attach verbal labels to objects they were able to select the matching object from a bag of objects using their left hand (understand the object using the right hemisphere and select the object accordingly) . The objects were behind a screen so they couldn’t be seen.
What was the composite word findings?
Two words were presented simultaneously one on either side of the visual field (e.g. key on right and ring on left) - the patient would write with their left hand the word ring and say the word key…….
.What was the matching faces findings?
The right hemisphere appeared dominant in terms of recognising faces - when asked to match the face from a series of other places the picture processed by the right hemisphere was consistently selected whilst the picture presented to the left hemisphere was consistently ignored. When a composite picture made up of two different ones was presented the left hem dominated in terms of description whereas the right hemisphere dominated in terms of choosing a matching picture
