{"id":189,"date":"2023-02-17T22:37:16","date_gmt":"2023-02-17T22:37:16","guid":{"rendered":"https:\/\/content.one.lumenlearning.com\/introductiontopsychology\/chapter\/learn-it-split-brain-research\/"},"modified":"2025-11-05T04:12:30","modified_gmt":"2025-11-05T04:12:30","slug":"learn-it-split-brain-research","status":"publish","type":"chapter","link":"https:\/\/content.one.lumenlearning.com\/introductiontopsychology\/chapter\/learn-it-split-brain-research\/","title":{"raw":"Studying the Brain: Learn It 2\u2014Split Brain Research and Neuroplasticity","rendered":"Studying the Brain: Learn It 2\u2014Split Brain Research and Neuroplasticity"},"content":{"raw":"
<\/section>\r\n
<\/section>\r\n
<\/section>\r\n
\r\n

Split Brain Research<\/h2>\r\n

Recall that the two\u00a0hemispheres of the brain are connected by a thick band of neural fibers known as the corpus callosum<\/strong>, consisting of about 200 million axons. The corpus callosum allows the two hemispheres to communicate with each other and allows for information being processed on one side of the brain to be shared with the other side.\u00a0<\/span><\/p>\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"786\"]\"Illustrations Figure 1<\/strong>. (a, b) The corpus callosum connects the left and right hemispheres of the brain. (c) A scientist spreads this dissected sheep brain apart to show the corpus callosum between the hemispheres. (credit c: modification of work by Aaron Bornstein)[\/caption]\r\n\r\n

Normally, we are not aware of the different roles that our two hemispheres play in day-to-day functions, but there are people who come to know the capabilities and functions of their two hemispheres quite well.<\/p>\r\n

\r\n

split brain<\/h3>\r\n

There are instances in which people\u2014either because of a genetic abnormality or as the result of surgery\u2014have had their corpus callosum severed so that the two halves of the brain cannot easily communicate with one another. For example, in some cases of severe epilepsy, doctors elect to sever the corpus callosum as a means of controlling the spread of seizures. While this is an effective treatment option, it results in individuals who have \"split brains\". The rare split-brain\u00a0patients<\/strong> offer helpful insights into how the brain works.<\/p>\r\n<\/section>\r\n

\r\n
For instance, a split-brain patient is unable to name a picture that is shown in the patient\u2019s left visual field because the information is only available in the largely nonverbal right hemisphere. However, they are able to recreate the picture with their left hand, which is also controlled by the right hemisphere. When the more verbal left hemisphere sees the picture that the hand drew, the patient is able to name it (assuming the left hemisphere can interpret what was drawn by the left hand).<\/section>\r\n
\r\n[caption id=\"attachment_2064\" align=\"aligncenter\" width=\"516\"]\"Simple Figure 2<\/strong>. One of the most well-known split-brain findings is that the patient claims verbally not to have seen the stimulus in the left visual field, yet indicates the identity of it with their left hand. This suggests that the left hemisphere (controlling verbal output) is blind to the left visual field, while the right hemisphere (controlling the left hand) does perceive it.[\/caption]\r\n\r\n

Consider this striking example: a split-brain patient is seated at a table and an object such as a car key can be placed where a split-brain patient can only see it through the right visual field. Right visual field images will be processed on the left side of the brain and left visual field images will be processed on the right side of the brain. <\/p>\r\n

Because language is largely associated with the left side of the brain the patient who sees car key in the right visual field when asked \u201cWhat do you see?\u201d would answer, \u201cI see a car key.\u201d<\/p>\r\n

In contrast, a split-brain patient who only saw the car key in the left visual field, thus the information went to the non-language right side of the brain, might have a difficult time speaking the word \u201ccar key.\u201d In fact, in this case, the patient is likely to respond \u201cI didn\u2019t see anything at all.\u201d However, if asked to draw the item with their left hand\u2014a process associated with the right side of the brain\u2014the patient will be able to do so!<\/p>\r\n<\/section>\r\n<\/section>\r\n

Though this video is old, it does a great job showing the challenges facing\u00a0a split-brain patient shortly following the surgery to sever\u00a0her\u00a0corpus callosum and demonstrates the visual field study explained above.