2502 upvotes, 15 direct replies (showing 15)
You need to check out Sperry's Nobel prize winning work on split brain patients, along with Gazzaniga. Several functions of the brain are lateralized, and in most people language resides in the left hemisphere (LH). This means you could chat with the left side of the brain (via the right ear or right visual field), but not the right because it cannot process language.
Nevertheless, you can still communicate with the RH. For example, in one experiment an object is placed in the left hand (processed by RH). The patients cannot describe or name the object. However, when later given a set of objects, the patient can match it. In other words, they were *aware* of what the object was or its properties, but they were not *conscious* of it.
Split-brain research has given us lots of clues to what each half of the brain might do:
https://en.wikipedia.org/wiki/Split-brain
Comment by meatmcguffin at 14/10/2021 at 19:44 UTC
396 upvotes, 16 direct replies
Is there a reason for the left hemisphere controlling the right side of the body, and vice versa?
I would have thought that, evolutionarily speaking, it makes sense to have some redundancy.
However, with this setup, if there were damage to the left side of the body *including* the left hemisphere, then it would lead to issues controlling both sides of the body.
Comment by why_not_start_over at 14/10/2021 at 20:02 UTC
50 upvotes, 3 direct replies
Yes, the split brain research is fascinating! The issue of "why not" u/TwizAU is the lack of subjects to study. It's a pretty extreme thing to separate the hemispheres of the brain, and even when they did have a case for it the ethics weighed heavy. There is so much room for study it's awe inspiring. Looking into split consciousness led me to "gut neurons and consciousness" research, which has a lot more activity since it doesn't require cutting up brains. We need to discover more non intrusive ways of studying brain and neuron activity to make substantially moves forward in this field. And, as fascinating as it is, experimental study is pretty scary/ethically ambiguous when it comes to consciousness.
Comment by Pls_PmTitsOrFDAU_Thx at 14/10/2021 at 20:36 UTC
20 upvotes, 1 direct replies
The brain is so insanely bizarre. I love to read these things that just make you wonder what else we don't know
Comment by kakushka123 at 14/10/2021 at 19:56 UTC
12 upvotes, 3 direct replies
If the LH (i.e person) would be asked how he knew to pair them correctly, what would he say? Somthing like "It just felt right" or more like "the hand moved itself to the right matching pair"? Or someting else entirely?
Comment by VorianAtreides at 14/10/2021 at 20:52 UTC
13 upvotes, 1 direct replies
To add on, we do something in Neurology called a Wada test[1] which helps to establish hemispheric dominance/lateralization prior to a surgery or interventional procedure.
1: https://en.wikipedia.org/wiki/Wada_test
Without going into too much detail, the test involves putting one side of the brain to sleep via injected barbiturates and running a series of language, memory, and visual tests before then testing the alternate side.
Comment by [deleted] at 14/10/2021 at 22:59 UTC*
9 upvotes, 3 direct replies
I remember when I was a kid seeing something that disturbed me greatly and I wonder if you could confirm. It was 60 Minutes or 20/20 or something and it said some people with a split brain the other hemisphere feels shut in and silenced and unable to communicate and will actually try to kill the person by using the hand on that side of the body trying to jerk the wheel of the car etc. Like there are two people inside the one person and one can't stand living anymore in that state after the corpus callosum was cut. Any validity to this?
Comment by Zkv at 14/10/2021 at 19:45 UTC
6 upvotes, 1 direct replies
Well, the right brain was conscious of it, correct?
Comment by [deleted] at 15/10/2021 at 06:21 UTC
2 upvotes, 0 direct replies
This is actually so cool, I didn't know that we had actually reached such a level in studying the brain that such a question could be meaningfully answered.
Comment by Implausibilibuddy at 14/10/2021 at 20:50 UTC*
1 upvotes, 1 direct replies
So I've come across this research before and I remember having a question then that I couldn't find an answer to. In the experiment I saw they didn't have a patient hold an object, but rather they showed them images. But isn't it the case that the R/L hemispheres don't take an eye each but rather half the retinal area of each eye? In which case how did they show images to just half an eye?
Edit: Found someone else who asked the same question[1], and yes they used special apparatus to split the image to the correct parts of each eye.
Comment by IAmA-Steve at 15/10/2021 at 00:17 UTC
0 upvotes, 1 direct replies
The patients cannot describe or name the object
So we're talking to the left brain here ... can the patient *feel* like they could recognize the object a second time?
Comment by SILENTSAM69 at 15/10/2021 at 00:34 UTC
1 upvotes, 0 direct replies
It almost sounds as if what we call the unconscious brain is just the hemisphere that can not convert thought to words.
Comment by SurprisedJerboa at 15/10/2021 at 02:27 UTC
1 upvotes, 0 direct replies
The brain seems adaptable for some amount as well. (This is obviously not understood that well... further research required!)
The boy had one-third of his right hemisphere removed, including a part of the brain responsible for sight.[1] But according to a new case report about U.D., the left side of his brain started to take on the visual tasks normally reserved for the missing part of the right side of the brain.
1: https://www.livescience.com/63216-brain-plasticity-lobectomy.html
One other article with studies...
Another recent study found a small group of women who could smell despite missing their olfactory bulbs, the region in the front of the brain that processes information about smells.[2] Though it's unclear how this happens, researchers think that it's possible another part of their brain took on the task of processing smells, according to another Live Science report.
2: https://www.livescience.com/hemisphere-removed-brain-plasticity.html
Now, the authors of the new study are hoping to better understand how the brain reorganizes itself after an injury or stroke, and how some regions are able to compensate for those that are damaged or lost. "Maybe down the line, that work can inform targeted intervention strategies ... to help more people with brain injuries," Kliemann said.
Comment by Bloodyfish at 15/10/2021 at 04:10 UTC
1 upvotes, 0 direct replies
Can the right hemisphere not learn to talk? Isn't that essentially what happens in kids after a hemispherectomy?
Comment by ideletedmylastacc at 15/10/2021 at 09:30 UTC
1 upvotes, 0 direct replies
This means you could chat with the left side of the brain (via the right ear or right visual field), but not the right because it cannot process language.
Interesting. I am deaf in my right ear, so if my hemispheres where seperated, I would be completely deaf, even though I can still physically hear, right?
Comment by m3tafisics at 16/10/2021 at 16:37 UTC
1 upvotes, 1 direct replies
It’s also now known that about 8% of the population has language in the right side.