Split brain patients

[Boots]

What I want to know is how split brain patients are able to recieve a picture of an object in their right hemisphere but still be able to identify that object with their left hand. I thought the corpus callosum was cut!

[vexx]

I don't understand.

How can split brain patients communicate with their left hand when they saw something that was recieved in the right hemisphere.
I thought the corpus callosum is cut.

i'm a little confused with your question, but the left side of the body is controlled by the right hemisphere, so functions involving the left hand when received in the right hemisphere will work since the right hem controls this.

[yien_quek]

yeah, actually LEFT visual field --> RIGHT hemisphere --> LEFT hand. the hemispheres are not doing any communicating at all.

[Spreadbury]

I think I see how you're thinking. but the right hemisphere doesn't have to transfer messages across the corpus callosum to control the movements and sensations of the left side of the body. they're directly connected (I believe)

[Boots]

I don't understand.

How can split brain patients communicate with their left hand when they saw something that was recieved in the right hemisphere.
I thought the corpus callosum is cut.

i'm a little confused with your question, but the left side of the body is controlled by the right hemisphere, so functions involving the left hand when received in the right hemisphere will work since the right hem controls this.

Yes, so how come split brain patients can do this if their corpus callosum is cut?

[Boots]

I think I see how you're thinking. but the right hemisphere doesn't have to transfer messages across the corpus callosum to control the movements and sensations of the left side of the body. they're directly connected (I believe)

REALLY, did your teacher tell you this? It says that for motor movement the corpus callosum is not used, but this doesnt sound right to me

[Spreadbury]

the hemisphere's don't have to coordinate to move the body and messages to say, move the left hand would be sent from the right hemisphere, down the spinal cord and along the somatic nervous system to the right hand telling it to clench without any input from the left hemisphere

[Boots]

By coordinate do u mean communicate, and by right hand telling it to clench, you mean the left hand?

If so, i never thought of it that way. Very interesting

[Visionz]

The primary motor cortex in the right front lobe controls voluntary skeletal movement of the bodys' LEFT side. The picture is recieved in the right side of the occipital lobe. Everything is happening in the right hemisphere so the corpus callosum is not used.

The person however would be unable to verbalise/name the object as verbal functions are controlled by the left cerebral hemisphere.

[Glockmeister]

I think I see how you're thinking. but the right hemisphere doesn't have to transfer messages across the corpus callosum to control the movements and sensations of the left side of the body. they're directly connected (I believe)

REALLY, did your teacher tell you this? It says that for motor movement the corpus callosum is not used, but this doesnt sound right to me

That is correct, and in fact, even if the corpus callosum is cut, there's still communication between the two hemispheres.

None of this below is actually in the VCE Psychology syllabus, but you may be interested.

What happens is the Motor Cortex in the brain, transmits information down to the body via what's known as the Corticospinal Tract. Most of these fibres will go down the Lateral Corticospinal Tract (LCT) (there's a few exceptions, but I'm a bit too drunk to remember what they are at the moment. One of those according to wikipedia that is controlled by the LCT). The reason why the left hemisphere is said to control the right side of the body is that the neurons involved in the LCT cross in the Pyramidal Decussation at the Medulla Oblongata. That's why you get the whole LH controls RHS body and vice versa.

[Boots]

Wow, thanks.

[littlebecc]

I get confused by this stuff too...
So if they were shown an object in their right visual field....it would be processed by their right hemisphere and they would be able to pick it up with their left hand?
But they wouldn't be able to name it...right?
Oh god. Lol.

[Spreadbury]

I get confused by this stuff too...
So if they were shown an object in their right visual field....it would be processed by their right hemisphere and they would be able to pick it up with their left hand?
But they wouldn't be able to name it...right?
Oh god. Lol.

no, information from the right visual field is received by the left half of each eye, and the left half of each eye transmits visual information to the left occipital lobe and as the left hemisphere controls speech, were it presented to their left visual field they would be able to name it. however were it presented to their left visual field they could point to it but not verbally identify it

[Visionz]

no, information from the right visual field is received by the left half of each eye, and the left half of each eye transmits visual information to the left occipital lobe and as the left hemisphere controls speech, were it presented to their RIGHT visual field they would be able to name it. however were it presented to their left visual field they could point to it but not verbally identify it

this.. (fixed)

[littlebecc]

Thanks guys.
I'll work on that ha.