Consciousness: not split in split-brain patients (General)

by David Turell @, Saturday, July 06, 2019, 18:01 (449 days ago) @ David Turell

A new study shows split brain does not split the person or the consciousness, but does alter some sensory perceptions which depend on one lobe or the other:

https://aeon.co/ideas/when-you-split-the-brain-do-you-split-the-person?utm_source=Aeon+...

"The brain is perhaps the most complex machine in the Universe. It consists of two cerebral hemispheres, each with many different modules. Fortunately, all these separate parts are not autonomous agents. They are highly interconnected, all working in harmony to create one unique being: you.

"But what would happen if we destroyed this harmony? What if some modules start operating independently from the rest? Interestingly, this is not just a thought experiment; for some people, it is reality.

"In so-called ‘split-brain’ patients, the corpus callosum – the highway for communication between the left and the right cerebral hemispheres – is surgically severed to halt otherwise intractable epilepsy.

***

"We’ve got to admit that split-brain patients feel and behave normally. If a split-brain patient walks into the room, you would not notice anything unusual. And they themselves claim to be completely unchanged, other than being rid of terrible epileptic seizures. If the person was really split, this wouldn’t be true.

"To try to get to the bottom of things, my team at the University of Amsterdam re-visited this fundamental issue by testing two split-brain patients, evaluating whether they could respond accurately to objects in the left visual field (perceived by the right brain) while also responding verbally or with the right hand (controlled by the left brain).

"Astonishingly, in these two patients, we found something completely different than Sperry and Gazzaniga before us. Both patients showed full awareness of presence and location of stimuli throughout the entire visual field – right and left, both. When stimuli appeared in the left visual field, they virtually never said (or indicated with the right hand) that they saw nothing. Rather, they would accurately indicate that something had appeared, and where.

"But the split-brain patients we studied were still not completely normal. Stimuli could not be compared across the midline of the visual field. Moreover, when a stimulus appeared in the left visual field, the patient was better at indicating its visual properties (even when he responded with the right hand or verbally!), and when a stimulus appeared in the right visual field, he was better at verbally labelling it (even when he responded with the left hand).

"Based on these findings, we have proposed a new model of the split-brain syndrome. When you split the brain, you still end up with only one person. However, this person experiences two streams of visual information, one for each visual field. And that person is unable to integrate the two streams. It is as if he watches an out-of-sync movie, but not with the audio and video out of sync. Rather, the two unsynced streams are both video.

"And there’s more. While the previous model provided strong evidence for materialism (split the brain, split the person), the current understanding seems to only deepen the mystery of consciousness. You split the brain into two halves, and yet you still have only one person. How does a brain, consisting of many modules, create just one person? And, how do split-brainers operate as one when these parts are not even talking to each other?"

Comment: as usual materialism as it relates to brain function is not supported.


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