The medical mystery of split-brain patients
If you split the human brain in half, by severing the corpus callosum (a network of neural fibres) connecting the left and right cerebral hemispheres, does this surgical procedure split consciousness as well? By that, I mean, do you end up with two conscious agents in the one human head?
A lot of neuroscientists would tend to think so.
Back in the 1970s, this question seemed to have a definitive answer which fitted in with the idea that the human brain was essentially a "computer made out of meat", with conscious awareness being the product of complex neuronal-firing across multiple cortical regions. This can't be proven as-of-yet, of course, since we still haven't located the neural correlates of consciousness - but research by two "split-brain" scientists seemed to be indicative of this.
The neuroscientists in question, Roger Sperry and Michael Gazzaniga, found data suggesting that when you split the brain, you split conscious agency as well. For this pioneering research into split brains, Sperry won the Nobel Prize in Medicine in 1981.
Bereft of the corpus callosum, the hemispheres have no means of exchanging information, other than through some nebulous subcortical process we don't know much of anything about.
Subcortical regions and their functions are typically postulated by neuroscientists to play absolutely no role in the rise of consciousness. This is due to the predominant view among researchers: which assumes that consciousness must be a higher-order cognitive function, meaning it can only therefore be dependant upon cortical regions of the brain, like the prefrontal cortex.
As such, if one assumes the validity of this paradigm, you wouldn't expect the severed hemispheres to be capable of producing a unified conscious agent - which seemed to be evidenced by Sperry's findings.
Unfortunately for this tidy framework, recent evidence published last year in the Journal Brain, contradicted the earlier conclusion and announced a shocking, perplexing one instead that appears to significantly muddy the waters, as you can see from this Science Daily article on the study:
Split brain does not lead to split consciousness
What do you think of these latest findings? What might they mean for the brain and how consciousness emerges from it, if the scientists are correct? Can we learn anything from it (for instance what current theories of consciousness might have to be thrown in the trash-heap, for instance)?
If you split the human brain in half, by severing the corpus callosum (a network of neural fibres) connecting the left and right cerebral hemispheres, does this surgical procedure split consciousness as well? By that, I mean, do you end up with two conscious agents in the one human head?
A lot of neuroscientists would tend to think so.
Back in the 1970s, this question seemed to have a definitive answer which fitted in with the idea that the human brain was essentially a "computer made out of meat", with conscious awareness being the product of complex neuronal-firing across multiple cortical regions. This can't be proven as-of-yet, of course, since we still haven't located the neural correlates of consciousness - but research by two "split-brain" scientists seemed to be indicative of this.
The neuroscientists in question, Roger Sperry and Michael Gazzaniga, found data suggesting that when you split the brain, you split conscious agency as well. For this pioneering research into split brains, Sperry won the Nobel Prize in Medicine in 1981.
Bereft of the corpus callosum, the hemispheres have no means of exchanging information, other than through some nebulous subcortical process we don't know much of anything about.
Subcortical regions and their functions are typically postulated by neuroscientists to play absolutely no role in the rise of consciousness. This is due to the predominant view among researchers: which assumes that consciousness must be a higher-order cognitive function, meaning it can only therefore be dependant upon cortical regions of the brain, like the prefrontal cortex.
As such, if one assumes the validity of this paradigm, you wouldn't expect the severed hemispheres to be capable of producing a unified conscious agent - which seemed to be evidenced by Sperry's findings.
Unfortunately for this tidy framework, recent evidence published last year in the Journal Brain, contradicted the earlier conclusion and announced a shocking, perplexing one instead that appears to significantly muddy the waters, as you can see from this Science Daily article on the study:
Split brain does not lead to split consciousness
Date:
January 25, 2017
Source:
Universiteit van Amsterdam (UVA)
Summary:
A new research study contradicts the established view that so-called split-brain patients have a split consciousness. Instead, the researchers behind the study have found strong evidence showing that despite being characterized by little to no communication between the right and left brain hemispheres, split brain does not cause two independent conscious perceivers in one brain.
January 25, 2017
Source:
Universiteit van Amsterdam (UVA)
Summary:
A new research study contradicts the established view that so-called split-brain patients have a split consciousness. Instead, the researchers behind the study have found strong evidence showing that despite being characterized by little to no communication between the right and left brain hemispheres, split brain does not cause two independent conscious perceivers in one brain.
What do you think of these latest findings? What might they mean for the brain and how consciousness emerges from it, if the scientists are correct? Can we learn anything from it (for instance what current theories of consciousness might have to be thrown in the trash-heap, for instance)?
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