I’ve written before about split-brain patients, those who, due to severe epilepsy, had the connections between the two hemispheres of their brain severed, yet were subsequently able to lead normal lives without themselves even noticing any cognitive change, which has profound implications for how consciousness works.
It turns out that there are people who are born with no connections between their brains, and one recently discovered patient still led a normal life: This Elderly Man Was Born With His Brain Hemispheres Disconnected. Did It Affect His Life? Hardly | Science Blogs | WIRED.
A new paper reports on an elderly gentleman, referred to as H.W., who aged 88 presented at a clinic complaining of recent intermittent problems controlling his left hand and some mild memory difficulties. Preliminary tests found him to be high functioning. He scored 30 out of 30 on the “mini mental state examination”, which is used to pick up signs of dementia or confusion. But when the researchers – a team led by Natalie Brescian – scanned H.W.’s brain, they made a surprising discovery. He had no corpus callosum. The main channel between his two brain hemispheres was completely missing.
The medical name for H.W.’s rare condition is agenesis of the corpus callosum, meaning that he was born with this structure missing. Given the importance of the callosum for connecting the bicameral brain, you’d think this would have had profound neuropsychological consequences for H.W. In fact, a detailed clinical interview revealed that he’d led a normal, independent life – first in the military and later as a flower delivery man. Until recently, he appeared to have suffered no significant psychological or neurological effects of his unusual brain. The problems with his left hand, H.W. said, were new.
When reading about split-brain patients, I always wondered if their ability to function might not have been reliant on functionality developed while their brain hemispheres were still connected. In other words, whether it was possible for a segmented brain to function if it had always been segmented.
According to the article, many patients who are born congenitally this way are not high functioning, but this man’s story indicates that it is often possible. In other words, our “self” can be split and still function as a unified self. Which just further confirms that our brains are not a centrally controlled mechanism, but one with information processing and decision making distributed throughout its structure.
And consciousness is a central information gathering mechanism, one that gathers information in any way it can, including observing the self’s actions and concocting an explanation of its actions, even when it’s not privy to the actual information processing that led to those actions, as would be the case when the other half of a split brain initiated those actions.
This seems to indicate that consciousness is not in control. The information it provides influences the brain’s actions, otherwise we couldn’t discuss it, but the initiation and execution of those actions appear to take place outside of consciousness.
Consciousness seems to function similar to how a city newspaper functions, gathering information about what is happening within the city and making its information available to the rest of the city, influencing what the city does, but not controlling it.
Until the newspaper reports on an activity, say a spike in crime, within the city, we could say that the activity is not yet in the city’s public consciousness. Parts of the city may respond to the activity, but the city as a whole doesn’t yet know what is going on. It is in the city’s collective subconscious. Once the newspaper has reported, it is in the city’s collective consciousness, and affects what the parts of the city, the citizens, the police, the mayor, etc, do.
The newspaper gathers information in any way it can, including sometimes interpreting the public actions of portions of the city for which it may not have direct access to the inside story. In my mind, that’s what the consciousness machinery in the brain of a split-brain patient is doing, and it’s why they can remain functional without themselves even noticing the difference.