Re-examining the Mind & the Architecture of Thinking
What One Man’s Brain Revealed About Human Cognition
Let me introduce you to PR: a married father of two, who works as a butcher in a supermarket, and might just be the only person known to have lived without a prefrontal cortex who can still reflect on his own thoughts.
In 2018, researchers at the University of Bordeaux invited him to take part in a study exploring metacognition, the remarkable ability we have to think about our own thinking [ref.].
But PR’s story began in 2004, when he experienced a generalised seizure and an MRI scan revealed that a diffuse low-grade glioma (a slow-growing tumour) had invaded the left frontal area of his brain. As a result, part of his left prefrontal cortex had to be surgically removed.
The prefrontal cortex sits right at the front of the brain, like a kind of command centre. This is one of the last regions of the brain to have evolved, and it’s where many of our most complex abilities live, such as skills like planning, self-control and critical thinking. The prefrontal cortex also plays a central role in metacognition, and there’s a small area tucked inside it called Brodmann area 10 that is believed to be key to it.
After the first surgery, PR began chemotherapy in an attempt to stop the tumour from spreading deeper into his brain. But it didn’t work. The menacing glioma kept creeping through his left prefrontal cortex, and in 2010, he went in for a second operation. This time, the doctors removed his entire left prefrontal cortex, and he was awake through it all.
But PR’s journey didn’t stop there. Sadly, in 2014, the glioma returned. This time, spreading into the right hemisphere of his brain. So, he went through a third operation. By the end of it all, both sides of his prefrontal cortex had been removed, including the entire Brodmann area 10.
According to the researchers, PR might be the only person in the world to have undergone such an extensive bilateral prefrontal resection.
But now, here’s the question:
What happens when someone loses the part of the brain believed to be essential for self-awareness, reflection, and the thinking about one’s own thoughts?
You might expect the answer to be obvious. If that region responsible for self-reflection is gone, then surely metacognition must be gone too. Hence, no self-awareness. Just automatic reactions, with no sense of perspective or insight.
BUT, PR’s brain had other plans!
The Role of Neuroplasticity
Human beings are remarkably adaptable. When something in the brain is damaged, whether by injury, illness or surgery, the brain doesn’t always give up. Instead, it begins to rewire itself, often shifting functions to other areas to make up for what has been lost. This ability is known as neuroplasticity, something you’ve probably heard of before, and to me, it is one of the most astonishing features of the human brain.
One of the clearest examples of neuroplasticity is seen in people with aphasia, a language impairment often caused by damage to the brain after a stroke. In many stroke cases, people lose the ability to speak, read or write; but over time, they gradually recover those functions. That is because the brain begins to shift language processing away from the damaged areas, sometimes to nearby regions, sometimes to the opposite hemisphere. This is a compensatory process, a functional reorganisation.
Could the same kind of adaptation happen with something as sophisticated and intricate as metacognition?
Metacognition Against the Odds
PR’s case had already surprised the researchers, who’d noted that after each operation, he was able to return to both his work and his social life. But the real revelation came when the researchers decided to take a closer look at PR’s metacognitive abilities.
See, earlier studies had shown that damage to the prefrontal cortex, particularly Brodmann area 10, tends to impair self-reflective thinking.
So the researchers set up a task. Actually, two.
To properly understand PR’s performance, they compared him with three other groups:
Nine patients who had their right prefrontal cortex removed, including Brodmann area 10
Nine patients who had surgery in the right prefrontal cortex, but not involving area 10
Thirty-eight healthy participants
Task 1
The first task was a test of perception. Participants were shown two rapidly flickering images and asked to decide which one contained a darkened pattern, known as a Gabor patch. It was a simple “first or second?” kind of choice, designed to test how well they could discriminate between the two.
Task 2
But the real focus of the study was the second task. After each decision, participants were asked to rate their confidence. “How sure are you?” they were asked, on a scale from 1 (very low confidence) to 6 (very high). This second part was where metacognition came in, because it’s not just about making a decision, but about knowing how sure you are about it.
All participants, including PR, took part in 350 trials. And despite everything, PR performed remarkably well. He got around 71 % of the perceptual decisions right, which was on par with everyone else in the study. But here’s the part that left the researchers stunned: his confidence ratings, the metacognitive part, were just as accurate as those of the healthy participants.
In other words, PR didn’t just make the right decisions. He knew how sure he was about them. What a legend!
When the Brain Has Time to Adapt
PR’s case raised an important question about how the brain works. For a long time, the anterior prefrontal cortex (especially Brodmann area 10) was thought to be essential for metacognition. And yet, here was someone who had lost that very region on both sides of the brain and still showed preserved self-reflective abilities. This may as well suggested that the brain might be even more plastic, and metacognition more resilient, than we once thought.
Of course, not every case unfolds like this. One reason PR’s brain may have had time to adapt and preserve metacognition abilities is the slow-growing nature of his tumour. Low-grade gliomas tend to progress gradually, giving the brain more opportunity to reorganise and redistribute functions. In faster-developing conditions, such as a sudden stroke or a rapidly growing tumour, this kind of adaptation is far less likely.
The Mind Remains a Mystery
In my opinion, PR’s story raises more questions than it answers. It doesn’t rewrite our understanding of the brain, of course, but it challenges what we thought we knew. Reminding us that in science, certainty isn’t a destination, it’s a story we revise as we go. That’s what makes studies like these so valuable. They show us science not as a fixed body of facts, but as something alive: a process of questioning, observing, and reshaping. And nature, for all our models and expectations, has a way of surprising us.
PR’s case invites us to look again at the relationship between brain & mind. It doesn’t offer a conclusion, but it leaves us with something else. A moment of awe. An invitation to deepen both our curiosity and our reverence; for nature, and for the mystery of being human.
Reference List:
Fleming, S. M., Ryu, J., Golfinos, J. G., & Blackmon, K. E. (2014). Domain-specific impairment in metacognitive accuracy following anterior prefrontal lesions. Brain, 137 (Pt 10), 2811–2822.
Lemaitre, A., Herbet, G., Duffau, H. and Lafargue., G. (2018) Preserved metacognitive ability despite unilateral or bilateral anterior prefrontal resection. Brain and cognition. Vol. 120, No. C, pp. 48-57.
Turkeltaub, Peter E. ; Coslett, H. Branch ; Thomas, Amy L. ; Faseyitan, Olufunsho ; Benson, Jennifer ; Norise, Catherine ; Hamilton, Roy H. (2012), The right hemisphere is not unitary in its role in aphasia recovery. Cortex, Vol.48, No. 9, pp.1179-1186.
Note: I originally published this piece in another forum, but I’ve adapted it for this thoughtful and curious community. It felt like the kind of topic that belongs here too.
I've known a few stroke survivors who have learned to speak again and regain mobility. It didn't occur to me until now that learning to do that again is literally the case of their brains rewiring themselves to allow it. (Forgive my layperson language!)
That makes me wonder, if the brains neuroplasticity can be utilised by default after brain injury, can it be put to work intentionally without the trauma to, for examples sake, allow me to remember where I left my keys? Silly example, but is something like a true photographic memory out of the question, if we train our brains hard enough? Or is is more a case of the brain tries to replace what was lost, by utilising undamaged areas to regain some sort of normality?
It's all very fascinating and it's frustrating that I don't think we, during our lifetimes at least, will ever know the full capabilities and workings of our brains.
The mind is a mystery! I have worked with so many stroke patients in the hospital and they all present so differently. Some recover this or that and some don’t — it’s so hard to know. Plus people’s prior experiences and personalities and social support and situations also impact recovery. Every stroke patient is different even if there are common impairments that we see.