This paper follows the journey of a 6 year old child who has had a significant portion of his right occipital and temporal lobe removed, where extraordinarily, the brain seems to find a way to do things, quite simply, it shouldn't be able to!
In the introduction to the paper the ventral pathway is noted. This runs from the occipital lobes, where the visual information received by the eyes is processed, (to form an image) to the temporal lobes, on both sides, where we also store banks of visual memories:
The ventral stream pathway on each side is carried by a bundle of nerve fibres called the inferior longitudinal fasciculus (ILF as explained in the CVI v OVI Neuroplasticity Paper we featured). If a person is recognising faces in a test, a certain part of their brain (usually in the right temporal lobes) will activate. This is a consistent response in a consistent part of the brain when measured in typical adults. There are other defined centres, for example for shape recognition, places and expressions. Each has a memory bank, like a storage file, in the brain.
So, for facial recognition, when we meet new people and learn to recognise their faces:
This paper is looking at how the brain might reorganise itself after major surgery.
And that is why this is an important paper, because our understanding of how the brain can reorganise itself is growing as there are more studies like this, but it is still in its infancy - what we understand about the human brain is likely to be tiny compared to the secrets it still holds.
In the film Jurassic park, the character played by actor Geoff Goldbloom says:
Life will not be contained, life breaks free... I'm simply saying that life finds a way
We know from the case of The Blind Woman Who Saw Rain (featured on our Blindsight Newspaper Feature), that a brain which should not have been able to see due to severe occipital lobe damage following a stroke, could see raindrops falling down a window. Life, found a way, here a different part of the brain responsible for detecting movement, intact following the stroke, progressively learned to see better, and these scientists are looking further at what other secrets the brain may hold, because once discovered, what we understand can be widely applied to affected people, having potentially huge impacts on their quality of life.
So, what happens after a major brain injury in a young child, including as in this case, a major surgery when a section of the brain serving vision has been removed or damaged? This paper notes:
To date, little attention has been paid to the recovery of function following the resection of regions of the cortical visual system. Theoretically, one may postulate a continuum of possible outcomes ranging from no plasticity to complete reorganization.
This is a neat way of saying that actually we don't know, but in theory, the brain could completely re-organise itself. We use the analogy of a computer for the brain a lot on this website, but there are important differences:
This is why research is so very important, pushing the boundaries of what we know, to learn more (and this is why we feature published research). We can all hypothesise, but must be cautious not to run away with fashionable theories - we explained this in our Developmental Dyslexia Paper, where one theory with a weak scientific foundation was followed as the only approach, for sixty years, probably to the detriment of innumerable people. Research may seem painstakingly slow and burdened by rules and regulations, but these serve a purpose, which ultimately is to protect and safeguard people.
The patient is a child called UD who started having epileptic seizures aged 4 and underwent brain surgery aged 6. UD's progress was followed during a 4 year period post surgery from the age of 7 to 10.
Figure 1 A (on the paper, link at bottom of page) shows images of UD's brain before and after surgery. The top images (pre-operative) show a shadow on the right side, this is the area responsible for severe and dangerous epilepsy that could not be controlled using drugs (hence the need for surgery). The bottom images, show the black areas where the section of the right occipital and temporal lobes have been removed (right ventral occipito-temporal cortex VOTC).
As was anticipated, following surgery UD had a left hemianopia.
Figure 1 C (on paper, link at bottom of page) show the visual field tests performed one year and three years post surgery, and the red stars on the left indicate the area where visual responses are absent
By removing the right VOTC, the procedure broke the right ILF, a bit like someone removing the only road between two main cities. Without the right ILF, visual information in relation to the complex memories that are stored in the right temporal lobes, which includes...
...have nowhere to go.
When UD met someone they knew, maybe a friend, and saw them on their right side (as UD does not see on the left side due to the hemianopia), the visual information would previously have travelled along the ILF pathway to the memory store and matched it correctly so UD could greet their friend. Now however the ILF is no more, so it would be expected that the UD would no longer able to recognise friends visually... or did life find a way?
This paper reports on assessments of the function of the 'higher order visual cortex'. This is looking at the areas of recognition that wold have been expected to have been severely affected by the surgery. UD was assessed (using psychophysics experiments) at different ages, between 7 and 10 years old, and compared to a control group of eight other children, who had age ranges between 7 and 11 years old.
The ability to recognise "faces, scenes, objects and words" (Figure 2 A) was assessed.
Figure 2B (on the paper, link at bottom of page) shows the typical brain activity in the children in the control group when undertaking the assessments. Figure 2C shows the brain activity in UD. The first image, one year after surgery shows no activity on the right side of the brain, this is expected, the road (ILF) has been removed, so how is traffic expected to get there? But look at UD's later scans - there is a small pink area on the right side, clearly and repeatedly showing brain activity in three subsequent scans - a new memory bank - but how did it evolve without a road (ILF)?
And what is this little pink blob?
...the only region that showed robust category selectivity... in the right hemisphere (RH), showed selectivity for faces.
Recognising faces - right where it should be, in the right temporal lobe.
The paper notes that whilst in the first assessment (age 7, one year after surgery) UD could not recognise faces, once UD regained this ability having made a connection to the face recognising centre, later shown in the second scan two years after surgery, this remained stable.
Our face memories are typically in the right temporal lobe and our word memories typically in the left temporal lobe, but it is not as clean cut as that (as we explained in our Recognition sections), and recent research has shown that our word memories are stored all over the brain.
What patient UD seems to have done is reorganise their memory storage system, and it looks like their brain is starting to use other routes, that in typical people are not activated because of the effectiveness and dominance of the ILF as a primary pathway. It's a bit like finding an unused old farm track to get from one city to the other - previously unknown because the superhighway (ILF) has been so efficient. Now the superhighway has been removed, the farm track, which at first may seem slow and difficult, over time becomes a fully viable alternative pathway.
Consider the 'Blind Woman who Saw Rain' - we all have Blindsight, but this is secondary, as our vision in terms of the image created in our occipital lobes dominates how we see things. Where sight was lost following a stroke, this patient, found that the old farm track was an alternative too, and over time developed and enhanced her visual skills.
This shows that the brain has a capacity to reorganise itself, particularly in young children. This patient now has a good facial recognition capacity
It is likely that in many other cases, unreported however, that the brain has started to reorganise itself - to do things differently. Potentially, with guidance, support and training, people could learn to harness this capacity, which could have a huge impact on recovery not just from brain injury or brain surgeries, but potentially anything altering the brain's processing capacity.
If interested in learning more we recommend reading Norman Doidge's books The Brain that Changes Itself and The Brain's Way of Healing.
UD was a child and had a major surgery and youth may well have facilitated recovery, because the brain was still developing and growing, and the surgery was so severe, that their brain found a new way. Possibly in some older patients, if the injury is less severe, the brain isn't 'motivated' to find that new route. For adult and older patients, the training may take longer as their brains are less plastic than children's, but they are still plastic, and can still learn, the brain does not stop learning.
This is quite a technical paper, but all the terms are explained.
Liu TT et al. Successful Reorganization of Category-Selective Visual Cortex following Occipito-temporal Lobectomy in Childhood. Cell Reports. 2018;24(5):1113-1122
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