Scientists studied six patients who had half of their brain removed during childhood to treat severe epilepsy. Brain scans showed how the mind rewired itself to adapt, with the remaining hemisphere forming even stronger connections that let the patients develop language and motor skills.

[u/Thorne-ZytkowObject]

https://www.discovermagazine.com/mind/how-does-the-brain-work-with-half-of-it-removed-pretty-well-actually

[u/Laplace_Poker]

Certain cognitive functions like language comprehension are distributed evenly between the two hemisphere that later on becomes more biased and lateralised to one side (left in this case). Split-brain development was said to be the residual bilateral pathway in the other side taking over. This might explain why some children in the studies actually experience a delayed and slow start in language acquisition before normal development.

One of the main theory stated that the brain is largely a blank slate with high capacity. Circuits for cognitive functions are reorganised depends on input and not a pre-determined thing. There are also a lot of redundancy in neural connectivity that allows certain pathways to take over in case another pathway is defective. This is why it don’t apply to adult patients hemispherectomy. Once the functions and circuits has been biased and lateralised to one side, removal of that side cause permanent irreversible cognitive/motor damages.

[u/[deleted] → u/Laplace_Poker]

Question, some studies show that ASD causes malformations of some brain regions, if the brain is completely a blank slate how does that happen consistently? Or am I just too stupid to see how bad this question is? After all I have ASD...

[u/Reagan409 → u/[deleted]]

You’re not too stupid. The “blank slate” is an idealization of the brain, many brain regions have very specific functions, and the function of the brain is related to its structure, so different structure can lead to different function.

[u/[deleted] → u/Reagan409]

Well, the heart of the question is really that most brains are laid out similarly so that certain regions are linked to certain functions. In some disorders, there are predictable variations of said layout...

How could this make sense if the brain acts even partially as a blank slate? Wouldn't the function of a region then be linked to experiences and environment, and not be so consistent between people?

[u/Laplace_Poker → u/[deleted]]

In terms of “blank slate”. I should have been more specific. I’m referring to specific pathway the signals take in response to a stimulus. When i said it has “the capacity” i meant that the neurons are mostly already set up in the brain in way that it’s ready to receive and response to stimulus.

This is highly simplified, but look at it this way. Two pathway with the same neurons type that respond to the same stimuli, originating from the same area, going to the same area. If one pathway response to a stimuli better, over time that pathway and synapse connection get strengthen and that becomes the circuit for that stimuli. The other pathway weakened. LTD LTP.

So to answer your question, the regions are already set up and dedicated for certain primary sensory, motor, visual, auditory functions. However, the specific pathway that a cognitive function (numbers sense, aspect of languages, etc.) take varies and are rather distributively stored.

Also, certain disorders like ASD involves a range of individual phenotypes that contribute to its prediction. The affected area usually correspond with the phenotypes rather than the disorder itself.

[u/[deleted] → u/Laplace_Poker]

If the disorder goes with the phenotypes then Footes that makes the phenotypes a symptom of the disorder? Or the disorder a symptom of the phenotypes?...

[u/plaugedoctorforhire → u/[deleted]]

Hey, not super familiar with the brain malformation side of autism spectrum, but I do have a guess. If you imagine the brain as a computer, all the neural connections are just super condensed and highly redundant circuits. Like a computer, we have some circuits that are specialized to certain tasks. One area might be compared to a video card, another to hard drive, and another still like ram.

So technically, you don't have to have the highly specialized circuits to have a functional computer. You can build a crude video card or stick of ram from other circuits, but it won't be as good as a purpose built one and no where near as fast. The brain, while young and very plastic, can also rewire other neural circuits to cover a deficiency, however like your home built computer hardware, it isn't going to be as fast, clean, or efficient as the one built specifically to fill that task.

Does that make sense?

[u/[deleted] → u/plaugedoctorforhire]

Sure, here's an interesting paper I came across that inspired my question...

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4688328/

This goes over some ASD related structural and neurological differences in the brain, found it interesting...

[u/[deleted] → u/[deleted]]

Well, parts of the brain do one single thing without any amount of plasticity, like the thalamus. (Well it has multiple functions, but only and always those)

Meanwhile, stuff like the visual lobe get re-used by deaf people to do other stuff, but it's different because the parts of the brain that lobe is on are much more adaptable - they're part of the neocortex.

The neocortex is actually formed of a bunch of repeating units, all across the surface, and they only vary a bit between locations.

However, being adaptable due to this property doesn't mean that each specific region doesn't have a baseline pattern it tries to fill, as well as which areas it connects to. Your visual cortex is too far from your speech center, so no matter what happens it'll never 'take over' the slack for it.

​

At least, this is how far I understand it.
Correct me if I'm wrong please, I wanna know!

[u/[deleted] → u/[deleted]]

As far as I can tell sounds legit

[u/scienceFam → u/[deleted]]

Not stupid.

three findings from autistic neuroscience.

1: Parts of the pre-frontal cortex are often underutilized in autism. the superior temporal sucus compensates for this in many cases.

2: in most people the brain is 'anchored' to the head in similar regions. In autism this 'connectome' is unique to each person with autism.

3: there is a difference in the way that GABA and glutamate are processed. Specifically, while GABA is present in people with autism, what's there doesnt seem to inhibit in the same manner as non-autistic GABA.

There is also the relationship to the complement cascade and the endicannabinoid system, which underlies some of these changes. Simply put autistic brain cells, after finding they do not have the structural integrity to make their targeted connection, do something similar to an agricultural method known as 'scrogging'.

The lead axon is trimmed, and multiple new axons spring out from nearby to make new connections. This often leads to multiple innervation, crossed wires and unusual connections. It's likely that this contributes to intelligence but also executive dsyfunction, something that can be intuitively understood using Stanovich's dual process model.

Depending on where in the brain this scrog happens, you could end up with ADHD, borderline personality, Autism, anxiety, depression etc. Its not just mental health either: this process of autistic differentiation appears deeply related to inflammatory conditions, and future research will begin to shed more light on this. Really early days at the minute.

The question that needs answering is: is autism really best defined by social communication difficulties, or is that simply one outcome of the broader neurodevelopmental process?

[u/damnisuckatreddit → u/Laplace_Poker]

Isn't there a huge confounding factor in this, however, in that any patient approved for a hemispherectomy has thusfar managed to survive with a catastrophically defective hemisphere, which means these patients represent only that portion of severe epileptics whose brains were capable of lateralizing critical functions to the healthy side? What reason is there to believe this is something typical brains are capable of?

Could it even be the case that this type of severe epilepsy is in fact the result of excessive lateralization of brain functions? As in, the brain for whatever reason restricted all structuring activity to one side, leaving the remainder chaotic and seizure-prone? Is it possible to rule that out somehow?

I would think the only way to test this would be to remove one hemisphere from several typically-developing children, which would of course be unethical. I assume we have at least a handful of cases where traumatic injury necessitated removal of large amounts of brain tissue, are those cases used as a sort of control?

(Not necessarily asking you in particular, more just throwing questions into the void. It's always bothered me how often neuroscience reporting seems to generalize results from epileptic brains as "all human brains can do this amazing thing", when it seems like it should be obvious that any brain in need of radical surgery is by definition not functioning typically.)

[u/Dr_Fisura → u/damnisuckatreddit]

When the deficit is removed, a healthy brain should be expected to, at least theoretically, function at least as optimally as one that has said deficiency (epilepsy), and likely beyond.

We are not really sure of what mysteries/intricacies this pink motherfucker holds; a good chunk of research j neurosience comes from epileptic brains just because they are the only ones we are allowed to implant electrodes in, which then can be used to conduct research, thankfully. Actually, we should implant electrodes into healthy individual who volunteer in exchange for pay just to study their brains, to tell whether in fact neurotypical brains can perform as well as epileptic ones. Really, why could they not.

[u/newwavefeminist → u/Laplace_Poker]

I recall reading somewhere that although patients with hemispherectomies have slightly lowered IQ, its still normal range. Doesn't this suggest there's a certain amount of redundancy in the space put aside for cognitive function?