/sci/ - Science & Math

Bumping with neuron cells

>>5569242

The impulses arise from enviromental cues.

We still know very little about the human brain. But we have come a long way, since say, 200 years ago.

I want to do neuropsych and it's a lot of info on explaining this so I'll screen cap some pages from my textbool (I also fucking got a 77 on my midterm today, thought I did good FUCK. At least the class average was a 74)

>>5569302

>>5569283
Yeah, but what exactly have we discovered for those 200 years?

Is the firing of the neurons completely dependent on external stimuli? A sort of an input/output connection as in computers?

>>5569302
cheers bro :)

>>5569323
>>5569315

these and this one should answer some of your questions

>>5569326

and this is the end of the section.

>>5569310

It's completely dependant on external stimuli, or lack thereoff.

Even in sensory deprivation chambers your neurons are firing. You do not need an external stimuli to produce an action potential in neurons. Internal intentions/thiughts/etc can as well. Just like you don't need to think about breathing, its regulated by the body.

>>5569339

dependant on external stimuli/internal stimuli**

here's some on visual perception, closer to OP's question

>>5569242
>How far have we gotten understanding how the human brain works /sci/?
How the whole human brain works? Quite far. That doesn't mean we haven't learned an awful lot about it in the last three decades though.

>Where do the impulses that neurons send originate from?
That differs per neuron. Most neurons have their own intrinsic firing rate: they contribute to the production of their own spikes regularly. Variations in firing rate though are produced by sensory input. E.g. the optic radiation is the major source of V1 spiking, tracts projecting from the medial geniculate are the major source of A1 activity, etc. There is also a great deal of lateral and retrograde connectivity in the brain, where neural populations 'higher up'* in the processing stream influence downstream areas. In simpler terms, neurons spike by themselves, but mostly because of their input from other neurons, which ultimately originates from sensory modalities.

>Do neurons work like logic gates?
Not really, no. A neuron isn't a simple on/off system. There is continuity in the processing of input signals that gets summed up in a non-binary fashion. There is weighting in input strength, and there are variations in output signal. A neuron can fire rapidly, in bursts, slow but steady like a pace maker, align its firing temporally to the ongoing field potentials, and there is information embedded in all these firing characteristics.

*I used the scare quotes because the term 'higher up' implies there is a set serial hierarchy in cortical processing. This view is outdated somewhat, and is a simplification of reality. Cortical processing occurs in parallel in a great deal of cases, and only occurs serially upon approximation.

>>5569348
And here goes the thread ....

Why do fucking tripfags always have to ruin everything? This is why we can't have nice things.

>>5569347

>>5569350

here's a diagram of >>5569350 and
>>5569352

>>5569242
>How far have we gotten understanding how the human brain works /sci/?

Not very far. We can't even explain qualia and consciousness.

>>5569349
My bad for posting on-topic.

>>5569355

>>5569339
So, dreams are like an "inertial effect" of the brain being active whole day?


>You do not need an external stimuli to produce an action potential in neurons. Internal intentions/thiughts/etc can as well
But how do we define a "thought"? Electrical charge passing through neurons?

>>5569362

and last one, have to go study so I actually do good.

later /sci/entists.

>>5569348
Interesting, you seem very educated.

On the top of my head, how would for example a visual stimuli that catches your attention translate to neural activity compared to one that doesnt catch your attention? I probably figured this while writing it though, it will pass through neurons that fire up rapidly right?

>>5569424
That's a big question, we've been trying to figure out how attention works for quite a while now. What you're describing though is close to the bare-bones mechanics of how we believe attention influences sensory processing. The difference being that a stimulus that falls within the attentional focus is processed 'with priority', though this priority is not necessarily governed by an increased firing rate of the neurons which process it.

Basically, stimuli compete for processing in visual cortex, and they laterally inhibit each other. Higher cortical areas such as the frontal eye fields modulate activity in visual cortex to give one stimulus a processing advantage over the other by temporarily increasing gamma band oscillatory power* over the region of visual cortex that is responsible for processing that stimulus. That leads to the lateral inhibition of processing of all the other stimuli in the rest of visual cortex.

*Oscillations are rhythmic fluctuations in the excitability of populations of neurons. An increase in the power of an oscillation means that the neurons which produce the oscillation are firing in a tight and coherent temporal relation to each other.

>>5569456
Hope I'm making sense here. If not, let me know.

>>5569456
Yeah I think I got it, the priority of the processing of stimuli is regulated by other neurons. But how is the "attentional focus" determined?

Though I was actually wondering how are sudden attention shifts handled, as in an unexpected situation. Which brings us to, how does the brain deal with expectations? :) They must have something to do with short-term memory? Or am I going to far again? :)

>>5569520
You must understand that examining the brain as different systems is just a way to understand it. In reality it's all so interwoven and constantly modulating that making a clear distinction becomes rather impossible.

Attention can best be explain with the work desk model: Imagine your brain (more precisely the prefrontal cortex) being a desk. The things on the desk are the ones you're paying attention to. There is a limited amount of space on your desk and it can only fit that much. A certain concept can hold little place on the desk, or a lot, the more space it takes the more attention it receives.
So, if a lot of your workdesk is taken by a book then you'll concentrate on that book and stimuli coming from that book will have a much higher priority than others. To the point where you can be so absorbed reading you won't notice someone calling your name.

Attention is in turn moderated by other things, such as things hardwired to your brain, like thirst and hunger. It's much harder to concentrate when you're hungry.

Also consider the fact that, for example, visual processing can occur in a crude and refined form. The refined one takes place in your occipital cortex, the crude one is a prelude to that and takes place in the thalamus. Now, if you see something alarming you will shift all your attention to it, before even getting a good view of it. Like an object rapidly moving towards you, you will instinctively get out of the way, even before you can properly see what it is. That's because the Thalamus processes the information quicker and gives an immediate response.
And that's just scratching the surface, the brain is pretty much the most complex thing known to humanity. And ironically enough I'm not even sure we have the mental capacity to fully and completely understand it in its entirety.

>>5569672
But that's wrong you faggot

>>5569672
tl;dr

How hard would it be to create some kind of implant that releases reward chemicals in your brain when you do something that isn't normally rewarding but is good for you. Like, the satisfied feeling your brain gives you after eating a big steak, except for like, homework.

>>5569807
eat a big steak after finishing your homework.

>>5569807
Leave jellybeans on every paragraph of your textbooks. When you reach a jellybean eat it.

>>5569807
This might sound weird, but masturbate while doing homework. You will eventually develop a fetish for it, but it might take a while.

But basically doing anything pleasurable while doing something non-pleasurable (like listening to music while doing homework) will basically train you Pavlov-style.

>>5569807
Be interested in what you're studying.
Realize that just because society says you need to get a job to survive in this world that doesn't necessarily make it true.
Realize that this is your life and you can make your own choices but that those choices have consequences.
When you can do that and be fine with it you will be better off.
Wait... what was the question again?

>>5569807
It's been done with rats, sorta.
They made a rat sized lever that upon being activated by the rat would trigger (I think electrically, if I remember correctly) the pleasure center in their brain.
What happened?

The rat kept pushing the lever, ignoring food, females wanting to mate and simulated danger stimuli until it eventually died of dehydration.

So in case of homework you'd literally work until you lost consciousness and died, probably becoming extremely aggressive to anything and anyone attempting to detract you from your work.

>>5569870
Yeah... if he was a rat.
Humans are not rats.

>>5569878
What do recreational drugs do?

They have different working mechanisms, but eventually they all lead to the same sensation, that of triggering pleasure.
If that alone can make people addicted, what do you think will happen if a person can expose himself to pure pleasure at will.

My favourite writers, the Strugatskys wrote a book about it.
https://en.wikipedia.org/wiki/The_Final_Circle_of_Paradise

>>5569896
That alone doesn't make people addicted in the majority of cases.