Ask a physicist anything. (5)

[Naraoia]

Archaea really fascinate me. They're like Scwartzenegger and Chuck Norris combined in a single cell organism. (well, or rather the people/machines those actors portray) Wherever and whatever no-one else can survive they thrive in. Heat stuff up? Still going strong. Cool stuff down? No problemo!

Good luck trying to get rid of them with an autoclave

And on top of all that, they are also really really abundant in less extreme places. That came as a total surprise to me a couple of years ago. They are always sensationalised as these sci-fitastic extremophiles that would survive even Coke, and then you do a bit of research and realise that most of them are perfectly ordinary microbes making perfectly ordinary nutrient cycles roll.

Of course I find bacteria fascinating too. Just consider extremely toxic environments like poisoned pools left behind after a mine has run dry. Especially older mines where really toxic chemicals were used. Bacteria - and even higher organisms - adapt and find a way to make things we thought were terminal to any and all life a source of food instead.

Just goes to show how much our idea of "toxic" is based on our own perspective as large eukaryotes

 

[Maxwell511]

Just goes to show how much our idea of "toxic" is based on our own perspective as large eukaryotes

Some eukaryotes can thrive in nuclear reactors, is that right?

 

[TheReasoner]

Some eukaryotes can thrive in nuclear reactors, is that right?

There are eukaryotes that thrive in the Chernobyl reactor. Or, the rests of it at least. A kind of fungus which is utilizing the gamma radiation for energy, so yes. Eukaryotic cells can also evolve to such environments. ( Cladosporium sphaerospermum, Wangiella dermatitidis, and Cryptococcus neoformans Wikipedia informs me. I haven't memorized their names, so I had to check)

That's not very normal though. Ionizing radiation is dangerous for all kinds of life precisely because it's ionizing... It can really wreak havoc on a cell exposed to it.

One reason why we see less of that I believe is that well, bacteria are more plentiful and they also have - normally anyway - a far shorter time between replications. Hence they can adopt more quickly to a new environment. And well... Amoeba and other single cell eukaryotes replicate far far more quickly than us humans do.

 

[Doveaman]

Ask a physicist anything.

When you think about something what causes your neurons to fire in patterns that are consistent with your thoughts?

Are the firing patterns the result of your thoughts, or are the thoughts the result of the firing patterns?

What physical mechanism in your brain initiates and drives the current flows in the neurons associated with your thoughts?

Thank you.

 

[Gracchus]

When you think about something what causes your neurons to fire in patterns that are consistent with your thoughts?
Are the firing patterns the result of your thoughts, or are the thoughts the result of the firing patterns?

The firing patterns are the thoughts.

What physical mechanism in your brain initiates and drives the current flows in the neurons associated with your thoughts?

Chemical changes cause electrical changes in potential, which in turn cause other chemical changes at the synapses.

 

[Doveaman]

The firing patterns are the thoughts.

What causes such specific firing patterns?

 

[chris4243]

The nerves have receptors for hormones, which when received set off a signal cascade that depolarizes the cell, rapidly transmitting the signal along the axon and ultimately releasing hormones at other synapses. Then it takes a while for the cell to repolarize. The neurons interconnect in circuits in a vast web, so that each neuron kind of contributes to its own firing again later on. This we call thought, mood, decisions. Damaging the neurons will impede thought (and certain neurons have been mapped to very specific mental abilities), also the network can be modified by inserting electrodes or temporarily some sort of focused electromagnetic pulse.

We have drugs to modify the neural network, for example dopamine re-uptake inhibitors will inhibit the re-uptake of dopamine at the end of the axon so that it spends more time stimulating the receptors at the synapse.

 

[mzungu]

What causes such specific firing patterns?

The same applies to insects. Also are you implying that Dynamite is intelligent because it knows how to explode? Or a Thermos is intelligent because it knows when to keep something hot or when to keep something cold?

Back to cartoon physics again?

You are trying to add the God equation to reality and this is like putting matter and anti-matter together!

 

[Wiccan_Child]

When you think about something what causes your neurons to fire in patterns that are consistent with your thoughts?

My thoughts originate as neurons firing, so if I'm thinking about X, it's only because my neurons are firing in the corresponding pattern.

Are the firing patterns the result of your thoughts, or are the thoughts the result of the firing patterns?

I'd say it's a bit of both. Arguably, my thoughts are the firing pattern.

What physical mechanism in your brain initiates and drives the current flows in the neurons associated with your thoughts?

My brain is constantly firing and firing and firing, so patterns exhibited now are just a consequence of patterns fired just now, which were caused by patterns fired a moment ago, etc. Part of a baby's growth is plastic change in the brain as the brain carves out 'grooves' of synaptic patterns. They learn motor control by essentially randomly sending signals to muscles, and then saying "OK, pattern A makes the right pinkie contract".

 

[mzungu]

My thoughts originate as neurons firing, so if I'm thinking about X, it's only because my neurons are firing in the corresponding pattern.


I'd say it's a bit of both. Arguably, my thoughts are the firing pattern.


My brain is constantly firing and firing and firing, so patterns exhibited now are just a consequence of patterns fired just now, which were caused by patterns fired a moment ago, etc. Part of a baby's growth is plastic change in the brain as the brain carves out 'grooves' of synaptic patterns. They learn motor control by essentially randomly sending signals to muscles, and then saying "OK, pattern A makes the right pinkie contract".

Also the brain does the same thing with vision; It learns how to see.

If you took a blind person who was born blind and gave him vision at say when he is an adult; Then his brain will not be able to recognise what it sees. It will all be colours, shades, unrecognisable patterns.

Humans are born prematurely because they would would not be able to be born naturally due to size. It is hard enough as it is already because our heads have evolved faster than the female pelvis. Thus when we are born we are like a house that is built and handed over to the owner without the wiring being completed by the electrician.

So the electrician is still wiring the house (brain) for months after the birth.

The Brain learns to make sense of what it sees, hears, and feels. In fact the human brain only sees less than 20% the rest it adds virtually from experience.

YouTube - Seeing Is Believing: How the Brain Interprets Vision

 

[Doveaman]

The same applies to insects.

I suppose.

Also are you implying that Dynamite is intelligent because it knows how to explode? Or a Thermos is intelligent because it knows when to keep something hot or when to keep something cold?

Nope. That would be intelligent design.

Back to cartoon physics again?

You are trying to add the God equation to reality and this is like putting matter and anti-matter together!

I don't have a clue what you're talking about.

Humans are born prematurely because they would would not be able to be born naturally due to size.

Again -->

Was Adam born naturally at full size?

 

[Doveaman]

My thoughts originate as neurons firing, so if I'm thinking about X, it's only because my neurons are firing in the corresponding pattern.

Okay.

I'd say it's a bit of both. Arguably, my thoughts are the firing pattern.

Will this, then, require an intelligent source in the brain to interpret those firing patterns/thoughts?

My brain is constantly firing and firing and firing, so patterns exhibited now are just a consequence of patterns fired just now, which were caused by patterns fired a moment ago, etc.

Interesting.

Part of a baby's growth is plastic change in the brain as the brain carves out 'grooves' of synaptic patterns. They learn motor control by essentially randomly sending signals to muscles, and then saying "OK, pattern A makes the right pinkie contract".

Why must the signals be sent randomly? Why not intelligently?

 

[Wiccan_Child]

Will this, then, require an intelligent source in the brain to interpret those firing patterns/thoughts?

No - the brain is the thing that pairs up neural patterns and resulting behaviour. Physiologically, those pathways which 'work' will be used over and over again, making them more deeply engraved in the brain, so the brain becomes better trained in knowing how to, say, walk.

Why must the signals be sent randomly? Why not intelligently?

Because the brain is still ascertaining its own body - it doesn't know what synaptic bursts do what, so it's trying them all out at once. That's why babies develop best when properly stimulated - they get to practice using their muscles.

So it's random because the baby doesn't yet know what does what. It's like being given a blank keyboard and being told to figure out what button does what. Effectively, your trial-and-error efforts are random.

 

[Doveaman]

No - the brain is the thing that pairs up neural patterns and resulting behaviour. Physiologically, those pathways which 'work' will be used over and over again, making them more deeply engraved in the brain, so the brain becomes better trained in knowing how to, say, walk.

I see what you mean, but this only explains a brain learning to walk. It doesn’t explain a brain that can already walk. In other words, why does the brain generate walking patterns only when we "choose" to walk? Where is that "choice" coming from? It seems to me like the brain only fires to walk after we "choose" to walk.

Because the brain is still ascertaining its own body - it doesn't know what synaptic bursts do what, so it's trying them all out at once. That's why babies develop best when properly stimulated - they get to practice using their muscles.

So it's random because the baby doesn't yet know what does what. It's like being given a blank keyboard and being told to figure out what button does what. Effectively, your trial-and-error efforts are random.

I suppose it depends on how you look at it.

If I don’t know which pair of shoes fit I can intelligently decide to try them all before settling for one. There is randomness involved, but the randomness is the result of an intelligent decision.

 

[Wiccan_Child]

.

Speechless?

 

[Doveaman]

Speechless?

Lost for words. But I eventually found them. See above.

 

[Wiccan_Child]

I see what you mean, but this only explains a brain learning to walk. It doesn’t explain a brain that can already walk. In other words, why does the brain generate walking patterns only when we "choose" to walk? Where is that "choice" coming from? It seems to me like the brain only fires to walk after we "choose" to walk.

Again, it's all from pre-existing patterns. Studies have been done which show that you 'choose' to walk after the brain has already begun moving the muscles to begin walking. It chose to walk because its algorithms and instinctive and learned behaviours lead to another instance of the pattern, 'walk'.

Right now, my brain thinks its good to perform the patterns that lead to me typing this post. Patterns upon patterns upon patterns.

I suppose it depends on how you look at it.

If I don’t know which pair of shoes fit I can intelligently decide to try them all before settling for one. There is randomness involved, but the randomness is the result of an intelligent decision.

Not quite - 'random' doesn't mean 'random with a uniform distribution'. You can use your intelligence and prior knowledge to tailor your choices and get a different distribution - you would be more likely to choose an adult shoe than a child's shoe, even though your choice is random.

 

[mzungu]

If I don’t know which pair of shoes fit I can intelligently decide to try them all before settling for one. There is randomness involved, but the randomness is the result of an intelligent decision.

Scientists grew rat brain cells on a circuit board. The board was connected to sensors. Pretty soon the cells began to organise themselves and react to the sensors. Every time the cells turned the robot and avoided collisions a chip would reward the cells with a pleasant electrical current.

Eventually the robot ended up reacting to all the sensors and voila; A biological brain was organised by the cells and it became an integral part of the robot.

YouTube - Robot with a rat brain

 

[TheReasoner]

Scientists grew rat brain cells on a circuit board. The board was connected to sensors. Pretty soon the cells began to organise themselves and react to the sensors. Every time the cells turned the robot and avoided collisions a chip would reward the cells with a pleasant electrical current.

Eventually the robot ended up reacting to all the sensors and voila; A biological brain was organised by the cells and it became an integral part of the robot.

YouTube - Robot with a rat brain

That
is
awesome

^^

I smell a focus for my degree and potential patents ;-)

 

[Assyrian]

Scientists grew rat brain cells on a circuit board. The board was connected to sensors. Pretty soon the cells began to organise themselves and react to the sensors. Every time the cells turned the robot and avoided collisions a chip would reward the cells with a pleasant electrical current.

Eventually the robot ended up reacting to all the sensors and voila; A biological brain was organised by the cells and it became an integral part of the robot.

YouTube - Robot with a rat brain

So if they are planning to take over the world, they know how to keep out of our way in the mean time?