/sci/ - Science & Math

[Anonymous No.5175158]

How does the brain decide when to release neurotransmitters?

And how much? I assume your experiences shape this, but how? why do we get pleasure from different things? are these 'locked down' in childhood, never to be changed again?

Do genetics play a role? because not every kid enjoys the same thing

[Anonymous No.5175206]

What do you mean when? Surely it's a case of stimulus, response (being release)?

[Anonymous No.5175229]

>>5175158

>How does the brain decide when to release neurotransmitters?

You receive some sort of sensory input from neurons that are designed to "fire" (initiate an action potential) whenever certain conditions are met. Example: when a sugar molecule touches taste buds on your tongue, it triggers that neuron to fire. One neuron activates another, and eventually the "signal" reaches your brain, where it is directed to the part that interprets that data.

Neurotransmitters are just how neurons signal to the next neuron to activate. Each neuron only has one neurotransmitter, which they use to signal to their neighbors (because exchanging changes in voltage across the synaptic gap wouldn't be "safe," to put it lightly). So our neurons use neurotransmitters as switches, and so our neural communication is called "electro-chemical" because it uses both changes in voltage within the neuron, and chemicals outside the neuron, to transmit signals.

When neuroscientists say that "dopamine causes pleasure," what they mean is that dopamine is the particular kind of chemical signaling device used in the parts of the brain that are responsible for pleasure. So it's more like "dopamine is commonly used where pleasure is created."

[Anonymous No.5175251]

>>5175229

Continued.

>And how much?

This is a little trickier. Each neuron typically releases the same amount of neurotransmitter per signal, but different neurons may have adapted to release more or less, depending on your genetics and your experiences in life.

Drugs work the way they do because they force your neurons to release unusually large amounts of neurotransmitter, or they prevent your neurons from taking it back in again (so the neurotransmitter sticks around in the synaptic gap, activating the next neuron repeatedly), or they prevent your neurons from releasing as much neurotransmitter. When you feel particularly strong sensations, like intense pain, your neurons are firing more frequently, flooding the gaps between your neurons with more neurotransmitter and activating them repeatedly.

>I assume your experiences shape this, but how?

Neurons, and even entire neuron pathways, that are not used are cut down. A lot of this happens during childhood. You can also obviously kill brain cells by abusing them with drugs, but a lot of loss just occurs because you don't need the extra neurons. This is a good thing.

[Anonymous No.5175268]

I've heard that stem cells migrate out along the radial glia to replace lost neurons, to a certain extent.

[Anonymous No.5175279]

>>5175251

Continued

>why do we get pleasure from different things?

Many of the things we get pleasure from are things that aid in our survival. Eating, sleeping, drinking, sex, fighting. The hypothalamus is responsible for rewarding/punishing you for doing these things, and it signals the reward pathways in the brain (dumping dopamine onto the nucleus accumbens) when you do something good. In this way, it helps to train you to take care of yourself. We can, of course, abuse this reward mechanism. We can use some drugs, thus training us to seek them out and associate them with pleasure. Drugs like methamphetamine and cocaine dump enormous amounts of dopamine into a lot of parts in your brain, but primarily in your reward centers. Because we need to survive, we are wired to be rewarded for survival activities, and then to seek those activities out. We can trick ourselves, though, with drugs.

>are these 'locked down' in childhood, never to be changed again?

A little bit. I talked about the "pruning" of the brain's circuits earlier, but also important is the brain's plasticity: its ability to adapt with what it has. The brain has been shown to rewire itself slightly to adapt to new environmental factors. People who lose some abilities are sometimes able to regain them because another part of the brain compensates. However, some parts of the brain are so specialized that they can't really be compensated for. If your hippocampus is destroyed, you cease to be able to form new memories, and every time you take a sip of coffee, it will be your first taste ever. Most compensation happens in the hemispheres of the cerebral cortex (the sort of fleshy, wrinkly sheet wrapped around your whole brain), where the right hemisphere can often compensate somewhat for lost functions in the left. But again, this is limited by specialization.

[Anonymous No.5175297]

>>5175279

Continued.

>Do genetics play a role? because not every kid enjoys the same thing

Yes. Everything psychological is also biological, and everything biological is at least in part genetic. When you develop a mental disorder, it is because your genetics made you susceptible to that disorder, even if your environment (everything happening outside of your body, including your social environment and chemicals in the air) caused the most drastic change. Likewise, your brain in its healthy state is very much a product of genetics. Identical twins, who have identical genetic coding, are very similar, though we often see differences more easily. In fact, adopted twins who are separated at birth often develop amazingly similar personality traits, and they are always significantly more likely to share mental illnesses.

But again, your reward pathways are dynamic, and even if they do not change, other parts in your brain that are responsible for signaling your reward pathways are capable of change.

So everything psychological has both a genetic and an environment basis. Many people actually don't realize that the "Nature vs. Nurture Debate" is no longer important to psychologists and neuroscientists, because almost everything is a product of both genetic and environmental factors. Personalities, temperament, likes and dislikes, and mental illnesses are all both genetic and environmental.

So I hope that all answers your questions.

[Anonymous No.5175319]

lolz OP left

[Anonymous No.5175327]

>>5175268
only in the olfactory bulb and hippocampus

[Anonymous No.5175344]

>>5175297
>>5175279
>>5175251
>>5175229
So much win. Not OP but just learned a lot. Thanks bro. I'm actually planning on majoring in neuroscience in college. Are you an undergrad?

[Anonymous No.5175357]

>>5175327
>only in the olfactory bulb and hippocampus
MOSTLY in the olfactory bulb and hippocampus.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2423203/

[Anonymous No.5175373]

I have learned a lot, thanks man

[Anonymous No.5175390]

>>5175344

Yes indeed, although my major is biochemistry. I started out as a neuroscience major, and it killed me to switch, but I like the chemistry of it better. It's a blast and I came out of class every day genuinely feeling like I had learned some of the most important stuff in the world.

Look up "neuroskeptic" on blogspot. His blog is good for a read sometimes. He talks about good and bad studies, and about imaging a lot. I can't post the link because spam filter is an asshole.

[Anonymous No.5175520]

>>5175229
>>5175251
>>5175279
>>5175297
>>5175390
Holy fuck thank you good sir. Any other neuroscience, neuroanatomy, or neurophysiology texts/papers/whatnot that you'd recommend from experience?

[Anonymous No.5175593]

Any good books/textbooks/sites you would recommend? I'm going into neuroscience next year

[Anonymous No.5176183]

OP here, thanks mate.