Neuroscientist Anil Seth Answers Neuroscience Questions From Twitter

Hi, I'm Anil Seth,

welcome to Neuroscience Support.

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My BF and I just watched that episode of Black Mirror,

which is fantastic, isn't it?

where they have a device that can harvest your memories,

kind of like in Meet the Robinsons

and it seems hella advanced,

but can we now implant fake ones?

The future is now.

that means yeah.

Can we implant new memories?

This is possible, I think in some limited way,

we can implant new memories,

our memories are just very unreliable,

people can reliably misremember what happened,

if they're told a plausible story,

but we can also do it more directly,

hypnosis is a powerful technique,

it's not just some stage trickery, hypnosis is real

and through hypnosis, you can induce false memories.

Watching a (bleep) ton of '90's music videos today

and I am wondering where in my brain

I've stored all of these really nonessential lyrics

and if I can clear that space for something useful?

Now, I don't know what's nonessential

about '90's music videos,

that's a central part of my own personality for sure,

so I don't wanna devote that space to anything else at all,

but it's a really good question, how do we store?

We seem to be able to remember

an enormous amount of information,

the adult human brain has about 90 billion neurons,

it has about 1,000 times more connections,

which means if you counted one connection every second,

it would take you about three million years

to count them all, there's a lot of connections in the brain

and if you think that a memory

is just a particular pattern of connections,

this repeated among a large number of neurons,

the number of memories that you could potentially

store in a brain is infinite.

BohemianMyAss,

Is it possible to punch yourself in the brain,

so that you just forget certain memories

and stuff like that?

I wish it was.

Actually forgetting is very adaptive, it's very useful,

it would be terrible to remember everything,

in fact some people with really, really good memories

have a lot of problems in their lives,

because they simply can't forget,

so is there a way to just get rid of particular memories?

We're not quite there yet,

but there's some interesting work

just with mice at the moment,

that shows that it is possible

to eliminate certain memories from mice,

whether that will also apply to humans or not

is a long way down the road,

but don't punch yourself in the brain,

that's not gonna do it.

It says (laughs),

Old people thinking that millennials use social media,

because you get a hit of dopamine when you get a text,

do you know how neuroscience works?

Dopamine, this chemical in the brain,

that's often associated with rewarding stimuli,

it means that many things can be rewarding,

it's not just a bit of chocolate,

so does a Tweet or a Facebook update,

does that really release dopamine in the brain?

It's a pretty good guess,

if we find something like that rewarding,

that will involve the release of dopamine.

Steffen Konrath asks, Is it possible to read our brain?

It's becoming possible in the sense

that we can record activity from the brain now

using a variety of different methods,

we're not in some weird science fiction scenario,

where I can point something like a hairdryer at your head

and know exactly what you're thinking,

but in a more constrained situation,

where the kinds of things

that you might be perceiving is restricted,

then yeah, we're beginning to make progress

and another way this is really helpful

is we can begin to read from the brain movement intentions

and this can be extremely helpful for people with paralysis,

because we can start to build

what are called brain-computer interfaces

and use signals directly from the brain

to control arms or control robotic limbs

and this is a great example

of why brain reading is still quite limited.

On the left, there's a duck

and on the right, there's a reconstruction

and it doesn't look that much like a duck yet,

actually this guy, Yuki Kamitani, he's actually,

he's one of the world's leaders in this area actually,

so Kamitani actually, he's done some brilliant work

on decoding people's dreams,

because if you can decode the brain, while people are awake,

you can also apply the same algorithms

while people are dreaming

and begin to generate all these weird patterns

of what the perceptions are that the brain

might be generating, while you're dreaming.

KT ATK asks, Is there a part of the brain,

that senses a bad decision and tells you not to do it?

'Cause I don't think I have that.

This is a great question,

it gets at one of the central issues

in neuroscience, which is free will

and there are different parts of the brain

that are involved in the execution of voluntary actions

and in the inhibition of voluntary actions.

There was a very famous case,

a guy called Phineas Gage in the 19th century

was working on the railroads and a huge piece of metal

went straight through his frontal lobes.

The first miracle was that he survived.

After he recovered, he seemed to be fine,

but it rapidly became clear that he'd lost all his ability

to monitor and control and withhold his actions

and he started behaving very inappropriately.

What happened to him was the loss of the part of the brain,

that helped exactly this question,

that senses a bad decision and tells you not to do it.

We've all been told to take a deep breath when stressed,

so what is the neuroscience behind

why this quick tip helps so much?

Well, there's a simple answer to this,

which is that the brain needs

a lot of oxygen to function properly,

so if you're starved of oxygen, taking deep breaths help,

but there's also more complicated story,

which we're only, as neuroscientists beginning to unravel.

We've known for a very long time now, that decision-making,

doing the right thing at the right time

is very strongly shaped by the state

of our body at a particular moment

and we call this emotion in another way,

so we won't make the right decisions,

unless we have the correct kind

of an appropriate emotional response as well,

but sometimes our emotional response can be too overpowering

and then we'll make wrong decisions,

so taking in a deep breath might just readjust this balance

between what we're thinking, emotions we're feeling

and the state our body is in, so that our brain activity

and our body can become more in alignment.

Is face blindness a real thing

or just an attention-seeking thing?

It's a real thing,

there's a condition called prosopagnosia,

which is the inability to distinguish between faces.

What you find is people with prosopagnosia,

they're still able to identify people,

but they do it in different ways,

they're very good at picking up other cues,

like how somebody walks or what clothes they're wearing

or what voice sounds like,

but they just cannot recognize faces.

When you dream, you dream of things

that you've seen and thought about and all that,

so my question is do blind people dream and if so, how?

Good question, yes, blind people dream, everybody dreams,

in fact, it's not only humans that dream,

it's pretty much every animal with a brain,

at least with this kind of cortex dreams.

Blind people, if they've been blind from birth,

maybe they won't have visual content in their dreams,

but they'll certainly have dreams

very rich in other perceptual content

and nobody really quite knows what dreams are for,

one idea is that when we perceive the world around us,

we have to use these very, very complex models

inside our head about what's out there in the world,

so we can interpret all this sensory data that's coming in

and when we dream, we're basically sharpening

and improving those models,

so that they work better the next day.

Arantxa asks, Can my amygdala like stop?

I wish it could,

the amygdala is a walnut-sized piece of the brain

very deep inside the base of the brain here,

the amygdala is very heavily involved

in fear and anxiety, things like that.

Without a properly functioning amygdala,

we wouldn't be sufficiently scared of things,

that should be scary,

so when we were evolving in the African Savanna,

as, you know, early humans were doing,

probably the most important thing

is to be scared of the right things at the right time

and you need an amygdala to do that.

Do you think transcranial magnetic stimulation

treatment could alleviate PTSD,

Post Traumatic Stress Disorder,

panic, anxiety or Alzheimer's?

Now Transcranial Magnetic Stimulation, TMS

is a relatively new method and what it does

is it just injects short, but very strong pulses

of electromagnetic energy into the brain,

it's not very precise,

you can activate one part of the brain,

for instance, I could activate the parietal cortex here

or the frontal cortex there, so it's pretty non-specific

and the longterm effects are not very well known,

it may be a technique which alongside many others

will help us refine new approaches to these conditions,

but by itself, it doesn't provide

any quick and easy answers.

How does memory work?

Is it/will it be possible

to surgically manipulate specific memories?

How does memory work?

This is a huge question,

one thing is there's more than one kind of memory,

different parts of the brain are involved

in these different ways of remembering things.

To say that we understand how any piece

of that puzzle works would be an overstatement,

but let's just take one, let's take autobiographical memory,

how do we remember things that happened to us specifically?

Now this depends on a very specific part

of the brain called the hippocampus,

the hippocampus is very deep inside the brain,

it's part of what's called the medial temporal lobe,

the hippocampus seems to take in perceptual information

as we walk around, as we move around the world

and then it consolidates these memories

back out into the rest of the brain, into the cortex,

so it's involved in the laying down of new memories,

the memories aren't stored in the hippocampus,

but we need the hippocampus,

in order to lay down new memories

and in order to recover old memories,

if you have damage to the hippocampus,

you will not be able to lay down any new memories,

you might still be able to learn a new skill,

but you will not remember what happened to you,

while you were learning that skill.

Voo asks, How does fMRI work?

This is a fantastic question, in fact, it's a question

I wish most neuroscientists would ask themselves again,

because many of us assume we know how it works

and we still don't really fully understand what it does.

Now fMRI is Functional Magnetic Resonance Imaging,

it's probably the most common,

the most popular method of brain imaging,

put very simply, what fMRI does

is it measures the amount of oxygen in the blood

in different parts of the brain in a very, very precise way

and this is important,

because bits of the brain that are more active,

where the neurons, the brain cells are firing a lot,

they will consume more energy

and so the blood in those parts of the brain

will have a bit less oxygen,

so we can tell how active a certain part of the brain is

by looking at how the oxygenation levels change

and in fact, it's still a very active area of research

to figure out how that signal of oxygenation

actually relates to neurons firing.

Neuroscience says doing this one thing

makes you just as happy

as eating 2,000 chocolate bars, what is it?

A smile.

One of our main sources of pleasure

in the world is social bonding,

so whenever we feel that we're getting

some recognition or some affection

or some positive response from another human being,

then we're gonna feel a lot better.

Whether it's exactly the same kind of pleasure

that we get from eating a chocolate bar, I don't know,

I don't generally feel guilty, if somebody smiles at me

in the same way that I do

if I've eaten a couple of chocolate bars on the sly.

Now I hope I've been able to answer some of your questions,

but the great thing about neuroscience

is there's so much more to discover.

This has been Neuroscience Support with Anil Seth.