
Can your brain really be full? - arnie001
https://theconversation.com/health-check-can-your-brain-be-full-40844
======
hliyan
No more than a neural network can be full. To anybody who has worked with
neural networks, the following comes as no surprise:

    
    
        old information is sometimes pushed out of the brain 
        for new memories to form
    

Weights in a NN like the brain would just gradually shift. Older, seldom-
accessed information will slowly fade.

That said, a NN can suffer from the trying-to-be-jack-of-all-trades, ending-
up-an-idiot problem.

~~~
rndn
Another possibility is that two activation patterns are so similar that they
interfere and thus they merge, one replaces the other or they both become
useless noise. See also:
[https://en.wikipedia.org/wiki/Forgetting#Interference_theori...](https://en.wikipedia.org/wiki/Forgetting#Interference_theories)

~~~
dingbat
this sounds like whats happening during an approach that is sometimes used in
therapeutic settings: where a patient or client is induced into recalling a
memory with negative emotional content, and then guided into transforming that
memory by introducing competing neutral or if possible positive
interpretations. for this purpose the result isnt useless noise, but instead
its useful because the patient or client then experiences less negative
pattern matching in daily life. at least thats the idea.

------
danieltillett
My brain is definitely full. Every new thing I learn comes at the expense of
something else I know (I guess this should be past tense).

The funny thing is I still remember when my brain had spare capacity - I used
to fill it with arbitrary facts like what page I was up to when I was reading
dozens of books at once. When I was young I never read one book at a time or
used bookmarks. I would just remember the page I was up to and whenever I came
back to a book I just turned to the correct page. Of course now I have to use
bookmarks and every book I read is at the expense of some part of my past :(

~~~
jotm
Don't know why you're downvoted.

Technically, our brains do get full, even this article basically says so.

It's just that we don't experience error messages or shut down when that
happens - instead, old memories are replaced with new ones.

The total capacity is limited, but the ability to create new memories is
unhindered.

I wish we could choose what we forget, but it seems it's possible to choose
what you remember - just relearn that stuff or recall it more often, then it
will be at the top of the search results, so to say :-)

~~~
danieltillett
Yes you can choose to some extent what to remember, but if you have a good
memory it is impossible to recall all your old memories so you don't forget
them. My memory is still really good (I am hardly suffering from dementia),
but it is not able to add new memories without losing the old. I hate this,
but I can't really do anything about it :(

------
deciplex
Has anyone who knew what they were talking about every seriously suggested
that your brain could "fill up", like a hard disk running out of free space?
It seems like the closest you could get to that is your neurons becoming
completely static (i.e. not-plastic), unable to form new connections or sever
existing ones. That would kill you pretty quickly, or maybe another way to
look at it is that it happens to you when you die, so the answer I guess could
be "sort of, when you die".

But while you're alive? Assuming you don't just "add more space", to continue
the analogy, it seems like what your brain does is probably closer to lossy
compression, over and over again. And the important bits remain more-or-less
readable.

~~~
rawnlq
To be technical ... from a information theoretical point of view your brain
definitely can't hold infinite information so it definitely fills up in the
sense you can't possibly be adding information without evicting/corrupting
something else. I personally don't think we can reach that point within a
human lifetime though.

Something more interesting to think about is the limits of
[http://en.wikipedia.org/wiki/Working_memory](http://en.wikipedia.org/wiki/Working_memory)
which you probably fill up on a day to day basis.

~~~
anotheryou
when we don't reach it in our lifetime, why do we have that over-capacity
than?

The brain already consumes something like 20% of our energy.

~~~
reagency
Why would you assume that unused spare capacity is a significant fraction of
that expense?

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fasteo
Having no scientific background and inclined to do computer analogies, I tend
to think that our brain works like a RRD database [1], that is, we don't
completely discard old information; instead, we store an aggregation of the
said information as new information comes in. Then, these aggregations become
our knowledge about a given subject; we don't need to store every detail, as
this aggregated view is enough to help us understand new information.

Of course, if we ever need to reconstruct every detail of old info, we simply
cheat, in the confabulation sense [2], possible with disastrous consequences
[3]

[1] [http://oss.oetiker.ch/rrdtool/](http://oss.oetiker.ch/rrdtool/)

[2] [http://www.spring.org.uk/2013/02/reconstructing-the-past-
how...](http://www.spring.org.uk/2013/02/reconstructing-the-past-how-
recalling-memories-alters-them.php)

[3] [http://www.scientificamerican.com/article/do-the-eyes-
have-i...](http://www.scientificamerican.com/article/do-the-eyes-have-it/)

------
anotheryou
Without reading the article: of course. Evolution would not allow for much
overcapacity.

However this will be done through lossy compression (you forget irrelevant
shorter term stuff, you forget details, things get abstracted and generalized
etc.)

~~~
danieltillett
Not that I disagree with your premise, but you can only use evolutionary
arguments for populations in equilibrium. The human population has undergone
so much recent evolution (I actually know of no non-domestic species that has
changed more in the last 100,000 year) that you can't use evolutionary
arguments like this. There may well be people alive that will never use all
the capacity of their brain given their lifespan.

~~~
learnstats2
I suspect this is wrong, although I recognise your apparent authority in this
field.

The human population has gone through more well-studied evolution than other
populations; but, for example, novel species such as the London Underground
mosquito are unlikely to be rare. You may claim that this is effectively a
domestic species, but I claim that's just what we can easily study.

Human lifespans are not very much greater: chimpanzees live to be 60 years
old, and they are 8,000,000-12,000,000 years of evolution away. The difference
in average lifespan is primarily due to progress with infant mortality rate.

~~~
danieltillett
Speciation and evolution are not directly connected, but this is a minor
point. For a population to be in equilibrium the population size has to be
approximately constant. The human population (and our domestic species) have
expanded so much in recent times that we are not in equilibrium. This means
that there are lots of genes of great selective value that have yet to spread
through the human population. My favourite is the ApoA-1 Milano gene which
basic stops you from getting heart disease [1]. This only arose a couple of
hundred years ago and unfortunately most of us don't have it.

1\.
[http://en.m.wikipedia.org/wiki/ApoA-1_Milano](http://en.m.wikipedia.org/wiki/ApoA-1_Milano)

~~~
learnstats2
Yes, human evolution (and heart disease) is overtly very well-studied, to the
extent that we can identify the likely patient zero for a gene mutation
occurring in recent generations.

Our study of any other species comes nowhere close to that. To think that we
can achieve that level of detail in another species is almost laughable. There
are only a few species where we can guess what their equivalent to heart
disease would be.

This doesn't provide evidence that humans are evolving more quickly: not at
all.

~~~
danieltillett
We are touching on a lot of different concepts here, but evolution speed is
proportion to population size not how much it has been studied - on the basis
of genetics fruit fly are much better understood than humans.

My original point is that you can't apply evolutionary principles to humans
since our massive population expansion and recent change from hunter-gather
lifestyles to being farmers make all such assumptions void.

------
mvanvoorden
"...old information is sometimes pushed out of the brain for new memories to
form."

Reminds me of this Married with Children episode I've seen ;)
[http://www.imdb.com/title/tt0642312/](http://www.imdb.com/title/tt0642312/)

------
LordKano
That's my greatest fear.

I'm terrified of the possibility that there could be a day when I hit my
maximum capacity and have to forget things in order to be able to learn new
things.

~~~
reagency
You forget things every single day.

~~~
LordKano
Perhaps but I can't remember what.

------
nodata
Yes, temporarily at least. Flood someone with information and they will stop
to make sense of the information they already have.

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xellisx
I'm sure the beer helps "tidy" it up. =)

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rebelidealist
Could it be that we consume too much useless information on social media and
the internet?

------
dang
Url changed from [http://www.scientificamerican.com/article/can-your-brain-
rea...](http://www.scientificamerican.com/article/can-your-brain-really-be-
full/), which points to this.

