
A neuroscientist had his brain scanned for a year and a half - bpolania
http://priceonomics.com/the-first-quantified-brain/
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russpoldrack
Thanks for the interest in the study (I'm the first author/experimental
subject). I seem to have survived with no lasting effects - at least small
pieces of metal are no longer clinging to me :-)

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alias123abc
This is awesome, would be great to see you speak at one of the Quantified Self
meetups in SF! -
[http://www.meetup.com/quantifiedself/](http://www.meetup.com/quantifiedself/)

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russpoldrack
would be happy to - I talked about it a few years ago at a QS meetup in Austin
when we were just starting

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alias123abc
cool - I'll do some work with the leaders of the SF meetup to see if we can
coordinate and be in touch!

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TaylorSwift
"Poldrack’s team found more connectivity in certain networks of the brain --
particularly between systems associated with movement and vision -- if he
didn’t have breakfast and coffee. Poldrack says that’s surprising: “If
anything we would have predicted that if you’re tired and caffeinated,
connectivity would have gone down.” Figuring out why this effect occurred
might be a fruitful avenue for research."

It is very intriguing and interesting that neural connectivity in systems of
movement and vision is increased when one is fasting. My speculation is that
those neural activities are handed down from our early ancestors. Perhaps when
we were hungry, our brain is actively scanning our surrounding areas for ways
of obtaining sustenance.

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OldSchoolJohnny
It made me nod in agreement when I read that. Anyone who has fasted for a
minimum amount of time, at least 10 hours or so can attest that you end up
with an incredibly clear head, powerful sense of smell and very "switched on"
vision system where everything seems sharper and clearer.

It's a well known effect and this shows one mechanism behind it.

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eecks
> Anyone who has fasted ...

I don't find that at all

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wyldfire
A link to the data:
[http://results.myconnectome.org/](http://results.myconnectome.org/) \--
pretty interesting, IMO!

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brechmos
As a note, there is a longer study, weekly for 3.5 years, that has been
published, in part, at:
[http://journals.plos.org/plosone/article?id=10.1371/journal....](http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0140134).

The results in this paper relate to the functional MRI aspect of the study.

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peter303
I wonder if there are any risks to spending a cumulative 20 hours in a MRI
machine other than the loud noise he mentioned?

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ska
None that are known or expected, although I don't believe effect of high field
and high field gradients are really well understood.

For what its worth there are people who have been in for far more than 20
hours (e.g. hundreds of cumulative hours).

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ihnorton
There can be one effect during diffusion-weighted scanning, which is muscle
twitching due to induced depolarization when the gradients are ramped hard.
I've had that happen a few times and it was a fairly weird sensation, but not
discomforting enough for me to stop the scan. No long-term issues that I'm
aware of though.

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ska
This is called peripheral nerve stimulation (PNS), and isn't specific to EPI
(e.g diffusion scans). This

That's fair though, I really should have been more specific: You can certainly
harm a human being with the piece of machinery known as an MR scanner. Much
more so than just PNS, you are dumping energy into the body via RF, so there
is a specific absorption rate (SAR) limit applied to avoid going into ranges
that will damage tissue.

What I was refering to was limited only to the effect of exposure to _fixed_
magnetic fields in an MR, and gradients and RF coils as they are constrained
for clinical use.

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codeulike
Tldr: he had an MRI twice a week. Cross referenced with other data about mood,
diet, blood. Didn't find much out because sample size = 1.

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agumonkey
Also interesting to know that someone can go through 104 MRI per year safely.

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cvarjas
MRI magnets primarily interact with the nuclear spin of protons, which can
align with or against the field. Adjusting the orientation of the spin should
not change any reaction chemistry, so there is no significant hazard. The
nuclear spin orientations shift back into their normal equilibrium once the
magnetic field is removed.

The radio waves generated for the technique can cause heating when the energy
is absorbed. This should be limited by how the MRI is designed, however I am
not familiar with the detailed design of MRI instruments.

More research could be done in this area for very long term effects, but I
haven't seen any convincing evidence for concern.

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FreeFull
Won't the strong magnetic field squish the electron orbitals somewhat, causing
a minor effect on chemistry? (an even stronger magnetic field would be toxic,
in a way)

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cvarjas
This might be possible but I don't think the effect is significant. Nuclear
magnetic resonance spectroscopy is used extensively to analyze molecular
structure and monitor reactions. NMR instruments commonly have about 7-14
tesla magnets.

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FreeFull
Yeah, we might not be capable of producing magnetic fields strong enough to
noticeably alter the chemistry of anything. I'm not sure at what intensity the
effects would begin to be noticeable.

