A neuroscientist had his brain scanned for a year and a half | Hacker News Reader

A neuroscientist had his brain scanned for a year and a half

priceonomics.com

77 pointsbpolania56 comments

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 :-)

Thank you for doing the study (especially the self-tracking drudge work) and for publishing both the raw data and the analysis code.

Terrific work! Not presently having time to read the entire paper, I am curious: did you find much of interest in the metabolomic and/or genomic data? Or did MRI prove most fruitful. Also, did you obtain any MRS data?

no MRS data, alas.

there is a lot of interesting stuff in the metabolic and RNA-seq data. metabolomics was mostly related to food and sleep, whereas gene expression was related to psoriasis severity and brain connectivity. Hard to know what to make of all of the relations but they definitely tell us that there is some interesting stuff in there.

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

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

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

You may be the most MRI'd person ever. If nothing else that's pretty neat!

other people have definitely spent more time in a scanner than I have - what's different about this study is how systematic we were, and all of the other things we recorded

How neat! Thanks for posting. I've been doing some long term EEG use, but can only dream of that kind of fMRI access. Trying to get a PhD thesis off my back, but when that's done I look forward to playing with your data!!

"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.

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.

> Anyone who has fasted ...

I don't find that at all

A link to the data: http://results.myconnectome.org/ -- pretty interesting, IMO!

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.....

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

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

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).

The only biological effect that I know of that uses spin is the detection of the vertical component of Earth's magnetic field in bird eyes. [1]

I don't think the effect has been reseached further (such as exposing birds to a very strong magnetic field and see if their perception is altered afterwards, not sure whether that would pass an ethics commitee..)

The floating frogs were supposedly fine afterwards. [2]

Supposedly, if any long term effects occur, they are subtle. There is a lot we do not know yet - for example, cells seem to be able to communicate through glass. (How? no clue. Photons have been proposed.)

[1] eg http://www.physicscentral.com/explore/action/pia-entanglemen...

[2] http://www.ru.nl/hfml/research/levitation/diamagnetic/#Whyfr...

</rant>

While I applaud your use of citations, do you have another one for cells being able to communicate through glass? That one seems very interesting.

Sure, lmgtfy:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2660427/

which is a study from 2009 on the phenomenon.

Agreed. I have been scanned around 1,500 hours over the years and I have not had any ill effects (at this point). And that is 1.5T, 3T and 7T MRI scanners

I am curious as to why you have been scanned so many hours over (?) years. How was that funded? Did you learn anything especially interesting other than no ill effects?

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.

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.

I had peripheral nerve stimulation nearly every time I did the diffusion weighted scans, but for me too it wasn't bad enough to stop the scan

Almost all people curious about the brain, especially neuroscientists, experiment (ha!) with drugs. I won't assume MRI is safe, but cocaine isn't safe either.

That's just my anecdotally supported prejudice.

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.

Well, there was more than one day.

But yeah, results limited to himself.

It's just a matter of time before there's a kickstarter for a limited functionality MRI-esk device that will allow the multitudes to scan 24/7.

Waiting for room-temperature super conduction and enough computation power to even out the effects of an uneven magnetic field (so you do not need to rotate the full device at high speed to average the field).

There is a lot of ongoing work looking at very-low-field MRI using SQUIDs, but it's doubtful that it will work for functional imaging at any point in the near future.

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

The physics behind MRI is great. All it does is line up the magnetic moments of all the hydrogen atoms in your body, flips their spin with a burst of energy then watches for electrons as they flip back to a lower energy state. Totally safe!

And spin don't affect biochemistry ? naively I'd say everything have a limit..

Pretty sure he was being sarcastic.

No, he was not. It is totally safe.

Chemical interactions are mostly about charge, not spin. I won't say there's no effect at all, but it would be a small effect.

You might be thinking of CT scans? MRI scans should be harmless.

No, but it was the source of my question. I was curious if MRI had negative side effects that would show when done as often.

There has been a lot of work looking at bioeffects of MRI in nonhuman animal models. We looked at this work before we started the study, and were convinced that there was no reason to be concerned about bioeffects at the levels of exposure that I was going to undergo. See http://www.mrisafety.com for a lot more info about MRI safety

You are more likely to get injured from someone misplacing a metallic object and it injuring you. As other people have stated high tesla magnetic fields don't have an inherent detrimental effect .

Why is it so limited in the US? In other countries, they can go well above 10 tesla leading to a dramatic increase in resolution. I assumed it was because there were some inherent danger from more powerful magnets.

That's not really correct.

There are high field research magnets, but most of the stuff over 7T are small animal magnets anyway (it is very much easier to maintain homogeneity in the main field over a smaller bore. So you're well into "research only" territory here.

There are other trade offs with field strength also, so it really isn't a matter of just "bigger is better".

I am talking about research, I almost worked on a project about 5 years ago using >10T MRI datasets from South Korea. The resolution was not on the same playing field as the US datasets available.

Such research scanners exist in the US as well.

None of this is clinically relevant, and none of it is US specific.

To be fair, the SAR problems become bigger at bigger fields too, which is related to what you are talking about. It's not really sensible to talk about this as a "problem of bigger fields" because it is there for all systems, and furthermore is also pulse-sequence dependent. By which I mean you may have a pulse sequence that is fine at 3T but woudl be dangerous at 7T, or 7T -> 10T or whatever.

That isn't actually surprising. There's no reason to think any of the effects are cumulative in any way.

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.

Ha, thanks for that nice explanation.

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)

There has been a lot of work in the past in terms of doing chemistry in a strong magnetic field. As far as I know, no one has actually seen any difference.

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.

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.

I have read that there is some DNA damage associated with MRI, but I don't see where that comes from. Any ideas?

ex: http://www.sciencedirect.com/science/article/pii/S0009912011...

PS: Ands yes I mean MRI not CT.

I agree with the researchers that expanding the sample size should help support whether this effect is substantive. They don't comment on any mechanism of action, and gadolinium contrast agents can be detrimental without an MRI exam.

It does not only change the spin, it can also change the movement of the electrons inside the orbital (oppose manetic field) and when entering a magnetic field the gradient can cause nerve/synapse(?) excitation because of the induced electric field.

True, but I was pretty surprised to see how large the differences were between his breakfast/caffeine state versus fasting state. That's a substantial difference and pretty interesting. I also think just tracking MRI variation (even for n=1) is useful - this kind of detailed longitudinal tracking simply hasn't been published before.

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