Brain_Hawk t1_jeh46nf wrote

Dti does not measure axons.

It makes a model of white matter tracts based on the characteristics os the direction of diffusion. Like so many things MRI, it's a model, and an estimate of how large bundles of axons are organized and traverse through the WM.

If you wanna learn more I bet you can find some good videos on YouTube. :)


Brain_Hawk t1_jeeqlqc wrote

This isn't sociological. It's interventional psychiatry.

Some things of course cannot be blinded, because well it's an intervention that people know they got. And it will design study you can compare the efficacy of different interventions.


Brain_Hawk t1_jedfu27 wrote

First, the average thickness of the cortex is more like 2.5 mm

Second, we aren't explicitly measuring ig each voxel is cortex or non-cortex with a binary 1-0 mask. The way that cortical thickness is measured is by looking at the signal intensity to each voxel, and an algorithm estimates the barrier between gray matter and white matter, or gray matter and the dura matter on the outside of the brain. It does so by considering the intensity of this voxel relative to deeper voxels that are clearly white matter, or voxels that appear more likely to be gray matter.

So let's pretend a voxel that a cortical voxel would have an intensity value of one. Let's say that a voxel of white matter has an intensity value of 0.5

If you encountered a voxel that was roughly 0.75, you could infer that roughly half of that voxel was in the cortex.

Free surfer runs the algorithm across the entire image and attempts to estimate the inner and outer barrier using this approach. I simplified it of course, it's not really saying 0.75 and half the voxel, the modeling is more complicated than that and frankly I don't understand it more than that.

But, the long story short is that by looking at signal intensity the different voxels we can build an estimate a model of where the ribbon of the cortex is relative to the edges of that voxel.

Interestingly these estimates are very reliable across MRI scans. If I scan you today and scan you next week, most cortical thickness measurements will be very stable

Then once you have the outer ribbon, representing the outside of the cortex, and the inner ribbon representing the inside, you can place a perpendicular vertex in that section and estimate the thickness of the cortex

The process isn't perfect, and errors are not uncommon. Particularly in lower quality MRI scans.

I hope that help explains it


Brain_Hawk t1_jed625v wrote

Ok, so first, I think Frontiers is trash. I am very biased against them. Disclosure : )

Where the heck is this 70K coming from? The consort shows 42k, and only 11k included, and 860 with depression.

So the REAL important sample size is 860 with depression. Compared to 10k without... but the focus on odds ratio may alleviate the sample size difference problems.

Also t he depressed and non depressed groups differ on almost EVERYTHING. So why the focus on this diet effect. They have different BMI, blood pressure, age, gender. You can't necessary jsut 'covary' those out. They could have run a sensitivity analysis limiting that 10k non depressed people to a sample matched across other variables. There are challenges here too but... would have strengthen the results.

Lastly, the measure of depression is weak at best, and not at all diagnostic. But that's very typically a challenge of cohort studies.

Some interesting findings maybe, but if I had to rate it (I don't but I'm gonna), C+.

EDIT PS: Seriously, where the hell does that 70k in the abstract come from? Seems so deceptive to me!


Brain_Hawk t1_jechvp1 wrote

Ok so first. Frontiers is trash..I'm embarrassed I ever published therein. Also what does it mean "improvement of symptoms but also their severity"? How is improving symptoms not the same as improving their severity, or am I misreading that?

And the language in that abstract. Wow. Relapse rate that cannot be ignored indeed. I suspect a non native speaker, for which I feel so much empathy ( so hard, imagine doing it in a.sdcond language!!) But that passed review and editors. Very non scientific language in the abstract.

Results ok maybe interesting. Bigger question toe is how it compares to other interventions (I'll admit didn't read that much!) To.some extent, doing nearly anything might improve depression. Sonia yoga better than, say, joining a lawn bowling league? Is it the yoga or the social, etc aspect.

Though one hopes many such studies on yoga had appropriate active controls so mayne im guilry of that thing where people dismiss research via a false belief the researchers lacked basic competence.

I should quick read it but I'm in a Lyft and.almost home, the science day is done :)


Brain_Hawk t1_jeah9f2 wrote

I can understand that. I'm not a big fan most art that you would find in galleries, I don't understand it and I don't think it really speaks to me. But I can understand how if you think of the right context it can help you, on a particular if you think about the technique and how the artists use certain tricks displayed some skillet can enhance the value of the art, or your appreciation

It's like how a musician will appreciate certain musical compositions for their challenging nature or for the way they break conventions or do something interesting or new.

I work in research, and when I see a really elegant research design, I always appreciate the study a bit more. Is somebody from the outside world who doesn't see that elegance as easily because it's outside their experience probably would not feel the same. On the contrary, they might find it a little disconcerting because it's easy to misunderstand or it sounds confusing or whatever.

At any rate, whatever works for people is what works for people.


Brain_Hawk t1_je2e2eb wrote

The kind of interesting question and there's been quite a few potentially interesting answers

The fundamental reason that we are the only species of our genus remaining is that we murdered and or interbreed with all the rest of them.

Some of them just couldn't compete. And some of them we basically made friends with enough of them to mix together and kill the rest. Primitive homo sapiens were not a sharing species with our cousins. At least as much as I understand early human anthropology, which is admittedly not well.


Brain_Hawk t1_je2bl04 wrote

I'm a cognitive neuroscientist. I'm not a specific expert on cognitive rehabilitation or training, though I've flirted with similar type of work. I work mainly in psychiatry.

Some of the things we have tried to do include brain stimulation to modulate cognition. Also I've at least read in the past about cognitive rehabilitation programs for different disorders. And I go to conferences where occasionally see posters on cognitive training and generalization

There is probably very little in the human brain that is as difficult to reliably affect as adult cognition. Our cognitive abilities are fairly set it seems by the time we are in our 20s. They can go down, and we can do things that maintain them. But it is very hard to increase those abilities. There may be certain transitory things, like going from a condition of sleeping very poorly to improving your sleep, which will have notable outcomes. But that's more the removal of something detrimental then adding something beneficial.

So I'm not surprised that the net result of a review paper is pretty much a null. Because the majority of things we have attempted to improve human cognition have not been very successful. Sometimes we can substantially train summon up on a few specific tasks, but then we find that extraordinary skill in one cognitive task doesn't generalize to non-trained tasks.

One of the downsides of a review, and I'll admit I didn't actually be the paper, is that they tend to jumble together several factors, and miss some of the nuance that can be happening. So it may be that some very specific cognitive abilities are somewhat enhanced either short-term or longer term by an increase in physical fitness. But a lot of studies that get done tend to be short, quick, and easy, or look at very broad strokes abilities. So maybe with further work we will identify some specific benefits, particularly in the cases of either very intense or longer term lifestyle type major changes.

And, none of this means exercise doesn't have other mental benefits. There's some decent evidence, at least last time I checked, of an antidepressant effect to physical activity. I had a colleague go off sick leave following chemotherapy treatment, because after everything was said and done they were exhausted and depressed. One of the things we talked about is the potential benefits if she can get back into running, because there is a mood boosting effect at least potentially.

So, information, cognition is very difficult to modify in adults. But there may be other mental benefits to physical activity as well. Get me have different benefits and different clinical populations.


Brain_Hawk t1_je2amlw wrote

This is not a form of specifically physical exercise that's going to be tested in a clinical trial. That's more whole experience that includes both physical, mental, and other potential benefits such as being able to nature. So I wouldn't call that approach based on physical activity

I'm not saying it wouldn't be beneficial. I'm saying it's out of scope for this kind of review. Typically the things reviewed include cardiovascular exercise programs on a gym, treadmill, or bike, or other sorts of activities like that. Things that can be done in the clinical setting.


Brain_Hawk t1_je16al7 wrote

That $10 per kilogram is an extremely optimistic estimate cited by a person who was well known to exaggerate in order to drive interest and investment.

Personally I suspect it's going to be quite a bit more than that, not that I'm an expert on launch cost. But I think we need to be a bit more skeptical of the claims being made at this time.

To the bigger question, I think any technology may be feasible in the future, but as far as I can see there's still a lot of challenges with orbital-based power. In particular the cost of sending it up and maintaining it, and the amount of power we can get generated back down on earth, and distributing that to a wide area.

But, if we don't come up with a better solution, it's definitely something I can see being in place in the next 50 or 100 years.


Brain_Hawk t1_jdxheiv wrote

Separate sounds did not necessarily require their own attention. We can still subtly differentiate numerous different sounds simultaneously but not necessarily be attending to the different sources or channels. But they're still an element to which the complexity of that sound is being processed.

Although I guess that comes back to your first point that it depends on how you define hears, and I may just be defining it a bit different than you. Maybe you're defining it as a sandwich is specifically identified, and I'm defining it as the full total complexity of this sound information regardless of whether specific things are process. But, to be fair to that perspective, sometimes we can think back on a sound we heard recently and reevaluated, drawing attention to the memory trace of different aspects of that sound

The end point limit of a TV types sound system is one that equates to being in the environment. But now that I've said that, I realize the limit of that is in fact the neuronal limit of our processing capacity, cuz the fidelity of real life is infinite. The maximum precision of sound in the universe is whatever the plank sound constant length is, which is effectively infinitely small. Sort of. Almost


Brain_Hawk t1_jdxgf04 wrote

Ozempec is not a miracle drug. It is being pushed hard by the pharma companies, and describe like some sort of game changing miracle in the media

But if you look at the actual data, the effects aren't always that dramatic. The case where I've seen, not that I've read a huge amount on it, but the case where I've seen where it worked the best was in a group of young people who had weight struggles who also received a strong support system to go with it. So it kind of facilitates weight loss in the case where you're doing other things that facilitate weight loss, including behavioral readjustments etc

The suggest this primary role might be as a facilitator and the existence of other interventions. Which is helpful of course, but not quite the miracle as described. And still part of a program that requires a lot of work, and it's less clear if this will be effective and people in their 40s

And not everybody who takes it gets significant effects.

And it's not clear if the effects really entrenched in their long-lasting, or if you stop taking it after 5 years you'll just bounce back.

Is extremely expensive.

Some hope there but we should be cautious in reading too much into the existing literature, which is fairly minimal, largely funded by the pharma companies as far as I've seen, and hasn't really been widely tested yet.

Ps caveat that I'm no expert on it, and I take it now and it didn't really have any long term impact on my weight, or on the other people I know who are taking it. I dropped 8 lb, then regained a pounds in 3 months, and stabilized where I was before I started taking it. Anecdote is not evidence though.


Brain_Hawk t1_jdw475j wrote

If you're drinking anything around a normal amount of water, extra is actually a little good for your kidneys as it helps them flush out things and not work so hard

Others have commented on water toxicity, and I thought it would be interesting to share this link

This woman died from drinking so much water during a water drinking contest on a radio show. However, this was pretty extreme, she was chugging it back and it totally unreasonable rate. So I might not recommend for example trying to drink 12 gallons of water one day, because you might die. But unless you're drinking insanely crazy amounts, you're not at risk

However if you do find yourself continuously thirsty and drinking a lot more than seems normal, you might go see a doctor. Excessive thirst can be a side effect of poor kidney function or high blood sugar. Amongst other things.


Brain_Hawk t1_jduukr7 wrote

Part that's missing in the above answer is that the original research was usually blinded. Typically a third person who is not involved in data collection or analysis is the one who was aware of the group labels.

To do properly, during the initial statistical analysis to groups are also done blinded. For example you label them groups a, b, c. Only after you have performed statistical analysis of the effects of the intervention, for example, then do you afterwards get to unblind

So it can happen you have what looks like a very nice effect, and then realize that it's the placebo group we got better! I've seen it happen :p


Brain_Hawk t1_jd92anz wrote

Very interesting ideas. I read this as a perspective possibility as far back is 20 years ago, during a nerdout phase where I was setting up a science fiction game. The idea has always really intrigued me, that there can be a planet where there's this narrow band of habitability scorching death heat of the sunglasses side and the infinite coldness of the dark side

Imagine the science fiction distant future where we could live on such a world, you live in a city that's quite comfortable, but if you go to one side of the extremes of the city the temperature drops 10°, and the other side it raises 10 degrees. While 10 kilometers inone direction and your at a pleasantly hot artificial beach, but 10 km the other way you can go skiing.

Kinda sweet :)

If simple life is as common as I would like to believe it is, I suspect there are many primitive organisms who are surviving on such environments. Not as convinced that such an environment would be well suited to the development of advanced life, but maybe I mean at the end of the day, we really have no idea.

But it's fun to think about


Brain_Hawk t1_jd63jzf wrote

Asteroids are not typically that large, of course there's exceptions. But the gravity on this supposed intersolar object would be almost definitely miniscule. Finding a very large asteroid passing through the solar system seems to be rare, as far as I am aware, though I admit my knowledge here is very limited

So why would anybody want to live on such an asteroid? It's not going anywhere fast. The nearest star intersection is likely to see will be somewhere in millions of years in the future. So all these people are going to go live on this asteroid which is basically living in outer space with no gravity, which will have all kinds of problems for your body, and now they're cut off from the earth and have to live in a small self-sustained society which is by its very nature going to have extraordinarily strict rules and limit people's personal freedom to be huge degree, limit what you can do what you can see if you can talk to, definitely limit who you can sleep with and how much population you're allowed to grow.

Also that in a few million years maybe it will pass through some of the solar system that may or may not have some useful thing to visit?

Nah. That's not a mission that's going to happen even if it were feasible


Brain_Hawk t1_jd637v6 wrote

This is a really good point that didn't occur to me right away, but it's totally true.

At that point the asteroids only helpful if it provides something more. And frankly, the second part release skills it as not worth the time and effort, hop on an asteroid and go... Nowhere