Can brain scans reveal behaviour? Study says not yet(nature.com)
nature.com
Can brain scans reveal behaviour? Study says not yet
https://www.nature.com/articles/d41586-022-00767-3
8 comments
I had a conversation with a PhD neuroscientist who was quite prominent and good in her field. She didn't have nice things to say about fMRI studies. Full Stop. That was ~10 years ago, so I'm sure techniques have improved, but she was arguing on the principle that the time scales on which it can measure just aren't conducive to measuring the actual activity that neurons produce.
The field is still mostly the same
One generalizable takeaway from this - smaller studies can only show really huge effect sizes. This is what statistical power means - to see small differences between groups you need really large samples. This is fine if you have actually have a huge effect - you probably don't need a large sample size to detect if sugar causes insulin levels to go up in people that are fasting.
But if you don't really have large effect sizes in whatever you are studying, then you are screwed. All your statistically significant results are going to have really large effect sizes, because those are the only ones you can see in your small sample size. If you didn't get a significant result, you don't publish, or you stop following up, and if you do get a significant result you publish and do more follow up studies. In time with larger studies or new technology that changes how we can measure things, it becomes apparent that you were chasing noise.
But if you don't really have large effect sizes in whatever you are studying, then you are screwed. All your statistically significant results are going to have really large effect sizes, because those are the only ones you can see in your small sample size. If you didn't get a significant result, you don't publish, or you stop following up, and if you do get a significant result you publish and do more follow up studies. In time with larger studies or new technology that changes how we can measure things, it becomes apparent that you were chasing noise.
When people can function at a high level without large parts of their brain I find it hard to believe brains are the source of truth for behavior.
Wounds heal without appreciable activity in the brain.
Neurons are just electrical state we call neurons as a shorthand way of saying “electrical state in the brain”.
This just smacks as some form of geocentrism; “why of course the brain is the center of being.”
Gabe Newell talks about interfacing with the cortex as a tractable problem but we have no idea where to start to induce a sensation of feeling cold.
Michael Levin at Tufts is triggering regeneration manipulating electrical state in limbs directly, not the brain.
There’s more to it than the brain itself, which is why I think using neurons as a model for consciousness will never achieve AI that isn’t obvious.
Wounds heal without appreciable activity in the brain.
Neurons are just electrical state we call neurons as a shorthand way of saying “electrical state in the brain”.
This just smacks as some form of geocentrism; “why of course the brain is the center of being.”
Gabe Newell talks about interfacing with the cortex as a tractable problem but we have no idea where to start to induce a sensation of feeling cold.
Michael Levin at Tufts is triggering regeneration manipulating electrical state in limbs directly, not the brain.
There’s more to it than the brain itself, which is why I think using neurons as a model for consciousness will never achieve AI that isn’t obvious.
It is a pretty long standing joke in medicine that neurologists know nothing about how the brain functions so the "bombshell" description is quite funny.
A lot of these studies use measures for, let's say, memory that are very general that mix multiple memory processes,depending on more distributed brain networks. Some types of memory tests are known to be especially hippocampal dependent, and thus larger effect sizes can be observed (e.g. requiring association between objects, and without the use of mnemonic strategies.)
I can‘t remember where I‘ve read it, but James Fellon was studying patterns in brain scans that indicate a psychopath. He found out, he himself is a psychopath.
I just remember the anecdote, not the outcome of his studies.
I just remember the anecdote, not the outcome of his studies.
His autobiography "The Psychopath Inside" is quite entertaining.