‘Neuroscience? Cool! So, can you read minds yet?’
It’s a truth universally acknowledged that a neuroscientist at a party will inevitably be asked this question. Along with several others – the answers to which should really be printed on a t-shirt, or at least a conveniently distributable business card (as you can tell, I’m a riot at parties):
- No, it’s not (usually) brain surgery, actually.
- For the last time no, that left brain/right brain thing is a myth.
- No, no one knows what consciousness is.
- You only use 10% of your brain at one time? That’s impressive efficiency. And here me and everyone else are using all our brains, all the time.
And, of course, no we can’t read your mind (at least not in the way you’re thinking). But we can read your brain.
Or so it would seem, according to a study published this month, which used a brain scanning method called diffusion MRI to generate individual brain ‘fingerprints’. Diffusion MRI is a technique which visualises white brain matter (the bits of the brain which act as connecting ‘wires’ throughout it – they literally look white compared to the ‘grey matter’ that makes up the rest of the brain) according how much water is travelling through it. Brain imaging isn’t exactly news, but this study was different because rather than looking at a person’s white matter connecting different brain regions, they focused on how connected tiny adjacent 3D sections within the white matter were. In a nutshell: instead of looking at how a wire connects your computer to a plug, they were looking at how the fibres within the wire itself were connected. They were looking at something called the ‘local connectome’.
By narrowing down the focus to the local connectome it appears that we may be able to accurately spot unique differences between brains. Using computer-based methods to calculate how different any two ‘fingerprints’ they generated in this study from 699 brains were, the researchers were able to correctly tell if two ‘fingerprint’ snapshots of the local connectome were from the same brain or not with 100% accuracy, across 17398 fingerprint comparisons.
Source: Yeh et al. (2015)
Not only this, but looking at brain connections in this focussed way might be able to tell us how a single healthy brain changes over time. Brains are nothing if not complicated: they constantly make tweaks and changes to how their different areas are connected in response to your experiences and how the world around you changes. So, not only is my brain different to yours – my brain will also be different to itself minutes, weeks, years from now. By comparing multiple local connectome fingerprints from the same brain – snapshots taken over time – the study found that connections were changing, and losing similarity from their first fingerprint at a rate where fingerprints were 13% less similar every 100 days (see blue arrows in the image above for examples of changes). So, next time someone tells you ‘you’ve changed, man’ – yes. Yes, you probably have.
And sadly, before anyone gets carried away, although ‘brain fingerprinting’ sounds like something taken from a futuristic court room drama – there’s an obvious flaw to this being used as a means of criminal identification, ever. (‘Well, we’ve been doing a lot of thinking and…those are not the defendant’s fingerprints!)
At first, this might all seem a bit obvious. At any present moment, our thoughts, the way we behave, view and experience the world – and so, our brains – have been shaped by our own highly individual past experiences. We are unique. To illustrate this, identical twins are more similar than any 2 humans you might grab (with their permission) at random. But imagine if being an identical twin meant you not only looked identical to your twin, but you also had literally the same identical thoughts and brain processes constantly running in synch.
Yet, conflictingly, if you look at any 2 healthy brains they largely just appear to be squiggly lumps of jelly: indistinguishable. Even if you know what the different lumps and folds and bits are, your average brain has all of them so still looks largely similar to any other.
It’s a similar question to the one genetics has posed in past decades: how come I can share as much as 98.8% of my DNA with a chimp and yet quite obviously not be a chimp? We can spot differences between healthy and non-healthy brains (though this doesn’t mean we know what the difference means) but what about those tiny differences that make my brain mine and your brain yours? It seems that focusing on the local connectome, as these researchers did, might be one promising way of looking at this accurately in future, as well as for identifying differences in diseased brains.
Now all we need is a litmus test for spotting a neuroscientist at a party.