it'd be pretty great to be able to tell what someone is thinking to be able to read their
minds you could use your powers for good you could use them for evil or you could just
get really good at card tricks but there are many times every day in all countries around the world
where doctors are desperate to try to read the mind of someone in front of them
who has had a severe brain injury that's left them entirely unable to communicate so maybe let's
think about that more selfless reason to be able to read people's minds how can we read minds well
if we're going to read minds we need to know where to look first where is the mind well the brain is
a pretty good place to start that's where all of your thinking happens that's where you are
but the brain is staggeringly complicated each of these flashes are brain cells neurons sending
signals to each other as you can see there's a lot going on however this is a video of neurons firing
in a larval zebrafish so that's a zebrafish a type of fish that's only recently hatched
and their brain is less than one millimetre across the human brain is a lot bigger than that it has
around 80 billion neurons that's 80 followed by nine zeros and eight hundred thousand times more
neurons than this zebrafish and each one of those neurons is connected to about ten thousand others
it's the most complicated structure in the universe and we all have one inside our
skulls so how are we possibly ever going to read anything from something so complicated
well maybe let's aim for something a bit easier first like a magician narrowing down the possible
cards you could be thinking of what if we narrow down the possible things that people could be
thinking about what if we first ask people to think of say just one of two possible things
and see if we can work out which of the two they're thinking of it'll be a start but first
we need to measure the brain activity of the person whose mind we want to read
these zebrafish were genetically engineered so that their neurons actually glow
when they fire so then it's easier to see what's happening under a microscope
now we probably don't want to be genetically engineering humans so that their brains glow
just yet but we can get a pretty good look at what people's neurons are doing with a
much less invasive method this fashionable piece of headwear is called an EEG cap EEG
stands for electroencephalography which literally means a recording of electricity from the brain
so when your neurons fire they produce tiny electrical currents but because you have so many
neurons when lots of them fire at the same time the sum of their electrical currents is big enough
to be detected from the surface of your head so now we can measure their brain we're a step closer
to reading their mind now what do we ask people to think about we need two possible thoughts from
which we can read the specific one that they're thinking of right now it turns out that asking
people to imagine that they're moving works pretty well we know that the parts of the brain that are
responsible for physically moving are very similar to those that are responsible for imagining moving
here's some processed EEG data from a healthy person who's imagining moving their limbs and you
can see it's quite a nice clear pattern of brain activity over the parts of the brain that control
movement and we can use this pattern to accurately work out whether this healthy person is imagining
moving their hands or their toes for example and we can be pretty accurate with this to the point
that healthy individuals can use these patterns of brain activity to even control video games
so now we can read their mind or at least we can work out which of
two things they're thinking about without them telling us which is a significant step
so how are we going to use our new found power to read minds for good well we can use this ability
to help understand people who've had severe brain injuries some people after a severe brain injury
will open their eyes and start to show some reflex responses to their environment
like startling at a loud sound but they don't show any evidence that they understand what is being
said to them or that they have any thoughts whatsoever these people with what we call
disorders of consciousness are a big challenge for clinical care because if we don't know
if the person in front of us is conscious or not then we don't know what sorts of medical decisions
are in their best interests or what their chances are of ever being able to communicate again
so how about we ask people with disorders of consciousness to imagine moving their hands and
their toes and then see if we can read their minds and detect that they're following our instructions
well it turns out that an estimated 15 percent of these patients produce appropriate patterns
of brain activity in this sort of task that is they think about what we ask them to think about
and then we can correctly detect that they are doing it in this image here you can see
the pattern of activity is remarkably similar between a control participant and the patient
so to emphasize this more these are people who show no evidence from their behaviour that they
are conscious and yet if we read their minds we can see that some have been misdiagnosed
they're actually conscious they're just only able to show it with our mind reading technology
now it's important to say here that this is only a minority of patients with disorders
of consciousness the majority of patients who are chronically unresponsive after a
severe brain injury are indeed unconscious and many will have a very low likelihood of
making any sort of meaningful recovery if at all these are difficult scenarios faced
by many people every day in hospitals around the world and difficult decisions are regularly made
about whether it's in their best interests to continue treatment or to allow them to
die but this research shows that by reading the thoughts of patients after severe brain injuries
we can find valuable information to help families make these very difficult decisions
in fact in some recent work we found that those patients whose brain activity looks
most like they're understanding what is said to them even if their physical behaviour doesn't
show that those patients are more likely to make a good recovery over the following six months
so this information can help us decide how best to treat these individuals
so learning how to read minds to know if and what someone is thinking can have a very real
impact on patients on their families and their medical teams all around the world
something else that's becoming clearer as we study the brain and the mind more is that thoughts and
experiences are strongly linked not only to the brain but also to the way that the brain and the
body interact you can understand this yourself on a fundamental level when you watch a horror film
or when you listen to your favourite song or when you have to speak in front of your peers
these experiences are accompanied by sensations from your body your thought
might be associated with feeling a bit sick or with your heart racing or feeling a bit dizzy
now this comes from your brain sending signals to your body about your current thoughts
and changing what your body is doing so it's prepared for what might come next
so for example increasing the level of adrenaline that's in your blood
and in turn your body sends signals back to your brain about what those chemical changes are doing
to your body so then the brain can adjust what it's telling the body to do and then this loop
keeps going on and on so that your thoughts your mind essentially is no longer limited
to your brain anymore but is found in the interaction between your brain and your body
so this means that we can actually read people's minds without even looking at their brain
we can look at what their body is doing instead for example how fast their heart is beating and
we know that just from measuring the subtle ways in which a person's heart rate changes over time
we can work out for example whether that person is paying attention to what's being said to them
it's a basic level of mind reading so far sure but one with potentially significant impact as
we've already seen with unresponsive patients so the question we asked at the beginning was
how to read minds well first you need a mind to read for someone to have a
mind to read they need to have a brain and probably specifically a brain inside a body
second you need a way to measure what's happening in the brain and the body you could use EEG as
we discussed earlier or any range of ways of quantifying signals from within the brain and
the body and finally you need to start small we're a long way from accurately knowing any possible
thing that anyone is thinking of in front of us unfortunately but we can definitely use methods
from psychology and from neuroscience to narrow it down to a couple of options and in many cases this
is enough to make sure that we're delivering the most appropriate care to people who are recovering
from severe brain injuries who can't communicate with us and so need us to read their minds