Thinking and speaking are the same thing in the brain.
The most words you've ever spoken in your life
weren't to others;
they were to yourself.
From the moment you wake up to when you fall asleep,
there is a never-ending monologue running in your head.
You think this monologue is perfectly safe
because it never leaves your mouth.
No air vibration,
no sound waves,
no physical trace at all.
It is your final domain of privacy.
But in August 2025,
a Brain-Computer Interface team at Stanford published a paper in Cell.
The title was "Representation of Inner Speech in the Motor Cortex."
This paper tells you one thing:
Every word you say silently to yourself,
your motor cortex is recording the entire time.
Hello,
everyone.
I'm Wang Lijie.
Let me recreate the scene of this experiment for you.
Four patients who could not speak due to illness
had microelectrode arrays implanted in their motor cortex.
Researchers asked them to do one thing:
Recite sentences silently in their minds.
No need to try to make a sound,
no need to move their lips—
just pure internal thought.
The result?
Neural activity in the motor cortex was clear, stable, and decodable.
Researchers used these signals to translate their internal thoughts in real-time.
Accuracy reached 86% for a 50-word vocabulary,
and even 74% for a 125,000-word vocabulary.
More shockingly,
the decoding speed matches normal conversational pace—
145 words per minute.
As you think a sentence,
the machine writes it out simultaneously.
What is the most counterintuitive finding here?
It's that researchers discovered,
when you think a sentence in your mind,
neural patterns in the motor cortex are highly similar to when you actually speak.
Not just vaguely related,
not just a weak statistical signal,
but structurally highly similar.
The only difference is signal strength and certain dimensions,
allowing algorithms to distinguish "thinking" from "speaking."
But the underlying encoding pattern is almost identical.
In other words,
your motor cortex doesn't distinguish between thinking and speaking.
To it,
they are just two different volume levels of the same thing.
You might say,
"What's the big deal?
Isn't this just another advancement in BCI?"
No.
What this paper truly shatters
is an assumption we've never seriously questioned.
We always thought
that thinking and speaking are two completely different processes.
Speaking
is the output stage of converting thoughts into muscle movement.
Thinking
is a purely internal, private cognitive activity
that involves no motor commands.
We feel there's a wall between thought and speech.
Thinking is inside the castle;
speaking is outside.
And there's a door in between that you can choose to open or close.
But this paper says
that door doesn't exist at all.
You think you're just talking to yourself inside the castle,
but the castle walls are transparent.
The motor cortex prepares for speech from start to finish,
it's just inhibited at the final moment.
Thinking
is not the prequel to speaking;
thinking is just the low-power version of speaking.
This makes me think of something.
Buddhism has a concept called "the arising of a thought."
For 2,500 years,
practitioners has emphasized one thing:
your thought itself is an action.
It's not that thoughts lead to actions;
the thought itself is already a form of movement.
If a greedy thought arises in your mind,
even if you don't reach out to take anything,
on a karmic level,
that thought has already planted a seed in your Alaya-vijnana.
This sounds very mystical,
right?
You didn't actually do anything;
you just thought about it.
How can there be consequences?
Now, this paper in Cell provides a precise neuroscientific footnote.
Thinking isn't just a pure mental game.
When you think,
your motor cortex is actually executing it.
It is firing neural signals.
It is encoding specific phonemes and words.
It goes through the entire process from intention to execution,
short only of amplifying the signal to drive your vocal cords.
Though this signal doesn't become sound,
it is a real physical event.
It changes your neural state.
It consumes energy.
It leaves a trace.
Buddhism says arising thoughts create karma.
Translated into neuroscience:
every thought leaves an encoded trace in the motor cortex.
Every repetition strengthens that neural pathway.
You think it doesn't matter,
but your brain doesn't see it that way.
To the brain,
thinking and speaking are separated only by an inhibition threshold.
Repeatedly rehearsing a malicious sentence in your mind
versus actually saying it out loud
is nearly the same thing at the neural encoding level.
This is why practitioners start with their thoughts,
not just their behaviors.
When you try to control your behavior,
your motor cortex has already practiced it a thousand times.
But the most interesting part of this paper to me
isn't the confirmation of Buddhist concepts,
but the researchers' own reaction.
They identified a problem:
if inner monologue can be decoded by a BCI in real-time,
what about the user's privacy?
If a paralyzed patient has a BCI implanted to help them communicate,
but that device also captures thoughts
they never intended to speak aloud, then what?
They insult the nurse in their mind,
and the device writes it out.
They ponder inheritance plans mentally,
and the device records that too.
This isn't a sci-fi movie;
it's an engineering problem.
The research team proposed a solution in the same paper.
They found that
while the patterns of thinking and speaking are highly similar,
there are dimensional differences that algorithms can capture.
They used this to design a privacy protection protocol.
One solution: the device only decodes when the user actively
switches to a "speaking" mode.
A more elegant solution: let the user set a mental trigger code.
Only after thinking that specific password
will the device activate the decoding function.
You can think of it as an imaginary "power-on" command.
Imagine that scene:
scientists build a mind-reading machine,
and in the very same paper, they install a lock on it.
And what is the key?
A password that only exists in your mind.
This is the first time tech ethics and tech capability have debuted together in one paper.
I think that alone is worth highlighting.
Because for decades,
the relationship between tech and ethics has been "act first, talk later."
We discussed nuclear ethics only after the atomic bomb;
we discussed algorithmic ethics only after social media addiction.
We didn't discuss reproductive ethics until gene-edited babies were born.
But this time is different.
This time, the moment researchers saw what they had created,
they immediately thought about how to constrain it.
What kind of spirit is this?
It is a kind of awareness.
You know what you are doing.
You foresee the consequences.
And you respond simultaneously.
It's not a post-hoc remedy.
It's not someone forcing you.
It's acting because you saw it yourself.
Alright.
Let's return to a deeper question.
If thinking and speaking are different intensities of the same thing in the motor cortex,
then what exactly is thinking?
Is it a rehearsal for speech?
Or is speech just an amplified version of thought?
Vygotsky proposed a hypothesis a hundred years ago.
He said,
human inner monologue is the product of internalizing external language.
Children start by talking to themselves out loud.
If you observe three or four-year-olds,
they talk to themselves while playing with blocks.
Later, this self-talk gradually internalizes,
becoming a silent inner monologue.
So thinking isn't a prequel to speaking.
On the contrary,
speaking is the original version;
thinking is the internalization of speaking.
But this Cell paper carries an even more radical implication.
Perhaps thinking and speaking have never been two separate things.
Perhaps from the perspective of the motor cortex,
all linguistic activity,
whether voiced or unvoiced,
is the same motor program.
Sound is just an occasional byproduct of this program.
Your brain doesn't think first and then decide whether to speak.
Instead, it's speaking all the time,
just most of the time you choose not to turn the volume up to the speakers.
If this is true,
then your inner monologue is not a quiet process of contemplation.
It is a never-ending, low-volume speech.
Your motor cortex is producing language every second,
encoding phonemes, word order, and intonation.
It is never quiet.
The so-called silence is just you not hearing the external audio.
This reminds me of a classic observation in practice.
What is the first discovery meditators often report?
"I never knew I had so many thoughts."
When you first sit down quietly,
doing nothing,
you are shocked by the noise in your own head.
Those thoughts aren't things you actively think.
They pop up automatically.
One by one,
like scrolling comments on a screen.
Now you know why.
Because your motor cortex is always running.
It doesn't need your instructions;
it produces language on its own.
This isn't a psychological phenomenon;
it's a physiological one.
Your brain is a language production machine that never stops.
So what is meditation doing?
If understood through the framework of this paper,
meditation might be training you to reduce the frequency of this machine.
Not to turn it off—
you can't turn it off—
but to make you aware that it's running,
so you are no longer hijacked by its output.
You hear the inner monologue,
but you know it's just the automatic output of the motor cortex.
It doesn't represent you.
It doesn't equal reality.
It's just a machine idling.
This is what Buddhism calls Mindfulness.
You see the thoughts,
but you don't follow them.
Finally, I want to ask a question.
If brain-computer interfaces ever become truly common,
and everyone has a chip in their brain,
what would be the first thing to collapse in human society?
I suspect it won't be privacy laws
or business models,
but the buffer between people we call "politeness."
We can maintain a civilized society
largely because we can separate thinking from speaking.
What's in our hearts and what we say are often different.
This isn't hypocrisy;
it's a necessary cost for civilization to function.
If this buffer zone disappeared one day,
would humans become more sincere or more lonely?
I don't have the answer,
but I do know this:
2,500 years ago, Buddha taught his disciples to practice starting with their thoughts.
This may not just have been moral instruction.
He may have already seen what this "Cell" paper
only discovered today using electrodes.
Your thoughts are not innocent bystanders;
they are actions being executed.
The only difference is the volume.
What do you think?
Do you think that wall between thinking and speaking
actually exists,
or is it just our wishful illusion?
Let me know in the comments.
I'm Leo Wang.
See you next time.