Population Coding: Mind Reading and More!

  • Published18 Oct 2013
  • Reviewed18 Oct 2013
  • Author
  • Source BrainFacts/SfN

Is it possible to read minds using science? While scientists cannot read thoughts, they are able to anticipate more basic neural responses through a process called population coding. Watch this video by Vania Cao, who recently defended her PhD thesis at Brown University, to learn about population coding. Discover how scientists use this process to “read” minds and make bionic limbs move. This video tied for second place in the 2013 Brain Awareness Video Contest

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Is it really possible to mind-read with science?

To control computers, hooked up to a brain-reading appliance?

“How do we link thoughts with tools?” you want to know

So let’s learn about the neural population code!

When we take a peek inside your skull

We’re in really, really noisy trouble

Electrical signals from each neuron we find

Communicate with other neurons to create our mind

Billions of neurons make electrical storms

And each neuron’s electrical signal has different shapes and forms

How do we know which cells respond to a stimulus or thought?

Let’s record their electrical activities and give this a shot!

Text and Narration: Vania Cao

Illustrations: Vania Cao

Clipart: Microsoft Office Images

Background music: “Lips” by Plurabelle, CC license


Using electrodes, we listen to motor cortex cells, important for action

They fire when we plan, rehearse or produce active locomotion

While some will be silent, many others will fire

This “on” or “off” pattern we can acquire

As an easy way to compare their activities, as a group

Here, we identify if neurons as “on” or “off”, shown in yellow or blue

Now ask a friend to think: “Move hand to the left” and then

Let’s record 25 of her motor cortex neurons , again and again:

To the left

To the left

To the left

To the left

Now we know when she thinks “left” what each neuron does

And then when she thinks "Move hand to the right", they go all abuzz

To the right

To the right

To the right

To the right

And you have a code from her neurons, and it’s quite a sight!

Now we know her code for “move left” and “move right”

The firing activities of her neurons gave us this insight

Now tell your friend to silently think “left” or “right” and what do you see?

We can ‘read her mind’ based on the group’s past activation history

This code looks like the code for “move left”

Is that what she was thinking?  Yep, you bet!

Let’s try that again.  She thinks, we record:

What was she thinking? 

“To the right”!  Yes, you scored!

And you find that you’ve just read her mind!

Now this might seem like just a cute parlor trick

After eavesdropping on her brain, to know what direction she will pick. 

But listening in on a neural population

To know what neurons do in different situations

Is how we understand our brain's population code

And more than just guessing-games can unfold

Population codes help patients who suffered serious harm

To control machines with their thoughts and move robotic arms!

By "mind-reading" like before?  Yep! 

Hook your friend’s brain up to an arm and put it to the test!

We can record her cells again to figure out their firing pattern

When she thinks different thoughts and tries to make different actions

Then we tell a computer to record as she thinks “left left left”

It translates her brain’s code to move “left” into robotic deft-ness

And lo and behold: she can move a ‘bot with a thought!

Or a cursor or a wheelchair, there’s the potential to do a lot!

Studying neural population codes is a way to decode the brain, so complex

And interact with it through prosthetics and external objects

We can translate the votes of many neurons into one

To control our bodies or computers, that’s how it’s done

So while we can't read minds directly without many clues

Studying population codes can make some dreams come true

Up in each of our heads, we have many neural ciphers that link

Up the brain and the body whenever you or I think

While it’s amazing what current knowledge of the brain has bestowed

We still have a lot to learn about neural population codes!