Skip to Content
77 Mass Ave

Parallel Processing

How the brain learns without forgetting.
February 18, 2014

When the brain learns a new motor skill, neurons form circuits that activate the body’s muscles to perform it. But the same distributed network controls related motor tasks, so when you try to learn many skills at once, new modifications to existing patterns can interfere with previously learned skills.

“This is particularly tricky when you’re learning very similar things,” says Institute Professor Emilio Bizzi. A new computational model he and McGovern Institute researcher ­Robert Ajemian developed explains how the brain solves this problem.

The brain is massively parallel, and each neuron connects to about 10,000 others on average. This could make interference seem more likely than it is in standard computer chips, which process data serially and store instructions for each task in a separate location.

But that connectivity allows the brain to test out many possible solutions to achieve combinations of tasks. Neurons are constantly changing the strength of these connections, a trait known as hyperplasticity. They also receive about as much useless information as useful input from their neighbors.

Without that very low signal-to-noise ratio, the hyperplastic brain would overwrite existing memories too easily. But without hyperplasticity, the noise would drown out the tiny changes in connectivity, making it impossible to learn new skills.

“Your brain is always trying to find the configurations that balance everything so you can do two tasks, or three tasks, or however many you’re learning,” Ajemian says. “There are many ways to solve a task, and you’re exploring all the different ways.”

Keep Reading

Most Popular

Large language models can do jaw-dropping things. But nobody knows exactly why.

And that's a problem. Figuring it out is one of the biggest scientific puzzles of our time and a crucial step towards controlling more powerful future models.

OpenAI teases an amazing new generative video model called Sora

The firm is sharing Sora with a small group of safety testers but the rest of us will have to wait to learn more.

Google’s Gemini is now in everything. Here’s how you can try it out.

Gmail, Docs, and more will now come with Gemini baked in. But Europeans will have to wait before they can download the app.

This baby with a head camera helped teach an AI how kids learn language

A neural network trained on the experiences of a single young child managed to learn one of the core components of language: how to match words to the objects they represent.

Stay connected

Illustration by Rose Wong

Get the latest updates from
MIT Technology Review

Discover special offers, top stories, upcoming events, and more.

Thank you for submitting your email!

Explore more newsletters

It looks like something went wrong.

We’re having trouble saving your preferences. Try refreshing this page and updating them one more time. If you continue to get this message, reach out to us at customer-service@technologyreview.com with a list of newsletters you’d like to receive.