Films help MIT create a detailed map of the cerebral cortex

Neuroscientists have created the most comprehensive map yet of the brain’s outer layer — and it turns out Hollywood movies were the secret sauce. While most looks into the cerebral cortex involved a brain at rest, researchers at MIT had people watch compelling movies while monitoring their neural activity. What they saw helped them identify 24 interconnected brain networks, each responsible for a different neurological function.

When you picture the brain, you probably imagine the cerebral cortex, or the wrinkled, pink-gray matter that surrounds the organ’s inner structures. Scientists typically think of the cerebral cortex in terms of its four lobes, each of which processes different types of information. But within those lobes lie complex networks that fulfill specific neurological roles. Previous attempts to understand these networks have been “plugged into” people’s brains while they rested or let their minds wander. While these efforts provided useful insights into the brain’s “default mode network,” which is active during daydreaming, they have neglected other vital networks.

Working with colleagues from the University of Cambridge, Canada’s McGill University and Google Brain (the research team now known as DeepMind), MIT researchers examined the brain scans of 176 people who had undergone fMRI (functional magnetic resonance imaging) while watching movies. Originating from a larger research initiative called the Human Connectoom Projectthis data captured neural activity while healthy adults watched clips Commencement, Home aloneand other movies. The team filtered this data using a machine learning algorithm, which analyzed the activity of each cerebral cortex region.

A 3D map of the 24 different networks of the cerebral cortex, along with screenshots from the film clips shown during the Human Connectome Project. Credit: Rajimehr et al, Neuron/DOI ​​​​10.1016/j.neuron.2024.10.005

According to one paper published in the magazine on Wednesday Neuronthe sorted data revealed 24 different cerebral cortex networks, each with different activity patterns and functions. Some networks were responsible for social skills, such as processing language or identifying faces. Others digested non-linguistic auditory information, planned movements, or recognized inanimate objects. Three of the networks were involved in what neuroscientists call “executive control,” or the way the brain plans and carries out goal-directed behavior. These networks were found to participate in a “push-pull” relationship with other networks, turning on them as levers when a particular movie scene required it.

“Our work is the first attempt to get a layout of different areas and networks of the brain under naturalistic conditions,” says first study author and neuroscientist Reza Rajimehr. said. “With resting-state fMRI there is no stimulus – people only think internally, so you don’t know what activated these networks. But with our movie stimulus, we can go back and figure out how different brain networks respond to different aspects of the movie.”

Rajimehr and his colleagues now want to investigate how the responses of these networks to movie stimuli might change depending on a person’s age or personal history. Future work could even look at how the 24 networks of the cerebral cortex work in a person with developmental or psychiatric disorders.