Summary: By analyzing fMRI scans of people watching films, neuroscientists have created a comprehensive functional map of the brain, showing how it activates in response to complex scenes. This study identified 24 distinct networks that process aspects like faces, speech, or movement, and revealed how executive functions shift between easy and challenging scenes.
Using machine learning on data from the Human Connectome Project, the research mapped areas that respond to diverse audio-visual stimuli. The findings could inform future studies on how individual brain responses vary with age or cognitive disorders.
Key Facts:
- Scanning brains during movie watching highlighted 24 networks for specific processing, like social interactions and object recognition.
- Complex scenes activate executive control areas, while simpler scenes activate language or sensory regions.
- This is the first detailed functional map created under naturalistic conditions using diverse film clips.
Source: Cell Press
By scanning the brains of people while they watched movie clips, neuroscientists have created the most detailed functional map of the brain to date.
The fMRI analysis, publishing November 6 in the Cell Press journal Neuron, shows how different brain networks light up when participants viewed short clips from a range of independent and Hollywood films including Inception, The Social Network, and Home Alone.
The team identified different brain networks involved in processing scenes with people, inanimate objects, action, and dialogue. They also revealed how different executive networks are prioritized during easy- versus hard-to-follow scenes.
“Our work is the first attempt to get a layout of different areas and networks of the brain during naturalistic conditions,” says first author and neuroscientist Reza Rajimehr of Massachusetts Institute of Technology (MIT).
Different areas of the brain are highly interconnected, and these connections form functional networks that relate to how we perceive stimuli and behave. Most studies of brain functional networks have been based on fMRI scans of people at rest, but many parts of the brain or cortex are not fully active in the absence of external stimulation.
In this study, the researchers wanted to investigate whether screening movies during fMRI scanning could provide insight into how the brain’s functional networks respond to complex audio and visual stimuli.
“With resting-state fMRI, there is no stimulus—people are just thinking internally, so you don’t know what has activated these networks,” says Rajimehr.
“But with our movie stimulus, we can go back and figure out how different brain networks are responding to different aspects of the movie.”
To map the brain during movie watching, the researchers leveraged a previously collected fMRI dataset from the Human Connectome Project, consisting of whole brain scans from 176 young adults that were obtained while the participants watched 60 minutes’ worth of short clips from a range of independent and Hollywood films.
The researchers averaged the brain activity across all participants and used machine learning techniques to identify brain networks, specifically within the cerebral cortex. Then, they examined how activity within these different networks related to the movie’s scene-by-scene content—which included people, animals, objects, music, speech, and narrative.
Their analysis revealed 24 different brain networks that were associated with specific aspects of sensory or cognitive processing, for example recognizing human faces or bodies, movement, places and landmarks, interactions between humans and inanimate objects, speech, and social interactions.
They also showed an inverse relationship between “executive control domains”—brain regions that enable people to plan, solve problems, and prioritize information—and brain regions with more specific functions.
When the movie’s content was difficult to follow or ambiguous, there was heightened activity in executive control brain regions, but during more easily comprehendible scenes, brain regions with specific functions, like language processing, predominated.
“Executive control domains are usually active in difficult tasks when the cognitive load is high,” says Rajimehr.
“It looks like when the movie scenes are quite easily comprehendible, for example if there’s a clear conversation going on, the language areas are active, but in situations where there is a complex scene involving context, semantics, and ambiguity in the meaning of the scene, more cognitive effort is required, and so the brain switches over to using general executive control domains.”
Since the analyses in this paper were based on average brain activities, the researchers say that future research could investigate how brain network function differs between individuals, between individuals of different ages, or between individuals with developmental or psychiatric disorders.
“In future studies, we can look at the maps of individual subjects, which would allow us to relate the individualized map of each subject to the behavioral profile of that subject,” says Rajimehr.
“Now, we’re studying in more depth how specific content in each movie frame drives these networks—for example, the semantic and social context, or the relationship between people and the background scene.”
Funding:
This research was supported by the McGovern Institute for Brain Research, the Cognitive Science and Technology Council of Iran, the MRC Cognition and Brain Sciences Unit, and a Cambridge Trust scholarship.
About this brain mapping research news
Author: Kristopher Benke
Source: Cell Press
Contact: Kristopher Benke – Cell Press
Image: The image is credited to Neuroscience News
Original Research: Open access.
“Functional architecture of cerebral cortex during naturalistic movie-watching” by Reza Rajimehr et al. Neuron
Abstract
Functional architecture of cerebral cortex during naturalistic movie-watching
Characterizing the functional organization of cerebral cortex is a fundamental step in understanding how different kinds of information are processed in the brain. However, it is still unclear how these areas are organized during naturalistic visual and auditory stimulation.
Here, we used high-resolution functional MRI data from 176 human subjects to map the macro-architecture of the entire cerebral cortex based on responses to a 60-min audiovisual movie stimulus.
A data-driven clustering approach revealed a map of 24 functional areas/networks, each explicitly linked to a specific aspect of sensory or cognitive processing.
Novel features of this map included an extended scene-selective network in the lateral prefrontal cortex, separate clusters responsive to human-object and human-human interaction, and a push-pull interaction between three executive control (domain-general) networks and domain-specific regions of the visual, auditory, and language cortex.
Our cortical parcellation provides a comprehensive and unified map of functionally defined areas in the human cerebral cortex.
