Summary: For decades, scientists have assumed that imagining an object—like an apple—was mainly the brain “replaying” the sensory signals produced when we actually saw or heard it, a view called sensory reinstatement. New precision fMRI data from Northwestern University challenge that narrow view, showing imagination relies heavily on higher-level brain systems that transform sensory details into concepts, scenes, and language.
The research shows that mental images and inner speech arise not by simple replay in early sensory cortex but within transmodal association networks that encode meaning and context. Those networks are especially developed in humans, which helps explain why our inner experiences support planning, memory, and complex thought.
Key Facts
- Beyond raw sensation: Overlap between imagination and perception was strongest in transmodal association regions—areas that integrate information and represent abstract meaning—rather than in primary visual or auditory cortex.
- Network specialization: The content of imagination determines which large-scale network is engaged. Imagining scenes recruits the Default Network and hippocampus, while imagining speech or inner dialogue engages the Language Network.
- Vividness tracks activity: Participants who reported more vivid imagery showed stronger activation in these high-level association areas.
- Evolutionary relevance: The association networks implicated here are substantially expanded in humans versus close primate relatives, suggesting they support uniquely human abilities like complex planning, language, and speculative thought.
Source: Northwestern University
Imagination is one of the brain’s most powerful capacities. It lets us revisit memories while walking, rehearse conversations silently, or feel the imagined warmth of a fire—enabling learning, planning, and risk avoidance without direct experience.
Why imagining often includes vivid mental images—seeing an apple in your mind’s eye or “hearing” a song internally—has been debated. Mental imagery has commonly been attributed to sensory reinstatement, where sensory regions reactivate in the absence of external input. The new study suggests a more nuanced account: high-level interpretation systems play a central role.
Researchers asked participants to imagine varied scenarios, such as a child’s birthday party or a castle on a hill, while collecting high-resolution fMRI data across multiple sessions for each person. Rather than finding imagination mirrored directly in early sensory cortex, they observed it emerging in later processing stages where the brain assembles scenes, words, events, and meanings.
“When you imagine the sounds of a child’s birthday party, you typically don’t only hear isolated noises—you also picture the scene,” said Rodrigo Braga, assistant professor of neurology at Northwestern University Feinberg School of Medicine and senior author of the study. “It makes sense that imagination operates in this holistic, higher-level space, because we use it to plan, to understand, and to speculate.”
The paper is scheduled for publication in Neuron. Its results indicate that mental imagery is tightly linked to higher-order cognitive systems rather than being purely a sensory replay.
“Our findings don’t overturn the idea of sensory reinstatement,” Braga added, “but they refine it. Imagery that feels rich and meaningful shows the strongest overlap with perception in areas that already represent the world as scenes or concepts, not in the earliest sensory stages.”
How the study was done
Eight participants completed eight MRI sessions each, producing more than 60 hours of precision fMRI data. The researchers mapped each person’s sensory and association networks and compared brain responses during imagination with responses while viewing scenes or listening to speech. Overlap between imagining and perceiving appeared mainly in high-level, transmodal association regions rather than in unimodal sensory cortex.
These transmodal areas are of special interest because they are markedly expanded in the human brain relative to close evolutionary relatives, Braga noted. They support advanced human capacities such as language and abstract reasoning, suggesting that the networks generating mental imagery are core to the human cognitive toolkit and interact with earlier sensory areas to produce vivid inner experiences.
After scanning, participants described what they had imagined. Those self-reports were linked to each person’s brain patterns: imagining scenes produced vivid visual imagery and engaged the default network with hippocampal involvement, while imagining speech produced vivid auditory-like imagery and engaged the language network.
Two main insights emerged: first, different forms of imagination recruit distinct large-scale networks; second, in both cases, the overlap between imagination and perception localizes in high-level, transmodal association networks rather than exclusively in sensory-specific regions.
“The default network is often implicated in internally generated thought,” said Nathan Anderson, first author and former postdoctoral fellow at Northwestern. “We see the default network engaged during many imaginative tasks, but different types of imagination clearly draw on different networks depending on their content.”
Activity in these association regions also varied with reported vividness, supporting the idea that naturalistic imagination depends heavily on higher-order interpretive systems. The results refine our understanding of how the brain supports self-generated, sensory-independent thought without dismissing a role for sensory cortex.
The study is titled, “Mental imagery and perception overlap within transmodal association networks.”
Key Questions Answered:
A: Your brain can make imagined sounds feel like real hearing, but this study shows the strongest activity during that experience occurs in higher-level regions that process meaning, structure, and lyrics. The brain is assembling the concept of the song rather than replaying a literal auditory recording.
A: Although the study did not specifically target aphantasia, it found that reported vividness correlates with activity in high-level association regions. This suggests vivid imagery depends on how strongly those meaning centers engage and communicate with broader brain systems.
A: Yes. Daydreaming about places or future events primarily recruits the Default Network and hippocampus, while the inner voice used to rehearse speech engages the Language Network. These are distinct but interacting systems for different kinds of mental simulation.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- The full journal paper was reviewed for accuracy.
- Additional context was provided by staff editors.
About this neuroscience and imagination research news
Author: Kristin Samuelson
Source: Northwestern University
Contact: SfN Media – Northwestern University
Image: The image is credited to Neuroscience News
Original Research: Closed access.
“Mental imagery and perception overlap within transmodal association networks” by Nathan L. Anderson, Joseph J. Salvo, Jonathan Smallwood, and Rodrigo M. Braga. Neuron
DOI: 10.1016/j.neuron.2026.03.013
Abstract
Mental imagery and perception overlap within transmodal association networks
Human cognition operates in two complementary modes: a perceptually coupled mode driven by sensory input and a perceptually decoupled mode featuring self-generated mental content. Imagined states that produce mental imagery have been linked to reinstated activity in sensory cortex, but transmodal association systems are also implicated in imagery-related processes such as mind-wandering, recollection, and projecting into the future.
In a precision fMRI experiment, participants imagined different scenarios inside the scanner and later rated their mental states using multi-dimensional experience sampling. Scene-based thinking activated parts of the canonical Default Network, while imagined speech engaged the Language Network. In each domain, imagination-related activity overlapped with perception-related activity, but this overlap was concentrated within transmodal association networks rather than in adjacent unimodal sensory areas.
We conclude that engagement of transmodal networks supports self-generated mental states involving diverse forms of mental imagery.