Summary: New findings illuminate how the prefrontal cortex contributes to sensory processing and perceptual experience.
Source: University of Toronto
Imagine a picture of a sunlit beach: you can almost feel the warmth on your skin and hear the waves breaking, even if you are sitting far from the ocean. How does the human brain create these sensory impressions from images and sounds rather than direct contact?
Researchers at the University of Toronto have uncovered evidence that the prefrontal cortex — a brain region commonly associated with decision-making, impulse control and flexible thinking — forms generalized sensory representations that reflect information coming from multiple senses. Their work offers new insight into the role the prefrontal cortex plays in perception and how it integrates sensory cues into higher-level concepts.
The team combined photographs, recorded sounds and actual tactile stimulation with heated and cooled massage stones while recording brain activity with functional magnetic resonance imaging (fMRI). They tracked neural patterns not only in primary sensory areas such as the visual, auditory and somatosensory cortices, but also in the prefrontal cortex to compare how different brain regions represent attributes like temperature and sound level.
“When participants experienced warmth directly or simply viewed images of warm scenes, we observed the same pattern of activity in the prefrontal cortex,” said Dirk Bernhardt-Walther, professor in the Department of Psychology at the University of Toronto and coauthor of the study published in the Journal of Neuroscience. “This suggests the prefrontal cortex can generalize perceptual experiences across sensory modalities.”
Rather than studying senses one at a time, the researchers designed two complementary experiments with the same participants to investigate how the brain represents scene attributes under different conditions. In the first experiment, participants viewed images of natural and urban scenes — beaches, city streets, forests and train stations — and judged each scene along two dimensions: temperature (warm vs. cold) and sound level (noisy vs. quiet). Brain activity was recorded throughout.
In the second experiment, participants directly touched massage stones heated to 45°C or cooled to 9°C and later listened to audio clips that were either noisy (people, waves, birds) or quiet. The researchers then compared neural patterns across the two experiments to see whether representations of temperature and sound level were consistent across real and depicted experiences.
Lead author Yaelan Jung, who conducted the work as part of her PhD at the University of Toronto, explained that patterns in the somatosensory cortex reliably indicated whether a participant held a warm or cold stone, while patterns in the visual cortex signaled whether an image depicted a warm or cold scene. Crucially, activity in the prefrontal cortex carried consistent signatures of temperature and sound level regardless of whether the input was direct sensory stimulation or a visual scene depicting those attributes.
A model trained on prefrontal cortex activity from the stone-touching experiment could successfully predict the perceived temperature of scenes shown in images. Similarly, noisy versus quiet sounds were decodable from auditory cortex activity and noisy versus quiet scenes were decodable from visual cortex activity. “The prefrontal activity patterns produced by viewing an image matched those triggered by actual experience of temperature and noise,” Jung said.
These results indicate that the prefrontal cortex forms multisensory, concept-like representations of scene attributes such as temperature and sound level. This capacity to generalize across senses could help the brain extract meaningful, task-relevant information from complex environments even when some sensory modalities are absent.
Understanding how the brain integrates sensory information into higher-level representations has practical implications for studying perception disorders and developing compensatory strategies for people with sensory limitations. “If the prefrontal cortex can arrive at similar conceptual representations using different senses, one modality might substitute for another to support decision-making about the environment,” Bernhardt-Walther said.
Funding: This research was supported by the Social Sciences and Humanities Research Council of Canada and the Natural Sciences and Engineering Research Council of Canada.
About this sensory perception research news
Author: Dirk Bernhardt-Walther
Source: University of Toronto
Contact: Dirk Bernhardt-Walther – University of Toronto
Image: The image is in the public domain
Original Research: Closed access. “Neural Representations in the Prefrontal Cortex Are Task Dependent for Scene Attributes But Not for Scene Categories” by Yaelan Jung and Dirk B. Walther. Journal of Neuroscience
Abstract
Neural Representations in the Prefrontal Cortex Are Task Dependent for Scene Attributes But Not for Scene Categories
Natural scenes convey rich sensory information. While decades of research have characterized how scene-selective regions in the visual cortex represent aspects of scenes, less is known about how such complex information is processed beyond vision, notably in the prefrontal cortex (PFC). It is also unclear how task demands shape which scene content the brain represents.
In this fMRI study, healthy adult participants viewed images from four natural scene categories that varied along two scene attributes: temperature (warm or cold) and sound level (noisy or quiet). Participants performed two tasks: judging temperature or judging sound level for each scene image.
Analysis of neural representations revealed that scene attributes (temperature and sound level) were represented in the brain only when they were task relevant. In contrast, scene categories were represented in both the parahippocampal place area and the prefrontal cortex regardless of task context.
These findings indicate that the PFC selectively represents scene content according to task demands, with differential task dependency: neural representations of scene attributes are modulated by task, whereas representations of scene categories remain stable across tasks. Together, the results show that scene information is processed beyond the visual cortex and that the prefrontal cortex adaptively extracts information relevant to current goals.
SIGNIFICANCE STATEMENT
This work demonstrates that both scene categories and scene attributes are represented in the prefrontal cortex, but with distinct patterns of task dependency. Scene attributes appear in PFC only when they are behaviorally relevant, while scene categories are represented regardless of task context. The study highlights how higher-order brain regions integrate multisensory information to form adaptable, task-oriented representations of the environment.