Summary: When you picture a map in your mind, your brain uses different pathways than when you actually look at one. In a study on spatial attention, participants recalled the map of France and judged which city was closer to Paris.
Brain recordings revealed that visual attention relied on posterior brain regions, while mental imagery depended more on frontal areas. These results show that the brain separates how it processes imagined and perceived spaces, engaging distinct neural mechanisms for each.
Key Facts:
- Distinct Neural Pathways: Visual attention engages posterior brain regions, while mental imagery relies on frontal networks.
- Mind’s Eye Navigation: People can direct spatial attention within mental images just as they do when viewing real visuals.
- Attention Duality: Imagining and perceiving space activate separate mechanisms, offering insights into memory and consciousness.
Source: SfN
Spatial attention enhances the processing of specific regions within a visual scene as people view their surroundings, much like a spotlight. Do people orient spatial attention the same way when processing mental images from memory?
Anthony Clément and Catherine Tallon-Baudry, from École normale supérieure, explored whether neural mechanisms of spatial attention differ when discriminating between locations in mental images versus visuals on a screen.
In their Journal of Neuroscience paper, the researchers present an experimental task they developed that enabled them to record brain activity while human participants performed spatial discrimination tasks.
One task triggered the “mind’s eye” by prompting participants to recall the map of France from memory and focus their attention on the right or left of their mental maps.
At the end of each trial, two city names appeared on a screen. Participants had to imagine where the cities were located on the map and choose which one they believed was closer to Paris.
People were able to orient spatial attention when retrieving images from memory, but the brain mechanisms were different compared to mechanisms for discriminating between visuals on a screen.
While visual perception relied on posterior brain regions, mental imagery relied more on frontal areas. Thus, there may be distinct mechanisms for spatial attention depending on whether people are imagining or seeing visuals.
Says Clément, “Our findings suggest that when we explore a mental image in our ‘mind’s eye,’ we don’t simply reuse the brain mechanisms we rely on when looking at the world. This distinction may help us refine how we think about internal experiences like mental imagery, memory, thoughts, and even consciousness.”
About this neuroscience research news
Author: SfN Media
Source: SfN
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Image: The image is credited to Neuroscience News
Original Research: Closed access.
“Mental Images from Long-Term Memory Differ from Perception: Evidence for Distinct Spatial Formats and Distinct Mechanisms of Spatial Attention Orientation” by Anthony Clément et al. Journal of Neuroscience
Abstract
Mental Images from Long-Term Memory Differ from Perception: Evidence for Distinct Spatial Formats and Distinct Mechanisms of Spatial Attention Orientation
How is spatial attention deployed in mental images?
Mental imagery is often assumed to share mechanisms with visual perception and visual working memory. Top-down, endogenous spatial attention in both visual perception and working memory modulates behaviour and parieto-occipital alpha-band activity.
However, working memory captures only a subset of mental imagery, which can also draw upon long-term memory.
Here, we ask whether and how spatial attention operates in mental images derived from general knowledge in long-term memory, and whether it recruits the same neural mechanisms as visual perception.
We recorded EEG in 28 healthy volunteers (13 males, 15 females) as they performed two discrimination tasks with spatial cues (70% valid): one involving the mental visualization of a long-term memory map (a map of France) and the other using visual stimuli. We show that spatial attention shortens response times in both tasks, but through distinct mechanisms.
Behavioural attentional benefits were uncorrelated across tasks, and spatial attention in mental imagery engaged distinct neural mechanisms, with frontal rather than posterior alpha activity modulation. We further reveal fundamental differences in the spatial structures of mental imagery and visual perception.
Altogether, our results show that mental images drawn from long-term semantic memory are spatially organized and are amenable to spatial attention deployment, but the underlying neural mechanisms differ from those of visual perception.
Our results thus point to marked differences between mental imagery from long-term memory and visual perception.