summary: A new study explores visual masking, a phenomenon in which a rapid sequence of images results in the first image being invisible.
This study successfully demonstrated visual masking in mice, mirroring human perception, and demonstrated similar neural processes. By training mice to respond to visual stimuli, the researchers identified specific brain regions that are important for this illusion, and explained how conscious perception is formed.
The results suggest that the generation of consciousness may occur in the visual cortex or higher cortical areas.
Key facts:
Visual masking involves failing to notice an initial image when that image is immediately followed by another image, and this study proves that this occurs in both humans and mice. Research identifies the brain region responsible for this phenomenon, suggesting that conscious perception originates in the visual cortex or lower cortical regions. The similarity of human and mouse perceptions of visual concealment challenges our understanding of how consciousness is generated in the brain.
source: Allen Institute
A new study was released today in Normal neuroscience About Visual Masking explains how we do it invisible This and refers to how conscious perception is generated in the brain.
In a phenomenon known as visual masking, individuals do not consciously perceive an image if other images are displayed sequentially. But the timing of shooting is important. The first image must turn on and off very quickly, and the second image must follow quickly (within 50 ms) for masking to work.
Sean Olsen, Ph.D., a researcher at the Allen Institute, and his colleagues investigated the science behind this optical illusion, and for the first time showed that it also occurs in mice. After training mice to report what they saw, the team was also able to identify specific areas of the brain that were necessary for the optical illusion to work.
“This is an interesting observation, because what is in the world is not accurately reflected in your perception,” Olsen said. “Like other optical illusions, we think they tell us something about how the visual system works and ultimately about the neural circuits underlying visual consciousness.”
Scientists discovered this strange phenomenon in the nineteenth century, but why and how the human brain does this is still a mystery.
This study narrows down the parts of the brain responsible for awareness of the world around us, said Christoph Koch, Ph.D., a distinguished scholar at the Allen Institute, who led the research with Olsen and Sam Gale, Ph.D. , a scientist at the Allen Institute.
When a barrage of photons hits the retina, the information takes a specific path from our eyeballs through several different areas of the brain, and ends up in higher processing areas in the cortex, the wrinkled outer layer of the brain.
From previous research on visual masking, scientists know that neurons in the retina and parts of the brain at the beginning of this pathway are activated even when a person is not aware that they are looking at an image. In other words, your mind sees things without you realizing it.
To explore where subconscious sensations turn into conscious perceptions and actions, the scientists first trained 16 mice to spin a small LEGO wheel in the direction of rapidly flashing images in exchange for a reward if they chose the correct direction.
The scientists then added different masking images on both sides of the screen, directly following the target image. With the addition of the mask, the animals were no longer able to perform the task correctly, meaning they no longer recognized the original target image.
Because visual masking had never been tested in mice before, the research team had to create a task for them, which meant that the images and the way they were presented were different from those used in previous human studies.
To make sure the optical illusion they showed in rodents worked for us, the team also tested it on 16 people (the wheel was switched by pressing a button). It turns out that human perception (or lack thereof) and mice’s perception of these hidden optical illusions are very similar.
These results mean that conscious perception occurs in the visual cortex or in higher areas of the cortex beneath it. This fits with the general feeling in the field that the cortex is the center of conscious perception in mammals, including us, Koch said.
About Visual Neuroscience Research News
author: Petrus Kim
source: Allen Institute
communication: Peter Kim – Institut Allen
picture: Image credited to Neuroscience News
Original search: Closed access.
“Dorsal closure in mice requires the visual cortex“By Sean Olsen et al. Normal neuroscience
summary
Dorsal closure in mice requires the visual cortex
Visual masking can reveal the time scale of perception, but the underlying circuit mechanisms remain poorly understood.
Here we describe a reversible concealment task in mice and humans, in which the location of the stimulus is actively masked.
Humans report decreased self-visibility that tracks behavioral deficits. In mice, visual masking and silencing of the visual cortex (V1) reduced performance over the same time period but had clear effects on response rate and accuracy.
Activity in V1 is consistent with persuasive behavior when measured over long, but not short, timescales. The dual complex model recapitulates mouse and human behavior.
Model and subject performance suggest that an initial spike in V1 can produce correct responses, but subsequent V1 activity causes a decrease in performance. In support of this hypothesis, suppression of visual masking activity in V1 completely restored accurate behavior.
Together, these results suggest that mice, like humans, are susceptible to masking and that target and masking information are first switched downstream of V1.
2023-11-13 22:44:28
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