Scientists see what people imagine in their minds

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Summary: By using electrocorticogram technology to capture brainwaves, researchers have found that the meaning of what people imagine can be determined from brainwave patterns, even if the image differs from what a no one is watching.

Source: Osaka University

They say a picture is worth a thousand words. Now Japanese researchers have discovered that even a mental image can communicate volumes.

In a study published this month in Communications Biologyresearchers from Osaka University have revealed that the meaning of what a person imagines can be determined from their brainwave pattern, even if the image differs from what the person is looking at.

When we see images in real life, whether we’re talking to a friend, watching a movie, or watching a beautiful sunset, our brain absorbs this visual information in a way that can be detected by a technique called electrocorticogram, which detects patterns of electrical activity in the brain. These models are not set in stone, however; they can be modified by what we pay attention to or imagine at the time.

“Attention is known to modulate neural representations of perceived images,” says lead study author Ryohei Fukuma. “However, we were unsure if imagining a different image could also alter these representations.”

To test this, the researchers developed new technology by working with epilepsy patients who already had electrodes implanted in their brains to record and display electrocorticogram readings of the images they imagined. Patients were shown an image of the real-time reading and asked to mentally imagine a different image representing a “landscape”, a “human face”, or a “word” (e.g., thinking of a human face while viewing various types of images) to control playback.

Electrocorticogram (ECoG) recordings were performed in 17 epileptic patients who had implanted subdural cortical electrodes linked to visual perception. A decoder was trained to estimate the semantic meaning of the images patients viewed from the intracranial ECoG recording using the visual-semantic space. Based on the semantic information deduced in real time with the decoder, an image was displayed on a monitor placed in front of the patient. The patient then tried to display an image with an educated meaning by imagining it. Credit: The Researchers

“The results clarified the relationship between brain activities when people look at images and when they imagine them,” says lead author Takufumi Yanagisawa. “The electrocorticogram readings of the imagined images were distinct from those elicited by the actual images seen by patients. They could also be modified to be even more distinct when patients received real-time feedback.

The time needed to generate a very clear distinction between the imagined image and the seen image was different for imagining a “word” and a “landscape”, which could have something to do with the different parts of the brain involved in the imagination of these two concepts. .

“Our results suggest that a reading image controlled by the subject’s imagery can be inferred by an observer using this technology,” says Fukuma.

Given the accuracy with which this new technology displays images that exist in the subject’s mind, a similar approach could be used to develop a communication device for severely paralyzed patients, such as those with amyotrophic lateral sclerosis. Similar devices already used by some patients with this disease rely on motor control, which degenerates faster than visual cortical activity, so an imaging-based device could be invaluable.

About this neuroscience research news

Author: Press office
Source: Osaka University
Contact: Press Office – Osaka University
Picture: The image is attributed to the researchers

Original research: Free access.
“Voluntary Control of Semantic Neural Representations by Imagery with Conflicting Visual Stimulation” by Ryohei Fukuma et al. Communications Biology


Abstract

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It shows a woman running

Voluntary control of semantic neural representations by imagery with conflicting visual stimulation

Neural representations of visual perception are affected by mental imagery and attention. Although attention is known to modulate neural representations, it is unclear how imagery alters neural representations when imagined and perceived images conflict semantically.

We hypothesized that imagining an image would activate a neural representation when perceiving it even while looking at a conflicting image. To test this hypothesis, we developed a closed-loop system to show images inferred from electrocorticograms using a visual semantic space.

Successful control of feedback images demonstrated that the inferred semantic vector of electrocorticograms approximated the imagined category vector, even when looking at images of different categories. Moreover, the modulation of vectors inferred by mental imagery depended asymmetrically on perceived and imagined categories.

Neural representation shared between mental imagery and perception was always imagery activated under semantically conflicting perceptions according to semantic category.

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