Amazing stuff! At least now we know where imagination is located. 😊
"The research ... found that a region in the brain known as the fusiform gyrus—located behind one's temples, on the underside of the brain's temporal lobe—is involved in helping the brain to determine whether what we see is from the external world or generated by our imagination. ...
While participants performed the tasks, their brain activity was monitored using functional magnetic resonance imaging (fMRI). This technology enabled the researchers to identify which parts of the brain showed patterns of activity that helped distinguish reality from imagination.
The team found that the strength of activity in the fusiform gyrus could predict whether people judged an experience as real or imagined, irrespective of whether it actually was real.
When activity in the fusiform gyrus was strong, people were more likely to indicate that the pattern was really there.
Usually, activation in the fusiform gyrus is weaker during imagination than during perception, which helps the brain keep the two apart. However, this study showed that sometimes when participants imagined very vividly, activation of the fusiform gyrus was very strong and participants confused their imagination for reality. ..."
From the highlights and abstract:
"Highlights
• Imagination and perception are intermixed in the brain’s perceptual system
• Their combined sensory strength predicts reality judgments
• This sensory strength is tracked by the bilateral fusiform gyrus
• Frontal brain regions encode binary judgments of reality
Summary
Humans are able to imagine scenarios that are decoupled from the current environment by internally activating perceptual representations. Although an efficient re-use of existing resources, it remains unknown how human observers classify perceptual signals as reflecting external reality, as opposed to internal simulation or imagination.
Here, we show that judgments of reality are underpinned by the combined strength of sensory activity generated by either imagery or perception in the fusiform gyrus. Activity fluctuations in this region predict confusions between imagery and perception on a trial-by-trial basis and interact with a frontal brain network encoding binary judgments of reality.
Our results demonstrate that a key mechanism through which the brain distinguishes imagination from reality is by monitoring the activity of the mid-level visual cortex. These findings increase our understanding of failures of reality testing and lay the foundations for characterizing a generalized perceptual reality monitoring system in the human brain."
Figure 1 Experimental paradigm and behavioral results
Figure 2 Univariate neural basis of a reality signal
(A and B) (A) Brain areas showing significant positive modulations by reality judgment response and by (B) imagery vividness rating.
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