海外「空がまるで川のように見えるんだけど…」

Perceptual transformation such as “the world looks faded, and I don’t feel life in what I see” can be experienced temporarily by healthy people, but there are symptoms of alienation and loss of sense of reality that persist for a long time and make them feel less realistic about themselves and the outside world. This symptom is often seen not only in patients with sense of detachment and loss of reality, but also in patients with depression and schizophrenia, but it was considered a mental illness, and little research was conducted, and the brain’s structure that caused a decrease in reality was unknown.

Using PET2) and fMRI3), which can examine brain function and activity, we have been able to figure out how the brain works that create psychological illusions. Therefore, in order to understand how the brain works when the sense of reality decreases, 14 healthy subjects were asked to change their perception to look faded during fMRI examination, and to measure brain activity while answering how realistic they felt about what they were seeing. In addition, PET tests were performed on the same subjects to measure dopamine receptor density in a region called striatum 5) of the brain and to analyze the relationship with brain activity. As a result, it was found that the higher the striatum dopamine receptor density 6) the higher the neural activity of the frontal lobe 7 and parietal lobe 8) when the sense of reality decreases due to the illusion that it looks faded.

Through the results of this study, it is expected that new diagnostic and treatment strategies will be developed based on progress in understanding how the brain works, which causes sense of alienation and loss of sense of reality. It is also expected that this mechanism, if reversed, will lead to a neuroscientific explanation of the philosophical question of “what is reality” by showing how we perceive what we see as reality.