Under the Hood

How Do Visual Hallucinations Work? Scientists Can Induce Hallucinations To Study Them

Hallucinations are typically associated with psychedelic drugs, fever, and sleep deprivation. Illnesses like schizophrenia, Parkinson's disease, migraines, and some forms of dementia can also cause them. In a new study published in eLife, researchers at the University of Pittsburgh teamed up with The University of New South Wales in Australia to induce these mysterious illusions in order to get a closer look at what causes them. 

Researchers wanted to see inside the mind of a person experiencing hallucinations, which are typically “irregular, transitory, and highly personal,” in order to better understand the phenomenon in people who are both sick and healthy, according to Medical Xpress.

visual hallucination Why do some people experience visual hallucinations? Photo courtesy of Pixabay

To induce hallucinations, the research team displayed a white ring that flickered against a black background between two and 30 times per second. The participants, college students with no history of psychiatric disorders or migraines, all said that they "saw" pale grey blobs rotating around the ring, first in one direction, then in the opposite direction.

"Because the pale grey blobs are much simpler and uniform than more complex hallucinations that people generally see, they are much easier to study objectively," said researcher Bard Ermentrout from the University of Pittsburgh, according to Medical Xpress.

To understand the strength of these hallucinations, researchers created a second ring with actual grey blobs inside the white ring. From there, participants were able to explain which blobs were lighter or darker, the hallucinated blobs or the real ones.

The researchers discovered that the same part of the brain, the visual cortex, was responsible for decoding both the real blobs and the hallucinations, and based on this information, they were able to create a computer model of the visual cortex. In the future, they hope this model can be used to study hallucinations associated with certain psychiatric disorders, Medical Xpress reported. 

Source: Pearson J, Chiou R, Rogers S, Wicken M, Heitmann S, Ermentrout B. Sensory Dynamics Of Visual Hallucinations In The Normal Population. eLife. 2016.

Read more:

The 5 Most Common Types Of Hallucinations

Bizarre Science: These 6 Things Can Cause Hallucinations

Inside The Mind's Eye: This Is What Happens To Your Brain When You Hallucinate

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